While having a wide ranging conversation recently with a fellow sea kayaking enthusiast, the person made a statement that surprised me a fair bit. They said that they've ordered their recent boats, whether for race use or not, WITHOUT gelcoat (these are fiberglass or kevlar composite boats). Their justification was that gelcoat provides no structural benefit to the boat, and going without it saves 5-8 lbs of essentially useless weight. When queried about what they did about repairing the inevitable dings, they said they just used clear epoxy. So, I got to wondering about the pros and cons of going with a skin-coat hull (or hull and deck) configuration. What do Paddlewise people think of the idea? Any direct experience with it? Now I know that finishing the boat's exterior with gelcoat doesn't improve the structural rigidity of the craft. It does provide color, of course, and I guess it protects the glass or kevlar fiber from UV exposure (does current generation fiberglass and kevlar fabric NEED UV protection?). In the end, I guess it's a bit like applying 10-20 coats of paint to a piece of wood. It doesn't make the plank any stronger, but if you give it (the plank) a good whack with screwdriver, you wind up with a nice scratch (or worse) in the paint, but the integrity of the wood will be preserved (which, I guess, is the real goal). I also know that some in the industry, Tom Derrer of Eddyline among them, have staked their reputation (and their business) on foregoing gelcoat. But even Eddyline's high-end "modulus" boats, which are vacuum bagged glass/kevlar composites, still use a Carbonlite (polycarbonate?) shell on the outside. Well, enough prattle, what do you think of the idea? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 5 Jun 2003 at 21:44, jwd_at_acm.org wrote: > Their justification was that gelcoat provides no > structural benefit to the boat, and going without it saves 5-8 lbs of > essentially useless weight. Not true. The gelcoat increases the thickness of the hull and provides for greater stiffness. Without the gelcoat, you're more likely to get oilcanning and possibly buckling at the limit of what the kayak can handle. (Unless you beef up the fibre and resin, which negates some or all of the weight saving.) > I guess it protects the glass or kevlar fiber from UV > exposure (does current generation fiberglass and kevlar fabric NEED UV > protection?). Fibreglass does not, but Kevlar and _the_resin_ need protection. At the very least, building without gelcoat means adding a UV coating. Varnish works and is used on strippers with exposed resin. The gelcoat also protects the resin and fibre from impact and abrasion. With the gelcoat, you've got a sacrificial layer. Without the gelcoat, the damage is done to the resin and to the fibres directly. I'd rather not see damage to the main structural element in the composite. > I also know that some in the industry, Tom Derrer of Eddyline among > them, have staked their reputation (and their business) on foregoing > gelcoat. But even Eddyline's high-end "modulus" boats, which are > vacuum bagged glass/kevlar composites, still use a Carbonlite > (polycarbonate?) shell on the outside. Six of one, half dozen of the other. Polycarbonate is a very tough plastic, but it still scratches. I'd rather get regular construction and know I can fix it. The only folks that see a real advantage in kayaks (or canoes) without gelcoat are the racers. They are willing to sacrifice the gelcoat in order to save a few pounds. The rest of us have little need for dropping a few pounds from our kayaks. Next time you see these kayaking friends, check to see if they are so buff that they couldn't lose 10 lbs weight and be more fit! Unless they're national team calibre, their likely wasting time and money on an ultralight boat. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
[ You're obviously pretty passionate about this, so don't misconstrue my comments as argumentative. ] On Fri, Jun 06, 2003 at 12:23:46AM -0400, Michael Daly wrote: > On 5 Jun 2003 at 21:44, jwd_at_acm.org wrote: >> Their justification was that gelcoat provides no structural benefit >> to the boat, and going without it saves 5-8 lbs of essentially >> useless weight. > Not true. The gelcoat increases the thickness of the hull and > provides for greater stiffness. Without the gelcoat, you're more > likely to get oilcanning and possibly buckling at the limit of what > the kayak can handle. (Unless you beef up the fibre and resin, which > negates some or all of the weight saving.) FWIW, here's a quote from Eddyline's website. It matches nearly word for word a phone conversation I had with Tom Derrer 2-3 years ago. "Gel coat adds color and UV protection, but it also adds extra weight, provides no strength to the laminate and contributes to atmospheric emissions." So, he at least, thinks it adds no strength to the laminate. Now, I don't necessarily agree. Or, to be more precise, I would say it doesn't necessarily add any **necessary** strength or stiffness to the hull. If you make the fiberglass/kevlar/carbon-fibre (w/ epoxy resin) laminate sufficiently thick so as to provide the necessary hull stiffness, can you still say you're more likely to get oil-canning or buckling? I would say that would only be the case if the laminate was weak in the face of forces perpendicular to, or nearly so, the lay of the fabric laminate. As to the argument about beefing up the fibre and resin, I would have to ask two questions. 1) Just how much beefing up is required, if any, given the typical glass/kevlar build, to provide a sufficiently robust hull for non-expedition use? 2) Even if you have to beef up the glass/kevlar laminate, cay you really say that's a one-to-one weight exchange with the gelcoat you're leaving off? That would require you know the comparative weights of the materials, and not simply for a particular thickness, but for the thickness necessary to give a certain amount of added "strength". I don't know that information. Do you? (and no, I'm not being a wise-ass, just asking). > The gelcoat also protects the resin and fibre from impact and > abrasion. With the gelcoat, you've got a sacrificial layer. > Without the gelcoat, the damage is done to the resin and to the > fibres directly. I'd rather not see damage to the main structural > element in the composite. This essentially covers the question I asked the person. The response was that (and these boats don't get babied -- nor do they get tossed about carelessly either) the damage done is to the outer layer of epoxy and not to the fabric within. And that damage is easily repaired with a little clear epoxy. I guess it boils down to whether or not the epoxy on the outside of a skin-coat boat provides enough "sacrificial layer" to withstand normal wear and tear. And, when it doesn't provide enough protection, if it isn't just as likely that the gelcoat outer layer of a more typical hull wouldn't fail just as easily, resulting in underlying fabric damage too. Hell, I don't know, that's why I'm asking. > The only folks that see a real advantage in kayaks (or canoes) > without gelcoat are the racers. They are willing to sacrifice the > gelcoat in order to save a few pounds. The rest of us have little > need for dropping a few pounds from our kayaks. That may indeed be the case. It certainly is for bikes (except for those doing time trials, and then only if they're seriously up to the task). That's why I ride lugged steel frames and only use titanium parts for personal amusement. As to the weight issue with kayaks, that is another can a worms for discussion. An argument I've seen floating about in print and on the web, and have heard from fellow kayakers, is that most boats will, if you put them on the scale, weight a good bit more than the manufacturer's stated weight (sometimes 8-12 lbs. on a claimed 40-50 lb. boat). That isn't a trivial amount of weight, either on an absolute basis, or as a percentage of total boat weight. If it were trivial, no one would knock Brit-boat builds for weighing in the 60+ lb. range. An argument for dropping the gelcoat was, in this conversation, that it certainly provided a way to get a boat that weighs what the builder claims for the design. Like I said, however, quite another can of worms. Maybe best left shut. > Next time you see these kayaking friends, check to see if they are so > buff that they couldn't lose 10 lbs weight and be more fit! Unless > they're national team calibre, their likely wasting time and money on > an ultralight boat. While they don't kayak just to race, they do race when they can. And they tend to finish near the front of the pack. I'm sure that's 90+% fitness and skill though, and not the boat. But they do have an even lighter boat just for racing, they just don't always use it when they race. Thanks for the interesting reply Mike. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 6 Jun 2003 at 2:46, jwd_at_acm.org wrote: > [ You're obviously pretty passionate about this, so don't misconstrue > my comments as argumentative. ] My passions only come from years of competition in other sports and seeing the futile waste in time and money on getting the "best" and lightest gear when the participant basically lacks skill, fitness etc. While there are ways to make kayaks better, is it worth the price (extra maintenance, etc)? > "Gel coat adds color and UV protection, but it also adds extra > weight, provides no strength to the laminate and contributes to > atmospheric emissions." > > So, he at least, thinks it adds no strength to the laminate. > > Now, I don't necessarily agree. Or, to be more precise, I would say > it doesn't necessarily add any **necessary** strength or stiffness to > the hull. Be careful to keep strength and stiffness separate. They are different properties and in some cases (like buckling) are completely independent. He's talking about strength; I was only addressing stiffness. (OT - what emissions are produced in the manufacture of polycarbonate? He only looks at _his_ use of the final product! BTW, this is not to suggest that polycarbonate is bad, just to ask the question.) > If you make the fiberglass/kevlar/carbon-fibre (w/ epoxy resin) > laminate sufficiently thick so as to provide the necessary hull > stiffness, can you still say you're more likely to get oil-canning or > buckling? I would say that would only be the case if the laminate was > weak in the face of forces perpendicular to, or nearly so, the lay of > the fabric laminate. First comment on terminology: epoxy is rarely used in commercially produced kayaks. Most manufacturers use a resin (vinylester, polyester whatever) which is cheaper and does not have the same properties as epoxy. Oilcanning will be reduced by increasing the layup thickness (and according to Nick, would be more weight efficient than using gelcoat). Buckling failure would also be reduced. (BTW oilcanning is due to forces perpendicular, however, buckling is due to forces in the plane of the laminate. Also you should say flexible not weak just to be clear.) This brings up a point that hasn't been addressed. If they order the kayak without gelcoat, what do they get? Thicker laminate? The same laminate? Different laminate? My comments assumed that they would get the same laminate without gelcoat. > As to the argument about beefing up the fibre and resin, I would have > to ask two questions. 1) Just how much beefing up is required, if > [...] > give a certain amount of added "strength". I don't know that > information. Do you? (and no, I'm not being a wise-ass, just asking). These things are easy enough to look up and calculate. However, it does beg the question - How much is enough? > This essentially covers the question I asked the person. The response > was that (and these boats don't get babied -- nor do they get tossed > about carelessly either) the damage done is to the outer layer of > epoxy and not to the fabric within. I'd call that naïve. I've seen enough frayed glass fibres on kayaks to know that's not necessarily true. > That may indeed be the case. It certainly is for bikes (except for > those doing time trials, and then only if they're seriously up to the > task). That's why I ride lugged steel frames and only use titanium > parts for personal amusement. Time trials don't need light weight. Criteriums, with acceleration out of every corner would benefit from lighter weight. This does remind me, though, of my cycling coach who was at least 20lb overweight and yet had a titanium chain on his bike! His bike was three pounds lighter than mine, but I could beat him up any hill you could find! Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
jwd_at_acm.org wrote: >> Their justification was that gelcoat provides no structural benefit to the boat, and going without it saves 5-8 lbs of essentially useless weight. [snip] Now I know that finishing the boat's exterior with gelcoat doesn't improve the structural rigidity of the craft. [snip] I also know that some in the industry, Tom Derrer of Eddyline among them, have staked their reputation (and their business) on foregoing gelcoat. But even Eddyline's high-end "modulus" boats, which are vacuum bagged glass/kevlar composites, still use a Carbonlite (polycarbonate?) shell on the outside.>> 1. Adding a thick layer of gel coat will stiffen the laminate __a little__, because the modulus of elasticity of the gel coat is different from the underlying FRP. "Structural rigidity" = stiffness, I guess. However, in my limited experience with FRP boats, too-flexible hull/deck sections flexed like hell when pressed too hard, and cracked the gel coat. The gel coat was not useful in preventing flex. I bet Matt Broze has better data than I do. 2. The main value of gel coat is two-fold: A. It protects the underlying resin (whether polyester-, polyvinylester- or epoxy-based) from degradation from UV. Coat a plank with a generous layer of epoxy and lay on a 6 oz of glass and then apply more epoxy to wet out the glass. Let sit in the sun for 6 months, and then see if you want that to happen to your boat. B. It protects the underlying FRP from __abrasion__ damage. B. Is very important -- any time you cut into the glass/resin layer, you are damaging both the rigidity and the strength of the boat. On an extended trip, it would be easy to eat all the way through the glass from running the boat onto the beach. Even boats with gel coat can have this happen. I've seen it in abused rental boats. 3. The quote from Derrer is somewhat out of context. In one case, he uses a polycarbonate layer __in place of__ gel coat ("A Carbonlite 2000 skin replaces the gel coat in a composite kayak"). See: http://eddyline.com/kayaks.cfm Note that none of their "Legacy Composite" (= FRP) models are in normal production any more. They would have needed a UV protector, as do their Modulus versions. Those Modulus boats must be heavier than FRP boats of equivalent rigidity (note: I did not say strength, because the Carbonlite 2000 layer is strucural). -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Fri, Jun 06, 2003 at 03:00:23AM -0700, Dave Kruger wrote: > 3. The quote from Derrer is somewhat out of context. In one case, > he uses a polycarbonate layer __in place of__ gel coat ("A > Carbonlite 2000 skin replaces the gel coat in a composite kayak"). > See: http://eddyline.com/kayaks.cfm I wasn't using the Derrer quote to suggest that he was a proponent of using no over-layer on top of the fiberglass/kevlar laminate. Just that he too has argued that gelcoat doesn't do much to make a "stronger" boat, which it seems is the popular perception. I'm sorry if that wasn't clear. My mistake. > Note that none of their "Legacy Composite" (= FRP) models are in > normal production any more. No, their not. But I believe this is half a business-based decision (it's more expensive to produce three variants of each model [Carbonlite, Modulus, *and* Legacy Composite], than just the present two), and half an "I'm going to prove my (Derrer's) point" basis. > They would have needed a UV protector, as do their Modulus versions. > Those Modulus boats must be heavier than FRP boats of equivalent > rigidity (note: I did not say strength, because the Carbonlite 2000 > layer is strucural). Actually, I believe they say their Modulus boats are lighter than would be an equivalent model using gelcoat. I don't know if that is, or is not, the case in practice. For it to be so, I guess one of two things would need to be true. One - the two approaches would use the same thickness laminate, and the polycarbonate shell would provide a weight savings over the use of gelcoat on the same design. Or two - the polycarbonate shell may weight the same as (or more than) the gelcoat equivalent, but its structural make-up allows for the use of a thinner laminate underneath. FWIW, according to Eddyline, the polycarbonate sheets they start out with for the Modulus boats are thinner than the ones they use for the Carbonlite models. But, I believe they can form them in the same molds. Now if you really want to get Mr. Derrer started, ask him about British boats such as NDK and VCP. He insists he can build kayaks that are just as strong as the 60-65 lb. NDK and VCP expedition boats, and bring the weight in at around 48 lbs. Now, I'm not talking about "strong enough to do the same job, but ultimately not as strong as the NDK and VCP designs" (which would imply he thought the Brit-boats overbuilt), but rather "just as strong as those other designs" (which implies he thinks the Brit-boats to be badly built. That is an argument I've heard from more than one designer on this side of the pond. But that is yet another can of worms. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 6 Jun 2003 at 8:50, jwd_at_acm.org wrote: > [...] Now, I'm not talking about > "strong enough to do the same job, but ultimately not as strong as the > NDK and VCP designs" (which would imply he thought the Brit-boats > overbuilt), but rather "just as strong as those other designs" (which > implies he thinks the Brit-boats to be badly built. We can evaluate these statements only when we have an objective measure of what the "right" design is. It's easy to make them strong, but how strong do they need to be? Until then, these are opinions that can't be judged as true or false. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Fri, Jun 06, 2003 at 03:00:23AM -0700, Dave Kruger wrote: > 2. The main value of gel coat is two-fold: <..snip..> > B. It protects the underlying FRP from __abrasion__ damage. > > B. Is very important -- any time you cut into the glass/resin layer, > you are damaging both the rigidity and the strength of the boat. On > an extended trip, it would be easy to eat all the way through the > glass from running the boat onto the beach. Even boats with gel > coat can have this happen. I've seen it in abused rental boats. Your point re: abrasion resistance is well made. What I'm curious about, however, is just how much of an epoxy skin-coat would you have to apply in lieu of a gelcoat top layer to get equivalent abrasion resistance? Are there epoxy resins applicable to boat use that can provide the same abrasion resistance as the fairly think gelcoat in conventional use, but do so with a thinner and lighter result? As an example, how abrasion resistant is your typical wood kayak (stitch-n-glue or strip-built) as compared to a gelcoat topped composite model? Anyone out there know? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
The idea that a thick gelcoat might be structurally useful is one of my pet peaves. Gelcoat serves two purposes: one cosmetic, it lets the boat have a color; the other is protective, it keeps UV light away from the structural part of the layup. It is not strong and does not provide good abrasion resistance for its weight. While making a layup thicker will make it stiffer, additional gelcoat is not a good way to do it. While gelcoat may add stiffness, it is brittle and will fail more severely than other methods of increasing stiffness. While gelcoat does provide some abrasion protection but only in a very weight intensive manner. If you really want abrasion resistance, the best way is to add more cloth, not more gelcoat. While this means that abrasion may cut into the cloth, so what. Glass or synthetic cloth added for abrasion resistance will be able to absorb abuse while maintaining higher strength better than gelcoat. Additional cloth would be stronger and lighter even if it is not as stiff. The reason for using thick gelcoat is simple: it takes no skill to spray in additional gelcoat and it is cheaper than cloth. You don't need highly trained (read expensive) labor to do it. A uniform thin layer sufficient to provide color and UV protection takes skill and the people who can do this are probably better paid over at the local autobody shop. More layers of cloth not only costs more in materials, it requires more skilled labor to achieve worthwhile results. Thick gelcoat is just a way to inexpensively manufacture a kayak that is strong enough for most uses. On Friday, June 6, 2003, at 06:00 AM, Dave Kruger wrote: > Their justification was that gelcoat provides no > structural benefit to the boat, and going without it saves 5-8 lbs of > essentially useless weight. [snip] > Now I know that finishing the boat's exterior with gelcoat doesn't > improve the structural rigidity of the craft. [snip] > > Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 USA Ph/Fx: (860) 659-8847 http://www.guillemot-kayaks.com/ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
* While having a wide ranging conversation recently with a fellow sea * kayaking enthusiast, the person made a statement that surprised me a * fair bit. They said that they've ordered their recent boats, whether * for race use or not, WITHOUT gelcoat (these are fiberglass or kevlar * composite boats). Their justification was that gelcoat provides no * structural benefit to the boat, and going without it saves 5-8 lbs of * essentially useless weight. When queried about what they did about * repairing the inevitable dings, they said they just used clear epoxy. * * So, I got to wondering about the pros and cons of going with a skin-coat * hull (or hull and deck) configuration. What do Paddlewise people think * of the idea? Any direct experience with it? * After building a stitch-and-glue boat, which is essentially a composite sandwich construction, I've been wondering about other sandwich materials. Lightweight airplane parts are constructed of glass (fiber- or graphite-) around a lightweight core. Has anybody tried this with kayaks? Granted, the abrasion-resistance needed in a boat is much higher, but it seems that a laminate of just fiberglass, with or without gelcoat, is a really inefficient use of the materials. I'm imagining either foam core panels laminated on both sides with glass, or a layer of glass coated with some sort of two-part foam, covered with a layer of glass on the inside. You could even "tune" the lay-up in higher-stress areas with layers of kevlar or graphite. I think one of the ideas behind a composite construction is to spread the structural requirements over a larger area, rather than concentrating them on individual structural members. In any case if a ding is causing structural failure, something is wrong. This works in skin-on-frame boats as well because the joints aren't rigid, so they have some give and spread stress around the frame. Clear varnish or paint provide UV protection for fiberglass. I think repairing dings on fiberglass alone is probably easier than repairing gelcoat. All that fuss over a shiny paint job... of course, if you don't HAVE to drag the boat down the beach because you can carry it on your shoulder... Severn *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Fri, 6 Jun 2003 09:07:01 -0400, "Severn Clay" <severnclay_at_earthlink.net> said: > After building a stitch-and-glue boat, which is essentially a composite > sandwich construction, I've been wondering about other sandwich > materials. Wenonah canoes website has a decent overview, with images, of different layups. Foam core, flex core, carbon, kevlar, or "tufweave" http://www.wenonah.com/canoes/ Under materials. Single hand carrying your boat is very pleasant ;-) -- Kirk Olsen kork4_at_cluemail.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Dear List, I have a fiberglass boat (Current Designs Solstice GT) that is orange all over (deck & hull). The boat is 7 years old, so naturally the orange is a bit faded. Along my keel line, I have the usual collection of scrapes, dings and gelcoat chipout. Some spots are getting a little thin and are turning on my worry light. I have put duct tape on the inside of the hull in these spots, but I'm now ready to attempt a more reliable repair. As I said, the boat is all orange except for the deck lines, fittings and rear hatch cover, which are black. The moulding that divides the deck and hull is also black. I thought the best way to do an "aesthetic" repair would be the following: 1. Use masking tape to create a one inch wide zone along the keel line. Actually the width of the zone would match the width of the side moulding, which is a little more than an inch. 2. Clean the area in the zone with an abrasive, alcohol and acetone. 3. Paint or trowel on a layer of magic keel repair sauce, perhaps topping with Saran wrap to give it a smooth surface and minimize postcure sanding. Now, the problem I need help with is identifying the magic keel repair sauce. I'm thinking that I probably need some kind of gelcoat repair material, however I'm afraid that all I could get would be white stuff. I want my new keel stripe to be black. So: A. Is gelcoat repair material available in black or can gelcoat repair be colored black? B. Is there any other materials I can consider for the magic keel repair sauce the are: i. Black ii. As abrasion resistive as gelcoat or better iii. Easier to work with than gelcoat iv. Cheaper than gelcoat I'd appreciate your ideas. Thanks, Bill Leonhardt *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 6 Jun 2003 at 10:29, Leonhardt, William J wrote: > A. Is gelcoat repair material available in black or can gelcoat > repair be colored black? Gelcoat comes in two colours - white and neutral (like paint). It gets its final colour from mixing in pigments. You can buy pigments in any basic colour and then mix to get a custom colour. For example, (where's that gelcoat colour chart...) adding white, bright yellow and red to neutral will result in pale orange. Bright yellow with a bit of light red in neutral will give Sunset Orange and so on. If you want black, just add black pigment. You mix the colour in the gelcoat before adding the hardener until you get a reasonable match. The reason I prefer white hulls is that you don't waste time mixing colours (problematic for me since I'm colour blind!) Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Kirk maintains: >Single hand carrying your boat is very pleasant ;-) < I just drag my kayak across the parking lot. Sure as heck made a bunch of those paddlers at San Juan County Park groan last week (they didn't see the plastic wear strip...hehehehe). Speaking of tough boats, err, not yours, I took my van in for an oil change Thursday. I chose a garage that has been converted from a logging truck repair facility to an automotive repair shop. Their oil changes are cheap, real cheap. Knowing these guys were a bit haywire, I brought Chris Duffs new book along to read, just in case. Well, it took an hour to get a filter delivered (and I phoned ahead the day before). I use these guys because I can leave my Nordkapp on top of the van, given the very high garage height. So, the mechanic jumps in the van while I'm reading, and drives my Nordkapp right through the partially opened garage door! CRASH!!!. I ran out aghast. The guy was using his most colourful redneck language. The kayak had penetrated three feet into this very tough multiple wooden raised panel door. Embedded. The term pops up again. What a mess, And what a very funny sight. The owner came running out too, "Oh my God, is your boat okay!?" I wasn't worried about my 100 pound Nordkapp at all (a little about the roof racks, but they were fine). My battering ram worked fine, better than any Romany. :-) And I was the one who felt bad, like I was carrying a weapon of mass destruction or something. Ah heavy boats. Heaven. Gotta love them. Hope that's not too religious for Matt. :-) Doug Lloyd Victoria BC ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~ "Whatever can be said at all can be said clearly and whatever cannot be said clearly should not be said at all." Ludwig Wittgenstein ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Dear List, I have a fiberglass boat (Current Designs Solstice GT) that is orange all over (deck & hull). The boat is 7 years old, so naturally the orange is a bit faded. Along my keel line, I have the usual collection of scrapes, dings and gelcoat chipout. Some spots are getting a little thin and are turning on my worry light. I have put duct tape on the inside of the hull in these spots, but I'm now ready to attempt a more reliable repair. As I said, the boat is all orange except for the deck lines, fittings and rear hatch cover, which are black. The moulding that divides the deck and hull is also black. I thought the best way to do an "aesthetic" repair would be the following: 1. Use masking tape to create a one inch wide zone along the keel line. Actually the width of the zone would match the width of the side moulding, which is a little more than an inch. 2. Clean the area in the zone with an abrasive, alcohol and acetone. 3. Paint or trowel on a layer of magic keel repair sauce, perhaps topping with Saran wrap to give it a smooth surface and minimize postcure sanding. Now, the problem I need help with is identifying the magic keel repair sauce. I'm thinking that I probably need some kind of gelcoat repair material, however I'm afraid that all I could get would be white stuff. I want my new keel stripe to be black. So: A. Is gelcoat repair material available in black or can gelcoat repair be colored black? B. Is there any other materials I can consider for the magic keel repair sauce the are: i. Black ii. As abrasion resistive as gelcoat or better iii. Easier to work with than gelcoat iv. Cheaper than gelcoat I'd appreciate your ideas. Thanks, Bill Leonhardt *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 6/6/2003 10:51:05 AM Eastern Daylight Time, wjleonhardt_at_bnl.gov writes: > Now, the problem I need help with is identifying the magic keel repair > sauce. I'm thinking that I probably need some kind of gelcoat repair > material, however I'm afraid that all I could get would be white stuff. I > want my new keel stripe to be black. So: > you can buy clear gel coat and black coloring - should be available at a good marine store. I know west marine carries both. You may want to consider putting on a keep strip of glass cloth sns *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Last year Wilderness Design was showing a composite kayak that weighed less than 30 pounds. I think it was just an engineering exercise, but it is certainly technically feasible to build light weight composite boats. Cost and durability may be limiting factors. Robert > * > After building a stitch-and-glue boat, which is essentially a composite > sandwich construction, I've been wondering about other sandwich materials. > > Lightweight airplane parts are constructed of glass (fiber- or graphite-) > around a lightweight core. Has anybody tried this with kayaks? Granted, > the abrasion-resistance needed in a boat is much higher, but it seems that a > laminate of just fiberglass, with or without gelcoat, is a really > inefficient use of the materials. I'm imagining either foam core panels > laminated on both sides with glass, or a layer of glass coated with some > sort of two-part foam, covered with a layer of glass on the inside. You > could even "tune" the lay-up in higher-stress areas with layers of kevlar or > graphite. > *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Thu, 5 Jun 2003 21:44:10 -0400, jwd_at_acm.org said: > So, I got to wondering about the pros and cons of going with a > skin-coat hull (or hull and deck) configuration. What do Paddlewise > people think of the idea? Any direct experience with it? Moving the summary to the top for brevity: I like having skincoat kevlar canoes, I store them in a bag and that works well. I would have no qualms about owning a skincoat kevlar or carbon/kevlar kayak. I've heard and experienced too many problems with skincoat over all carbon, the recent thin gelcoat over carbon works well and I would recommend it over skincoat all carbon. I LOVE being able to carry my boat with one hand. Long version: I've got 5 skin coat boats, 4 kevlar canoes and one carbon surf ski. The boats gain stiffness from having a foam core. The foam core is done as a diamond shaped insert in the bottom plus 4 inch wide ribs. I believe, on the lightweight canoes, there is one layer of kevlar on the sides, 3 on the bottom and 5 on the bow and stern. The surf ski does not appear to have a foam core insert in the bottom laminate but does have internal walls adding some rigidity. The oldest boat is a 1980 vintage tandem racing canoe. It was the last year of non-vacuum bagged boats from Wenonah. That boat is nicknamed "the beater". It's been highly abused. Twice it's been paddled straight into fixed objects (accidently) with enough force to throw the bow paddler over the front into the water. The boat was also used frequently and kept on our car which was parked in a wide open parking lot about 200 days a year - lots of potential sun damage. The boat is still water tight but it's REALLY ugly. There are some 15' scratches that compress the foam core. I've put a couple new skin coats of epoxy over the bottom and it's holding up surprisingly well. I keep my 3 newer skincoat kevlar canoe in travel covers. The covers only come off when the boat is in use. I get in and out of the boats while they are afloat and do my best to avoid hitting anything. Scratches are highly visible and deep ones go right into the weave. The more interesting example is the surf ski. This boat is skin coat carbon. It's dying. It's 19'6" and weighs about 24 pounds. There wasn't enough resin when the boat was laid up so there are lots of pinhole leaks where the resin did not saturate the carbon fabric. Additionally the internal support structures and the rudder mount were made from wood and wood inside of a sealed object hasn't worked well long term. The boat takes on about a half gallon of water every hour that it is paddled. Last fall I pulled over for the hourly draining of the boat and chunks of wood floated out with the water. At some point the boat is just going to sink or break. I accept that. My most recent boat is also carbon fiber. It came with a thin gelcoat coating. Thus far no leaks at all. But it's heavier, about 30 pounds for a 21 foot boat. The outrigger canoes which I've been paddling are extremely light, the canoes are from outrigger connection and Current Designs (http://www.outriggerconnectionworldwide.com). I think the singles are under 30 pounds. All of the ones that I've used have come with a very thin gelcoat finish. I treat the boats like they are eggs. I've seen one of the amas dropped 2 feet to asphalt and it crumpled like a hard boiled egg would. The carbon fiber 6 man outrigger arrived yesterday, I haven't seen it yet to see what the layup is - it' 185 pounds for a 45 foot boat, versus 385-400 pounds for the traditional layup. We bought our "family" canoe as a skincoat kevlar boat because my wife was accustomed to the skincoat boats and she hated (eventually refused) to help lift the fiberglass canoe. Don't underestimate the advantages of moving a 30 pound boat from the car to the water. My wife would paddle more if she could maneuver her boat without assistance. I know she could use rollers and a cart but she has seen the lightwieght boats and that's where she wants to be... Kirk -- Kirk Olsen kork4_at_cluemail.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> > The response > was that (and these boats don't get babied -- nor do they get tossed > about carelessly either) the damage done is to the outer layer of > epoxy and not to the fabric within. And that damage is easily > repaired with a little clear epoxy. I guess it boils down to whether > or not the epoxy on the outside of a skin-coat boat provides enough > "sacrificial layer" to withstand normal wear and tear. I know one place where going with a skin coat boat is not only normal but semi preffered - the boundary waters canoe area. You see a lot of skin coat canoes there. I have one and it's made 5 week long trips. Believe me it isn't babied. It would be next to impossible to avoid scraping across rocks, there are just too many rocks and too many shallow areas. My boat has numerous scratches, scrapes and bumps. The nose gets run up onto gravel to land. The loaded boat will get dragged further up onto land. After three years I added some kevlar skid plates at the front and back. I also put a small kevlar patch on two really nasty bruises (no danger of a puncture, just a little over kill on my part). And I repainted the entire bottom with a fresh coat of clear epoxy - all better (until the next trip). The boats are obviously strong enough that the outfitters will rent them (and we all know how rentals are treated). I had a guy at a gas station comment on my boat, "That's a boat that's been to the Boundary Waters. All sorts of pretty scratches." The bottom of the canoe may look ugly but I don't care when I'm carrying it over a 1/2+ mile portage. At that point I'm glad it's lighter. :) Mel *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
----- Original Message ----- From: <jwd_at_acm.org> To: <PaddleWise_at_paddlewise.net> Sent: Thursday, June 05, 2003 9:44 PM ..........They said that they've ordered their recent boats, whether > for race use or not, WITHOUT gelcoat (these are fiberglass or kevlar > composite boats). Their justification was that gelcoat provides no > structural benefit to the boat, and going without it saves 5-8 lbs of > essentially useless weight............ > So, I got to wondering about the pros and cons of going with a skin-coat > hull (or hull and deck) configuration. ------------------------------------------------ ------------------------ ---------------------------- I have been thinking this idea over while building my stitch & glue kit. I am going to paint the hull. Why do I want to add epoxy to fill the weave of the glass if it doesn't increase the strength? Is my thinking correct? Would there be a significant change/increase in drag by leaving it rough? Is the fill coat only to make it look slick or does it help protect the glass? Jim et al *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I have two boats without gelcoat. One kevlar, the other carbon/kevlar (that black/gold sheen is delicious). It saves some weight and certainly shows off the fact you have an exotic lay-up. The manufacturers of kevlar boats with gelcoats always put "KEVLAR" in big letters on the hulls so everyone knows the paddler spent extra bucks. I find myself babying the clear coat hulls. Every serious scratch goes right into the weave. Not so with my gelcoat boats. They can usually take a full season plus of inattention before dealing with scratches and gouges. A gelcoat boat can easily outlive the owner. IMHO clearcoat is great for racers, fine for that second "special" boat, not so good for everyday use. The Eddyline hulls are a separate issue. They are lighter. I've read their information on repairs and it seems punctures can be fixed. They claim the manufacture of them is more friendly to the environment. Wear from dragging the hull over sand and rocks for five years is not addressed. I'm not sure the environmental argument holds up if I have to buy three Carbonlite boats and only one gelcoat boat over the same number of years.The jury is still out on Carbonite. Paddle lots Bob ----- Original Message ----- From: <jwd_at_acm.org> Subject: [Paddlewise] Spare the gelcoat -- pros & cons of skin-coat boats > So, I got to wondering about the pros and cons of going with a skin-coat > hull (or hull and deck) configuration. What do Paddlewise people think > of the idea? Any direct experience with it? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Not to spin the thread too far off course, but I thought I would mention something else about the use of polycarbonate in kayak hulls. On Thu, Jun 05, 2003 at 08:17:57PM -0700, Vaughan wrote: > The Eddyline hulls are a separate issue. They are lighter. I've > read their information on repairs and it seems punctures can be > fixed. They claim the manufacture of them is more friendly to the > environment. Wear from dragging the hull over sand and rocks for > five years is not addressed. I'm not sure the environmental > argument holds up if I have to buy three Carbonlite boats and only > one gelcoat boat over the same number of years. The jury is still > out on Carbonite. I think the verdict is still out on Eddyline's Carbonlite (whether the pure poly Carbonlite 2000, or the composite Modules versions) boats. And I expect Tom and Joe at Eddyline will admit that in a quiet moment. But the only way to really prove this is to use the material in some type of well designed, thorough, extended study, or else bet your company on it and let the results from use in the field (and warranty repairs, plus dealer and customer feedback) provide the result. This is their second year without using any gelcoat in their boat making. Maybe at year five we'll have an answer. A comment that has been made to me one several occasions by a kayaking veteran, that I've not seen mentioned elsewhere, is that the use of polycarbonate as the hull material, or as the outer layer of a composite lay-up, presents limits over the more conventional approach to building fiberglass and/or kevlar composite boats. Specifically, or so the person claimed, the use of thermo-molded polycarbonate sheets places limits on the boat's hull design -- you can only "form" the stuff so much under heat and pressure. I would really be curious as to whether or not this is the case (I expect it is, to some extent at least). And, if so, I wonder what classic hull designs you couldn't pull off using this material in manufacture. Oh, by the way, thanks to all for an interesting discussion. I don't know if there was any definitive answer, but there was certainly plenty of good points raised to consider. The more I'm learn about this sport, the more it reminds me of the motto for Perl -- namely "There's more than one way to do it!" Now we just need cool t-shirts that say as much (and a logo like the Perl camel) :-) *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
At 12:02 PM 6/6/2003 -0400, jwd_at_acm.org wrote: >Oh, by the way, thanks to all for an interesting discussion. I don't >know if there was any definitive answer, but there was certainly >plenty of good points raised to consider. The more I'm learn about >this sport, the more it reminds me of the motto for Perl -- namely >"There's more than one way to do it!" Speaking as a Java programmer, that motto is not unique to Perl. >Now we just need cool t-shirts >that say as much (and a logo like the Perl camel) :-) We already have coot t-shirts with a cool logo. John Fereira jaf30_at_cornell.edu Ithaca, NY *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
J. Dubya said (snip): >Now if you really want to get Mr. Derrer started, ask him about British boats such as NDK and VCP. He insists he can build kayaks that are just as strong as the 60-65 lb. NDK and VCP expedition boats, and bring the weight in at around 48 lbs.< One of the older paddlers in our club recently acquired a Jubilee Nordkapp, standard layup. It is surprisingly light. I had a hard time keeping up with him (well, I was loaded for bear). He's feeling guilty because other paddlers keep rushing to his aid to assist him lifting his "British Heavy." He feels guilty as it is so much lighter than appearances. I told him to let folks continue to think it's a heavy, and impress all the girls. As for Mr. Derrer: He's running a business; he's heavily marketing; he's an American. ;-) Doug Lloyd Victoria BC ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~ "Whatever can be said at all can be said clearly and whatever cannot be said clearly should not be said at all." Ludwig Wittgenstein ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~ *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Vaughan <vaughan_at_jps.net> wrote: >> The Eddyline hulls are a separate issue. They are lighter. I've read their information on repairs and it seems punctures can be fixed. They claim the manufacture of them is more friendly to the environment. Wear from dragging the hull over sand and rocks for five years is not addressed. I'm not sure the environmental argument holds up if I have to buy three Carbonlite boats and only one gelcoat boat over the same number of years.The jury is still out on Carbonlite. >> Well put. I believe your remarks are directed at the boats made solely of Carbonlite. I have "issues" with their "Modulus" boats, which have composite FRP structure overlaid with Carbonlite. The drawback to use of the exterior, "sacrificial" material (Carbonlite) as part of the structural integrity of the boat is that as the Carbonlite wears, so also does some of the strength of the hull. I suspect this might be a small problem, because most of the wear will be at the keel near the bow and the stern, and not in the center of the boat. However, in a traditional FRP boat, it is easy to replace lost gel coat with more of the same. Can the Carbonlite be similarly renewed? I doubt it. Anybody know? I'm an Eddyline fan, and own two of their older composite designs. But, I wonder if abandoning composite construction in favor of polycarbonate or composite/polycarbonate is a good thing. Sure, it sells more boats, and at a lower unit cost/boat. But who buys a Carbonlite boat? Someone who will wear the boat out? Or, someone who will paddle it for three seasons and then let it sit in the garage? I think "marketing" may have clouded Derrer's judgment. Or, maybe it was too many years sniffing styrene fumes (grin)! [Actually, avoiding wet layups and vacuum bagging of FRP in favor of heat-formed structures does have human health advantages for workers -- I'll give Eddyline that.] -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Back in the early 1980's Eddyline didn't use gelcoat on their vacuum-bagged kayak hulls. The color was put in the resin with translucent dyes. The boats were as strong as they would have been with gelcoat but were lighter (and I assume given the relative costs of gelcoat and dye, less expensive to build). So why did they start using clear gelcoat (at first on the decks and then also gelcoat on the hulls a little later)? I don't know for sure, it wasn't my decision, you'd have to ask Tom Derrer about that. For years before switching totally to Carbonlite exteriors, Eddyline used gelcoat on both the hulls and decks and their kayaks lasted a lot longer and had better resale value because of it. I suspect Tom's decision had something to do with how those no gelcoat boats were aging. The problem was that after a few years of sun exposure the surface resin eroded ever so slightly. The pressure from the vacuum-bagging process had plastered a lot more of the glass fibers up against the mold surface during construction so it didn't take much erosion to expose significant amounts of glass fiber on the boats outside surface. Have you ever seen one of these no gelcoat kayaks? You'll recognize them by the silvery, sparkly sheen on their surface. Touch the surface with a tender area of your skin and you'd get the fiberglass itch from all those little needle sharp slivers. The more weathering the boats got the quicker this would happen. This would happen to hand laid boats with no gelcoat as well, but it took a little more weathering for them because the glass fibers only touched the mold surface at the points where the cloth's weave touched it. When it happened though, the hand-laid "skin coat" kayaks would look like they were covered with a rash of glass fiber spewing pimples/mini-volcanoes every 1/8th inch or so across the surface. The had the same itch too. If only stored indoors and out of the weather, the non-gelcoat kayak can last a long time before this happens. Kirk Olsen's experience with his canoes is an example. His first is ugly but the ones he always keeps covered or indoors have aged very well. Clear gelcoat can be sprayed on thinner without the need to worry about good coverage (with pigmented gelcoat it must be thick enough so you can't see through it in places, making it look mottled). These clear gelcoat kayaks can be somewhat lighter than some of the pigmented gelcoats but not as light as with no gelcoat. Don't mistake them for non-gelcoated boats though just because you can see the glass weave through them. Given the same kayak lay-up they are also a little more flexible because their are no reinforcing fibers in clear gelcoat as there is in pigmented gelcoat and the laminate (including gelcoat) is a little thinner. I think getting a thin even coat of gelcoat on the mold without much of it running down and pooling into the bottom of the mold (eventually becoming a thick brittle part of the boat) takes quite a bit of skill. Most of the kayaks I've seen from Europe are mainly constructed (especially the decks) with chopped strand glass mat, the most brittle of fiberglass construction materials used in kayaks (because they are very resin rich). The mat conforms around recessed fittings much better than the stronger more expensive materials with a hand lay-up. Most kayaks I've seen that were imported from England get good strength and stiffness on the deck by making the chopped strand mat laminate on the deck very thick, but that also translates into a very heavy kayak. Those that attempt to make the mat decks thinner and lighter end up with a very brittle kayak. To my mind by far the biggest benefit of gelcoat is the UV protection and long-term itch free environment it provides the user. Speaking of the environment, it is clear that gelcoat gives off some styrene fumes before it cures and that makes its use in kayak building much more expensive to meet government regulations for a spray booth and fans and filters and periodic inspections by the EPA. My question is: does polycarbonate give off any potentially toxic chemicals in any stage of its manufacture or use. It is my understanding that polycarbonates can leach out some chemical that mimics a female hormone and that some folks are now warning against its use for water containers for that reason. Matt Broze www.marinerkayaks.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I have two boats without gelcoat. One kevlar, the other carbon/kevlar (that black/gold sheen is delicious). It saves some weight and certainly shows off the fact you have an exotic lay-up. The manufacturers of kevlar boats with gelcoats always put "KEVLAR" in big letters on the hulls so everyone knows the paddler spent extra bucks. I find myself babying the clear coat hulls. Every serious scratch goes right into the weave. Not so with my gelcoat boats. They can usually take a full season plus of inattention before dealing with scratches and gouges. A gelcoat boat can easily outlive the owner. IMHO clearcoat is great for racers, fine for that second "special" boat, not so good for everyday use. The Eddyline hulls are a separate issue. They are lighter. I've read their information on repairs and it seems punctures can be fixed. They claim the manufacture of them is more friendly to the environment. Wear from dragging the hull over sand and rocks for five years is not addressed. I'm not sure the environmental argument holds up if I have to buy three Carbonlite boats and only one gelcoat boat over the same number of years.The jury is still out on Carbonite. Paddle lots Bob ----- Original Message ----- From: <jwd_at_acm.org> Subject: [Paddlewise] Spare the gelcoat -- pros & cons of skin-coat boats > So, I got to wondering about the pros and cons of going with a skin-coat > hull (or hull and deck) configuration. What do Paddlewise people think > of the idea? Any direct experience with it? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Dave Kruger wrote: > Matt Broze wrote: > > To my mind by far the biggest benefit of gelcoat is the UV protection and > > long-term itch free environment it provides the user. Speaking of the > > environment, it is clear that gelcoat gives off some styrene fumes before it > > cures and that makes its use in kayak building much more expensive to meet > > government regulations for a spray booth and fans and filters and periodic > > inspections by the EPA. My question is: does polycarbonate give off any > > potentially toxic chemicals in any stage of its manufacture or use. It is my > > understanding that polycarbonates can leach out some chemical that mimics a > > female hormone and that some folks are now warning against its use for water > > containers for that reason. >> > My guess is the leachate from polycarbonate (PC) is probably a phthalate [snip] I was wrong. The estrogenic material in polycarbonate bottles that is under scrutiny is bisphenol A (BPA), a principal ingredient in epoxy resins, also. Here is a summary of current (as of 2001) concerns about BPA: http://www.pdf.co-operative.co.uk/pdfs/hazardous_substances.pdf I suspect the degree of hazard to humans from BPA during PC manufacture is unsettled, as of yet, in contrast to the well-established concerns about styrene from polyester resin manufacture. I suppose no matter how you slice it, there is some hazard from any of these materials: styrene from polyester resins (trad. fiberglass composite boats), BPA from either epoxy/Kevlar boats or polycarbonate boats. Take your pick. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Matt Broze wrote: >> To my mind by far the biggest benefit of gelcoat is the UV protection and long-term itch free environment it provides the user. Speaking of the environment, it is clear that gelcoat gives off some styrene fumes before it cures and that makes its use in kayak building much more expensive to meet government regulations for a spray booth and fans and filters and periodic inspections by the EPA. My question is: does polycarbonate give off any potentially toxic chemicals in any stage of its manufacture or use. It is my understanding that polycarbonates can leach out some chemical that mimics a female hormone and that some folks are now warning against its use for water containers for that reason. >> Great post, Matt (much snipped). Re: the last two issues you raised: My guess is the leachate from polycarbonate (PC) is probably a phthalate, similar to the plasticizers in PVC (IIRC) tubing tht some are concerned about in use for IV lines in hospitals, etc. Very much less hazard from incidental contact with a PC boat than from IV PVC lines or water containers, leaving aside whether the estrogenic concern is valid. If I get some time to research manufacture of PC, I'll try to address the other issue. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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