Couple of questions: 1. Is there any value in a kayak builder post-curing the kayak when deck and hull are joined, with the aim that the resin in the join is raised to a sufficient temperature to bond with the hull and deck more effectively? 2. Why do not more kayak manufacturers use the QCC type overlapping join? See http://www.qcckayaks.com/kayaks/hulltodeck.asp. Is that a superior joint? *************************************************************************** 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/ ***************************************************************************
Peter Treby wrote: > Couple of questions: > 1. Is there any value in a kayak builder post-curing the kayak when deck > and hull are joined, with the aim that the resin in the join is raised > to a sufficient temperature to bond with the hull and deck more > effectively? Most marine resins or epoxies only need room temperature and there's no need for excessive heat other than to accelerate the cure rate. The only reason I can think of to accelerate the cure is to save time on the shop floor. > 2. Why do not more kayak manufacturers use the QCC type overlapping > join? See http://www.qcckayaks.com/kayaks/hulltodeck.asp. Is that a > superior joint? I like it and that's what is used on mine (Boreal Design). I agree that I'd like to see it used more often, but mating the curved surfaces as shown in the QCC diagram makes for tight manufacturing tolerances (though it should not be an issue with composites). 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/ ***************************************************************************
Peter T said: > Couple of questions: > 1. Is there any value in a kayak builder post-curing the kayak when deck and hull are joined, with the aim that the resin in the join is raised to a sufficient temperature to bond with the hull and deck more effectively? > 2. Why do not more kayak manufacturers use the QCC type overlapping join? See http://www.qcckayaks.com/kayaks/hulltodeck.asp. Is that a superior joint? 2. Looks superior to me. New glues are incredible powerful. How about this joining method and a taped seam inside and out? 1. Here's a quote from your neck of the woods from Sisson kayaks (who make the Nordkapp down-under): "The hull / deck joins are cross-linked solid: All kayaks are joined within hours of the original hull and deck lay-up. All kayaks are joined the same day they are laid up using the same materials used to form the hull and deck. No 'bog' here! All boats keep their design shape - unlike other brands that are joined out of the mould. All 'joined' kayak hull / decks are 'Post Cured' in the mould. This demands 'cooking' overnight with heat for optimised hull and deck strength. Which means that the hull / deck unit is cross linked (chemically fused - not just bonded) together into a solid unit. This sometimes means extra hours must be worked into the evening. No substitution or compromise. Which means your kayak hull to deck join is the strongest in the business." No affiliations Doug Lloyd *************************************************************************** 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/ ***************************************************************************
"...Sisson kayaks (who make the Nordkapp down-under):" There are so many boats called "Nordkapp". Here's a review of Nordkapp LV: http://seakayakphoto.blogspot.com/2007/01/valley-nordkapp-lv-test.html *************************************************************************** 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 an original Nordkapp HS (prior to mold itineration degradation and purposeful design itineration). There is no other Nordkapp. :-) Doug "...Sisson kayaks (who make the Nordkapp down-under):" There are so many boats called "Nordkapp". Here's a review of Nordkapp LV: http://seakayakphoto.blogspot.com/2007/01/valley-nordkapp-lv-test.html *************************************************************************** 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/ ***************************************************************************
Peter T said: > Couple of questions: > 1. Is there any value in a kayak builder post-curing the kayak when deck and hull are joined, with the aim that the resin in the join is raised to a sufficient temperature to bond with the hull and deck more effectively? > 2. Why do not more kayak manufacturers use the QCC type overlapping join? See http://www.qcckayaks.com/kayaks/hulltodeck.asp. Is that a superior joint? Doug Lloyd responded: >>>>>2. Looks superior to me. New glues are incredible powerful. How about this joining method and a taped seam inside and out? 1. Here's a quote from your neck of the woods from Sisson kayaks (who make the Nordkapp down-under): "The hull / deck joins are cross-linked solid: All kayaks are joined within hours of the original hull and deck lay-up. All kayaks are joined the same day they are laid up using the same materials used to form the hull and deck. No 'bog' here! All boats keep their design shape - unlike other brands that are joined out of the mould. All 'joined' kayak hull / decks are 'Post Cured' in the mould. This demands 'cooking' overnight with heat for optimised hull and deck strength. Which means that the hull / deck unit is cross linked (chemically fused - not just bonded) together into a solid unit. This sometimes means extra hours must be worked into the evening. No substitution or compromise. Which means your kayak hull to deck join is the strongest in the business." No affiliations<<<<<< 1. It looks like mostly a "red herring" from my viewpoint. The only time I've seen a seam bond that came unbonded was because the smooth fully cured vacuum bagged surface wasn't sanded well. Most of the few broken seams I've seen have been due to folding or tearing at the joint itself rather thant he fiberglass bond failing. and in most of those cases the rest of the kayak suffered serious damage as well. Even that folding damage is very rare but could be prevented by making the seam heavier or using a higher tensile strength material such as Kevlar for one of the seam layers. The trouble with making seams too heavy (and not tapering in thicknesss/stiffness towards the edges-- #2?) is that the sudden transition creates a stress riser at the seam's edge that may create a fold line. Post curing may make a better bond but I think the advertising is taking advantage of the seaming inside the mold they use (that is easier to do with a hand lay-up--which is weaker pound for pound than vacuum-bagging). Also with hand lay-ups the seam's chemical bond is already stronger than the mechanical bond (to a rough sanded surface as with a vacuum-bagged part). If a hand laid part is not contaminated with something like a petroleum product (oil, wax, grease) the air inhibited surface that makes this so would bond very well with resin years later. The rush to join the parts likely has more to do with production efficiency or maybe curing evenly and more quickly in the mold to get the parts out so it can be used again. Without sufficient heat the resin won't set but I doubt an even higher heat is making a really significant difference in the bond strength. Do a lot of seams come apart in Oz? If by: "no 'bog' here" the manufacturer is referring to the better alignment of the parts and the curing together of the seams and parts (to cause the shrinkage to be even and leave the parts a little less likely to be deformed by uneven curing--because it is held firmly inside the molds while this takes place) there is a little something to that. It certainly makes it easier to get a smoother join between parts. 2 Overlapping glued joints--time will tell if they hold up. Gluing is a lot cheaper to build with so I assume many manufacturers will tend go that way. That's how most thermoformed kayaks are put together. I believe Epic uses an overlapping joint and also I remember one local builder that used it as well. The reality is that the seams are the strong point of kayaks that use an adequate thickness and strong materials in the joint. I couldn't tell you how good or bad QCC seams are because I've seen very few of them and have not heard of any problems. I'd be willing to bet that they are a lot cheaper to build than inside and outside fiberglass seams though and I suspect that is a major motivator for any company to use them. Anyone out there in Paddlewise land who has seen or had problems with overlapping or glued joints? 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 had a hatch pop open in my QCC in the surf. After the surf rudely deposited my boat on the shore, it had a 3 foot split in the seam from the bow back. Don't know if that was something a boat should be able to endure, but it resulted in a free boat replacement for me. If there seam design is not the absolute best, their guarantee is darn good. I almost hate to complain that my new boat was the wrong color. Mark Sanders www.sandmarks.net ----- Original Message ----- From: "Matt Broze" <mkayaks_at_oz.net> Anyone out > there in Paddlewise land who has seen or had problems with overlapping or > glued joints? > > 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/ ***************************************************************************
On Saturday 07 April 2007 19:33, Matt wrote: > Anyone out > there in Paddlewise land who has seen or had problems with overlapping > or glued joints? In the world of aircraft design gluing the skins to aircraft frames is today popular, but to prevent the joints from running, if the glue joint for some reason fails, sometimes, sparsely applied rivets are used. Works very well, as any glued joint, when the glue gets old and brittle, might fail catastrophically! Maybe that could be applied to kayaks? Tord *************************************************************************** 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/ ***************************************************************************
Did the glue joint delaminate, or was it split just above or below the overlap joint? Doug Lloyd >I had a hatch pop open in my QCC in the surf. After the surf rudely >deposited my boat on the shore, it had a 3 foot split in the seam from the >bow back. Don't know if that was something a boat should be able to endure, >but it resulted in a free boat replacement for me. If there seam design is >not the absolute best, their guarantee is darn good. I almost hate to >complain that my new boat was the wrong color. > > Mark Sanders > www.sandmarks.net > > ----- Original Message ----- > From: "Matt Broze" <mkayaks_at_oz.net> > Anyone out >> there in Paddlewise land who has seen or had problems with overlapping or >> glued joints? >> >> 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/ ***************************************************************************
[Please remove all old content that is not pertinent to your reply including old headers and footers. It's list policy.... this post was modified to meet policy] From: "Doug Lloyd" <douglloyd_at_shaw.ca> > Did the glue joint delaminate, or was it split just above or below the > overlap joint? It was a failure of the glue joint. I notice on my new boat you can see a couple screw heads throught the seam tape that I didn't notice on my first boat. Perhaps along the lines of the rivet use in aircraft. I figure the narrow bow and stern might be the weak link in getting pressure on the two surfaces while the glue cures. Mark *************************************************************************** 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/ ***************************************************************************
Thanks Mike. Tord mentioned rivets too. Seam joints can be such a riveting discussion I guess. Well, actually, I was just speaking with Mike about his Michigan Lake crossing; he said he was in the borrowed Epic Endurance because his own Epic Endurance had undergone catastrophic seam failure in the surf prior to the trip, both sides of the cockpit I believe. It was subsequently fixed but apparently he didn't want to use it for the crossing (I think he said there were some further complications that hadn't been dealt with). Generally, the Epic kayaks are very well made using epoxy resins, etc. I believe the Epic kayaks use the overlap seam joint (someone correct me if I'm wrong), so I'm not sure if that is a weakness, or if the surf on Lake Michigan was a little too severe for the kayaks intended, designed use. Apparently, Lake Michigan does get some big surf I was reminded tonight. I made a joke the other day about glassing both sides of an overlapping joint. Maybe that ain't a bad idea. Well, I have about 5 pounds of epoxy seaming I added to my Nordkapp. Overkill for a boat perhaps, but underkill perhaps for the paddler. :-) Doug L > It was a failure of the glue joint. I notice on my new boat you can see a > couple screw heads throught the seam tape that I didn't notice on my first > boat. Perhaps along the lines of the rivet use in aircraft. > I figure the narrow bow and stern might be the weak link in getting > pressure on the two surfaces while the glue cures. > Mark > > > >> Did the glue joint delaminate, or was it split just above or below the >> overlap joint? >> >> Doug Lloyd *************************************************************************** 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/ ***************************************************************************
Sorry Mark - mean't to say Mark, not Mike. I noticed the Epic website mentioned post-curing at elevated temperatures. I'm still not sure how important this is. The guys who build the strip boats usually elevate temperatures temporarily in musty basements or mid-winter workshops - but that's just to finish off curing. Doug > Thanks Mike. > > Tord mentioned rivets too. Seam joints can be such a riveting discussion I > guess. Well, actually, I was just speaking with Mike about his Michigan > Lake crossing; he said he was in the borrowed Epic Endurance because his > own Epic Endurance had undergone catastrophic seam failure in the surf > prior to the trip, both sides of the cockpit I believe. It was > subsequently fixed but apparently he didn't want to use it for the > crossing (I think he said there were some further complications that > hadn't been dealt with). Generally, the Epic kayaks are very well made > using epoxy resins, etc. > > I believe the Epic kayaks use the overlap seam joint (someone correct me > if I'm wrong), so I'm not sure if that is a weakness, or if the surf on > Lake Michigan was a little too severe for the kayaks intended, designed > use. Apparently, Lake Michigan does get some big surf I was reminded > tonight. I made a joke the other day about glassing both sides of an > overlapping joint. Maybe that ain't a bad idea. > > Well, I have about 5 pounds of epoxy seaming I added to my Nordkapp. > Overkill for a boat perhaps, but underkill perhaps for the paddler. :-) > > Doug L > > >> It was a failure of the glue joint. I notice on my new boat you can see a >> couple screw heads throught the seam tape that I didn't notice on my >> first boat. Perhaps along the lines of the rivet use in aircraft. >> I figure the narrow bow and stern might be the weak link in getting >> pressure on the two surfaces while the glue cures. >> Mark >> >> >> >>> Did the glue joint delaminate, or was it split just above or below the >>> overlap joint? >>> >>> Doug Lloyd *************************************************************************** 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 Sunday 08 April 2007 05:28, Doug wrote: > I noticed the Epic website mentioned post-curing at elevated > temperatures. I'm still not sure how important this is. The guys who > build the strip boats usually elevate temperatures temporarily in musty > basements or mid-winter workshops - but that's just to finish off > curing. The important thing is elevated temperatures to kick off the curing and to make the epoxy more fluid - people vacuum-bagging their their stuff (like (model) airplane makers, from one-offs to series production) often use elevated temperatures to get an even, reliable glue joint. Some 3M spray glues, like #77, need heat to activate fully, thus is nice to work with: First you spray, sparingly, with #77, let it dry (an hour or more - all solvents should have evaporated) till it is no longer tacky, then apply the glass cloth/CF/Kevlar, and heat (a small iron is ideal, or you could use a hair dryer), bit by bit, till the glass (or whatever you use - veneer, maybe?), is applied just as you want it - any mistake: apply heat and redo, till OK. Then slow-curing epoxy, a release film, like Mylar (or similar), and then into the vacuum bag, tape it closed, attach the hose and then attach the pump, and now some heat - mirror-smooth finish is the norm! Some do entire boats, or complete bar tops, this way, saving lots and lots of time and money! If you do an entire kayak this way I guess you have to fill it with dry sand, or some other rigid stuff, that can't compress! You have to do the inside first, of course, before progressing to the exterior. Or make a big flotation bag, that fills the entire interior, that is slightly pressurized, to make a bag-in-a-bag, so to speak! Tord Tord *************************************************************************** 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/ ***************************************************************************
This "post-cure heating" discussion may be at apples and oranges. Most resins need a certain minimum temp for curing in a reasonable time. Heating these post-layup only speeds the ordinary curing process. However, some are formulated to require a "post-cure" cooking at an elevated temperature to establish cross-linking. These are special materials. I do not believe ordinary polyester or vinylester resins benefit from post curing at elevated temperatures; neither do most epoxy formulations. Here is one epoxy formulation which does; note it is completely different from the other formulations this manufacturer sells: http://www.systemthree.com/p_phase_two.asp It has a very long pot life, making it unsuitable for ordinary uses, but ideal for vacuum layup in molds. And, it does not work well with wood, unlike most epoxies. -- 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/ ***************************************************************************
Dave Kruger wrote: > However, some are formulated to require a "post-cure" cooking at an > elevated temperature to establish cross-linking. These are special > materials. I do not believe ordinary polyester or vinylester resins > benefit from post curing at elevated temperatures; neither do most epoxy > formulations. Another reason for post-curing is to allow for very long working times. If you're laying aircraft skin onto a frame, you don't want the epoxy to have a working time of an hour - you might need a full shift to get the parts all together and ready to cure. Once assembled, you then put it in an autoclave to cure. In other manufacturing environments, they can use UV curing resins. This allows long working times under normal light. Once everything is ready, move into a room with UV lighting and the cure commences. Just because this is used for high-tech products doesn't mean it's the best technique or that it produces a superior product. 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/ ***************************************************************************
Tord Eriksson wrote: > a release film, like Mylar (or similar), This is a common bit of confusion. Mylar is a sheet form of polyester. Polyester is not a low-surface-energy plastic and is not suitable as a release film. There are Mylar products with surface treatments to minimize surface energy, but these are specialty films. If you buy generic Mylar from, say, an art store, you might end up with a sheet of Mylar securely bonded to your project. Some release films sold are almost indistinguishable from Mylar to most of us. So if you want release film, don't ask for Mylar. Ask for release film and buy it from a place that sells epoxies and related materials. 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/ ***************************************************************************
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