I was asked to explain the advantage or disadvantageous of swede versus fish form hull designs the other day. I started off by saying I was not an expert. After that I had nothing else to say. So if there is someone out there that can bring some clarity to this - Matt Boze maybe - I'd be grateful. Gordin warner *************************************************************************** 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 09:32 PM 2/17/2003 -0800, Warner Family wrote: >I was asked to explain the advantage or disadvantageous of swede versus >fish form hull designs the other day. > >I started off by saying I was not an expert. After that I had nothing >else to say. > >So if there is someone out there that can bring some clarity to this - >Matt Boze maybe - I'd be grateful. A while back I asked the same question. Some quite interesting discussion is archived on the web page. http://www.paddlewise.net/topics/boatdesign/pro-conswede.html .Hal *************************************************************************** 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/ ***************************************************************************
[Moderator's Note: Content unaltered. Excessive quoting (i.e. headers/footers/sig lines/extraneous text from previous posts, etc.) have been removed. Please edit quoted material in addition to removing header/trailers when replying to posts.] From: "Hal Christiansen" <hchristiansen3_at_comcast.net> > At 09:32 PM 2/17/2003 -0800, Warner Family wrote: > >I was asked to explain the advantage or disadvantageous of swede versus > >fish form hull designs the other day. > > A while back I asked the same question. Some quite interesting discussion > is archived on the web page. > > http://www.paddlewise.net/topics/boatdesign/pro-conswede.html This reminds me that not long ago someone asked about vacuum-bagging vs. hand lay-ups, and that I'd replied (privately?) that there had been an excellent discussion on that topic in an issue of Sea Kayaker magazine a few years ago, between a proponent of each method, the proponent of hand lay-ups having been Lee Moyer. Can that exchange be reproduced here for the benefit of Paddlewise subscribers? - Bill *************************************************************************** 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 Tue, 18 Feb 2003 11:54:59 -0500, "William Lloyd" <lloyd_at_execpc.com> said: > This reminds me that not long ago someone asked about vacuum-bagging vs. > hand lay-ups, and that I'd replied (privately?) that there had been an > excellent discussion on that topic in an issue of Sea Kayaker magazine a > few years ago, between a proponent of each method, the proponent of hand > lay-ups having been Lee Moyer. Can that exchange be reproduced here for the > benefit of Paddlewise subscribers? Copyrighted material should never be forwarded to paddlewise without explicit permission from the copyright holder. Posting a link to an online version of the copyrighted material is usually the easiest method of letting people see copyrighted stuff. Kirk paddlewise admin. -- 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/ ***************************************************************************
Since this article is not available on Sea Kayaker's website and even if I got permission I wouldn't type it all, the best I can do is give you our side of the argument (just what we gave to Sea Kayaker for further editing). This is how it is in my computer just as it was written and formatted in 1984 on a Kaypro II in the Perfect Writer program using a CPM operating system (pre-MS-DOS). When you were as poor a typist as I was it was a little easier to edit with this program (at least after a tough few weeks learning the program) than using a typewriter (but still it was clacked out on a daisywheel printer) but definitely it was not nearly as easy as WYSIWYG ("What you see is what you get") editing that came a little later with Windows. It had to be clacked out on the daisy wheel several times to get the formatting right. Cam and I both wrote it together but as I was already their Safety columnist Cam's name is on it in the second (ever) issue of Sea Kayaker Magazine where it appeared (after some editing). Lee Moyer did the pro hand lay-up section. His valid points were that hand lay-ups are easier bond to for seaming and bulkhead installations and also for repairs, especially in areas where it is difficult to sand because sanding is not necessary to bond to a hand laminate. (note: This is true only if no sealing coat is added to fully cure the hand laid surface). We would have preferred a format where each party was allowed to respond to the other sides points since I believe we could have easily refuted the other points Lee made concerning issues (of importance to the consumer rather than to the builder) such as flexibility vs. stiffness and exterior finish (at the time Eddyline hadn't been using geloat on their. vacuum-bagged hull's exterior--which Lee said was the reason they were lighter). Actually a hand lay-up is lighter for equal stiffness/thickness because glass weighs more for an equal volume than resin does and there can be a far higher glass percentage in a vacuum-bagged laminate than possible with a hand laid one. It is the extra glass fibers in the laminate that makes vacuum-bagging stronger pound for pound. Sea kayaker sells reprints of articles. This one was on page 55 of Vol. 1 #2 (Summer-Fall 1984) if you wish to get a copy of exactly what Lee wrote and see what was edited out of our version please order it from them. The following is what I believe we sent to Sea Kayaker. _at_pagefooting[ ] _at_style[spacing 2 lines] _at_style[justification no] _at_center[VACUUM BAGGED VERSUS HAND LAMINATED KAYAKS] _at_center[by Cam Broze, Mariner Kayaks] _at_blankspace[1 line] _at_flushleft[_at_U(What is Vacuum Bagging?)] In vacuum bagging a thin plastic sheet is sealed around the edge of a mold containing fiberglass and liquid plastic resin. The air is then pumped out. Atmospheric pressure uniformly squeezes the materials between the bag and the mold and holds it under pressure until the resin hardens. _at_flushleft[_at_U(Putting The Debate in Perspective)] When selecting a sea kayak such factors as paddling ease, handling characteristics under various conditions, suitability to your purposes, safety features, fit and comfort are much more important considerations than the method by which the kayak was laminated. Also, the type and quality of materials used are likely to have a far greater effect on the strength of the laminate than whether it was hand layed or vacuum bagged. _at_flushleft[_at_U(Strength)] Even laminates made with inexpensive polyester resin and nothing but (or mostly) fiberglass mat can be made sufficiently strong by using more of those materials to build thickness. The major disadvantage to this approach, often found in British made sea kayaks and others with recessed deck fittings, is the considerable excess weight. Most experts (mainly in the aerospace and aircraft industries) agree that for equal weight, using the same quality and type of materials, an expertly vacuumed bagged laminate will be tougher and more flexible than an expertly crafted hand laminate. The optimum resin to glass ratio for maximum strength is beyond the ability of the hand lay up process to achieve because the resilency of the glass material will cause it to expand and suck in air if not held under pressure. The additional toughness of a vacuum bagged laminate means it can withstand harder bangs and blows without serious damage. For whitewater kayaks this is important. For most sea kayaks this toughness is tested much less frequently. Beyond the optimum glass to resin ratio, the smooth inside surface of a vacuum bagged laminate carries tension across it better than the rough hand laminated surface which provides many places for a crack to begin (much like a notch in a stick). This is one of the reasons why those who have tried removing bag wrinkles (because they can be seen through translucent laminates) by using a layer of nylon that is peeled off the part after it cures (Peel-ply) have found that they were producing weaker kayaks than those they produced with hand lamination. Because of the uniform pressure vacuum bagging also allows the use of heavier weave fabrics, such as woven roving, without layers of the much weaker fiberglass mat between them. To avoid air gaps when hand laminating with heavy fabric, the mat is needed to reduce the draining of resin out of the weave on vertical surfaces of the mold. Other reasons we prefer to have our designs vacuum bagged are: 1) The resin is fully cured on the inside surface because the vacuum bag separates that surface from the air during the curing process. Fiberglass laminating resin is air-inhibited, which means it never fully cures if left in contact with air, as with hand laminating. This uncured surface erodes (over time) when in contact with water, leaving pits between the weave of the cloth and weakening the laminate. (These pits are often seen as dark spots where they have filled with dirt.) Between uses care should be taken that water not be allowed to sit in a hand layed kayak, and float bags should be removed so moisture is not trapped against the uncured surface. Chlorinated water of swimming pools is especially corrosive and often turns this uncured surface white. The uncured surfaces become soft and somewhat sticky while in contact with water. Touching this for a period of time often causes a local skin rash in the area of contact (most often seen at the knee or where the thigh braces contact bare skin if those areas are not padded). 2) The smooth interior surface means there is less wear on gear bags than there is against the rough abrasive surface of hand lay-ups, and the heel area of your footwear won't get holes worn through. 3) The smooth fully cured inside surface is also far easier to clean. The main disadvantage of vacuum bagging is higher cost. This is due to the additional equipment needed, the cost of the 12 or 13 yards of rather expensive bag material that is required for each kayak, and the extra labor required to prepare the parts for seaming or installation of bulkheads. Any bag wrinkles, which are almost unavoidable near the ends of the kayak, must be scraped out and any surface that will be bonded with fiberglass (seams, bulkheads, etc.) must be well sanded. This is all unnecessary with hand laminates. One other benefit of vacuum bagging is that people working with this process are not as subjected to solvent fumes. We feel that the advantages to the customer outweigh the extra cost of vacuum bagging. Matt Broze http://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/ ***************************************************************************
Gordin Warner <hmgwarner_at_shaw.ca> wrote: >I was asked to explain the advantage or disadvantageous of swede versus >fish form hull designs the other day. In a heated discussion on P'wise a couple of years ago, Matt B. mentioned that fast birds, fish, and submarines are fish-form. They generally "operate" in one fluid. All other things being equal (which they're not), fishform kayaks have more directional stability--they tend to track in a straight line once set (note that this also means they can be more difficult to bring back onto one's desired course after a broach). I'm told that a lot of Brit boats have more volume in the bow than stern, which is supposed to sink the stern before the bow in a following sea, lessening the tendency to broach. (Note here, though, that this can be done with volume distribution without altering the plan shape -- fishform and swedeform are largely descriptions of plan shape) Fast ships and kayaks are Swedeform--they operate at the interface between air and water fluids, so their wavemaking shape is more critical than simply how they push straight through the fluid. I am told (and have noted) that often Swedeform kayaks are more maneuverable, and more responsive to leaned turns, although I don't know the mechanics behind this (but am eager to learn it!). As an aside, I suppose the S in Swedeform should be capitalized as a proper adjective. (But maybe the Norwegian in me would tend to spell it with a lower-case s. Just kidding, Swedish list-members!) Slightly-OT: Did you try Joe Greenley's Redfish King at R2K2? What a gorgeous Swedeform!!! Shawn __________________________________________________ Do you Yahoo!? Yahoo! Shopping - Send Flowers for Valentine's Day http://shopping.yahoo.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/ ***************************************************************************
In a message dated 2/18/2003 11:45:19 AM Eastern Standard Time, shawnkayak_at_yahoo.com writes: > ... I'm told that a lot of Brit boats have more volume in the bow than > stern, which is supposed to sink the stern before the bow in a following > sea, lessening the tendency to broach. ... How so? Best regards, Ralph Ralph C. Hoehn Ralph_at_Atlatl-Kayaks.com / Ralph_at_PouchBoats.com www.Atlatl-Kayaks.com / www.PouchBoats.com phone: +1-203-324-0901 *************************************************************************** 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 2/18/2003 8:31:34 PM Eastern Standard Time, shawnkayak_at_yahoo.com writes: > Supposedly... Thank you, Shawn. An interesting approach. Best regards, Ralph Ralph C. Hoehn Ralph_at_Atlatl-Kayaks.com / Ralph_at_PouchBoats.com www.Atlatl-Kayaks.com / www.PouchBoats.com phone: +1-203-324-0901 *************************************************************************** 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 archive was generated by hypermail 2.4.0 : Thu Aug 21 2025 - 16:33:32 PDT