Kelsall - KSS Build Method

[geekclothing]

Hi,
We are considering building a 42' Kelsall designed GRP catamaran. I would like to hear from anyone who has experience with this method, (preferably other than just a workshop). Someone who is building or has built their toy with this method. It seems there is a lot of "testimonials" on the kelsall website from people who have been to workshops but not many who are actually building one of his designs.
Thank you in advance,
Nathan

[waikikin]

Hi Nathan,
I have no personal experience with Derreck Kellsal besides a conversation with him at a boat show some years ago & considered attending the Toowoomba workshop, his methods seem wellfounded & to me a slight evolution on composite panel construction in regards to the hull forming/shaping process- from there onwards composite panel production would be similar for any boat for bulkheads & fitout etc although his experience in infusion would be advantagious if thats the way you want to go. There may be some more insight on boatdesign.net ? but you'll have to look, also Rob Denny has experience of his (posts here) of the build method. Depending on your location I may be able to help you with build premises & labour supply, if your in east coast Aus- use the private message facility if theres an interest in that regard. All the best from Jeff.

[rob denney]

Originally Posted by geekclothing

Hi,
We are considering building a 42' Kelsall designed GRP catamaran. I would like to hear from anyone who has experience with this method, (preferably other than just a workshop). Someone who is building or has built their toy with this method. It seems there is a lot of "testimonials" on the kelsall website from people who have been to workshops but not many who are actually building one of his designs.
Thank you in advance,
Nathan

G'day,

After the workshop stage, it is pretty much the same as any boatbuilding method. However, the workshop stage gives you a hull and deck in a weekend, so it is a significant part of the build, particularly in terms of ego boosting.

KSS is everything Derek says it is, and now that he has figured out how to compound the foam, there is less effort than there used to be. There is also no double glassing, cutting or shutting.

He can get pretty much any hull shape and his fees for converting another designers hull lines to KSS will pay for itself in time and effort saved.

The workshops are also a great way to learn about infusion.

regards,

Rob

[BigCat]

There are a few websites put online by amateur builders who are building Kelsall designs. One is:
Connemara Catamarans
A lot of people are doing the more or less flat parts of catamarans (including the topsides, which curve very little,) on laminating tables these days, usually with vacuum bags and resin infusion. Kelsall has his own method (3 by now, actually,) of doing the bit under water. On my website, you will see my version. Kurt Hughes is now doing the same, except he is still doing hull bottoms the 'old fashioned' way, using foam planks and lots of sanding.

[geekclothing]

I had seen that website before... that guy has spent something like 8000 hours and from what still has a boat with no wiring etc... i was hoping to find someone that had built with this method alot quicker than that. We were hoping to build one in two years...

[BigCat]

Google Image Result for http://www.geocities.com/TheTropics/Shores/1748/hullf4.jpg

CorkyPerry.com

Are a couple more KSS builders, but the Irish site is probably the most comprehensive. Building a hull and deck is only the beginning of building a boat, and there's not much Kelsall or anyone else can do about that. If you are going to have inboard engines and lots of elaborate systems, that will take lots of money and time, no help for it. Kelsall's system or similar is definitely going to save thousands of hours of filling/sanding/fairing compared to other glass one-off systems.

[Designz]

Originally Posted by geekclothing

Hi,
We are considering building a 42' Kelsall designed GRP catamaran. I would like to hear from anyone who has experience with this method, (preferably other than just a workshop). Someone who is building or has built their toy with this method. It seems there is a lot of "testimonials" on the kelsall website from people who have been to workshops but not many who are actually building one of his designs.
Thank you in advance,
Nathan

Nathan,

I am a professional naval architect and I have attended one of these workshops. While I fully understand why this method appeals to so many people, I have the following concerns about this construction method;
This is my view.
1) During the building of the hulls considerable stresses and loads are inherently locked into the structure (the sandwich laminate). This does the following;

• Reduces the reserve strength of the laminate (because some of it has been taken up in resisting the loads imposed during construction).
• Make the structure less flexible, i.e. it will not be so forgiving of a "bump" or collision of some kind during use.

2) Many of the infusion practices presented at the Kelsell need to be revisited and improved. After my workshop I spent a considerable amount of time researching resin infusion techniques and I was horrified at the lack of in depth understanding that was displayed during the workshop. As a qualified boat builder (with many years experience in a wide range of techniques) I was not impressed with some of the answers that I received to questions, nor some of the practices I saw him demonstrate.

Many people (and probably Dereck himself) will say that they have had few failures during construction, but that is no excuse for poor practices. One of the issues with sandwich construction is that it is hard to be absolutely sure of the final product (without doing extensive destructive testing), so every caution should be taken to minimize the risks.

By all means attend a workshop (if you feel that it will assist you), but I think there are plenty of other ways to learn about infusion techniques and depending on the final design you choose the designer can also assist you with the build process. Also be aware that Dereck has a vast amount of practical experience, but poor technical experience (by his own admission to me during the workshop), thus he sounds very convincing and many people love him for that, but the technical aspects of catamaran design (and especially structural analysis) are ignored at your peril.

Regards,

designz

[Robertcateran]

From what I have seen, there doesn't seem to be a great deal of tension locked into the fibre, there is plenty of surplus strength in the material, Even if the infusion techniques are far from perfect, they end up with a skin with better fibre to resin ratio and much better contact than a hand lay up with a lot less mess. The ratio was adequate for the boats to sail for many years without problems before the use of infusion. As long as the resin gets to all the parts before going off, I really can't see what the problems are. If it was infusing a high stressed material with poor wet out properties , then one would put the effort into getting the system near perfect. While I don't necessarily agree with some of his ideas, such as the raked bows on his boats, I have never heard of one with structural problems. Yes, the boats could be made lighter and stronger with more exotic techniques, but on a cost benefit analysis for a cruising boat, it makes no sense.
There are professional boat building companies using his techniques to good effect on price and quality. eg Barlotta boats. There is time saved in build and even more in fairing. Unfortunately you have only just started when you have the hulls built,
Robert

[Robertcateran]

Yes composites are lighter and stronger, but stressed ply hulls do pretty well. Tornado catamarans have done pretty well for longevity

[catty]

With any boat building system there's good and bad. But to suggest that an amateur builder will get a finished hull and deck in a weekend using KSS is plainly misleading. The recent Australian workshops with many able bodies present couldn't achieve this. At the end of the day with KSS you get a hull shape with flat sides and a roundish bottom that in the words of Mr Kelsal still require fairing and painting . Geeze for the amount of money and time the amateur is investing in the project you may as well build in a method that gives you an optimal and pretty hull shape with very little extra effort such as Mr Farriers verticle strip foam system. Remember a thing of beauty is a joy forever.

[S/V Elusive]

whewwwwwww .. you guys like keeping us busy, thats for sure. Posts are under review because they appear to me to be inciting problems without adding to the TOPIC!! Responses to the inciting posts have also been put under review, and may have to be edited later to remove the references and retaliational remarks. Otherwise this seems like a good discussion - lets keep it that way. In the future, may I suggest that when you have a situation that violates our rules of personal attacks and inciting problems, that you take a moment to report it using the exclamation warning triangle at the lower left of the post you wish to report. This will help us Mods / Admins help YOU keep your topics on track. Please - only ONE report is necessary.

Thanks
Thomas
Cruiser's Forum Moderator

[Boracay]

Having built a ferro yacht and a WEST plywood yacht if I was to build again (and had the space!) I would build a plywood cat.

Using the WEST system the ply (and all other wood) is totally sealed.

Many of the components could be prefabricated before assembly, saving time, effort and money.

Two pack linear polyurethane (buy a supplied air mask before starting) gives a superb finish.

Have a look at the EasyCat site and see how many builders have actually finished (and read between the lines to work out how long they actually took).

I would suggest rethinking the 42' size unless it is essential to your plans. Many of the Easycat builders look to go for the 37 or the 11.6. These are probably the largest boats that an individual builder can make without BID (Boat Induced Divorce) striking.

[BigCat]

Catty, here http://www.nwmultihull.org/builders/.../KSS39hull.jpg
is a photo of a Kelsall designed hull upside down-I think the shape is perfectly reasonable.

I don't think the topsides or hulls of Farrier catamarans are very different. See:
http://www.f-boat.com/media/catamara...chchcrane1.jpg

[waikikin]

I think I'm missing something, I got an email notification for this thread I think & the posts not here in context? & seemed to include attendance at a Kellsal workshop as requested by the original thread. Whats goin' on. From Jeff.

[northerncat]

2 years, build an easy i did it in this time and i worked part time, 2 peopl would knock an easy out in at least 9 mths
sean