Whats the best material for hulls for home built 30' cat

[John Thompson]

Which materail is best plywood or strip plank construction for hulls

[frosh]

Hi John, The question needs much more qualification to be able to be answered by forum members with any justification.
Is it an own design? If so, what is your previous experience in design? What is your boat building experience? Is cost very important? What is the availability and price of lumber such as cedar for strip planking where you are?
How important is aesthetics in the hull shape? Are you considering even a combination of sheet ply and strip planking? Is it a long term project?

These is not a full list, but is enough to get started with some dialogue.

[John Thompson]

Thanks frosh, I have been considering different designers. I think I will go with Kurt Hughes 30' open bridge deck. My experience is beinge a house builder and designer and finish carpenter for the last 30+ yrs. I have built wind surfers and repaired many surf boards, built a wood camper and glassed it and have a garage that is big enough to pull it off in. My experince in sailing has been a prindle 16 for 20 years. Every time I drive by the ocean I wish I was on it sailing (steady as she goes) and can only afford to build verses buying something new like a Raider or Dakota cat. Any way all my reserch on home building refers to Strip Plank and Kurt Huges design is for plywood. I want a boat that can stand up to strong conditions including beaching and I have not been able to find anything for comparison on hull materials except composite and metal and fiberglass. I have a lot of time to build and am not to conserned about cost difference between the two. Aesthetics is very important, form and function.
Thanks for any feed back on this. John

[Chris Ostlind]

Hi John,

Send Kurt an email about your interests, concerns and your questions. Let him know of which model from his portfolio you are interested. He has a lot of experience dealing with first time builders of his designs and can probably share a few documented diaries, complete with photos, of the exact boat being built.

He's a very approachable guy who really wants to see you find the right project for your pasison.

Chris Ostlind

[frosh]

Hi John, you are very wise to go to a recognised designer first up. Many people on this forum want to design, build and then sail, when they have no experience in even one of the three.
By the sound of it you should be able to achieve a good result first time round. The difference in durability of a properly engineered plywood or strip planked hull is not an issue at all.
All plywood gives a hard chine or multi chine shape. Strip planking gives a nicer looking round bilge.
For durability of the surface (as I assume that using a designer will lead to a structurally sound craft), there are many types of reinforcements.
If you intend beaching regularly than the maximum abrasion resistance will come with sheathing the hull or maybe to the waterline with Dynel and epoxy resin. This fabric virtually will not scratch or break with moderate impacts, and of course provides a watertight skin to the timber.
Some cats have been built with sheet plywood topsides, and strip planked bilges and bottom. Ask the designer about it.

[John Thompson]

Thank you Chris and frosh,
I am going to keep kurt in the loop and feel that we I will get a good product. Thanks for the feed back.John

[T.McCaw]

John have a look here
http://www.f-boat.com/pages/trimarans/index.html

Tom

[catsketcher]

Hi John,

If you want a round bilge hull then I would recommend strip plank. In fact when costing my latest little project I found foam much cheaper than strip cedar. I am paying about $35 a metre square for 10mm foam. Cedar costs a lot more than this in Oz.

If money is no concern you may still like cedar - it is nice to work with wood but I think vertical strip foam is easier and will probably produce a higher resale value cat. If you work on your own the fiddly bit of laying filler between the planks - takes a lot of time.

When it comes to the flat panels in the boat I am a fan of ply until it takes a lot of framing to keep it stiff. In a 30ft cat the interior furniture should be arranged to stiffen the structue and reduce stringers and the like. For the deck I would consider foam for insulation and ease of building as the ply deck needs stringers.

My 38ft cat is strip cedar/ ply and it is very light. Ply gets no fairing inside which I think really adds on the weight on some boats. My little folding cats have been strip Kiri and ply and now vertical strip foam and ply with foam decks.

To save time and money see if Kurt will give you DXF cutting files of all the furniture so you can get all the flat ply pieces computer cut. It is very nice to walk over and get a part pre cut, even if it requires a little trimming.

My web site has a log of the foam and ply build procedure. It may give you a little of the processes involved - www.foldingcats.com

Good luck with your build

Phil Thompson

www.foldingcats.com