JEM Watercraft

I am looking at building, some time in the future, a 30-40' cruiser which I hope to sail across the Atlantic with my dad.

I have been looking at some plans on the web and the materials I have available locally and there is a local timber merchant who supplies cedar strip in 'bead and cove' or 'rapid strip' which is similar to tongue and groove which I would of course cover in a layer of glass. This obviously negates the need to caulk the seams reducing costs(?) and time.

My question is this - how thick should I make the hull as the strip come in a variety of sizes? I have also heard that the strength can be increased if the epoxy is used in a way to create a composite by surrounding every piece of strip - is this true?

Any help you can give would be of great help.

Cheers

Gaffers

Much will depend on the specific design and materials used to build it. Thinner planking can be used if you're using thicker fiberglass. Thicker planking if no fiberglass is used.

Is this a design of your own?

You would have to epoxy saturate the wood ( put at lease one coat of epoxy) so the fiberglass and new epoxy has something to bond to . That will help strengthen the wood but the glass is the main item for additional strength and protection.

The epoxy saturation will also help to bond (glue) the strips together plus waterproof and strengthen them.

Chuck.

I was considering epoxy coating the strips but only when I was fitting them instead of coating each one, then having to sand them before glueing them to one another with more epoxy. obvioulsy the whole hull will need a sanding before putting on the FG sheets but is this type of construction really that strong?

I was just wondering if I could get away with thinner planks, say 9-12mm rather than 15-18mm, for this size boat. I was thinking of using some medium density FG just for the ease of use but the size of the planking is purely for finances!

Many thanks in advance!

Gaffers

If we knew the boat type and design, it would be easier to offer suggestions.

I am looking at the Roberts Spray centenial 38 or the Roberts 370E. Just for my learning on the subject, what in the design would affect the size of the bevel and cove strip and the FG used?

Many thanks in advacne.

Gaffers

The designer will go through the engineering calculations to determine the best scantlings.

Scantlings are a term that describe the combination of materials, their type and characteristics, to make up the hull.

The designer typically makes decisions about materials cost, ease of build with the materials, material availability, etc. And all of those must meet the load pressure demands placed on the hull with a reasonable safety margin.

So you get something like: Use 1/2" thick bead and cover strips with 9-ounce clothe over the wooden substrate, inside and outside the hull. That's just an example I pulled out of the air.

If you have a design in mind already, then those plans should specifically provide what you'll need to build. If they don't, then you might want to consider other plans that are more complete.

Bruce Roberts, the designer of the Centennial Spray 38, is a very accomplished yatch designer. I'm confident his plans will be very complete. Looks like they have an e-mail you can contact them at. I have not heard how quick they respond. With that many designs, I'm sure he'll get back to you about specific questions.

But you're more than welcome to continue to post thoughts here.

I e-mailed Bruce Roberts to let him know there was a question about his designs and he replied already!

So shoot him an e-mail and looks like you'll get some good service.

G'day Gaffers and welcome aboard mate. I have delayed responding to your original post here because I was curious bout where it might lead.

If I understand you correctly, you are planning on building a strip plank boat to cross an ocean?

Have you built a stripper before? If not, I very respectfully suggest that you build a strip plank canoe first. There are benefiets to this.

The first is that it will give you a good base of knowledge on how the stripper process works.

The second is that it will give you a very real idea of the magnitude of the task you are planning to undertake.

It is all well and good to lay up a bunch of timber strips and then cover them with epoxy/fibreglass and take it out on the local pond or river. It is something else altogether, to build a boat to take you across oceans. Literally, you will be betting your life (and those with you) on your build.
While finances are allways important, you need to build the best boat that you can. Skimping on the hull build is not a good idea IMHO.

The Roberts boats are very popular in Australia and there are a lot of them running up and down our east coast. All the owner/builders are very happy with them. Good luck with your build mate

Firstly many thanks for your time in helping me with this. The timelines for this build are well in the future and to give you an idea I will am building one of the stitch and glue from boatplans.dk (how i got to know your website btw) to get a feel for working with epoxy and to have something I can mess a bout with on the lake here in Munster, germany.

I was planning to build a small craft using strip planking before attempting anything as big as the boats I mentioned - not just for practise which is all very important but also to have a tender for the larger boat once it is finished.

I emailed Bruce with a couple of questions but he seems to plug his study plans which I understand. If I was in the business you gotta eat, right?! I am looking to get these study plans before I go to ´sunnier climbs´ for 6 months so hopefully the info will be there. I love his boats and designs but I want to make sure I can build it without it falling apart in the middle of the Atlantic before I undertake a massive job like this, besides the missus still needs a bit more convincing! She has seen me reading George Buehlers book as has been nagging me to wait till we have more money first!

I will update this as and when I get more info.

Thanks again fellas great advice as always,

Gaffers