boat building

[Glenn Wood]

Greetings,

I am somewhat new to woodworking and have tried to choose projects that required me to practice specific jointery or woodworking skills. However, my Grand-daughter decided I should build her a sailboat. I have settled on an "Optimist" primarily because it is a very large class of boats (it is raced here at the the SYC) and , relatively speaking, simple to build.

Even before I get started (You have to order the plans from Holland) comes the decision of what kind of plywood to use. Names that have come up are, Okoume, Meranh, Sapele, & MDO. MDO is the only one I have ever heard of.

Anyone have any comments on pros & cons of these materials?

After this hurdle is cleared, I would appreciate any comments/suggestions on this project.

Thanks

Glenn Wood

[Peter Lyon]

Glenn,

Although I'm hardly a boatbuilding expert -- I built three sea kayaks a few years back -- IMHO, the Okoume well work well and will finish quite nicely. I guess one thing I would consider if I were in your situation is what final "look" are you going for? Bright (clear) or painted? Obviously, the MDO will have to be painted but is likely much cheaper.

Good luck. Due to the need to develop a fair curve, boats present a unique challenge to woodworkers. One has to develop a "touch" with a block plane, rasp, or wood shaping instrument of your preference.

Peter Lyon

[Chris Messier]

I am not to sure about the types of wood to use. I have read some stuff some where that suggest Teak, White Oak, Marine Plywood, and there was some others that I am drawing a blank on. I do have some links that you can check out that hopefully will lead you in the right direction. If you would like the links please contact me by PMing me or e-mailing me at Messmanswoodworking@cox.net

[Robert Ducharme]

Welcome to the CREEK!! By the way, just because it is called Saw Mill Creek, does not mean you have to build a boat to traverse it. :D What you are doing sounds like fun.

[Tyler Howell]

Welcome Glenn,
We have a few resident experts here!

[Dave Richards]

Glenn, welcome to the Creek.

The Optimist Pram dinghy should be a great first boat.

Okoume, Meranh (Meranti) & Sapele are common veneers on marine grade plywood. Marine grade plywoods have no voids in them and are made with waterproof glue. Most are made to a British standard (BS1088) and the fact that there are no voids allows them to bend and make fair curves. A void in an inner ply could create a stange area in the curve and also a weak spot.

These plywoods are desirable also because the won't check with exposure to UV which common fir ply will do. Even with paint on it, fir ply is prone to this checking which, with water around, is not a good thing.

If you look around in your area, you should easily find marine grade plywood. If the price is a turn off, you might also consider using luaun plywood. It depends on the thickness required for the boat--I can't remember what it is on the Optimist. Luaun is usually used as an underlayment plywood for flooring. The glue is waterproof and the luaun won't check. It isn't normally sanded as smooth as the marine plys but it will sand out fairly easily. Also luaun tends not to have voids because of its application. A void would eventually telegraph through the veneer layer and through the vinyl on your kitchen floor.

I used a bunch of luaun on the sailboat I built--decks, cabin roof, hatch covers, port window trim rings--and had great success with it. I used 3/8" ply but I know it is available in 1/4" as well.

As to making fair curves, that's not really all that hard. When laying out the curves to cut on the plywood, you make marks at points as given in the plans, set small finish nails at those points and bend a batten (clear, thin strip of wood) around the nails. Trace your line and check it for fair by sighting down it at a low angle. Actually, if you find the batten misses a nail when you bend it, that point or one on either side may not be correct. Reset the nail and check.

Cutting the curves is most easily done with a circular saw. That's right, I said circular saw. Set the blade so it will just pierce the plywood and cut following the line. the big, sweeping curves you are cutting come out quite nicely.

I don't remeber how chines are done on the Optimist. If there's a chine log on the inside, that will help you get the fair curve you want, too. Saw the plywood a hair proud of the line and then attach the chine log floowing your line. Start at one end and screw and glue bending the chine log in as you go. Once the chine log is attached, trim the plywood to the log. Then adjust the mating piece of plywood as needed. It actually wouldn't hurt to leave a slight gap between pieces of plywood at the chines. The gap can then be filled with thickened epoxy and radiused after it cures.

I expect you'll glass the outside of the hull. This is a simple procedure but I won't go into that now since I've gone on quite enough. I will say that you might consider putting the back face of the plywood out if you'll be painting it after glassing. That way, you'll have the nicer face on the inside where you might varnish it and leave it bright.

Here's a picture of the sailboat I built and launch last August.
http://www.woodshopphotos.com/albums/Dave-R1s-Album/sub10a.jpg
http://www.woodshopphotos.com/albums/Dave-R1s-Album/hatch.jpg
In the last picture, you can see the lauan hatch cover on the cabin as well as the one behind the wheel.

Good luck and keep us informed on your progress.

Dave

[Glenn Wood]

Dave,

Thanks very much for your comments. The Optimist is not nearly as complicated as your boat but, based on your results, neither am I as experienced a woodworker.
I found an outline of the construction @ www.optiworld.org.
In your comments, you didn't mention MDO. Any comments on it as an option?

Thanks again & I will keep you posted.

Glenn Wood




Glenn, welcome to the Creek.

The Optimist Pram dinghy should be a great first boat.

Okoume, Meranh (Meranti) & Sapele are common veneers on marine grade plywood. Marine grade plywoods have no voids in them and are made with waterproof glue. Most are made to a British standard (BS1088) and the fact that there are no voids allows them to bend and make fair curves. A void in an inner ply could create a stange area in the curve and also a weak spot.

These plywoods are desirable also because the won't check with exposure to UV which common fir ply will do. Even with paint on it, fir ply is prone to this checking which, with water around, is not a good thing.

If you look around in your area, you should easily find marine grade plywood. If the price is a turn off, you might also consider using luaun plywood. It depends on the thickness required for the boat--I can't remember what it is on the Optimist. Luaun is usually used as an underlayment plywood for flooring. The glue is waterproof and the luaun won't check. It isn't normally sanded as smooth as the marine plys but it will sand out fairly easily. Also luaun tends not to have voids because of its application. A void would eventually telegraph through the veneer layer and through the vinyl on your kitchen floor.

I used a bunch of luaun on the sailboat I built--decks, cabin roof, hatch covers, port window trim rings--and had great success with it. I used 3/8" ply but I know it is available in 1/4" as well.

As to making fair curves, that's not really all that hard. When laying out the curves to cut on the plywood, you make marks at points as given in the plans, set small finish nails at those points and bend a batten (clear, thin strip of wood) around the nails. Trace your line and check it for fair by sighting down it at a low angle. Actually, if you find the batten misses a nail when you bend it, that point or one on either side may not be correct. Reset the nail and check.

Cutting the curves is most easily done with a circular saw. That's right, I said circular saw. Set the blade so it will just pierce the plywood and cut following the line. the big, sweeping curves you are cutting come out quite nicely.

I don't remeber how chines are done on the Optimist. If there's a chine log on the inside, that will help you get the fair curve you want, too. Saw the plywood a hair proud of the line and then attach the chine log floowing your line. Start at one end and screw and glue bending the chine log in as you go. Once the chine log is attached, trim the plywood to the log. Then adjust the mating piece of plywood as needed. It actually wouldn't hurt to leave a slight gap between pieces of plywood at the chines. The gap can then be filled with thickened epoxy and radiused after it cures.

I expect you'll glass the outside of the hull. This is a simple procedure but I won't go into that now since I've gone on quite enough. I will say that you might consider putting the back face of the plywood out if you'll be painting it after glassing. That way, you'll have the nicer face on the inside where you might varnish it and leave it bright.

Here's a picture of the sailboat I built and launch last August.
http://www.woodshopphotos.com/albums/Dave-R1s-Album/sub10a.jpg
http://www.woodshopphotos.com/albums/Dave-R1s-Album/hatch.jpg
In the last picture, you can see the lauan hatch cover on the cabin as well as the one behind the wheel.

Good luck and keep us informed on your progress.

Dave

[Dave Richards]

Glenn, I can't comment on the MDO since I've never used it. I've heard that some boat builders have used it but I don't know what their experience was. I don't know how the price of MDO compares to luaun but from prior experience, I would be inclined to use the latter. If you plan to glass the hull, I don't think you'll have any problems with it.

I did do a little looking and saw photos of an Optimist being built. The builder braced the bottom against his shop ceiling to induce and hold the rocker while he installed the sides. I don't know that you'd need to do that.

It does appear that there are chine logs which should make fairing the chines a cinch. Just do as I wrote above.

BTW, the paint is only the premium grade extrerior latex from a big box. Cheaper than marine paint, holds up as well and is easier to touch up. Colors were mixed based on colors from Kirby's (http://www.kirbypaint.com/).

I don't know if any of that is helpful. If I can obfuscate any more, just let me know.

Dave

[Lynn Sonier]

I've built two 10 foot stitch & glue boats and I don't think it matters very much what plywood you use as long as you encapculate it in epoxy. There is an excellent boat-building forum at bateau.com. You can read up there on different building methods.
Lynn

[Mike Swindell]

Where else to try but www.woodenboat.com? They have a great forum and are full of .... well experience. I totally rebuilt a Chris Craft Runabout, lots of fun when you have never fit a curve before. Don't worry about plywood construction, the curves have all been calculated, boat wood ain't cheap but you find some for chines, decking, etc. in SC.

Good Luck