> I just ordered plans for a Chesapeake 17 and I am still trying to decide on
> whether to use okume or not.

If cost is a factor, or this is a first attempt with the intent (and budget) to do better job later, or you just want to evaluate the boat's design, then you can use the cheapest materials you can find. If you looking at this as a once-in-a-lifetime project, then save your money until you can afford to have the best materials shipped to you. Those are the two extremes. Numerous `middle' options/opinions are possible.

> I have read the arguments against using 1/4
> inch or 1/8 inch luan but I have never heard of people using two 1/8 inch
> sheets epoxied together. It seems that the core thickness problem and
> voids of 1/4 inch luan would be minimized. Has anyone ever tried this?

If you carefully examine and fill any checks cracks or voids in the back of the 1/8 inch sheet, and then laminate the two worst side together you might achieve this goal. Your 1/8 lauan might not be a true 1/8th inch, but a nominal size. Maybe it is actually 3mm.

Near me they sell nominal 1/4 inch lauan sheets for under $8 for a 4 foot by 8 foot panel. The true thickness is listed as 5.2 mm. If you do the math of 25.4 mm equals 1 inch you'll find that 1/4 inch is really 6.35 mm, so these panels are a bit over 1.1 mm thinner than 1/4 inch. For that matter, they are only about 1.2 mm thicker than 4 mm. What would not work with 1/4 inch (6.35mm) just might work with 5.2 mm. For the price of a few panels you might want to experiment.

I have a few thoughts about laminating two sheets of 1/8th inch (or 3 mm). First, when you laminate them you make a thicker sheet that is more difficult to bend. The thickness of the epoxy you apply is going to be thicker than the precisely measured, miserly amount, of adhesive used by the guys who make up plywood panels for a living. This will probably make it a bit more difficult to bend. On the other hand, if each sheet is 3 plies, then the combination you propose will be 6 plies, with 4 of those plies going up and down, and two going left to right. By contrast, a factory made panel would be an odd number of plies (probably 3 for an inexpensive panel, and perhaps 5 for something like structural aircraft plywood). Of that you would have either 1 thick middle layer that is oriented left-to-right, or two thinner ones. It is your guess as to which one will bend easier, but the latter is closer to what you would be making.

I have some 1/8th inch (3mm) Meranti panels in my garage waiting for me to assemble into a Yare, following the plans in Chris Kulczycki's book. The stuff is like Lauan, and sold as an inexpensive floor underlayment. It is amdee with an exterior-rated glue, and has one good or 'A' side and one rough side, which would be either a `C` or `D' rating. I went through the stack at the lumber store to find those with the best backs. When I could not find as many as I wanted, I selected some with flaws in areas I could cut around. It helps to have a good mental grasp on the plans before buying your lumber if you chose to do things this way. Just to be safe, I bought extra panels. They were about $7.50 a panel.

I thought of laminating them with epoxy (good sides out) to build up a nice `A-A' panel, as you asked, but have not done so. The Yare design calls for the panel to be flexible enough to be bent into shape, and suggests 4mm. What I will do is to build the hull from the thinner material, and bend it into shape. Then I'll cut additional pieces that are a bit smaller, and use them to line the hull. In the cockpit area the hull material will be at least 6mm (about 1/4) thick. I'll probably not extend the added thickness all the way to the bow or stern, as I expect it would be hard to get it into those areas. Besides the added thickness in the cockpit area I'll be able to cover the bad side of the plywood, giving a pretty interior. I'm not a bit concerned about the `looks' in areas that people can't see.

I expect a few problems with getting that interior piece to fit. Unless I can get enough weights or wedged props on the interior to force the wood to bend, I might have to put a few blocks of wood on either side of those panels and drive screws through to pull them together until the epoxy sets.

> Also could I run the two 1/8 inch sheets through my thickness planer to
> get them to the 4 mm thckness.

I don't know how good your thickness planer is. It might work. BUT, if you glue the two bad sides together you will be tearing off the veneer from a good side -- and it is not very thick. You might consider planing down the bad sides of both shhets of plywood before you laminate them. On the surface planers I've seen the cutter heads stay about an 1/8th of an inch above the feed table, so I think you'll need to build up the base of most planers to work on materials as thin as 1/8 th inch. A piece of 3/4 inch plywood should work. If you make it long enough it will also help keep the plywood supported. Another post has suggested that a planer will rip up thin plywood, and that may be a good reason to avoid this. If you decide to see for yourself, take care.

A thought: Unless you can plane an entire 4 foot wide panel (pretty expensive tool to do that) you'll probably be planing a piece about a foot wide, or narrower. You could use a temporary adhesive, like rubber cement, to hold the GOOD sides of two pieces of ply together while you cut out your parts. Then, while they are still attached to each other, pass them through the plane, shearing off an entire ply from the one bad side. If you take off the entire layer of wood you just might get a smooth cut. If this is still too thick, flip it over and take something off of the other bad side. when the thickness suits you, separate the materials, apply glue to the two bad sides, and laminate them with the good sides out. Your mistakes/rough cuts etc. are buried inside. (Gee isn't this how the big companies make those panels).

If you decide to laminate thin plywood to make thicker plywood you can make panels any length you like. Forget scarf joints. Butt one panel up against another, and lap over the seam with the second panel. If you need long 1/4 inch panels you can make them easily from stacking 1/8th inch panels.

Let's look at another thing here. You are trying to get 4 mm materials? Why? Is it for the strength, or are 4mm panels a compromise that allows the most strength that you can still flex into shape? Well, obviously a MORE flexible, thinner, panel will be easier to pull into shape. After that you can increase the strength by adding fiberglass cloth and epoxy resin. Geore Roberts has been using 1/8th inch cedar strips (instead of the more commons 1/4 or 3/16th strips) and covering them with multiple layers of thin fiberglass cloth. If I remember correctly, he likes to use 3 layers of cloth on the outside and 2 layers on the inside. He uses 2-ounce cloth instead of 4-ounce or 6-ounce cloth. (George: If I'm mis-stating your technique here, set me straight)

3 layers of 2-ounce cloth weighs the same as a single layer of 6-ounce cloth. With either way you should use the same amount of resin. Similarly, two layers of the 2-once cloth weigh the same as a single layer of 4-ounce cloth, so the weight of the boat is not affected and you shouldn't have to buy more resin. A yard of the lighter-weight 2-ounce cloth is less expensive than 6-ounce cloth, but not by much. It is not 1/3rd the price (unfortunately), as you can frequently get better deals on the more commonly used 6-ounce and 4-ounce fabrics. If it is any consolation, shipping costs (which are usually based on weight) should be the same.

There have been numerous debates on this BBS about which method is better: Single layer or multiple thin layers. Read them when you have the time. For now let me just say that you can use fiberglass fabric to cover the inside and outside of a hull made from 3 mm or 1/8 th inch plywood and build up as many layers as you want to make the hull as strong, or stronger than one constructed using 4mm plywood. For myself, if I was trying to save money by using doorskins I'd use a single layer of 6-ounce fabric on inside and out, and I'd use the left over scraps to make a second layer under the center for scratch resistance.

Since you have a planer you might want to experiment with a concept I've been considering: Make your own 4 mm thick panels from edgeglued woodstrips. For strength and convenience I'd start with 3.5mm to 4 mm strips (a tad over 1/8 th inch thick) ripped from the same cedar or pine stock I would use for a strip-built canoe or kayak. I would make a work table from a sheet of 3/4 inch particle board (Cheap and flat) and assemble panels a foot or two wide. I'd drill 1/4 inch holes in the particle board (at intervals like those used for adjustable shelves in book cases) and insert sections of dowel rod, or 1/4 inch bolts, and use wedges shoved against those to exert a clamping action on the woodstrips while the glue set. I could make clamps like this from several 2 x 4 foot sections of particle board, and by laying these on a reasonably flat area I could just keep adding strips and particle-board clamps until I ran out of space to work. After the glue (epoxy?) set I would either smooth the panel with a belt sander, or, if it was narrow enough, run it through the planer again. I might add a layer of thin fiberglass cloth (4-ounce or lighter) over one face (which would go on the inside of the boat) to ensure the strips are firmly connected. The second sdie wouls also be sanded of planed smooth, and to a perfect, even thickness. I'd then cut my parts for a stitch and glue from these panels, and procede as if I was working with plywood.

The `look' of the boat would strongly suggest it was a stripper, but I would not need to cut out frames, or construct a strongback. By being able to apply the first layer of glass cloth to a flat panel I would (hopefully) avoid runs and drips. By running the panel through a surface planer I would greatly reduce sanding as all the joints would bethe same height. (No `bridging' when I put on the glass cloth) By sanding the flat panel I would avoid having to sand the concave interior. I would not need to use cove and bead bits or scarfs to achieve long lengths or widths. If the wood strips were exactly 1 inch wide I could even use them as my graph paper lines when laying out the panel shapes!

> If not does anyone know of a supplier of Okume on Long Island. Thanks.

You would have to ask at least one question I can't answer, wouldn't ya.

Best of luck to you on this. I hope some of these comments help you out.

Paul Jacobson