Cheap Plywood

[jem]

The quality of plywood in your various home improvement stores is usually lacking. Ok....it sucks.

But I had a small project where some mods were required for a prototype and didn't have the time or $$ to wait for more Okoume (it's not sold locally where I live). So off to Lowes I went. I used to check out Home Depot but their quality in lumber is really getting bad.

Anyway, I picked up some "exterior 5.2mm hardwood". Wasn't exactly what I wanted but it would do for my task. I'm not exactly sure what species "hardwood" it was. Had a almost pinkish color so I'm thinking some variation of mahognany. It was harder than Okoume but softer than oak.

Upon cutting it, it splintered a worse than Okoume but I found facing the "good side up" and using my portable circular saw gave me better results. Still plenty of splinters but a trade off I was willing to except for $9 a sheet.

I got to inspecting the wood after cutting and I was shocked: No voids. I was cutting several thin strips so I got a good sampling of the entire sheet.

Upon assembly, it bent well as was ok to work with. I wish I would have weighed the sheet before cutting.

Wasn't real resin thirsty either. Maybe a little more than Okoume but the faces were very clean with no knots so that helped.

If I was on a tight budget or it was my first boat, I'd be very tempted to use it. I'd go with a 4-ounce cloth on all surfaces to prevent checking.

As far bang-for-the-buck goes, 100% thumbs up.

My next project I'm going to try out some .25" "underlayment" and see how that works out.

Okoume is still the best around but it's so hard to come by in some places.

[NAJ]

Glad to see you approve of my choice of wood for my bookshelf/ first attempt at boat building. I too am impressed with the quality of this $10.00 a sheet ply but my experience is lacking. The 1/2" was three ply and not to bad but requires a lot of sanding to look good. I am doing this on the CHEAP and am using bondo polyester resin from Lowes also cutting tape from cloth I bought there. It goes off fast and my tape seams on the insides suffered a bit but the surform helps me clean it up. I bet tape would be worth every penny but I couldn't wait and am just cutting strips from the cloth. I glued the bow and stern seams first, then the bottom and am working on making the inside look good before I glue in the shelves. I think I will finish the shelves before I install them also. I am planning on coating the inside and out with the polyester resin and not planning on covering it with cloth. Is there anything wrong with this idea? Has anyone else used polyester resin for their boat? I am sure it is not as good as epoxy but this will never see the water. Is checking a problem with polyester? This has been a great project and a good confidence builder. The plans made perfect sense to me and I didn't have to redraw to many lines. (Good thing I remeasered). Not to sure what I am going to do for gunnels and thwarts yet. Will I have to steam them to get them to bend properly?

[jem]

I am planning on coating the inside and out with the polyester resin and not planning on covering it with cloth. Is there anything wrong with this idea?

Nope no problem there. Since it's a book shelf, you don't need to cover all wood with resin.

Has anyone else used polyester resin for their boat? I am sure it is not as good as epoxy but this will never see the water.

I've never used poly to build a boat with wood. I've helped out in a shop with laying up one that made of all fiberglass. It's reasonable easy to use and cheap. But it stinks to high-heaven and is not as versitile as epoxy.

Is checking a problem with polyester?

That has more to do with the wood. But it's an indoor shelf. You shouldn't have a problem.

Not to sure what I am going to do for gunnels and thwarts yet. Will I have to steam them to get them to bend properly?

No steaming required. Wood should bend with a little force ...young Jedi Boat Builder.

[Rick Tyler]

Not to sure what I am going to do for gunnels and thwarts yet. Will I have to steam them to get them to bend properly?

No steaming required. Wood should bend with a little force ...young Jedi Boat Builder.

Heh. I think you mispeledded "Would should bend with a little force... my padawan boat builder."

[aub77]

Here in Birmingham, the Lowes 5.2mm exterior is exactly as you describe. Pretty good stuff for small boats and seems to have true exterior glue. It is a luan or "Phillipine Mahognany" (sorry about the spelling). A tropical hardwood of some sort but not a true mahognany.

By the way, the Virola 5.2mm "Moisture Resistant" stuff from Home Depot is worthless as a boatbuilding material unless you want to toss the boat in the garbage after only one season.

[jem]

Couple of draw backs I've noted when using it.

1) It splinters a lot. Got more than my fair-share in my fingers. Use a saw blade with as high as tooth count as you can find. For a jig saw, 32 teeth/inch helps keep the splinteres down. I also played with the blade speed. A medium power cut seemed to give less splinters than a wide-open full speed.

2) I think it will check (get small cracks in the surface) after a while. This is just what I suspect. Nothing to prove that with. Applying a 4-ounce cloth to all suraces would probably be a good idea.

Not a bad trade off for $10 a sheet. Just depends on what you value.

[aub77]

My experiance with it is that it does not check. The 4 or 6 oz cloth might be a good idea to build up its strength, if necessary. It has rather thin external plies and the lone internal ply is just some sort of filler. But for flat water canoes and kayaks it is a good deal in my opinion. Not for a masterpiece but good for a cheap, get me on the water boat.

[Momo]

How I-ron-ic!!
I was just in Lowes yesterday looking at ply and saw this same product, still the same price all this time later.
So, I could use this if I up the weight of the fibre cloth?
First boat, gonna be mistakes.
I didn't want to screw up $35-$40 sheets on newbie goofs!
Thanks again!
Momo

[hairymick]

Heya Momo,

Up until now, I have used cheap, interior grade ply allmost exclusively.

You probably know the type of stuff, I am talking about. A thin veneer of wood on either side of a thicker filling type stuff. Generally my sheets have had some football shaped things in the veneer like a filler of some kind and I have simply cut around them and convinced myself I was saving money by using this cheaper stuff.

T now believe that my thinking may well have been false exonomy.

Look at it this way,

I don't know about American prices but I will tell you how it has worked out for me over here.

I have been buying 3.5mm, or 1/8th ply we calll "blonde" in 8 X 4 sheets. It would seem to be very similar to your Luan. I pay about $15.00 per sheet. because I have to get it freighted here from Brisbane, I have been buying it in 10 sheet packs. in that 10 sheets there are ALLWAYS two or three very sub-standard sheets with the football things all over them. I use these for bits and pieces and temporary frames etc. They dont go into my boats.

Generally speaking, I will use 5 sheets of ply or more to make a 4 sheet boat. This is caused by re-doing the lofting to cut round the football things. (A very time consuming proces.)

Without the extra work, my $15.00 sheets have suddenly gone up to around $20.00 per sheet at least because of the extra sheets I have used. Add to that, the extra 9unenjoyable) time spent in working out measurements that are not in the orignal lofting sheets. Even at a quarter of what ever the minimum wage is, the $20.00 sheet is that much dearer again, to such a point where this cheap, inferior ply is probably dearer than your good marine ply that has water-proof glue between laminations and actually has three layers of timber, no voids or football shaped things in it.

My cheap stuff has held up well in all of my boats, but in the long run, in the total cost of building a boat, I don't think it worked out cheaper at all.

My next order of ply will be a slightly thicker, (4mm) marine ply with an A grade finish on both sides. I feel as guilty as heck, building my South Wind with the cheap stuff. When or if it fails, I will be talking to Matt, about building another one. The design is worthy of using only the very best materials and that is what I will be using.

I still have 6 sheets of the cheap stuff in the shed and a couple of experimental boats I want to have a play with. I can use the stuff on them.

If you can afford it mate. I would recommend you use at least, basic grade marine ply of some sort. not only is it better, it is also easier to work with.

If Matt recommends that you use a particular thickness or grade of ply, or anything else for that matter, then listen to him. He won't steer you wrong. He will have recommended it because he has tried it and found that it works.

[jem]

Using the cheap stuff is a crap-shoot. Sometimes you get lucky. Sometimes you spend more time, money, and effort than you would spent on the good marine ply.

For a "first boat" type thing, so much depends on the design and hull shape. For a craft like a simple pirogue or canoe that doesn't have panel twists, you can work with it.

The more complex the design, the more risk you run of getting bad results.

I build with the cheap for experiments to tests concepts. I know when the Lowes ply will not work and when it should get the job done. But I don't invest in an entire project in it.