Here is WHY you use good plywood! **UPDATE on pg 6 **

[gk108]

No matter how good it looks on the outside, exterior sheathing grade plywood will never have the same quality of glue layer between the plies. It's not made for any kind of bending and is engineered to rely on the nails used during construction to help hold the plies together. That's fine for covering a stick built house with a 2x4 frame, but totally unsuitable for any monocoque applications, like these boats, where the plywood is part of the main load bearing structure. You must have 100% glue coverage. If George picks at that crack in the bottom picture, he'll probably find a delaminated spot larger than the crack, with glue coverage that looks like freckles, but it still meets that sheathing grade specification. The freckles of glue probably failed in shear the first time the plywood was bent around his frames.

[rjezuit]

I used BS1088 on my FL14 and it still checked. Ended up sanding down to the epoxy and covering the whole thing with 6 oz. glass. That fixed it for good.

[ks8]

Even marine fir will check, and some cheap pine. My boat is BCX and ACX. Not one hint of problems after ??? 9 years? But *everything* has a layer of glass. Well, except two very small areas that I keep a vigilant eye on. Don't think I ever want to do that again on a design that doesn't require it. Lots of extra time, expense, weight. I'm well sold now on BS1088 Meranti or Okoume for anything I expect to last and bear any serious loads. I may still proto some fun ideas in bcx, just to test the panel development and waterline and handling, but without expectations of any sort of durability. I think bondo made cheap plywood templates for just about everything for his AD14, but the boat itself is some beautiful wood. Thanks for that post George.

[chicagoross]

I'm starting a third year of use in the tropics (high heat and humidity) saltwater use only, the HMD made of exterior philippine mahogany ply still looks great. the inside from chine up, and the pilothouse and roof, are not glassed, just epoxy coated prior to several coats of rustoleum marine paint. I know that is not what you get stateside for mahogany ply at HD or Lowes, which is junk. I did do pretty serious quality inspections all through the build to make sure I wasn't putting in a bad piece of ply.

Caught a few tuna trolling out of it Sunday!

[topwater]

Ross how about some pic's Its been two years and it is sure nice to see the boats in there element.

[gstanfield]

as Ross pointed out there is a huge difference in what you get based on your location. I always assumed that everything in the continental US would be the same, but boy was I wrong. When I moved to Wyoming I bought a house that needed some fixing up. My first trip to Home Depot was shocking! Same big name store as back home, but the quality was nothing compared to the lumber we could buy in Georgia. Ever since then I have been having to get used to the fact that wood products in Wyoming are terrible regardless of what store you go to. In Casper there are 5 lumber yards/home improvement stores and 3-1/2 of them are junk as far as I'm concerned. Menards has some good stuff and some bad depending and Pro Build has the best in town (still not great), but the prices reflect that of course.

I guess my point is that there is more to wood shopping than just going in the store and buying the most expensive sheet of plywood they have and assuming you have good stuff. You might have to shop around to find decent wood or you might find yourself in Wyoming and nothing good is to be had at which point you drive to Denver 250 miles away to buy marine plywood

[Nanate]

I was thinking of going with Lauan at about $19 a sheet. Is that good wood for here in central Mississippi? It gets hot and humid and cold and wet here. I might put the layer of glass on the all of the wood just because I do want this boat to last as along as it can. I am very ready to get started building this boat but not going to rush it. Getting all the info I can before starting! Thanks!

[gstanfield]

Luan can be good, or it can be terrible, it just depends. There is some underlayment stuff that several people swear by that is about the same price, but much higher quality. It's called ultraply if my memory serves and I've used it and would use it again. I'd still put a layer of thin glass on it, but I would do that with marine ply too

What boat are you building?

[Nanate]

The FL14. Sorry. I started the thread Thursday on the Resins, glass, paint section. You gave me the link to this thread which brought up this question of the wood.

[gstanfield]

I remembered after I posted who you were For the FL14 I'd probably use the heavier exterior grade instead of the luan, especially if it'll be on a trailer. I use the underlayment (better luan) on small projects, but on a boat this size I'd go heavier myself. If you can afford good quality plywood then by all means do it. Marine ply will only add about a $100-$150 to the cost of this build and the results will last you much much longer.

Sometimes $150 is the difference between building and dreaming though, I know this all too well. Just think about it and be honest with yourself.