TOPIC: Transom and floor materials

Hi guys, wondered if anyone could recommend a good place to get marine plywood for the transom in my Crosby. Just read the latest tutorial - very helpful. I've heard of people using MDO or something like that. Anyone ever tried it or know where to get it?

you can also use ACX grade ply for the transom and floor . it gets the job done and is easier on the wallet . just not the junk at Home Desperate or Lowes . just my .02

AC grade plywood works just as well for boat building as marine stuff IMO, especially once resin, mat\cloth and paint are thrown into the mix...and FAR less expensive. Installed properly and taken care of, it will outlast you.

Home Depot or Lowes sells it for roughly 30-35 bucks a sheet for 3/4". I shopped around ALOT for wood before i did my floor earlier this year and they sell the exact same stuff as all the other lumber yards...not sure why everyone always bad mouths them...?

Be selective and take your time when buying the wood...check the sheets over really well for any voids, patches, etc and for straightness.

I think you will find if you take a CLOSE look at what they built these classic boats with in the 50's and 60's, youll find that the materials we have today, even HD or lowes brand, are FAR better quality. Some of these boats were really slapped together with some pretty low quality materials and they still lasted what...30-40+ years...i dont plan on having any boat i own that long.

Steve, Since you just read the latest tutorial you know perfectly well that a good quality marine plywood that has ZERO voids in it is what is in order. Voids cause pockets which cause the layers to delam then eventually transom failure. Good call. I searched Google and found a local supplier. They ship too...Here is a link alliedveneer.com/joubert-okume.html alliedveneer.com/



3 mm (1/8") - 3 ply
4 mm (3/16") - 3 ply
6 mm (1/4") - 5 ply
9 mm (3/8") - 7 ply
12 mm (1/2") - 9 ply
15 mm (5/8") - 11 ply
18 mm (3/4") - 13 ply

I spoke with Susie @ Allied Vineer on 9/2/10 She gave me a few prices on marine grade plywood. Joubert Okoume is the PREMIUM marine grade ply in the world. The next up is Hydrotec and a lower grade and the bottom grade marine ply is aquatec.
Pricing out of Los Angeles...
Joubert certified Okoume 6mm is 64.80
9mm is 74.24 imported and stamped.
hydrotec 6mm 30.20
9mm 32.00
aquatec 6mm 25.45
9mm 38.15


Here is another supplier

www.goosebaylumber.com/MarinePlyAll.htm

I will never use the home depot crap in my boat again. I am a finish carpenter and now know the difference. We use 3/4 thick strips of plywood that is 1 1/2" wide as wall cleat to hang and mount counter tops from. All of a sudden my company switched from marine grade to the homedepot exterior grade to save a few bucks and my screws that go through the wall cleat and into the studs started going through the strips of wall cleat and the wood just splits and breaks. It is supposed to hold the wood firm to the dry wall... Try it for your self. The strips cant even stay lamonated together. Try if for your self. Us installers complained and that was it, they went back to the marine grade stuff that holds it self together.

Guys, try cutting the exterior wood to 1" X 8 FOOT strips your self and drop it on the ground or try bending it..IT WILL COME APART.

I just learned this a few months back. I will spend the little extra for marine, Mike


PS I used to think that homedepot exterior was good enough too, I WAS WRONG!.

Lots of good information here, thanks for your help! Would you recommend the same for the flooring? My Crosby doesn't have stringers, etc, so it was essentially some planks between 2 layers of glas. I wasn't sure if I should try and copy the planks, or try plywood here too.

There is NO COMPARISON between marine and exterior ply. True the adhesives are the same but the strength of the panels are very different. Why is marine so much more? Better species woods, void free in ALL laminations, more plies per given thickness, meets
flex and bending criteria set by the industry. Exterior is for sheathing on a house which is an entirely differnt situation than
a boat. THAT IS WHY THERE IS MARINE PLYWOOD. Okume is very light yet stronger than fir which is most likely what was in your boat because it is less expensive. A 1/4 inch sheet of marine Okume will have 5 laminations H.D. or Lowes will have 3 and the middle one is junk. On thicker sheets marine will almost double the lamination count of H.D. or Lowes. Plywood gets it's strength
from cross grained layers, the more the better. Installation of Marine will be much stiffer against twisting and pounding which
are the two big loads your boat deals with. Most floors are not just a surface to walk on, they are na itegral part of making the boat stiff against twisting like you would encounter if crossing
a wave at an angle.
Whether ot go with marine or not depends on your expectaitions for use, and the time and effort you are going to put into the boat, it's not that you cannot get ayway with exterior ply, it
just is not as good, but then again maybe the boat is not worth
the extra money for it.
My opinion is after all the time and effort don't get cheap on materials, that's why you need to work on the boat you have, materials and workmanship compromises by the manufacturer.
A good resource is BOULTER PLYWOOD in Somerville MA I'm not sure where you live as far as shipping goes but their site has
lots of plywood info. weights of various species plywoods and relative strengths. I get all my materials from them.
Randy

Knew i was opening a can of worms with this one...

Just out of curiosity, who here has actually seen a transom, floor or stringers, that had a quality install, fail because of not using marine grade wood....

Anyone???

Im not saying either or is "right"...but considering the low quality of building materials that most of these vintage boats were put together with and they lasted many decades, i dont see any reason why one must use ridiculously overpriced Marine grade wood when the Home Depot "crap" is of higher initial quality than what they were built with originally. Heck, both of my Glasspars and my Performer both had\have wood, from the factory that were full of voids, knots, patches and voids both in the transoms and the floors. Im a firm believer that longevity of these builds has more to do with technique and after care than it does with materials.

Take that for what its worth but my boats as well as all my pops boats built with Home Depot "junk" work flawlessly...

I use Coosaboard, but it's EXPENSIVE! I'm old enough not to worry about the transom and floors rotting out while I'm alive, but I like the light weight advantage of Coosaboard. I use big four-strokes on the back of my boats and they are HEAVY!