False Floor & decks

[Tailortaker]

G'day All, I'm about to replace the floor and extend my casting decks on the weekend. I'm planning on using structural ply but not sure if I should use 12 or 15 mm. Will the 12mm be strong enough as I'm worried about the excess weight that will come with the 15mm. The boat is a 3.9m quintrex with a 25hp, bait tank and will have a 55lb electric motor.
Cheers TT

[Fish'n Junky]

Mate, I just re-fitted mine and used 12mm.
The largest span I have between bracing is about 600ml.
The flex is barely noticeable, and it holds the weight easily.
Be sure to use a good sealer though or the weight will increase heaps when it gets waterlogged.

[Scott nthQld]

I just used 12mm in mine as well, and it holds upto a 110kg bloke plus gear no worries.

You may find that you only be able to install the same size ply as is already there. I was a bit iffy about only using 12mm, but I wouldn't have gotten 15mm ply with carpet under the space I had under neath the side pockets.

12mm is ample, I sealed mine with Bondcrete diluted 3:1 (water to bondcrete) 3 coats, allowing to dry completely between coats and a ratio of 2:1 around the edges and anywhere I cut any holes for seats etc. I did mine about 12months ago and with the humidity and nearly sinking the boat twice, floor is still perfect. For the carpet I used Gel Bond to glue it down and there's no way you can get that off without ripping the ply apart. Take your existing floor out, use a grinder with a snading pad to take off the carpet around the egde (to get the board's true size) and use it as a template for the new floor and cut out with a steady hand and jigsaw.

[laugag]

Mate I put a full floor in my old 3.7m Savage and used two 6mm ply sandwiched together. I couldnt get a hold of marine ply so just used normal stuff (hell of a lot cheaper) and just coated everthing in paint several coats. Then used marine carpet sold from bunnings. Worked brilliantly and was the best thing I ever did for that little boat.

[Trev_ally]

G'day. Is structural ply much different from marine ply? I was told the only difference is appearance but would like confirmation before I do the job. Thanks.

[Scott nthQld]

There is little difference between cheap 'marine' ply a CD (structural Ply). Cheap marine ply will just be CD Ply with a maple (or similar) veneer. True Mrine Ply is a different story though, it is a hardwood all the way though, usually maple or cedar and is a lot heavier for it. CD Ply is pine, and you'll get knots and such that you won't get in marine ply. They all use the same bonding agent to hold the sheets together, so don't let anyone tell you otherwise.

You will always get one 'good' side with any CD ply you get, that it a side with very minimal blemishes, but lets face it, once you find the smooth sorfuace, in a boat your going to put carpet over it anyway so look don't really matter.

[Fish'n Junky]

Proper marine ply has a seal coating, and I have been told (but remain unsure about) that a different adhesive is used in the manufacturing.
I have used plain old ply for both this tinny and the one I had before it.
The last floor was in the tinny for 11 years! :-)
Use a good exterior sealer, and paint and you will have no problems..

[Tailortaker]

I ended up getting 12mm marine ply for bugger all more so job is all done.
Thanks for all the advice

[QuinnyDory]

Late reply I know, but I have used basic waterproofing compound (like you use in the batchroom or under tile seal) on my last 2 boats and no waterlogging issues for years. You just need to make sure you cover the edges well - 1 Coat only is needed ! (not 2 or 3 or more) Then i carpet because the waterproofer I use is bright blue....

[Swamp]

Hi - just a question

I have vague memories of mention of poly board now available, does anyone know anything about this ?

Thanks, Bill