Composite Decking for boat floor?

[mp_2008]

I recently purchased a very nice 14' mirrocraft deep-V wide Aluminum boat with a 9.9 Johnson motor. I want to put a floor in it, about 4-6 inches off the bottom of the boat in each section between the 3 seats, in the back section, and create a platform over the front seat to the front of the boat. Ive been doing research into different flooring such as marine grade plywood, exterior plywood and composite decking. Id rather not go with any of the plywoods because Id pay $90+ a sheet for the marine grade and $40 a sheet for the ext. and still have to seal it with epoxy so if I can Id rather go with composite decking cause it would be durable and i would not have to seal it. I can get 1x6x8' composite decking for $10 a piece that weighs about 1.4 lbs a board foot. My questions are, has anyone had experience with composite decking for a boat floor and how well does it work? At 1.4 lbs a board foot is weight comparable to plywood? Any advice on mounting? Will marine carpet glue adhear to it? Any advice will be appreciated.

 

[Bob_VT]

Make removable decks. Every ounce of weight you add takes away from your payload.

Composite is not marine materiel go with a slatted wood deck or forget the deck. People have made removable decking but most settle for no decking and just use some non-slip deck paint.

 

[mp_2008]

Hello Bob, no matter what I use i plan on covering with marine carpet. I just want something durable that wont rot or have problems getting wet and will allow carpet to adhere to it. I plan on making it removable but only when needed. Is there any reason the composite wont work or is the main reason you say its not a good idea is because of weight?

 

[glenn property of pam]

composite decking isn't really a composite its just recycled plastic with a wrapping. Nice stuff but a lot heavier than wood. Starboard is great stuff but the postage would be a killer. Personally stained and sealed wood works the best as it doesn't affect the drainage to the bilge and it can be removed. Carpet is the worse as you need open loop or the hooks get stuck and it holds water which means you need sealed ply as a base.

 

[mp_2008]

Thanks for the advice thus far. The decking im talking about is actually hollow with two supports running through the inside of the boards length. Ill have to do the math I guess to see what the overall weight would be compared to ply. Say its similar in weight, why would it be a problem with the carpet holding water if its a plastic or composite material?

 

[jigngrub]

Wet carpet breeds mold and mildew.

 

[mp_2008]

How would mold and mildew be a problem with the plastic or composite material? The carpet im going to use is outdoor plastic patio carpet. Says its mold and mildew resistant. No padding or nothing. Doesnt seem like it would hold much water at all.

 

[mp_2008]

Well i guess 3/4 ply is about 2.3-2.5 lbs a square foot and the composite board would be 2.8-3.0 lbs a square foot. Not a huge difference but definitely heavier.

 

[glenn property of pam]

most people don't use 3/4 for decking in a boat. 1/2" is the standard.

 

[mp_2008]

1/2 inch? So it would be almost double the weight. Ya, Im probably going to scrap the composite board idea then. I can get 1/2 inch marine grade plywood for $50 a sheet but ive heard exterior plywood is not much different and a lot of people use it instead? Thoughts? Suggestions on best way to seal it besides fiberglass/epoxy. Will just epoxy work? Anything else that will do just as well and wont cost as much but will seal the wood making it last decades?

 

[jigngrub]

With that 9.9 adding weight to the inside of the boats is going to decrease performance, you should consider going as light as possible.

I personally would go bare bones with maybe just a front deck made out of 1/2" plywood and aluminum angle. 1/16" (.063) thick aluminum angle.


Some people love carpet, I'm not one of those people. About the longest I can get carpet to last in a boat is about 6 yrs.... and to look decent it should probably be changed out every 3 or 4 years.

 

[mp_2008]

Thanks for the advice jigngrub. Personally I am a fan of carpet. Is it possible to replace the carpet without replacing the ply or having to reseal the ply? As for the aluminum angle, how would you mount it to the boat?

 

[jigngrub]

Sealing or resealing the plywood is the fun part for me, I love playing with the epoxy resin.

If you seal your plywood well the first time, you can remove (rip off) the carpet later and just sand the old glue off and reuse the plywood. Sanding the old glue off is a major pain in the arse though and unless your decking is made of high dollar plywood it isn't worth it.

Mount the angle to the boat with closed end blind rivets... post some pics of your boat and I can draw you up a little framing plan for a front deck.

 

[mp_2008]

Alright, I'll get pics tomorrow. So you use just epoxy resin when sealing the plywood?

 

[mp_2008]

How many coats of epoxy or how thick?

 

[jigngrub]

I like 4 coats of a thin viscosity epoxy:

The thin viscosity really penetrates the wood on the first coat, and then is self-leveling on the next 3 coats. When you're done it's like a sheet of Lexan covering your plywood.

 

[Chris1956]

Gee, why not use 1X4 fir? The wood would need some polyurethane varnish to help seal it, but will be lighter and more robust than plywood. Use sleepers for support and stainless steel fasteners. Spacing the boards will help the carpet dry from underneath.

 

[jigngrub]

Gee, why not use 1X4 fir? The wood would need some polyurethane varnish to help seal it, but will be lighter and more robust than plywood. Use sleepers for support and stainless steel fasteners. Spacing the boards will help the carpet dry from underneath.

Aluminum framing is a fraction of the weight of wood framing.

Plywood is stronger than dimensional lumber.

Carpet laid over dimensional lumber with spaces between will take on the appearance of the wood below, you'll be able to see and count the boards below the carpet.

Urethane sealer isn't nearly as strong, durable, or as long lasting as epoxy resin.

Aluminum rivets are much cheaper than stainless steel fasteners.

 

[mp_2008]

Alright well I think I have a plan. Im going to put a floor between the three seats and a platform up front. I know weight is a factor but I want a floor for noise reduction and ease of movement throughout the boat. The space between the three seats 6" off the bottom of the boat is 30"x4' and 33"x 3.5'-4' with the platform being about 4' at its widest and 4' long coming to a point(because its the front of the boat). Id like to go up the sides of the back and middle seat as well for purposes of mounting padded seats using a clamping mount so its not clamping to the aluminum seats themselves baut has plywood and carpet between the clamp and aluminum seat. Also plan on going up the one side of the front seat to connect the platform to the floor. That adds about 4'-5'x4'+. Ill be using marine plywood sealed with marine grade epoxy only. Ill need 2 sheets but will use about 45 square feet of it so will use less than a sheet and a half of plywood. I have a few ideas of how to reduce the amount im going to use such as only going up the sides of the seats 2' wide in the middle among other ideas. I was wondering how much epoxy will i need to properly seal two sides and edges of about 45 square feet of 1/2 inch marine grade plywood. Will a gallon kit(epoxy+hardener) suffice? Also how thick and how many coats should i apply?

 

[jigngrub]

A half gallon will be plenty for 4 coats.