rotton deck what thickness and flotation

[hypnotist]

I just discovered that I am going to have to replace the rotton deck (floor) from the seats back to the bilge hole in my checkmate tirmate boat . My question is how thick should the marine plywood be for replacemjent ? Im thinking 3/8ths inch ply wood. any suggestions ? also the flotation material seems to be intact but has been exposed to much moisture. Should this be replaced also and if so will the canned flotation material work well ? please I would appreciate any suggestions.

hypnotist

 

[watermellonI]

Re: rotton deck what thickness and flotation

Hi Hypnotist
First off get the wet stuff out and make sure the rest of the boat is ok, stringers aren t rotten, and transom is good, then start lookin into floatation and deck.

I used 2 part pour foam I got it from us composites, ya mix it and pour it quick and get outta the way. Dont use the spray stuff, I don t think it meets Coast Guard Regs. If you do a search theres tons of info on the stuff here as well as a debate on whether to use it or not. I used it cause if my boat takes on water or somethin happens I want somethin to hold onto till help gets there.

As far as the deck is concerned depends on the size of the boat and how much support your gonna need based on the number of people your gonna have aboard. 3/8 seems too thin to me

 

[fishmen111]

Re: rotton deck what thickness and flotation

What he said plus just go to the restoration section and search "foam", "plywood thickness", "rotten deck", etc. and you will be reading for days. Those guys know how to rebuild a boat!

 

[hypnotist]

Re: rotton deck what thickness and flotation

ok... I am having trouble fuinding marine plywood in my section of the country. No body seems to carry it and if i special order they will only order it if i order a full bale of it. Any sggestions as to what else I can use in place of marine plywood ? also my hull and decl is only about 2 ft wide the flotation material is intact and i think the sun will dry it out. im sure it has been soaked would i still need to replace it . and the "stringers" seem to be running up the middle .. what would I use to replace them and what are they attached to ? i'll post pictures next time .
thanks

 

[Lou C]

Re: rotton deck what thickness and flotation

You will want to duplicate what was there originally, if you start changing things as far as thickness it will make the finish work that much more difficult. My 88 Four Winns had a 1/2 in thick deck. You can use good grade exterior AC plywood if you coat all sides and edges with resin. Check the stringers carefully, unless you caught the rot early there is likely to be some stringer rot as well. I installed the 2 part foam before installing the floor and then cut it off even with the stringers with a hand saw, that's easier in my opinion than trying to inject it through holes in the floor.

 

[hypnotist]

Re: rotton deck what thickness and flotation

ok... I removed rotton floor, found that the flotation foam was soaked ..ive had it exposed for two days and it is still soaked . So I decided to replace it. Upon removing some of the foam I found that the stringer was completely rotted. I can't even tell what material it was made of. It looks like maybe 1/2" to 3/4" plywood. It was anchored to the boat hull by what appears to be some type of glue. I plan to remove the rotted stringer, attach it to the hull with fibreglass, reinstall the foam and replace the deck with 1/2" plywood. Then I plan to fibreglass the deck and perhaps sand smooth and paint, It was originally carpeted but I think I'll sand it smooth and do away with the carpet.
While I was ripping out the deck a retired boat mechanic came by and looked at my work and wasn't too positive. He told me that the boats he had refurbished he didn't install foam flotation as he didn't think it was needed because it was only put there to keep the boat from sinking in the case it became swamped. i will replace the flotation regardless.

ok a question. What material would be best for the stringer, I was thinking maybe solid 1" lumber, and am I doing the correct thing by using fibreglass to anchor it to the hull ? will I be able to get it to stick.

All these questions and just think before I found the iboat forums I didn't even know what stringer was. I thought it was a cord to tie fish on ..lol

any guggestions will be appreciated,
thanks,
hypnotist

 

[dodgeramsst2003]

Re: rotton deck what thickness and flotation

From what I have read, you want to use plywood laminated together to get your thickness, its stronger than dimensional lumber. Also, I was doing this, I would replace your flotation foam as it was put there by the factory for a reason.

Chris

 

[Bondo]

Re: rotton deck what thickness and flotation

He told me that the boats he had refurbished he didn't install foam flotation as he didn't think it was needed

Ayuh,..... You were talking to a very Wise Man......
The Purpose of Foam might be Floation,... Another Lawyer driven Safety feature....
Truth is,... It's there to Rot your boat......
If boats lasted Forever,... There wouldn't be much of a New boat market......

The Stringers are usually made of 3/4" Plywood,... It's Stronger than dimensional lumber....

 

[firemanjonny]

Re: rotton deck what thickness and flotation

Just FYI...I forget where on here but, there is a link to the coast gaurd regs site. I am doing the exact same process as you, as we speak. I had the same questions also. Guys here are extremely helpful! In any case, on the uscg site it explains the rationale, amounts, ect. for pour foam. Basically you do not "have" to use it. You MUST have a closed cell polystyrene type device, permanantly adhered to the structure of the boat. The pour foam is a convieniant way of doing this to make the production of the craft cheaper for the manufacturer. foam give support as well as adhesion to the decking, i.e. less width wise stringer are needed. Now, the question is do you need pour foam, and only pour foam? After reading the standards for the uscg, I interpret this. Pour foam is freakin expensive! I'm short on dollars. A member here had the idea of using swimming noodles. Problem is, they were put "in" his decking but, not secured. Boat gets smashed in half, noodles float from their respective compartments. Why not take up a large amount of the area previously foamed, put noodles in there (have them at the dollar store here) pour foam on top. I believe this is a tremendous savings, also meeting regulations! Comments? Am I nutz?

 

[DRIFTER_016]

Re: rotton deck what thickness and flotation

ok... I am having trouble fuinding marine plywood in my section of the country. No body seems to carry it and if i special order they will only order it if i order a full bale of it. Any sggestions as to what else I can use in place of marine plywood ? also my hull and decl is only about 2 ft wide the flotation material is intact and i think the sun will dry it out. im sure it has been soaked would i still need to replace it . and the "stringers" seem to be running up the middle .. what would I use to replace them and what are they attached to ? i'll post pictures next time .
thanks

If you have to you can use pressure treated plywood.

 

[tmh]

Re: rotton deck what thickness and flotation

hypnotist, you REALLY need to search rot, Floor, Deck, etc... and read. You have no idea how many times this exact thread has been rehashed. You'll learn a ton by reading. Then you'll make faster progress with your questions. Good luck, it's a big job! many here have been there so you're in good company.

btw, from your first post, all of us who had the same sad discovery knew the next thing you'd find out was wet foam then rotted stingers. That's the progression in the sad rotted deck process. You might as well know some more potentially bad news now - good chance your transom is rotten also....another big job. better to find out with a few hole 1/2 into it on the inside than find out after you've done lots of other work.

PT plywood shrinks and warps while it drys. You need to hang it for some long period before using it for this (I screwed mine down against my garage wall for 5 mths, no idea how long is enough though, I just had the fall/winter to wait to get back at the boat.

Again, good luck. If you're handy you can get thru it. You'll learn alot about how boats are built in the process! you'll also learn never to buy a boat with a rotten deck again! (well, I've at least learned that lesson from my floor/stringers job!). No foam in mine, btw, I used the ever-fun-to-agrue over soda bottles. I had a very rigid stringer system though, so the foam wasn't needed for support. The bottles worked fine, although whether they'd keep me afloat if swamped - i hope to never find out.

 

[oops!]

Re: rotton deck what thickness and flotation

welcome to the resto forum, this is where all the rotters hang out...

first.....all the foam....needs to come out.....you will be dead and buried before it drys, and the second it comes in contact with water, it will soak it up like a sponge......

you need 2 part expanding foam.....

1/2 inch ply for the deck...(minimum) forget marine grade.....(unless you aboslutely must have it)

ext grade ply, or pressure treated)......you will need to dry both types...but pt must be dryed a lot longer.....

you will aslo need to investigate fiberglass.......

but first things first.....get in there....rip it all apart, and see what needs to be replaced.......

if the transom need it....do that first......we will walk you thru it

cheers
oops

 

[hypnotist]

Re: rotton deck what thickness and flotation

had eye surgery and its raining here so project is on hold and gives me time to research. Ok I checked transom it is solid , area that I need to refoam and redeck is actually about 16" by 8' right down the middle of the boat. It tapers from 16" to about 6" at the front where the steering wheel is.
my only problems now are the types of epoxy and adhesives to use, such as what to imbed the stringer in. I removed the material it was originally imbedded in. It appeared to be some sort of hardened putty. I am wondering if Rock Hard wood putty would be ok. It looked like Checkmate boats just plopped it down then put the stringer in and no resin or fiber on the original stringer which was made of 3/4" plywood. As soon as I am able I will include pictures. Probably later on today

 

[oops!]

Re: rotton deck what thickness and flotation

read bondos earlier post....2 times.

and also boat rot, wet foam prevention.......

the putty they bedded the stringers with is probably a mix of ingreadints. we call "peanut butter"....search it, or read the hull extension thread for pics and the list of ingrediants.

the new stringers can be made of exterior grade plywood, or pressure treated.

if you use pressure treated, it must be dryed a long time before you put it in and fiberglass over it.......

so in your case, i would use ext grade.....

you can use epoxy or poly fiberglass resin.
epoxy is way stronger and bonds to wood very well.....some say easy to use.

poly is cheaper, will work perfectally for what you need...but it is your choice....you will use the same amount of each product

 

[fixb52s]

Re: rotton deck what thickness and flotation

As for bedding in the new stringers, some use the "peanut butter" mix, where others use the PT poly construction adhesive. I went with it and it worked great. Just ensure the wood is not sitting directly on the hull. Have some adhesive between them and you will be just fine.

For the stringers, 3/4" ply is what you can use, just measure the thickness to be sure. I used cabinet grade ply with excellent results, but did seal it all up with resin and glass.

Like the others said, read this forum. It has a gold mine of information.​

 

[Coors]

Re: rotton deck what thickness and flotation

If you use f/g or epoxy, with mat, roven, biax, cloth-your pick.
From the hull, up, and over the stringers, about 1/4" or more thick-it doesn't matter if they rot again. The plastic now makes the stringer.
Read old threads in here, many ways to do it, and much experience on the "gotcha"s.

 

[hypnotist]

Re: rotton deck what thickness and flotation

ok just ordered the following material for flotation

AeroMarine 2# Density Foam
1/2 Gallon kit; includes one quart each of Part A and Part B. Yields two cubic feet (24"x12"x12"). (cost $28 plus shipping) ordered 2 units.

this the foam flotation I plan to use.

Now I wonder if I should order the following:

AeroMarine 300/21 1 1/2 Quart Kit- Total yield of 1 1/2 quart mix epoxy with hardener. Consists of 1 quart of #300 resin and 1 pint of #21 Non Blushing Cycloaliphatic Hardener.

I am wondering if this is the material I need to glass in the stringer and coat the decking material.
Anybody have suggestions ?

I can get regular fiberglass resin and mat locally is this all the same material ?

 

[hypnotist]

Re: rotton deck what thickness and flotation

I need a recipie for making peanut butter using resin plastic bubbles and wood flout ..need to know the ratios of each and also amount of hardner . to use
please anybody..

 

[fuzzeywiggler]

Re: rotton deck what thickness and flotation

I go virtually 1 to 1 If you want it runny a littly more hardener if you want it to stay were you put it (on a vertical surface for instance) put a little more of your additive just make sure that all of your additive is thorughly mixed in. Its pretty easy to put on with a paintbrush or a scraper.

Fuzzey

 

[wca_tim]

Re: rotton deck what thickness and flotation

Be sure to check the core.... Unless I'm mistaken, that's a hand-laid balsa-cored hull. It could be fine, but then again... if water got into the core, parts of it could be rotten as well... as long as you've got the deck off, you might as well chack and consider fixing any rot there as well...