Replacing the floor, ugh!

[apollo5646]

Hello all, well I decided to replace the rotted floor in my boat since we have had 80 here in Michigan which is just unheard off in March. Well I got most of the floor out and of course most the two stringers are rotted to a point, I debated for a long time on weather to try to take the stringers out and replace them but I'm apprehensive for two reasons, One I'm not good with fiberglass and second I don't have the means to pull the engine and I'm not sure if I would have to yank the engine to replace them. I'm not planning on having the boat for more then 5 years more so I had weigh the cost benefit life of the boat etc to decide to just work around it. I did cut the worse of the rotted stringers out and will replace those section and also injected a bunch or git-rot to help. Now my question is what to do with all the foam that is under the decking. I'm sure that its water logged could I rip out and just for go it or does need to be in there for some reason? Could I just rip it out and an leave the space open? Is there structural properties and necessity to the foam or what? What is my best coarse of action here? Also I'm want to use treated 3/4 ply for the new deck. Do I need to do anything special to make the fiberglass stick to it? Will I run into adherence problems with using it or is there a special resin that i have to use with treated wood? Thanks for all the help!!

 

[Bob_VT]

Re: Replacing the floor, ugh!

"Most" foam is not structural however it depends on the boat. We are fairly safety concerned and replace the flotation during rebuilds. It might be replaced with something different then was originally used but it is flotation.

Yes, you can replace stringers w/o removing the motor but, it is more work and considering the design of how the stringer's tie into the transom it is not advised.

Post some pictures of the situation and let the fiberglass people guide you

 

[rickryder]

Re: Replacing the floor, ugh!

Some pics will be very helpful I wouldn't use PT plywood.... too heavy and wet with chemicals.... bad bonding...

The foam most likely is for flotation but depends on the hull design like BOB stated ^

So lets get some pics and we will guide you along to make the boat safe

 

[Woodonglass]

Re: Replacing the floor, ugh!

If your motor mounts and transom are as bad as it seams your stringers are, then I'd say the short cuts you are attempting will not be effective in extending the life of your boat. You really need to do some intensive investigation as to the overall condition of the substructure to determine the course of action you should follow and to ensure the safety of the craft.

 

[rickryder]

Re: Replacing the floor, ugh!

+1 ^^^^^

 

[ratking20]

Re: Replacing the floor, ugh!

i just redid my floor. had to replace all the stringers, not the transom(thank god) and had to pour new foam.
the fiberglassing part is tricky but do-able(very messy though). as for the stringers, not too bad either. gonna be a real pain if you leave the engine in. as for the foam. probably not structural. not even necessary if your boat is under 30 feet i think. read that somewhere on here as per coast guard standards. one thing is for sure.... its ALOT MORE WORK THAN YOU THINK. AND WILL COST PROBABLY 3 TIMES WHAT YOU ESTIMATE BEFORE YOU START. but like my boat, if it needs to be done then it needs to be done!!!!

 

[apollo5646]

Re: Replacing the floor, ugh!

Well that's the crap thing about it... how much do I want to do with it just to keep it going for a few more years. I did do some investigating the motor mounts seem to be very solid under the fiberglass and the transom is in good shape as well. What I'm guessing is that there were two cross members between the stringers that have gone away at some point and were left open which promoted the stringer degradation I think. truth be told I would to just rip it all out and replace it all but that's is just not feasible right now for me. Maybe this fall I'll get a chance to do it. Was still pretty solid all last year no drive-line issues and the alignment is still good. So I guess I'm back to the whole foam thing and what to do with it. I'm working on some pictures right now.

 

[apollo5646]

Re: Replacing the floor, ugh!


here you can see the old decking is removed and the old carpet is out as well and you can see all the foam outboard of the two stingers down the middle.

 

[bgc]

Re: Replacing the floor, ugh!

Hey apollo5646,

Just sharing a couple things I have learned from my first rebuild.

Woodonglass has some great information about glassing on his rebuild threads, follow link on his signature.

Glassing is not that hard (stringers and floor). US Composites is a great source for glassing components and some of the folks here are using ARAUCO plywood from the “Big Box” home improvement stores.

Measure all the dimensions of the boat before cutting. That way if she shifts when cutting away the skeleton you can get her back to original when reglassing.

Woodonglass had a great tip, cover the air intakes on the grinder with a Scotchbrite/3M pad. It acts like an air filter for it. (My first grinder started burning while I was grinding)

Cover yourself well, wear a respirator, and use plenty of baby powder….the fiberglass itch will eventually stop…..I hope…

Although it gets expensive, make the repairs with safety in mind. You can’t pull off to the side when you have a problem and wait for AAA on the water.
Many of the folks here have found creative ways to replace the foam in their boat without breaking the bank. I’m going to try “Pool Noodles” in mine 2 bucks each at Leslies Pool Supply
The shop I work at will pull an engine and put it the back of a truck or on a pallet for minimal money. If you do decide to do the motor mounts and transom, call around to some shops (We only do the lifting, boat owners have to disconnect everything first)

I certainly hope you get her back on the water soon.

 

[ezmobee]

Re: Replacing the floor, ugh!

as for the foam. probably not structural. not even necessary if your boat is under 30 feet i think. read that somewhere on here as per coast guard standards.

You have this backwards.

 

[rickryder]

Re: Replacing the floor, ugh!

If your removing stringers the foam will have to go also......if its wet foam it wil NEVER dry out.... I used blue foam board Dow.... Its the same as flotation foam closed cell... It's in my resto thread.

 

[Woodonglass]

Re: Replacing the floor, ugh!

What have you done to ensure the Transom and motor mounts are solid? Did you core sample them? That is the Only way you can be sure.

 

[salty87]

Re: Replacing the floor, ugh!

foam is required of boat manufacturers (boats meeting certain size requirements). if you're going into business you better get it right.

if you're not, you can do whatever you want with your boat.

the only bad thing about flotation foam is that fact that it acts more like glue when poured. it prevents drainage. drainage is very important. an option is to pre-pour the foam. line the area with plastic (cut a trash bag wide open) and pour the foam. once it sets you can peel the plastic off and you have a custom shaped flotation block that won't prevent drainage.

 

[apollo5646]

Re: Replacing the floor, ugh!

So is there a way to determine if the foam is structural or not? I core sampled the mounts and transom by drilling some small holes in to them and checking the quality of the wood that came out. What was coming out was dry and solid. I'm going to fill the wholes with epoxy to keep them water tight. Is there a better way to tell? I'm working on an NDT machine to try and check other areas without drilling.

 

[rickryder]

Re: Replacing the floor, ugh!

What boat is it? Maybe contact the manufacture and ask about the foam.....

 

[apollo5646]

Re: Replacing the floor, ugh!

Its a 1989 Marlin, I don't know the model and I don't think that the manufacture is still in business. I cant find them on the web.

 

[Bob_VT]

Re: Replacing the floor, ugh!

Marlin boats did not use structural foam but they sure used cheap plywood where they could.