Floor replacement Project at hand

[Matrex]

I bought my first boat this summer, a little 1985 Doral runabout. Well, I had no idea what I should be looking for when I bought it, and after reading many posts in this forum I realize that that spongy feeling in the back corner or the floor is probably not a good thing.

Well, this weekend I pulled off the cushion of the back seat (right side of the motor well) and see someone has cut a hole in the floor, maybe 6"x4"... i think they were probably trying to see what was down there too. What seems to be down there is totally rotten plywood. I can put my hands in and just pull it out in sopping wet clumps.

Having no prior knowledge of boats I am making some assumptions...

1) First step is to find out why it is so wet down there... no obvious leaks.

2) I assume that this rotten plywood mess I am finding is the actual floor and was under a top coating of fiberglass in the rear of the boat, and has rotted from the bottom up. It seems to go from just in from of the rear seat back to the transom on one side of the motor well.

3) Even though this rot seems to be on only one side, I assume this will likely mean ripping the entire floor, possibly fixing/replacing stringers, laying plywood floor (covered first, top and bottom with fiberglass) and re-glassing it to the sides of the hull.

3) If I reach in and double-joint my arm I can touch what I think is the bottom of the hull - at least it feels like fiberglass. Can I assume then, that there is no foam in this boat? I read a lot about it, but not sure what it really is (Styrofoam blocks?) or looks like.

Am I on the right track here?

many thanks

 

[Cast-A-Way]

Re: Floor replacement Project at hand

you can almost count on a rotted transom as well !

 

[Renny_D]

Re: Floor replacement Project at hand

you can almost count on a rotted transom as well !

How does a rotten floor = a rotten transom. I've seen this response a couple of times and I'm curious. It would be good to understand how those two are related other than the rotten floor shows signs of the boat not being cared for. I'd love to hear the gurus chime in and edjumicate me..

Thanks
Renny

 

[erikgreen]

Re: Floor replacement Project at hand

It's mostly that all the wood under the glass in boats that have that type of construction tends to be protected the same way.

The deck, being usually partially exposed to air, having the best drainage of the structure, etc tends to rot slower than anything else.

Gravity being what it is then, if the deck is rotten then there's a good chance that whatever's beneath is has been wetter longer than it has. Because what's underneath probably has as much waterproofing or less than the deck does, odds are very good it's rotten too.

The transom itself usually, but not always, rots at the same rate as the rest of the structure, usually because of penetrations... holes drilled from inside or outside the boat and not sealed, cracks, etc. Also the transom is subject to more stress than most of the rest of the boat.

Basically, in our experience the deck rots the most slowly of the whole structure. So if the deck's rotten, chances are good everything else is too.

Edit: Forgot to mention wicking. Most of the wood in a boat's structure is touching other wood, before foam or glass is sprayed in. If one piece of that wood gets wet, it can easily wick water to the dry pieces. Where water goes, rot follows. So a soft spot on the deck could be just the point where water is entering the woodwork, and traveling throughout the boat.

It also doesn't help that under most small boats' decks are a giant foam sponge waiting to absorb water and hold it against the wood, in exactly the wrong place to prevent rot.


Erik

 

[TommyA]

Re: Floor replacement Project at hand

I also believe that due to the deck butting into the transom on most boats it allows the moisture in the deck to wick up through the transom causing at least rotting in the lower part. Still if your in that far you might as well.

 

[Cast-A-Way]

Re: Floor replacement Project at hand

couldn't of said better then that erikgreen