Spongy floor remedies...

[robfish 1]

Hi Guys...jumped in the boat to give it a thorough clean after a long, wet Melbourne winter, to discover the floor has become (a little) spongy in my 1985 glass half cab - (pictured in my avatar). Obviously, the underfloor stringers are falling apart, due to age and water intrusion. Whilst it doesn't appear to be too bad, (I'm 185cm and 135kgs, and it only flexes a couple of cms), I'm concerned that it's only going to get worse. Given that a new floor will set me back around $1500-$2000, which I don't have at this time, and health won't allow me to do the job myself, I'm thinking about a stop-gap measure. I'm considering drilling some holes in the floor and injecting some expanding foam, by way of aerosol cans. I may need 10 or 15 cans, but that's still far short of $1500. Allowing a drainage channel down the middle to funnel away any excess water, this should provide some stiffening until I can afford the new floor.
My question is - has anyone else tried the same - with success, or am I flogging a dead horse? Or does anyone have any better suggestions?
All comments gratefully accepted.

[gazza2006au]

easiest thing would be to cut out the floor than cut along the top of each stringer than chainsaw out all the wet wood and fill it with seacast www.transomrepair.net theres a aussie dealer who sells this product the yanks use, its a liquid pouring product u just simply pour it into the stringer cavity let it set than glass over the cap u cut off earlier than lay the floor down

your floggin a dead horse with the foam idea

[ifishcq1]

at best it would prolong the inevitable
the trouble with expander foam is it may not sit where you need it if the area between your supports is too big
if you are going to do something more permanent later why not just sika flex a sheet of ply over the top and paint it with paving paint
it may be rough but at least you won't go through the floor

cheers

[Shark Poker]

Another trouble with expander foam is that some of those products absorb moisture over time and soften and you will potentially have a sponge under there that never dries out.

The plywood is a very good temporary idea. Notice he said sika - not screws - but I would use an ordinary silicone sealant to enable easier removal of the plywood panel in the future.
An alternative to plywood would be a piece of 3 or 4mm aluminium.

Pauly

[ifishcq1]

Yeah you're right Pauly
I thought about that (not quite enough) if the whole floor is coming out down the track, you don't have to worry about new fibreglass not sticking to silicone
cheers

[Gon Fishun]

Are you sure the stringers have gone and it is not just the floor? Is the floor ply coated with fibreglass? I thought the same with the Haines V16C, but it was only the ply floor. The stringers were fibreglassed and in good condition. $200 new floor.

[cormorant]

Foam - no

You need to determine if it is only the floor ply that is stuffed and if the rest of the boat is structurally sound. . At manufacture they back then didn't use the best quality ply, never quite thick enough for 135kg and also didn't seal the back of it. the glue in the ply may have just failed with age and moistire or becuase of freshwater you may have wetrot/ dryrot ( fungus ) Fungus breaks the wood down.


Not sure if you have any inspection hatches/ covers in the floor but I would be inspecting ( or making some) to see if it is just the floor of if you also have rotten stringers. Can use borescope or just a digital camera and take photos if you already have small holes. Back then stringers should have been a hardwood and sealed but they to can break down and a lot depends on how they were glassed.

Before trying any cheap shortcut fixes find out what the real problem and it's extent is. You don't want to be in the bay hanging onto a structurally failed boat for the sake of not having a look now and depending you may be better off with another boat if you find something really nasty.

I have been in boats with 2nd ply layer covered floors knowing that the stringers are good and they have gone for years treated like crap before actually having the floor lifted and done. Worth checking how much flex is in the transom as well so you know what is ahead of you. .

[Shark Poker]

That's fine in theory Cormorant but inspection by photo would only show dark coloured crap, would it not?
The first time I saw a half inch plywood sheet stuck down over the old floor I was disgusted. But after thinking about it for a while and listening to the owners point of view, I kind of softened to the idea myself.

The description provided by Robfish 1 was that the stringers are most likely stuffed, and from reading his other posts he is a very sensible guy. So we can assume the transom has been sussed out and he is asking for help with the floor.

You know fully well that there will be no inspection ports throughout the deck.
Possibly the best idea would be to cut a hole big enough for decent inspection under what will be a new temporary cover/floor patch.

Can we agree on that?

[robfish 1]

Gentlemen...thank you one and all for your sage advice. I'd hoped that there was a quick and easy remedy, but knew deep down that it wasn't going to be easy.
I have checked the hull and transom, both with a rubber mallet and bouncing the 70hp, two stroke yammie up and down without any distressing noises from the transom, so I think it may well be just the floor has given way. Whenever I drain the lower bung, there's dark brown water, (not much, but it's there), indicating rotten wood down there somewhere. I think I like the idea of marine ply and silicone, with a quite a few sst screws to hold it down.
Given that my health won't let me do the full replacement floor job myself, (dodgy knees that also need replacing), I'll happily pay someone to rip up the old floor down the track. Given the dark colour of the water draining, I'd hesitantly say that it was the hardwood stringers that have given way as well as the glassed ply floor.
I like the idea of some inspection ports too, before adding the new ply floor - it will let me see what's down there.

[cormorant]

You still have to poke it but you can get away with much smaller holes if you use a camera like a go pro , even video on phone while you are poking away . Much easier than a mirror and torch. If there is already holes for bilge pumps or anything since 1985 you can start there without cutting anything new. If the stringer it is soft there, away from the glass it will be soft everywhere . I haven't read his other posts so didn't know his level of ability or common sense but always wary for every one that posts a question there is 100 others that read the suggestions down the years and might not have his common sense and end up using a boat that is structurally dangerous but with a solid floor.

I have seen a full garden of orange dry rot fungus and some glow in the dar stuff under a rotten floor but year you may or may not be able to see if the ply has turned to dust, rotting, delaminating etc,


As for seacast - well to do a proper job you have to have it all apart for access to get the old crap out anyway so you may as well do it with cheaper original materials ( just sealed better) so it is good for another 20 years. .

Edit - added a bit as rob posted while i was typing.

[gazza2006au]

As for seacast - well to do a proper job you have to have it all apart for access to get the old crap out anyway so you may as well do it with cheaper original materials ( just sealed better) so it is good for another 20 years. .

Edit - added a bit as rob posted while i was typing.

i think the seacast is a revolutionary product, i havent used it my self but i like the idea of pouring it into the stringer channel and letting it set to trying to mess about with plywood stringers getting the right curves, with the seacast u know u will have 100% bond to the shape of the hull and seacast is supposedly guaranteed for life

[Shark Poker]

I am not interested in Seacast either. Like I said in the thread re that product, we could do better IMO.

So as we do not agree on how a camera could help, do you have any examples of underfloor photos that helped to make a decision?

[cormorant]

yeah I'll get em off the old PC when I have a minute. I found previous repairs that was the reason for softness and a whole fungus farm as drains were clogged with fungus and ply bits holding fresh water .

[Shark Poker]

So you can actually tell this from a pic? Thanks.

[Shark Poker]

i think the seacast is a revolutionary product, i havent used it my self but i like the idea of pouring it into the stringer channel and letting it set to trying to mess about with plywood stringers getting the right curves, with the seacast u know u will have 100% bond to the shape of the hull and seacast is supposedly guaranteed for life

Please refer to an earlier thread re this product.
Research that I carried out left me rather unexcited. Not from reviews, but from application strategy.
It appears not to be an all too easy just pour in product.