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Help With Boat Floor

Captain Crunch

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Hello all,
I will soon be finishing a project started last fall, and would welcome any opinions or advice on it. Thanks to the internet I've become brave enough to try and tackle it! Believe I've searched the earlier threads, perhaps I missed some. I have a 1975 17.5' 'V' hull fiberglass Mark Twain I/O with a 6 cyl 160 HP Mercruiser. I've had the boat for 6 years now, and the past few the floor had developed some weak spots. 9/10 people I asked said to go over the old floor with plywood, but I preferred to go what I believed the right way and replace it. Last summer I removed the old flooring, which was quite rotted, only the carpet was holding in some spots. I removed all the old wood the best I could; used a Skill saw set to the thickness of the wood to rough out the main area, and CAREFULLY used a die grinder for trimming the tight areas. All the while using proper respiratory protection! What good's a boat if you have no lungs! I cut and fit new 1/2" marine plywood, using cardboard or the old floor where possible for templates. Soon I will be doing the glass work to finish the job. The stringers are surprisingly in pretty good shape, the old glass covered them quite well, except maybe some small areas. My questions are:
1. I've read on other sites of saying to have the boat off the trailer when doing the floor, to avoid putting a "hook" in the shape; are they talking in a line from right to left? Would raising the sides to accent the "V" shape of the hull help?
2. For the stringers, is it advisable to use a product like Boat Life Git-Rot on them? Then put more 'glass over the top of them? I thought of using West Systems Epoxy Resin, would this be best way? (albeit an expensive way wink.gif )Should cloth be added over it? The factory had chopper glass over them. I would like to add another stringer to reinforce the floor near the front. Could I use the epoxy and cloth for that?
3. For the floor I'm thinking of encapsulating the plywood by putting a coat of resin on the bottom and sides, and filler where needed, then resin and cloth on the top. Is one coat enough for the bottom? And what cloth should I use on top? There's the heavy woven kind, or the lighter and thinner mat kind. Should I use cloth over the whole top surface? Think I seen someone who just did the edges, would think the whole area would be stronger.
4. Finally, The stringers which run parallel along the sides, front to back, are basically isolated from the bilge. Any water which could enter, has no place to go. Would drilling holes in the stringers, perhaps at the tops, to allow air to cirulate be a good idea? I could keep them plugged until winter, then remove to let dry. There was water sitting in these channels when I removed the floor. I believe it entered through seat screws which had been broken at one time. They had been fastened with plain zip screws, not even stainless.

Thanks in advance for any ideas!

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I wouldn't recommend modifying V angle, you might put too much stress on original fiberglass structure.
You did correctly on plywood, I would use a thick cloth (not mat) to cover whole area, then glass everything.
I have a mid '70s Searay 24ft, I rebuilt whole floor, and I had same problem with stringers. What I did was drilling 2 3" holes trough bottom of them (then glass holes too), so water collected will flow into bilge area.
Beware of stringers rotting, they are very important since they hold motor, and they are subject to a lot of strain. I would poke through glass to find out if they are rotten, in which case replacement is suggested, but tough to achieve.

Also, very important is to check flotation foam, if it's soaked with water, you will have to replace it, since it will release moisture into new floor and joining areas, and you did all this work for nothing.

There are other people on this forum that are more expert than me, you might want to check their opinion also.

Val Vignati

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Sounds like you're well on the way to recovery and have done a bang up job from what I can see.

I've replaced a couple and the single most impotant part is what you've already done - get ALL the old wood out! Years ago my dad and I did the floor in the family '67 Glastron twice because we THOUGHT we'd got the rot out the first time....

I agree w/Valv - he's a man in the know and has probably owned/sold/traded more boats than I've thought about. When we did our Glastron, we replaced all the floatation because some was water logged and it was a type that resembled 2X4's which allowed some of them to drop down and impede water flow to the bilge just as your stringers have.

I'd get a dense solid foam and cut it so you have a clear run and attach/jam/tie it so it doesn't drop down to the hull. I would also simply brush a coat of resin on the downside of your plywood - should be enough of a barrier to outlast the rest of the boat. If your stringers are solid I'd likely douse them with resin as well. If they are weak you may have to marry some supports to them - beats tearing the whole mess out but glass'em in like Valv said.

If you have a forward compartment that isn't underfoot or in the way, I'd put a vent of some sort if possible for just because sake. We cut/glassed in a 1" PCV piple with a ninety degree elbow pointing fwd under the bow deck to just get some airflow - if you think she's taken some water hook up a vac backwards and let it blow dry for a while.

If you've any gaps in the deck against the hull wad up glass and make it solid dripping resin on it before you mat it.

If you're going back with carpet I'd brush a extra coat of resin on the top side just for measure.

Sound like you'll have a nice rig when she's back together - and the satisfaction that you've likely done it better than anyone you could have paid to do it!

It's fun when it's done!

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  • 'we have more fun' FishingMN Creators

Moving to equipment forum.

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