Deck repair for seats?

Hey all. I am absolutely new to the world of boats and have encountered an issue I believe would be best answered by the type of people who woule be a part of this community. Knowing that I am very new, I will also apologise in advance for any names, terms, etc, I simply don't know the name of. Here goes.

I purchased a 1993 14' Swiftcraft Sea Otter a few months ago and am at the point where it is ready for the water. I believe the previous owner knew even less than I do and appears he has carried out some "work" to the boat prior to me purchasing it. The current problem I need help with is the deck/floor. The 2 pedestal seats have round bases and 6 screw holes to secure them to the floor. However, I had a suspicion the seats were merely screwed into the fibreglass floor and didn't have any type or reinforcement below the floor. This was confirmed when my chubby butt took a clumsy tumble and tore the seat screws out when I tried to save myself by grabbing the seat.

I have an idea about cutting a section of the deck out on both sides in an areas larger than the seat bases would sit, then adding some epoxy treated plywood under the deck spanning in a larger area than the goles created, fibreglassing them into place, and then sealing it shut with more fibreglass. According to my thinking, this would give the seat screws something strong to anchor to and provide more strength for the stresses the seat and deck joining will have to endure when boating in rough waters.

I have no illusions about my lack of knowledge and capabilities, so please feel free to give me your thoughts in regards to whether my idea is sound, or if you would scrap that idea because you know a better way and can tell me.

Cheers, Dan

welcome to the forum.


i think you plan is workable. I am a fan of T-nuts. You can maybe even just cut a hole large enough to get your hand in and use existing holes if the wood is still good.

Damn, that has opened up another line of thinking for me, Thanks Joe. Perhaps if I can make up a rectangle piece of plywood with the centre cut out and then cut it down the centre, I could figure outwhere the screws would line up and attach T-nuts to the under-side before fibreglassing it in.

Being a bigger bloke, I don't want to have to worry about dedstroying the floor every time I hit a wave lol

When I redid my boat I wanted ZERO penetrations into the floor. What i did was after I glassed the floor before gelcoat I cut plywood pedestal base mounts that were almost as wide as where the seats went, drilled and installed stainless t nuts. Then I taped off the tnut holes to keep them clean. Then I glued them down with resin mixed with 1/4" chopped glass mixed in and then I tabbed and glassed over the base. I have a stable seat mount that won't pull out and no water can get to foam cavity.

Being that it is a 33 year old boat, there could be gremlins lurking below the decks. Most are in this subforum because of that at one time or another.

Froggy has a good design there. Make sure that you seal the existing holes before proceeding and seal seal seal. Water getting into places where it is not designed to go is always a bad things.

Once all in place, you might even pick up a gallon of white gelcoat and recoat the entire deck to match.

not sure what core material is in the floor or what is under the seat bases.

we have seen people drill holes into fuel tanks, etc. I have personally screwed into under deck plumbing

Here is what I would do

drill the holes where the screws go to 3/8". you just want to go thru the top layer of glass down about 3/8. if the shavings are wet, you are into a restoration and the floor is coming out if the shavings are dry, then continue.

then chuck up a 1/8" allen wrench in a cordless drill.
in each hole, chew out the coring
vacuum out the chewed up coring.
mix up some PB (see the stickies). fill the voids and let cure
then drill your pilot holes for the screws. it will hold as long as the rest of the deck is not rotten.

alternately, the top-mount that @froggy1150 posted is what I did for the tower mount because I built coolers under my floor in 2011 and didnt want to drill into them.

other people have used toggle bolts on some decks. there are stainless toggle bolts that have the little plastic retainers to hold the threaded portion under the deck while the epoxy/methacrylate/resin cures.

below is from mcmaster carr which is half of what the marine shops sell it for (because they get them from mcmaster carr)

I have never tried these, but they are stainless steel which is essential. Garelick is a good name as well.

I went a similar route to what Froggy took. You can check it out in my resto thread (https://forums.iboats.com/threads/t...rson-186-sei-i-o-bowrider.552555/post-3970663) starting around post #92 and discussed on and off to post #141. Like Froggy, I didn't want any thru-deck fasteners if I could avoid it.

I used stainless steel T-nuts buried into the bottom of the bases; the bases were then peanut buttered to the deck and then glassed in. They are quite strong and have help up extremely well.

I like the raised base idea. I don't think I've seen that model, but tour core material is going to be the deciding factor in how you handle this. If it's wood, I would just replace the whole floor, assuming the stringers aren't rotten too (probably are if wood). If it's synthetic, like nida core, I would use Scott's method to fill the holes, and then froggy's seat base. T nuts are only as good as the material they are set in. So if they are in rotting wood, they'll just pull back out later.

Also .... Just for general knowledge....
Seat pedestal have different ratings. Some are not rated to use while underway. I think they were class a,b or c. Class a was for underway.
I looked into this about a decade ago so might be off with the letters....

If you have a couple of free inches under the deck, you could drill a hole in the deck in the center of the mounting holes. Now drill out the mounting holes to accept Stainless steel bolts, installed from the underside, and secured by stainless steel t-nuts on the top of the deck.

Now put a plug in the hole you drilled, install the pedestal over the studs and plug and install SS nuts and washers. I would caulk the t-nuts to the studs and bed the pedestal with caulk as well.

I apologise to all of you who took the time to reply. For some reason, I stopped receiving notifications about new comments and assumed only 1 person replied and then nothing after my first response.

Your idea looks promising froggy1150. The only concern I would have with doing that myself would be when it came to lay the carpet and also have a tripping issue - I am a klutz I had no idea about the seat ratings either. I will definitely be looking into this before going any further.

Thanks bakerjw. I definitely don't want water finding it's way into places it doesn't belong on a boat!


Hi Scott Danforth and Chris1956. My update below will take care of some of what you suggested. I too thought of some type of stainless steel toggtle bolts but I ended up choosing not to go in that direction due to not being confident enough in sealing up the 12 holes they would need.

Thanks for your help too JASinIL2006. I am concerned about the toggle bolts and haven't fully decided which direction to go yet.



MikeSchinlaub, I believe the floor is mostly ok, but my update will hopefuly explain a bit more.

UPDATE 31/10/2026
After many arguments with myself, I finally decided I had to find out what was going on under the floor before I could make a choice or which direction to go. The pedestal bases have a diameter of 250mm (just under 10") with the length diagonally between the centres of the screw holes of 230mm (about 9"). I measured where best the seat bases would be installed (because they weren't originally installed symmetrically) and then used a shallow bit in my jigsaw to cut out 2 holes with diameters of 200mm (just under 8"). This exposed a stringer running from front to rear under each hole and also showed me the tops of the stringers are slightly rotten.

I have replaced the 2 drain plugs with new brass and screw in bungs, but I feel I need to find out if water is finding it's way into the boat between the deck and hull. If this is the case, I will then need to find out where it is leaking and then repair it. Does anyone have any suggestions on how to easily find out if it is leaking and where it is leaking from?

Cheers, Dan



So I don't miss anyone, I would like to thank everyone who has helped so far:

redneck joe
froggy1150
bakerjw
Scott Danforth
Chris1956
JASinIL2006
MikeSchinlaub

If the tops are a bit rotten, it's likely that the bottoms are nearing mulch.

MikeSchinlaub said:

If the tops are a bit rotten, it's likely that the bottoms are nearing mulch.

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Damn, that is a scary! I am trying to figure out if I can dry it out completely and then drill a series of small holes through the deck and into the stringers so I can inject something like WOTROT in each hole to "fix" the stringers. I really, really don't want to have to tear up the floor and replace the stringers. I just don't believe I am capable of doing such a big job.

Thinned epoxy is a fools errand

You can't unrot a boat.

If water is in the stringers, it's in the flotation foam

Dannal said:

I just don't believe I am capable of doing such a big job.

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Hey, I started right out of high school as about the dumbest kid you could find, and I can do it. It's a lot of work, but

MikeSchinlaub said:

Hey, I started right out of high school as about the dumbest kid you could find, and I can do it. It's a lot of work, but

Click to expand...

did you get out of the dumb?

redneck joe said:

did you get out of the dumb?

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Depends on the day.

I still do dumb things. Just ask my wife

Scott Danforth said:

Thinned epoxy is a fools errand

You can't unrot a boat.

If water is in the stringers, it's in the flotation foam

Click to expand...

I don't believe it has any flotation foam??? As far as I can see there is only fibreglass and timber. Nothing else appears to be under the floor aside from water. I am waiting for better weather in order to try and locate where the water is coming in from. I am hoping if I can get it dry and plug the leaks properly then I can get a lot of use out of it before having to carry out major repairs. Also, the transom was rebuilt about 18 months ago and from what I can tell, it is quite solid.

I too have had my fair share of dumb moments