Swivel seat base...fiberglass strong enough?

On an 83 Chaparral that I am working on restoring, I would prefer to have a single swivel seat for the driver and a back to back next to it for the passengers. My question is about the strength of the fiberglass floor and whether or not it will support the forces transferred to the floor from a relatively small seat base. I could see the leverage of the chair and a person in the chair being enough to tear up the glass that the base is mounted to. I was thinking about mounting the base of the swivel to a larger piece of wood, and possibly that piece to an even larger one (trying to stay within the confines of the size of the chair itself so as not to intrude on floorspace). Has anyone done this with any success? I'm thinking that this would work similarly to using a washer to spread out the force applied by tightening a bolt (greater surface area to disperse the force of the chair and driver).

Thoughts, ideas, suggestions?

Re: Swivel seat base...fiberglass strong enough?

there should be plywood under the glass, it's condition is the item in question. they make marine toggles for mounting pedestals.
http://www.discountmarinesupplies.com/Other_Seat_Hardware-GARELICK_TOGGLE_BOLT_ANCHORS.html

Re: Swivel seat base...fiberglass strong enough?

You mean something like this?

Used wood screws.

Re: Swivel seat base...fiberglass strong enough?

Alright, so TD say that the wood under his fiberglass is in good condition. would i be able to support that weight of the swivel seat?

Re: Swivel seat base...fiberglass strong enough?

zach103 said:

Alright, so TD say that the wood under his fiberglass is in good condition. would i be able to support that weight of the swivel seat?

Click to expand...

I will let TD answer that. In my opinion, if the wood under the deck is good he should not have a problem. However,if he can live with the stacked wood scheme the OP mentioned, the base will exert less force on the deck.

Re: Swivel seat base...fiberglass strong enough?

that is a good question, the way i suggested is one option, used in a lot of new boats, some manufacturer also install a backing plate under the deck, for added stability. i have seen someone that makes a split backing plate, that you cut a small hole where the seat is going, and insert each half thru the hole.

Re: Swivel seat base...fiberglass strong enough?

the reason i asked is because i want to put the swivels in mine when im done with the deck..when i tore it up there was a 1/2in square peice of plywood then thin metal peice same size then the deck.. should i redo that and put it under the deck for the added strength for the swivels

Re: Swivel seat base...fiberglass strong enough?

Through bolting with a backing plate is the only way to do it.
As TD mentioned there is a "split backing plate" available.
Lot of strain on a mount like that.
http://www.overtons.com/modperl/pro...Pedestals-Sliders&aID=11E&merchID=1009&r=view

Re: Swivel seat base...fiberglass strong enough?

That split backing plate is sweet!!! However, if you are building the deck I would to the plywood with the steel. In my last resto I used a 3/4 ply with them nuts that are recessed in the wood. I added some big washers to it. My son is 170+ pounds of muscle. He has been laying down in his seat for the past 2 years and he has only manage to actually break the seat (I whacked him upside the head, LOL). However, i wonder how will it hold 10 years by know... I wont have that boat then to see though...

Re: Swivel seat base...fiberglass strong enough?

yah thats why i asked lol... im only 160 but my brothers 200+ so i wanted to make sure when he sat in it the base wouldnt go thru the floor