Installing new seat pedestals . Have questions

[mjbuck]

I am about to replace my original boat seat pedestals with Springfield Marine air ride pedestals. These are for flush mount to the floor pedestals with 9 inch base and have six mounting holes for screws . My original pedestals have the same set up and the screws are about 2 inches long . It appears there is wood and a layer of metal in the floor my boat , although I cannot get below deck to see exactly what is there . I have read many different suggestions as to how to properly mount these pedestals. I am going to reuse the original screws , but is or anything else I should know before I drill pilot holes and secure these pedestals to the floor? My boat is a 2006 Polar Kraft 17.6. I have to drill new holes as my original seat pedestal bases were 10 inch and my new ones are only 9 inch in diameter.

 

[bonz_d]

Good question. Are these wood screws or machine screws?

I've always used cleated tee nuts with machine screws but with a metal plate under the base it would be difficult to add tee nuts.

 

[Texasmark]

I don't know what boat you have nor how pickey you are about aesthetics and all that, but if you want to do a safe, secure installation I have a suggestion. Remember you are sitting on a seat mounted on this pedestal. It and the steering wheel are your connection to your boat while under way.....in ALL sorts of environments.

I have been thrown from a pedestal seat in an 18' Starcraft Holiday in rough water and know how humble it makes you feel until you get ahold of something solid and right yourself. Mine didn't come loose, it was OEM, aluminum, had 4 triangular gussets, about 4" long, around the pedestal which were welded to it and to the bottom mounting plate.....the welds broke and besides falling out of the chair with the pedestal tube still mounted to it, under me were 4 spears sticking straight up. Luckily (and I put that mildly) I didn't land on any of them.

I'd make an access hole adjacent to the pedestal and investigate just is under you and determine the solidity of the mounting surface. If a metal plate, great and I'd mount with screws, washers and self locking nuts, all stainless steel. Then just make yourself a nice patch over the hole you made and be about your business in a safe manner. You can install the T nuts bonz suggested and nice SS screws and a SS plate of ⅛" thickness or something of the sort. Wouldn't be any more unsightly than a round, slotted, deck (floor) drain cover that you probably already have visible.