Recommended bolt/screw to fix pedestal to floor

[stingau]

Just brought new pedestal's and seats to go into boat. Anyone have any idea what are the recommended fasteners to fix.

The pedestals are 650mm high fixed height sliding Springfield bases. Because of the extra height I want to make sure that the screws/coach bolts are big enough to ensure that the leverage provided by the height doesnt rip them out of the floor. The floor area has been reglassed.

I have checked springfields website to see if they have any guidelines but it appears that there isnt any. I am leaning towards coach bolts because of the better gripping strength

[rumy1]

If you can get bolts in them then go bolts but if you can only go screws I had approx 70mm x 6 mm hex head screws holding down my pedestials. Make sure you take your time and Sikaflex the screws in.

[mowerman]

Recently put a second pedestal in the Haines.

Cut a piece of 12mm ply slightly larger than the pedestal base.
Mark out on the floor where the ply is to go then scuff this area with a grinder.
Apply a coat of fibreglass resin and stick the ply to it with some stainless screws using silicon in the holes.
Put a sheet of fglass over the ply and about 70 mm out onto the floor. Resin this down. When dry apply flowcoat in the same colour as the floor.

Screww the pedestal to this with stainlees screws long enough to go thru to the floor. Use silcon in the holes.

The new seat will not go anywhere..

Rod

[gofishin]

... The floor area has been reglassed....

Sting, was this to strengthen the floor for the new pedestals, or did you have rot etc?
Mark holes first & drill all with a 3mm bit, noting depth before the drill bit bursts through. This will tell you what length screws will suit. If one or two seem solid all thru, this means you are going into stringers/bearers below. Longer screws here will provide more strength.

s/s screws, and the largest gauge you can get that will fit thru the holes in the pedestal base. Will be something like 16 or 18g, and you may need to get them from a specialist bolt merchant. Hex drive & bit if you can get them, otherwise get 2 new large philips drive (one for b/up in case you rip the ears off the 1st one)

Get one or two extra screws for pilot hole testing (in case you stuff one). Ist select a pilot drill size that is at least the same as the shank (solid) part of the screw. Get a solid piece of timber roughly the same thickness as your floor. Drill one with the pilot & try to drive a screw through (drill-driver only, not by hand). It will be hard to do and you will need to keep a lot of force down on the drill, and keep it plum. If it stalls, screw breaks etc your hole's to small. If there is a thick layup of glass in your floor, the pilot size will need to be be bigger - go up in 0.5mm increments until you get it right. Next try one in the floor (with a new screw) with pedestal base & neutral cure sealant, if OK proceed, otherwise up one plot size again.
cheers

[TJ Bear]

Best way to do the job is when your puting your new floor in glass a alli plate under the floor where your pedestal base is going to be, put your pedestal base down on the floor, drill through the floor and alli. Tap the alli to the bolt size you require then bolt them down. Any other way is a compromise.

[BM]

Sting,

Use a pad of inch ply and make a base larger than the pedestal. Insert bolts through this from the bottom and then glass the pad to the floor.

Then bolt your pedestal on with nylock nuts.

This way you in no way compromise the floor by screwing into it and creating a penetration point for water.

Pedestal seats are typically a bad way to go as the forces on them are extreme and they will ultimately damage the floor at some point in time. Look at boats like Cruisecraft etc that use a skeletal frame for the seat bases as it spreads the load far better. Likwise a fibreglass seat box also spreads the load very well.

Cheers

[stingau]

Gofishin,
I originally thought that I had rot as the previous pedestal on the starboard side when rocken made the floor ripple. I sent theboat to a boat builder to repair,upon inspection he reported that the floor was sound and the problem wasnon stainless bolts were used which had rusted allowing the play, he instead of cutting out the floor simply put 3 or 4 sheets of glass over the areas where the pedestals bolt down and then resprayed the entire floor. Originally the floor had artificial grass this has now been ripped up and a nonslip top coat laid down. I was at first surprsed that the floor didnt need replacing because of the movment but as I had already authorised him the cut the floor out and agreed to his price,when he didnt do it i accepted that it wasnt necessary.

That's why I am trying to work out what fasteners are required as each seat had different sizes and types

[BM]

Artificial grass??????

You know, you can put 3 layers of glass over shit timber and have a flexible layer of glass over shit timber....

Mate, unfortunately there are many shit repairers out there and sadly I have to say that some of the absolute bullshit stories I hear come from QLD.........

[litenup]

Try roofing screws, but s/s with thread for timber. They are available. They have a good course thread to grab the ply and glass. I relocated my pedestals in a Haines and worked perfectly. Cheers Pete.