Attaching Frame with coach bolt

[foxdog]

A frame we have above our console has come loose We didn't fit it and were very concerned and worried when we found out it was attached to the deck buy just 6 large selftapers We cannot gain access to under the deck were it is fitted and do not want to cut Inspection holes as we do not have a plan of how the hull is constructed.

Now my question

Has anyone ever fitted a heavy frame using Coach bolts through a steel plate then through 3/4 plywood ?

We were also considering lining the holes through the ply with steel pipe so that the coach bolt will push upward onto steel rather than wood

Or has anyone any better ideas than coach bolt

Any help or advise would be greatly appreciated

[Hightower]

Bit of a tricky one without first seeing the bottom of the frame fixing points and knowing how big they are.

One soulution you could try is to hole saw the deck where the frame feet go, choose a size of hole that is smaller than the PCD of the fixing holes in the foot.

Manufacture two stainless rings to the same dimentions of the foot, 4mm thick but with the addition of a hole in the middle and tapped holes suitable for the bolts you're using. Saw this ring in half (4 fixing holes) or 2 thirds/1third (3 fixing holes), this will act as your under deck spreader.

Next is the tricky bit! Silkaflex the ring and place though the hole in the deck (Don't drop), line up the holes in the deck and place your bolts though, do this with the other part of the ring. Nip the bolts up and leave overnight. Repeat for other side.

In the morning remove the bolts very carefully and you should have the ring glued to the underside of your deck.

Fit your frame and re tighten your bolts.......

Voila....Job done.

Andy

[foxdog]

the 2 feet on the frame 650mmx100mmx13mm with 6 x 13mm holes There were 6 x 25mm bolts screwed through the feet into the base plate which is same size as the feet ( the base plate was held to the deck with the 6 selftaping wood screws).

When you looked at the top fixings you assumed that the construction was very secure and that the base plate was fixed by the bolts

Thanks for the input any suggestions are welcome

[Hightower]

If you could modify your base plate to sit inside the hull ie:under the deck your more than halfway there, just need to tap out 6 holes M6 and you're away

[foxdog]

Because we do not know the deck layout ( where supports are) we are not going to cut a hole to insert base plate for fear of damaging something else
or weakening hull integrity

Thats why we are thinking of using coach bolts It means only drilling 6 holes

[jwalker]

Originally Posted by foxdog

..Thats why we are thinking of using coach bolts It means only drilling 6 holes

Ah, now I understand. You don't mean coach bolts, you mean coach screws. If the deck is thinnish they may fail. I've been disappointed with the holding power of shortish (25-30mm) coach screws. Long ones can be very powerful, I hold my bench vice down with them and they take more punishment than you might imagine.

[Chopppywaters]

duct tape....its waterproof

lol i say go to whoever you bought it from and get the hull plans

[Pete7]

Rogue Wave recently had an A Frame tear out because it was screwed to the deck with bolts set into what looked like aloy inserts 25mm in length.

Thats a big frame you have there, I think you might have to add a third leg either to the deck or to the console to secure it. The Ribtec Camel ribs had problems with a S/S frames breaking. One other suggestion would be to glass over the whole foot to the deck in addition to the coach screws. Osprey fit some of there A frames this way and a lot of divers bottle racks are also glassed down.

Pete

[Scary Des]

I have never used these through fibreglass but have had success using bolts like these in steel. The thing that would worry me is that all the load is on a relatively small area (the drop down bar) but i suppose if you used a lot of bolts you would overcome this issue Des

[mark-f]

The way i did it on an old rib was to get a piece of stainless plate and fix bolts through the plate then screw and fibreglass the plate to the deck using plenty of chop strand matt over it then mounted the aframe over the bolts and fitted the nuts on the top. the repair lasted longer than the hull did :-(

[foxdog]

Thanks for all the input

I'm going to try the Blind bolts suggested by Scary Des

I'll let you Know how we get on with them and how thay are performing after some sea trials

[Tim M]

I've used "blind bolts" for fixing things to the deck in the past. They performed very well. The only issue was when I needed to un-do them; but the ones I used had a spring to hold them open. This sort looks like it might be easier to remove...