Swim Platform Issue 2010 Mainship 395

[JWA1967]

Hello,

I recently hauled out for bottom paint and found the swim platform support posts almost completely detached. The #12 screws had almost all sheared of at the screw head. see photos. I was wondering if anyone else has experienced this and what was the best fix? I do not like the idea od 12 more holes under the waterline but thru hull bolts would be the best engineered fix. Please help

Thank you

 

[CharlieO.]

What were they screwed into? I'm about to refasten my swim step brackets. I have studs protruding from the transom with nuts on the outside. There seems to be blocks fiberglassed in the lazarette and some how my studs are embedded in that and exit out the transom. Mine are not through bolted on the transom. I need to check the integrity of my backing blocks before rebolting. Only one of my studs wouldn't tighten up.

You could drill out the holes and fill with thickened epoxy, I'm just wondering what you are screwing into.

 

[Comodave]

I would drill the mounting brackets out so you could get some larger bolts in them. Then through bolt the brackets to the transom. Read marinehowto.com article on bedding equipment. You want to countersink the holes in the transom just a bit so you get O rings of caulk around the bolts. Then on one of the blots inside connect it to your bonding system.

 

[Shrew]

You need to make sure that the screws you're using have a 'shank'. This is the smooth portion right below the head. IF the screws is threaded all the way to the head there are two issues:

1) The thickness is now lowered to the unthreaded diameter weakening the hold

2) The threading acts like a scoring like promoting shearing along that line.

In your case the load on the screw is lateral, so these considerations are very important.

 

[JWA1967]

Thank you all for the info. Yes these screw go into the transom but are not thru bolted.

 

[Comodave]

Do you have access to the inside of the transom where it is attached? If so then I would through bolt.

 

[Rearmount]

Mine are through bolted on my pilot. I just replaced mine as a couple were leaking. I went from 1/4 to 5/16 because I don't think the factory drilled proper size holes. If you go this route and that is recommended, make sure you put a backing block of MARINE GRADE plywood and plenty sealant. Use fender washers and nylock nuts. I also drilled holes a little smaller so they had to be driven in with a nice dollop of 4200.

 

[boatnbump]

I would be looking through bolting or redesigning those brackets. I can't imagine them doing much with a following sea slamming up under there.