Dive ladder installation help

[mrieder79]

I just got a windline 4-step dive ladder with breakaway dive bracket. Unfortunately the hardware did not come with any installation instructions. My father and I plan to install it and both have some experience working on fiberglass but neither of us have installed a dive ladder before.

I am aware of the need for a backing plate and stainless hardware and have had two people recommend 5200 as a sealant. I would appreciate any advice or information on the matter.

Right now I plan to bolt the bracket to a stainless steel backing plate 4" x 6" through the transom about 2" above the water line and use 5200 in the holes and around the backing plate and bracket to seal.

Thoughts?

 

[TTPaws]

Only thing I'll mention is that 5200 is permanent. I mean really really permanent. For stuff near the water line I use a a boatlife caulk, seals well but can be removed if it needs to be. Just about the time you patted yourself on the back for using 5200 and what a great job you did, you notice a slight gap that requires that the bedding plate has to come off Of course that happened to some else...

 

[Eric Sedletzky]

If you're going through the transom find out what the core is made out of. Many times the coring is two layers of plywood with a skin of fiberglass on inside and outside.
I would consider oversizing the holes slightly so the bolts are not pressure fit, you want them to slide easily with out a lot of extra slop. Then take a Q tip and wet the wood core with west system epoxy to seal up the wood. After the resin sets use Sikaflex 291 as your sealant (48 hour cure). There is also Sikaflex 291 LOT which stands for long open time (7 day cure). Sika is all we use in the marine business anymore, nobody I know uses 3M especially 4200 ( the supposed removable sealant) We use 5200 occasionally for permanent applications, but more routine bedding is done with 291. It's far superior in adhesion, workability, flexibility, longevity, and it doesn't bubble like we've be seen with 3M products.
the other thing you want to do is bevel the outer holes with a counter sink bit. This allows the sealant to form an O ring much like a scuba tank neck.
When you run your bolts in butter up the last 3/4" of the bolt with a donut of sealant to make sure it gets drawn into the hole and seals around the shank and fills the counter sink space. The last thing you could do is after everything is installed, don't fully tighten down the bolts to get a full "squeeze" on the sealant. Instead leave it barely tight so you get some squeeze, then when the sealant fully cures then tighten down the bolts and you will get a pressure gasket affect.
Remember that fresh water is the enemy of wood that can't breathe, water WILL find the smallest pinhole to get in and wreak havoc.

You can take this advice to the bank, I'm in the marine repair business and do this for a living.

 

[manni-yunk]

I second Erics advise.


What I do on anything cored is overdrill - fill with thickened epoxy (West Systems usually), then drill to the appropriate size. A little extra time can prevent catastrophic core failure.

 

[mrieder79]

Thanks very much for your advice Eric. I will let you know how it all comes out. We have the components and are going to start work next week.

 

[mrieder79]

The design of the bracket makes it so that two of the bolts will have to go from the inside out so that their nuts are on the outside. Is this a problem? Should I consider having a machine shop alter the bracket so that all the bolts can go from outside in? It would be a pretty significant modification.