Postby Viper » December 1st, 2018, 10:20 am
Keith, perhaps a Santego owner of the same model and vintage can confirm but if memory serves me, some models had engine exhaust through the hull sides and some through the swim platform through four or five holes on each side. At the very least, exhausting through the platform would indicate that all or part of the platform is hollow. Again, hopefully someone can confirm.
GUY brings up a good point in that the platform is not very deep so you want to ensure you are within required specs before you start drilling any holes. Hurley has a layout and requirement specs on their site. If I recall, they also have an extension assembly to accommodate short platforms.
No matter which davit system you go with, you can't go wrong with stainless steel fasteners. The size and length of the fasteners will depend on the unit you're installing as the holes provided in the mounting hardware will dictate fastener size. This should be in the instructions provided or simply measure the diameter of the mounting holes in the base plates.
Just as important, is the installation process. I assume it's a cored platform and if you never want to worry about it again or your core rotting from it taking on water a few years down the road, here is a good installation practice. Drill your holes and do a dry fit with your fasteners. When you’re satisfied with the fit, remove everything, then dig out the core inside around the holes a 1/4 inch or so all the way around. An allen key in a drill makes this easier. You may have to start off with a very short end and progressively work your way longer depending on the core material but the “L” shape makes this easier to get around the bend in the hole. Balsa will be a cinch as it’s a soft wood while ply will be a little more difficult. After you’re done digging, tape the bottom of the hole, then fill the entire cavity with thickened epoxy. After it cures, re-drill the holes starting off with a much smaller drill bit to act as a pilot hole and ensure it comes out through the middle of the hole on the opposite side.
The above serves two purposes; even if your seal (caulking) around the fasteners fails, no water will come in contact with the core since you have effectively drilled through an epoxy plug and the hole isn't surrounded by the wooden core material. Secondly, the plug serves to prevent collapsing the top or bottom glass layers and crushing the core when you tighten the fasteners. This is the way all hardware that experiences high loads/stress should be fastened to cored substrates. Your swim platform will undergo high stress levels with a dinghy on it especially in rough seas so don’t skimp here. Any movement in the fasteners or substrate will cause caulking to fail and an unprotected core will saturate pretty quickly ($$$).
My motto is that hardware gets thru-bolted where possible. Even in an enclosed/hollow swim platform, access holes can be cut underneath the fastener areas, and as long as the core is properly addressed with epoxy and the hole covered with a sealed access plate, this is the way to go. Guys have used marine grade anchors for fastening in hollow areas that can’t be accessed through the other side without cutting holes, and while these work for some applications, you want to be careful using them for fastening assemblies susceptible to high stress levels.
Good luck and let us know how it works out.