We are looking to replace an existing stainless steel
davit system on our Cabo Rico
38 that has been on the boat for many years with a new aluminum
arch with integrated davits
panel supports, and an engine lift
We learned long ago to move the dinghy
onto the deck
when we anticipate rougher weather
or when doing an extended coastal or offshore passage
, so the davits
would only have to deal with unexpectedly sporty conditions for a short period, until such time we could anchor
The existing davit system has "forward" legs that sit flat on the deck
and are through bolted. It then has two "stern" legs that are bolted onto the stern, which is sloped inwards from the cap rail to the water
Not being a mechanical engineer
I am trying to understand the dynamic forces involved and how to best design the arch to support a dinghy
in moderate sea conditions, with my main concern being the sheer forces on the stern mounting.
Would schedule 40 tube 2.5" in diameter be sufficient for this design? Would it be best to plan to have the tube project
into the stern of the boat by an inch or so and then welded on the outside by a plate that is through bolted? Or is it best to weld the pipe to the plate and only have the plate bolted through?
What angle to the arch should I avoid?
I'm not trying to reinvent the wheel
, just design something sturdy with an emphasis on making sure it is not weak at the transom mount.