Dinghy Swinging - Heavy Load

[Pblais]

Isn't the main stress point for a davit on the stern rail, where the top of the davit mounts to ?

They really can't tell you how to do it since all boats are different. For the St Croix Davits we have there is a custom SS bracket that looks like a "7" made of 1/4 SS and the overall height is about 18 inches. This lets the mount sit aft of a line extended up from the transom. It gives a few more inches away from the transom when lifting. The top of the 7 attaches to the cap rail and the bottom to the hull in multiple points with backing plates. The davit itself slides forward into a shoe (supplied by ST Croix)attached to the top of the custom bracket and is locked in place with a pin through the base of the davit and the shoe into the bracket. This lets you remove the davit if you like with no tools required. It was custom fabricated bracket and not part of the davit purchase.

It also means the davit is now attached to both the cap rail and the transom spreading the load. In this case the davit will break before it can rip out of the hull. That would be the goal because in a severe situation you can afford to lose the davit as bad as that sounds but you can't ever afford a hole in the transom or a torn stern.

The shape of your stern and transom will best determine how to get a good attachment.

As Gord notes above if the davits are inboard from the dinghy attachment points then the two lifting lines are no longer parallel and will oppose each other as the dinghy swings and thus tends to dampen the pendulum effect.