Davits.....Part 2

     As the design process unfolded, one of my goals was a very robust and rigid dinghy support system. I did not want something hanging off the back of my boat that would come loose in the first storm. Most of the davit systems I see on smaller boats are retained with 4 screws and a small bracket, mounted right at the trailing edge of the swim platform.

     In place of these thin, stamped brackets, I machined my own pair out of a 3 inch diameter piece of 316 stainless steel bar stock. I cut it into 2 half cylinders, and machined the resulting pieces to through-bolt to the swim platform, from the trailing edge. On top of each bracket, I drilled and tapped a 3/8" - 16 through hole, to secure the trailing edge of the new davit assemblies.

     To mount the forward sections of the davits, I decided that I did not want to penetrate the swim platform in any way. Every penetration is just one more area for water to intrude into coring, and it adds to the maintenance load too, since core penetrations should be re-bedded every 5 years or so. Fortunately, there are several openings in the swim platform already, where the 4 elliptical drains are screwed down. I made up a couple 316 stainless steel backing plates, out of 1" x 1/2" x 12" 316 stainless, and along with some 3.5" long flat head stainless cap screws, screwed the davit arms down. The swim platform is effectively sandwiched between the davit arms and the backing plates, making for a very strong structure that required drilling no holes in the top of the swim platform. The finished davit system looks like this:

This is a mock-up assembly, before final sanding and polishing of the stainless. Once the dinghy enters the picture.....

     One person can load and unload the dinghy, although it is easier with two people. In the next post, I will show the final elements of the davits, and a modification I made, to help keep the dinghy in place.

Davits....Part 1

     My wife and I went on vacation recently, and before we left, we had decided that we wanted to spend more time anchored in less crowded areas, instead of spending each night at a marina. I did considerable research concerning dinghy davit systems, and came to the conclusion that I really didn't like any of them.

     Weaver style davits are a pain, since the dinghy has to be tipped up at a 90 degree angle, so the outboard has to be either removed, or pivoted on Weaver's special transom bracket, which costs more than their davit system. This dinghy placement also reduces rearward visibility, and adds considerable aerodynamic drag. However, it does have the advantage of tipping the dinghy up away from the water, which is an advantage in rough seas.

     Hurley and Nautley make systems that support the dinghy in the horizontal position, which is convenient, as the outboard can be left on the dinghy, and the drag and visibility issues are solved. However, in rough seas, or at certain running angles, this placement can become problematical. I also feel their systems are overpriced, and not as robust as I would like.

     In the end, I decided to fabricate my own system from scratch. The dinghy I picked up is an Achilles LSI 260, with a 4' 9" beam. Since my swim platform is only about 33" long, and I wanted to be able to walk on it when the dinghy was mounted, I knew I would have to extend the davit pivot point beyond the trailing edge of the platform. So, I used 316 stainless steel box tubing, in a 1" x 11/2" x 1/8" size, to get the extra length I needed. In the pictures below, you can see the progression, as the pieces were machined, and then TIG welded into the final assembly:

     These are the arms that will support the dinghy, and act as the pivot point for the plastic cradles. Note that ALL components are machined from 316 stainless steel, and all the nuts, cap screws, and washers are 316 as well.

     The cradles themselves are made from 1" thick HDPE, and are custom contoured to fit the bottom of the Achilles dinghy:

In the next post, I will show how the davits are mounted to the swim platform, and how the dinghy is supported.