Take Care of the Davit so it Let’s you Down Easy
For the last four years I have enjoyed a great davit to lift the dinghy without a hitch. It has been pieced together using different fittings without complaint. It was time to give some love to the giant shiny boom on the front of the boat. The biggest challenge I thought would be figuring out the rusty and corroded cartridge on the boom. I learned the cartridge is for load handling keeping the boom from dropping too fast when loaded. This is what the block looked like when I started.
Over time leaking or broken hard lines were replaced. The top left line looks like steel brake line and the top right was replaced with a hose and non-stainless fittings. I was afraid to remove the cartridge so I removed and capped the entire assembly. I worked with Matt at Maximum Performance Hydraulics in Seattle, WA to figure out what to do. My original idea was to replace the cartridge and hard lines using the same block. Matt was patient when explaining the difference between a load handling cartridge and one that only allows the boom to drop slowly. The load holding valve or counterbalance insures that the boom stays in place when you need the boom to stay in one position. It is also a positive stop in case a line bursts or fitting comes loose. You don’t want to be in your dinghy up in the air when a line breaks and the davit drops unexpectedly. The old design slowed the motion with a spring cartridge but did not provide a positive stop. Matt determined this by the old block design. A true load holding cartridge requires ”pilot pressure” in order to open or move at all. This could have been done by piecing “off the shelf” parts together but I wanted it to look nice also. Fortunately, Maximum Performance Hydraulics has a full machine shop and talented machinists. Matt made CAD drawings and I had some suggestions on how I wanted to install it on the davit. Matt made the modifications and here is the result.
Instead of a combination of fittings the new design is clean and all stainless, including the fittings. The Sun Cartridge is not stainless because it was ten times more expensive and not available for at least six months.
The rest of the davit work was simply removing the ram covers cleaning off the old white paint inside, prime and paint the inside then polish the outside.
The last item on the list is to remove the six old hydraulic lines make new ones and reinstall. I used six colors of shrink tube cut in rings to mark which hose goes on each fitting. I will wait until the snow clears a bit to remove the hoses. So in the words of Billy Currington ”…if I fall, can you let me down easy”. Another project in the books.