Sanding / painting on a cradle
My new (to me) boat is currently on a cradle and about to begin a fun pox repair session. What is the safe / recommended method for handling the hull area that's currently under the cradles 4 pads?
Do I just find a single boat jack, place it close to the current cradle pad, chain it to the opposite side of the cradle, then back off the cradle pad's threaded rod to get it out of the way? My cradle's "legs" that the boat sits on have the same kind of threaded rods that the top of boat stands use.
Having never worked on a boat in the cradle it's a bit unnerving having all that boat over my head and wondering if my idea is structurally safe :) I'm sure it's not as bad as it seems, but I have a pretty vivid imagination that depicts 6800 lbs falling off the cradle being a bad thing!
It's only 6800 pounds, what could go wrong? :)
Keep in mind that the weight of the boat should be resting on the keel, so the pads are only holding the boat upright. You're on the right path, but will be a bit constrained by the cradle frame.
Take two jackstands and an appropriate length of chain. Position one on each side of the boat immediately forward or aft of the cradle pad as appropriate. Put 1/2" plywood under each corner of the stand. The base of the jackstands are triangular; position the stand such that they are angled in toward the hull and the points of each base are pointing toward each other (look around the yard at other boats for an example).
Connect each stand with the chain. THIS IS EXTREMELY IMPORTANT - the stands can be pushed away from the boat if not chained together. Raise the pads on each jackstand so that the contact the hull. Take up all the slack on the chain, and pull the stands away from the boat to take up any remaining slack. THIS IS IMPORTANT.
Tighten the jackstands as much as you can by hand. They should not be supporting the boat. Now take a deep breath. Loosen ONE pad on the cradle a little bit, give the boat a good push with both hands to make sure that it doesn't shift. Keep backing off and shoving until the pad is away from the hull. The idea is to make sure that the jackstands are solid and not going to move.
Do the work that you need to under the pad, then restore the cradle pad to the original position. Repeat the procedure for each pad. Alternately, you may be able to take pressure off both forward cradle pads and do your work, but I would restore the cradle pads at night or extended periods.
I've done this many times and it's not that bad. I don't have a cradle, so I'm not as constrained by space. I personally don't like cradles since I can't add pads where I want them.
Thanks! Doesn't sound too bad at all. Hopefully I can borrow a pair from the yard I'm in so I don't have to buy them for a short term project.
When I stored my 7000 lb boat on a cradle with 4 pads, I routinely used one stand on the centerline (near bow or stern) to permit backing off the nearby two pads for sanding and painting. After my work under each cradle pad, I would screw it back to within a fraction of inch of the hull just in case until the bottom paint dried. Never had a problem.
First off, I'm a cruiser---not a racer---so I'm not Fanatical about bottoms.
Four pads at 25 sq. in. apiece ain't gonna make a whole lot of difference to me, compared with the entire bottom.
So I leave a small soda bottle half full of bottom paint, along with a disposable foam brush, hanging in a ziplock bag from one of the jackstands. When they launch in the Spring, the yard crew lifts the boat with their straps, then touches up where the pads were.
Does the fresh paint have time for a proper cure? Probably not. But next season the chances of having the jackstands placed in Exactly the same spot are, well, ....
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