Winter storage on a lift.

[Oldhokie64]

I had asked this question before and got some good answers - thanks but now have additional input:

I have a boat lift that can easily handle my 272. I would need to rig it to properly support the hull and wing keel. Every boat that I have ever seen in dry storage is set squarely on the keel with some sort of supports to keep it from tiping but I assume not supporting much of the load except in strong wind conditions.

My keel is lead, the specific gravity of lead is 11.34 so when it is out of the water in slings, the load which is carried by the hull is increased only about 9% and that does not even consider dynamic loads applied when in the water. When it is on its keel, the load changes from perhaps 1 ton in tension to 2 tons in compression on the connections from the keel to the hull. O'day states that the propeller shaft should be disconnected when ever the boat is hauled and that the hull should be supported at the bulkheads to avoid compression of the frp.

My question is: would it not make more sense to support the keel by the hull, close to and on either side of the connection point to the hull then addtionally support it at the bulkheads?

I have a neighbor that has a 22 wing keel supported on standard bunks and another that has a larger traditional hull supported square on the keel with jack screws as I would see in a boat yard.

 

[BarryL]

Hello,

What problem are you trying to solve? As you wrote, almost every boat in the yard has the weight sitting on the keel and stands against the hull to keep the boat from falling over. Since that has been working for a LONG time, why do you want to change it?

Lastly, I never disconnect my prop shaft and I have never had a problem (with boats stored in winter since 2004).

Barry

 

[Oldhokie64]

Hi Barry, thanks for your feed back. The problem is the fabrication of a lift hanging over water. I have a 13k lift set up for a Grady I can store the Grady on a trailer over the winter, It is easier to fabricate curved bunks than to try to support a keel 3' below water on an aluminum crossbeam before lifting, then support the hull as well so it does not pitch when I lift the rig.

I have been storing trawlers on their skegs since the early 90's and never knew to disconnect the shafts. When I sold the first one, a 48 HiStar, I had to replace the cutless bearings, I have no idea what caused it but ground storage is a strong possibility. My larger trawler,a 52' 45 ton Defever, actually warped the frame of the engine room door. Once back in the water, it fortunately corrected. The point is that the other storage configuration would be closer to the design load distributions that I would assume Hunt used in his design for normal conditions (floating in a corosive environment ). Marinas probably set boats on their keels because it is easier than supporting them uniformly by the hull.

 

[jibes138]

What is the normal stress configuration?

A sailboat is normally supported by the hull with the keel applying a tension load to the keel stub. On the hard it is supported by the keel with the stub in compression. I've always thought it better to wet store a boat just for this reason. The problem with dry storage supporting the hull is not distributed like a boat in the water. It is concentrated loding only on the support points. The travel lift slings might be better than stands at select locations. Why not use multiple slings under your hull to distribute the loading versus rails? On your lift I mean. A guy in my marina has a lift he uses for a MArshall Catboat. I rests on two rails on the hull but also on the keel beam (it is a centerboardt boat)