Jerry Cozort [mailto:gcozort@earthlink.net] wrote: I'm looking for some input on what type of hoist I can use to lift a dinghy and engine up to the flybridge. Jerry Arild writes; Two years ago I worked for a large yard that specialized in making major modifications to yachts, including adding cranes, cradles and hard tops to boats not fitted with them from the factory. What specially concerned me was the fac that we would often build a hard top 15 feet X 20 feet that weighed well over 1000 pounds. This hard top would then be mounted over the main after deck using pipe stanchions etc. As often as not we would then also install a crane weighing about three hundred pounds to lift a dinghy or PWC which weighed around 400 - 500 pounds. By the time this was all completely installed, we had added about 2000 lbs ( 1 ton ) to the boat located 15 - 18 feet above waterline. On a boat that weighs 10 - 14 tons this is an appreciable increase. Especially that high above the waterline. I once asked if anyone had bothered to check what effect this had on the stability of the boat. Nope!! What's more, no one seemed to care. The bosses response was; " we provide what the customer asks for, is isn't our job to tell him he can't do it". Unfortunately, the owner usually didn't know enough to understand what effect on stability the requested modifications had. Static stability is not the same as dynamic stability. A boat in calm water may still float upright with the added loading up top. However, when that same boat gets into a seaway the roll period will greatly increase. In addition, the degree of roll may also increase. In some cases it would be possible to roll the gunnels under. There are formula for calculating this but I do not have that information. Does any of the listee's know what they are? Cheers Arild

>>>What specially concerned me was the fact that we would often build a hard top 15 feet X 20 feet that weighed well over 1000 pounds. This hard top would then be mounted over the main after deck using pipe stanchions etc. As often as not we would then also install a crane weighing about three hundred pounds to lift a dinghy or PWC which weighed around 400 - 500 pounds.<<< When I see this kind of arrangement, I always wonder if anyone ever thinks about just how easy it would be to launch or retrieve the dinghy or PWC from way up there if the conditions were anything other than glassy smooth. Even then, one good wake from a passing boat could set the whole thing swinging badly enough to cause serious problems. >>>I once asked if anyone had bothered to check what effect this had on the stability of the boat. Nope!! What's more, no one seemed to care. The bosses response was; " we provide what the customer asks for, it isn't our job to tell him he can't do it".<<< A few years ago a charter boat turned turtle up in the Pittwater, an fairly placid enclosed waterway just north of Sydney. The boat had been hired for some kind of party, and almost everybody on board had crowded onto the flybridge. The weather was calm, and the cruiser was travelling slowly. The boat just rolled on its side, filled and sank. I guess the skipper thought his job was just to give the customers what they wanted. Regards, Robert Bryett Sydney, Australia mailto:rbryett@ibm.net

rbryett@ibm.net writes: > we would often build a >hard top 15 feet X 20 feet that weighed well over 1000 pounds. This >hard >top would then be mounted over the main after deck using pipe >stanchions >etc. As often as not we would then also install a crane weighing >about >three hundred pounds to lift a dinghy or PWC which weighed around >400 - 500 >pounds.<<< According to the Poseidon Formula, for every pound added above the waterline, one must add two pounds lead or other ballast below. This maintains adequate stability even in rough weather - unless of course adding the extra ballast has lowered the waterline sufficiently to allow the ocean access through windows and portholes. (In which case stability resumes at the bottom of Poseidon's domain).... Gg