Crane for lifting sailboat mast, dock gangway and other stuff

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Hi Folks,I had this thread in the math section a year or more ago, as I originally was lookin gfor advice on design,etc.Now that it is done,  Ithought I would share it here, and I am always inetrested in improving, or knowing better for next time.This spring I decided to continue with the plan of buidling a jib / derrick style crane. It's been a few months, so I can't remember exactly, but here are some specs. It turned out well, and as a test I lifted a large boulder ( 6 - 7 cubic feet of rock, so likely 600 - 800 lbs). This was without any "support / guy " lines from the main pole. You will see some in the pics, as I am considering lifting a larger boulder, near the dock, and I wanted to reduce stress on the main "vertical" pole. - approx 10 ft of 8" galvanized pipe (1/4" + thickness) with flat 3/8" plate cut in circle welded on as collar) bolted to the crib dock and foot wedged between large boulders and cemented in place with about 800 lbs of concrete - Main vertcial pole about 18 ft or 7" pipe (about 3 ft of which overlaps / rests inside above pipe) , similar collar welded on and teflon ring in between collar, pipes heavily greased so this pipe turns inside fixed dock pipe. - 26 ft "jib" boom 4 1/2" diameter (two 13ft sections butt welded together with a 4 ft sleeve inside as joint and plug welded as well) - two 2600 lb boat trailer winches - **** Yes, I know they are not rated for overhead lifting, but we generally don't stand under the load, and as well have safety / backup rope lines on jib boom and load separately***** - 1/4" wire rope, ran with 2:1 ratios to raise jib boom and load separately. - It has vertically lift range of about 30 ft, from the crib dock level and a horizontal range of out to about 15 - 20 ft, but of course, load capacity is reduced as it stretches out.... - Rotates 360 degrees - doubles as a flag pole when raised completely vertical ( jib boom rests against mail pole) Worked well to lift mast on a couple of months ago. I move the boat to the inside of the tee dock, to put the mast on / off, if you are wodnering how the crane "reaches' the boat.... Cost approx $600 - 700 total for steel (all scrapyard finds), winches, new 1/4" wire rope ,etc
Reply:There is a crane at one of our local yacht clubs that is very similar to yours. It works great for placing/removing your mast,(I have used it on my San Juan).
Reply:Cool!I always wanted to build something like that for outside the shop for lifting, instead I got a skidsteer.
Reply:A very good illustration of the power of the straight line.Small structural elements held together by strands of cable, but the strands exert opposing forces that defy gravity. SERIOUSLY!!!!!Ever look at the cranes at the top of high rise buildings under construction.................same principle"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Hey Brian - Nice to see some fellow Maritimers here!  I've been to Charlottetown nany times, and been at the docks downtown, but either didn't notice the crane, or it is at a differnent marina.  Most marinas have some pretty heavy duty ones, as the mast for my 30' boat is a bit heavy / being an older design, but it is still nothing in weight not height, compared to the masts fom some of the larger boats.   Iwould have loved to juts copy a design, but most were not quite what i needed - some don't have the ability to reach in and out -  I wanted this feature so I can lift different objects, like each end of the 14' gangway separately, one end being very close to the crane base, and the other, well, 14' away....etc.
Reply:I'll take a picture the next time I'm downtown. They have 2 cranes at the Charlottetown Yacht Club,(the only marina out of the 3 downtown that has a lift), a hand winch one similar to yours and another 10,000lb electric/hydraulic for boat lifts.
Reply:OK, tyhabks!  I only remember seeing the larger one.