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Started by talbot, Apr 07, 2023, 06:03 PM
Quote from: Riggerdood on Apr 07, 2023, 10:50 PM. . .forces would be much lower if point A were higher on the mast, i.e. using/connecting to the headstay or jib halyard. I'm sure you have a good reason for A to be where it is tho ...
Quote from: talbot on Apr 08, 2023, 06:04 PMMaybe. But as the angle of pull moves higher on the mast, the force is mainly directed to driving the base of the mast forward. I used to pull from the spreaders, and it was no easier. I'm trying to get the most upward pressure on the mast as early in the lift as possible. That is where it's needed. After the mast reaches 60 degrees or so, it takes little force to tip it the rest of the way. FYI, MacGregors lift their masts much faster than I can with a tiny derrick that attaches to a special fitting on their mast steps. So I'm still waiting for an actual calculation of the force. Where are those engineers?And, yes, the Mast-Up can extend to give you a couple of extra feet at the start of the lift.
Quote from: Roland of Macatawa on Apr 08, 2023, 08:22 PMtalbot, a couple of questions:Which boat model is this?--P21Do i assume correctly that:1. Your gin-pole is a pivoting gin-pole --Yep2. And that line AB is discontinuous with line BC--Yep3. And that there is enough forward clearance for the gin-pole to rotate 90 degrees forward--Yep4. Aren't you concerned about the tension in line BC rather than that in line AB? --No. I'm mainly concerned with getting the lightest possible gin pole that won't collapse on me. Current one is a perforated steel A-frame. So it's actually the max downward force on the A-frame that I would like to know. Do you have adequate lateral stability?--Yes. Not a problem.