[Rhodes22-list] Mast Crutch

[Michael D. Weisner]

Mark,

I sincerely hope that you are not thinking of transporting the boat with the mast in the crutch and connected to the tabernacle.  The resultant angle will place the top of the mast much too high for transport and the base will probably cause the tabernacle to pull out of the cabin top.  The attached photo shows my home built crutch with the mast ready to be raised, illustrating the height of the top at the stern.  You might also look closely at the image to see the lower crutch crossmember which I rest the top of the mast on when transporting (the foot rests on the bow pulpit).

For those who are questioning the crutch height necessary to achieve the proper mechanical advantage of the mast crane, please review the attached pdf output of my Excel spreadsheet to calculation tension/compression on the crane throughout the motion from resting on the crutch to fully stepped.  Please note that my crane is homebuilt designed using a 6 foot gin pole attached to the base of the mast.  The crutch must be high enough to limit the tension to safe working loads for the line used.

Mike
s/v Wind Lass ('91)
Nissequogue River, NY


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