20231RE: Alluminium mast wall thickness
- Mar 5, 2014On Wolftrap 30ft long cat ketch rig I put a 36 ft mast 5 inches in diameter 1/8 inch thick The bottom 3 foot was buried therough the dack and was 1/4 inch thick and welded together. This gave me 36 ft above the deck. She carried a perpendicular top yard 2 1/2 inches in diameter and was set another 10 feet higher. The mast carried a main of 500 square feet. The mast was unstayed. In addition she could carry a 300 square foot flat spinnaker.
The boat had a full length hollow keel about 12 inches deep with a large centerboard. She was not as stiff as a keel boat I guess. This might give you some idea about just how strong a 1/8 wall 5inch round aluminum tube is. I have always woundered if an unstayed aluminum mast might be stronger than a stayed one that does not have lower shrouds. The lower shrouds keep the mast from and kinking under the compression load of upper shrouds. I don't know but it may be worth thinking about. There is no compression load to kink and break an unstayed mast. Doug
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