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To the right is what a mast under vacuum looks like as the excess epoxy is squeezed out through the bleeder sheet into the absorbent material layer. |
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The mast core has been filled and sanded |
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Final shaping with a plane |
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Ready for final sanding |
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Above, epoxy is ready; the bleeder material and absorbent are in place; the mast is bagged and the pump is on. Above right: the pump and vacuum tanks. |
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The GX-2 Summer 2006 - Mast Construction - |
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Page 4 of 4 |
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16 August 2006
The mast form began as 2-1/4” x 9” x 20’. Do to the cost and shortage of carbon we made an original lay-up of seven layers of glass:
One full length/full wrap of 6 oz E. Glass. Two full length/full wrap layers of 9 oz unidirectional glass. Two partial layers of 9 oz – one from 18” above base up to the hound and one from 30” above the base up to the hound. One full length/full wrap of 10 oz biaxial. One full length/full wrap of 6 oz E Glass. Final lmast thickness 2-3/8+ inches
This proved to be too light and came in at 50 lbs/in when supported at the hound and the base and 16.2lb/in supported at the ends. Bob recalculated and figures that a mast 2-1/2 in wide would be +/- 40% stronger.
To get the specs that we had originally targeted, we added two 15 ft strips of carbon fiber (one 4 in wide and one 2 in wide) starting at a point 30 inches above the base. The mast then got a full length/full wrap of 6 oz glass cloth. The mast is now right on target at 28.4 lbs/in supported on the ends and 75 lbs/in supported at the base and hound.
Final mast weight is a respectable 34 pounds. Had we used carbon fiber cloth to begin with, we estimate that two layers of carbon and three of glass should have reached our 75 lb/in goal and the mast could have weighed as little as 27lb +/-.
All that said, we are still very pleased with the final outcome because the mast it is as straight as an arrow; the vacuum bagging went very well for our first try; we think that the profile is great; and last but not least, we can’t wait to sail it come December! |
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Now to install the base and top caps and the halyard rollers and we will be good to go. |