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Cracks in mast joints


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There are small cracks in all of the joints where the smaller diameter tubes are fiberglassed to the larger diameter tubes. Does anyone else have this? Do you think I should be worried?




Frank San Miguel

San Jose, CA

Core Sound 20 Mk 2








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As long the thinner uppermast protrudes long enough into the thicker undermast i wont worry so much.
The fiberglass putty seems not elastic enough to stand the flexing of the parts.
for 100% safety i would remove the putty and look if there are any cracks into the uppermast.
After that i would laminate longitudinal rovings above that part.

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Hi Frank,


I am glad that you are still enjoying the boat. It was good to see your video of her sailing herself.


You do not have any worries with the masts. They are just collars that keep the upper mast sections positioned. The upper section is buried into it's lower partner by about 9" and there is a lower bushing. With free standing masts there is very little mast compression, with most of the forces being side loading the glass epoxy layup can easily handle all the loads that the section can put on it. We bond the bushings because fasteners add potential corrosion in time, plus a slight weakening of the small section where it has it's maximum load. The same reason why we do not to weld them in place as you lose about 30% of the tensile strength from the high temperatures taking the temper out of the high strength aluminum.


We know of one set of masts on a CS17 that were welded and as far as I know have not failed. This is because of the happy coincidence that the masts are stronger than they need to be to get the stiffness we want to get the right sail carrying power. It still goes against my grain to weaken a mast by that much.


Over time corrosion is our enemy but I am not seeing any in your pictures.

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Thanks, I was hoping to hear that!


The addition of a tiller clutch has really made a difference in self steering at different points of sail. Depending on the intensity of the wind, I can even self steer close hauled.



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