I've stuffed foam noodles up my mast after removing the mast cap. I think I put about six of them in there. Seal the rivets and mast caps with silicone. Take the mast to the water, submerge it a little, and mark any bubble locations that may show up. Seal those. The mast will now provide a lot of floatation resistance to turtling. The noodles only weigh a few ounces. It would take days spent in the water to soak the noodles if the mast does leak and even then the noodles will still provide flaotation.