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Ice in Mast Step

B-L Bandit

Leeward Bound and Down
A sunfish I have was moved from a garage to outside on it's trailer. The mast step filled with water in a rainstorm and subsequently froze with some colder weather we had move through. It's warmer today so i'm going to go drain it and cover the hole, but my question is does this automatically mean the tube might have cracked? Anyone else have good luck with them surviving some ice?


Does it automatically mean it cracked? No.

Depends on how the ice expanded as it froze - it might be ok with no damage. A leak test, or just filling the mast step with water (on a warm day) to monitor if any leaks would let you know.
I leave mine outside on a trailer all winter in central Indiana, but flipped over (bottom up, deck down) so that water can't collect in the mast step, or the cockpit. I have outfitted my trailer with two long (8') 2 by 4 bunks that support the deck well.



Well-Known Member
How much rain did you actually get?

Depending on any debris collected within the mast step, even a leak-down test won't indicate anything wrong. If you can pressurize the hull (a few pounds) through the deck drain, maybe a soap/water mix will show a crack.

Based on my efforts to make a giant ice cube—that lasts many hours in my iced-tea—I've devoted half my freezer to different attempts using plastic containers.

If your driveway is steep enough, I've found that ice won't crack a plastic container (or mug) that is tilted. (Outwards stress is diverted). Otherwise, a great deal of pressure is produced toward the bottom—bending it severely.


B-L Bandit

Leeward Bound and Down
It was enough rain to fully fill the mast step, when I first saw it it was filled to the brim but had begun to melt and a single piece of ice was left in the center surrounded by water. Last night i drained out the ice and covered up the hole with tape. It's going back into the shop to do some lass and gel-coat work .

It was at a slight angle where it was on the trailer so that hopefully helps, but was completely filled.


Upside down?
Staff member
Follow tag's advice.
I will add though that the tube may not leak while the hull is at rest, but mine did leak when sailing in waves due to the hull flexing a bit and opening a minor crack.
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Alan S. Glos

Active Member
An easy way to keep water out of the mast hole: Stuff a tennis ball about half way in the hole - it is just the right size to keep water out when the hull is left deck side up.

Alan Glos

signal charlie

Well-Known Member
Staff member
What BB said. Make sure water does not get in the cockpit. If it fills up enough, it can get inside the hull through the vent hole on the forward cockpit wall and then there will be wet foam.