Currently, I store my cat out in the open with mast up. But I'm thinking perhaps it would be better to drop the mast between weekends.

I'm in Indonesia, so sun and rain are the only elements that get to it.

I would keep the mast up. The wear and tear and potential injury risk of raising and lowering the mast every weekend outweigh the minimal wear and tear of keeping the mast up. Just my opinion, of course. Additionally the convenience and the time saved of keeping it up makes it even less of an argument.

You should be fine storing it mast up. You should look to replace your shrouds more often if you leave it up all the time. I store mine mast up all summer. If you aren't going to use it for a month or two I would take the mast down. But if you use it most weekends no need to take it down.

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Scott,
‘92 H18 w/SX wings
‘95 Hobie Funseeker 12 (Holder 12)
‘96/‘01/‘14 Hobie Waves
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I leave mine up all summer. It might be prudent to take it down if you are in the path of a serious typhoon.
In some ways metal is not as good as wood, it suffers from fatigue after being subjected to numerous load cycles. Cats are usually left on dry land, so don't experience the constant rocking that a moored boat would. I do slack off the shrouds & diamond wires a bit, but is just way easier to leave the stick up.

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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Personally I store mine with the mast up except in the winter where it doesn't get used much (and the winds are higher)... I also remove the mast if a storm is due. Some insurance companies here in the UK don't cover your boat if you leave the mast up in the winter...

Trev