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  #1  
Old 01-23-2014
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why does it spin?

ok. here is an odd question. the boom on my cal 27 spins around the gooseneck fitting. i think it's not a roller furling boom, though. no crank and the boom isn't round. in order to hook up the boom kicker, i have to secure the boom with an additional kit to keep it from rotating.

never had a sailboat with a boom that rotates, that way. never read anything about booms that do that, except for roller reefing booms. very curious as to what the purpose was for that design. seems to me, it wold be easier to produce without the rotating feature. so, it must have a purpose. anyone have an answer so i can stop wondering?
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Last edited by captain jack; 01-23-2014 at 11:39 PM.
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Old 01-23-2014
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Re: why does it spin?

Not all furling booms were round, but with no crank it's unlikely to have been one.

I wouldn't invest a lot of worry about it.
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Old 01-24-2014
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Re: why does it spin?

not really investing a lot of worry but i am curious as to the purpose.
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Old 01-24-2014
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Re: why does it spin?

You'd need to post some pics of your setup to be sure, but I have known setups like you describe where the main-sheet was fixed to the bottom of the boom (not on a bail or boom claw).

The theory was that a fixed mainsheet fitting should pull in line with the sail rather than impart a twisting force on the gooseneck (potentially snapping it) when the main is let out. It allows the manufacturer to choose a smaller, flimsier, boom profile than you'd need otherwise..
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Old 01-24-2014
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Re: why does it spin?

Mine is the same. I can only assume that it was a rolling furler and over time people have gradually taken all the bits off. End boom sheeting and the attachment point of the mainsheet spins freely at the end of the boom. Mine is also a sliding gooseneck so I have a very mobile boom (aside from the rigid vang).
It does mean that the sail foot always pulls nicely since the boom can rotate slightly in line with the cloth, that's about the only good thing I could say about it.
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Old 01-24-2014
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Re: why does it spin?

I'm betting Paul is right. Decommissioned exterior roller boom. Decom for a reason.
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Old 01-24-2014
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Re: why does it spin?

That is just the cheapest and most practical way to attach gooseneck fitting to the boom. All smaller boats I have been sailing have been like that.
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Old 01-24-2014
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Re: why does it spin?

Because it can rotate, it reduces the likelihood of passing sealions seeking it out as a place to snooze.You know it must be functioning when they avoid it.
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Old 01-24-2014
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Re: why does it spin?

Quote:
Originally Posted by captain jack View Post
ok. here is an odd question. the boom on my cal 27 spins around the gooseneck fitting. i think it's not a roller furling boom, though. no crank and the boom isn't round. in order to hook up the boom kicker, i have to secure the boom with an additional kit to keep it from rotating.

never had a sailboat with a boom that rotates, that way. never read anything about booms that do that, except for roller reefing booms. very curious as to what the purpose was for that design. seems to me, it wold be easier to produce without the rotating feature. so, it must have a purpose. anyone have an answer so i can stop wondering?
On the older Cal's (we owned a '76 Cal 2-29 for 20+ years), the foot of the sail was attached to the boom. With this arrangement, the boom was allowed to rotate about a pin to align its vertical axis with the surface of the sail to eliminate torsional shear in the boom at the goose neck. A vang could be connected to a hooped bail fitting. To employ a solid vang, one would simply use a fitting plate on the underside of the boom that was oriented transversely rather than along the length-wise axis with a pinned connection.

FWIW...
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Old 01-24-2014
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Re: why does it spin?

Quote:
Originally Posted by Classic30 View Post
You'd need to post some pics of your setup to be sure, but I have known setups like you describe where the main-sheet was fixed to the bottom of the boom (not on a bail or boom claw).

The theory was that a fixed mainsheet fitting should pull in line with the sail rather than impart a twisting force on the gooseneck (potentially snapping it) when the main is let out. It allows the manufacturer to choose a smaller, flimsier, boom profile than you'd need otherwise..
the mainsheet attaches to a piece of flat stock, bolted to the cap at the end of the boom. this flat stock is free to rotate.

i think you may be right about the purpose, though. that makes sense. allowing the boom to pivot in line with the sail to reduce stress. looking about on line and in marinas, it seems that was a 70s thing. i could be wrong, though.

outside of the pivoting gooseneck fitting, the boom looks the same as any other boom. so, i don't think they used a smaller boom profile.
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