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Lowers? Diamonds?

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Smight at BBSC View Drop Down
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    Posted: 16 Sep 07 at 6:25pm
What do they do? How do they do it? 

Edited by Smight at BBSC
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 6:47pm
Lowers stop the forward load from the boom/kicking strap bending the bottom of the mast.

Diamond stays are an alternate to spreaders for keepig the mid mast straight. Normally the spreaders are in line with the mast so they control side bend only, but sometimes (Tornado Cats I think are an example).
The big advantage of diamonds is that they are independant of the load in the shrouds, so the mast doesn't go floppy when the crew gets on the wire.
The big disadvantage is that there are two wires up the mast each side instead of one, so more drag and more weight aloft.
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tgruitt View Drop Down
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Post Options Post Options   Quote tgruitt Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 6:48pm
Lowers control mast bend in the bottom section of the mast near the gooseneck, (this obviously affects the top of the mast a bit too) and stops sideways bend too if they are pulled on tight. Diamonds control mast bend in the middle to top section by adjusting their tension, this means you can sail with good prebend which is not completely controlled by the shroud tension. The diamonds also support the mast sideways too, especially with the kite up. I think I have got this right, any corrections??

Edit: I seem to have been beaten to it, not too far wrong from what the Oracle has written.


Edited by tgruitt
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Wave Rider View Drop Down
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Post Options Post Options   Quote Wave Rider Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 6:48pm

Beat me to it

 

 



Edited by Wave Rider
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Splosh View Drop Down
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Post Options Post Options   Quote Splosh Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 6:48pm

Originally posted by Smight at BBSC

What do they do? How do they do it? 

Lowers and dimonds are put on trapeeze boats to stop the mast bending in the wrong places when someones on the wire. When one of our lowers snapped on our old 4k you could clearly see the differnce it was making.

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Smight at BBSC View Drop Down
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Post Options Post Options   Quote Smight at BBSC Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 7:08pm

Cheers guys but what does it ultimatly do to the sail(s)

 

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tgruitt View Drop Down
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Post Options Post Options   Quote tgruitt Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 7:26pm
Gives more or less power by controlling stiffness and bend in different sections. To increase power pull on lowers to straighten mast, to give more bend and less power let off the lowers.
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 7:29pm
If you have a boat set up for lowers and sail off without them on what you notice is that the bottom mast bends alarmingly to windward. You can't get any decent kicker tension so the leech flop offs, and the bottom of the sail is flattened off and depowered due to the overbend... So basically no power.

Shall I leave diamonds/spreaders to someone else?
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tgruitt View Drop Down
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Post Options Post Options   Quote tgruitt Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep 07 at 7:30pm
Jim go for it, I don't have enough experience of diamonds to comment...
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Post Options Post Options   Quote Chew my RS Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep 07 at 6:49am
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