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JimC View Drop Down
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    Posted: 07 Mar 18 at 11:14am
After several iterations this was my preferred Cherub layout. Track on the front bulkhead so fastenings are in shear, cam cleat on the track for height adjustment on the barber hauler, just pin stops on the track for slot width. ISTR I drilled a couple of extra ones in the critical area.
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Cirrus View Drop Down
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Posts: 590 		Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 18 at 11:15am
Bit curious about the big lump of shiny at the back of the chute?  Surely that could be lighter and cheaper in GRP? Or do we need a bit of chrome for some markets?  :-)

Lightweight stainless ... always 'slippery' and not prone to damage from lines.  There for good technical reasons - although it does look rather good as well !  
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 18 at 11:22am
Yeah, the stainless is a good call on a production boat. A laminate will end up grooved and goodness knows what else. If there was space I'd prefer a large diameter alloy tube, but I strongly suspect there wasn't. Also rather more expensive to fabricate curved I imagine. I ended up with a layer of kevlar mixed with graphite filler, which lasts, but is not aesthetic.
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Cirrus View Drop Down
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Posts: 590 		Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 18 at 9:38pm
Racing in IRC Events 'Big Brother'
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Sam.Spoons View Drop Down
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Posts: 3401 		Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 07 Mar 18 at 11:29pm
Originally posted by mozzy

Originally posted by PeterG

Regarding the alloy boom: In a SMOD I see no reason to go carbon. Unlike a mast you can make it plenty stiff by increasing diameter.  It doesn't need variable bend characteristics over it's length, so why waste money on making it out of carbon? 

It hurts less when you get your head in the way!

Really? A heavier boom may carry more momentum, but a lighter boom will accelerate to faster speed. The total amount of energy in the impact will be the same, and that comes from the sail. 

A alloy boom can be pretty light, even compared to a carbon one once you extend out the diameter. Extending out the diameter will also make it a significantly more blunt object, which I would think would have more effect on the damage should it hit you on your head. 

That would be true if the boom was the only element being accelerated but it is attached to the mainsail which generates the acceleration. I suspect with either a carbon or ally boom the resulting terminal velocity in a gybe (or tack) will be related to the sail with the boom having a very minor effect, but when it makes contact with your noggin it's, to all intents and purposes, floating around loose so the one with least mass hurts less......
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maxibuddah View Drop Down
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Posts: 1760 		Post Options Post Options   Quote maxibuddah Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 18 at 7:00am
I've been hit by a round carbon boom, a round ali boom and an ali Finn boom, and they hurt the least to worst in that order. Im thinking it doesn't matter how fast they go but how easy it is to deflect their current trajectory when they hit. Those with the least mass are probably going to deflect the easiest. Oh and round is obviously better than square
Everything I say is my opinion, honest
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 18 at 10:40am
Do booms 'float loose'? The kicker will stop it deflecting up. The energy and force comes from the sail, so I can't see the weight of either carbon or alloy having any effect. You have the weight and momentum of the sail and the air which would surely make the weight of boom less significant. I can imagine a round and larger diameter would hurt much less. 

Obviously, there seems to be a consensus that carbon booms hurt less, but you all admit suffering many blows to the head too... so...  Ermm

I am genuinely surprised that people consider how much it hurts when selecting materials for a boom! Maybe consider shape in a training boat, but this is a racer! Carbon or alloy, both are pretty bloody hard. If you're getting hit regularly enough for it to be an issue wear a helmet or put padding on the boom. 

Anyway, sounds like they're going with a carbon boom... I guess it will fatigue less and avoid some corrosion issues so the outlay may be worth it over time. But i'd take a SMOD that was £500 quid cheaper over one with a carbon boom, or one that had £500 better mast, or £500 better sails, that's all. 


Edited by mozzy - 08 Mar 18 at 10:57am
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Cirrus View Drop Down
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Posts: 590 		Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 18 at 11:05am
Carbon (ie light) booms are better for many reasons. 

But on the one issue of  its effect on contact (with head or whatever) try to imagine it being made not of carbon or of alloy but let's say steel, nice heavy gauge industrial steel ....   who still wants to suggest that mass/weight makes no difference ?   .... on your head be it !

It might initally be slow to get moving in a gybe because it has to be accelerated but once it gets going just keep out of its way !  This is of  course only a mind experiment - so just make sure you don't place your head in its way in some sort of real but totally bonkers practical experiment.




Edited by Cirrus - 08 Mar 18 at 11:06am
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Old Timer View Drop Down
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Posts: 370 		Post Options Post Options   Quote Old Timer Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 18 at 11:10am
Looks nice; carbon boom is defiantly superior for a whole range of reasons including being bashed about the skull.

I would have tried to juggle the jib and chute mouth to put the chute ahead of the jib tack but too late for that now...

Good luck; who is building it?
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 18 at 11:18am
Originally posted by Cirrus

This is of  course only a mind experiment - so just make sure you don't place your head in its way in some sort of real but totally bonkers practical experiment.
Me this weekend: 
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