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Multi mast quiz of the week :)


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When sailing upwind, does less mast rotation increase or decrease power ?  

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  1. 1. When sailing upwind, does less mast rotation increase or decrease power ?

    • Increases power
      4
    • Decreases power
      13


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Ok - how about a biplane rig a la Shionning Radical Bay. Two full sized mains would be more sail than a main and jib???????

 

In the Americas Cup just gone those guys could have used any configuration that they wanted.

 

The wing mast had a jib, some zero's and some gennakers.

 

Alinghi used a more conventional rotating wing mast with a main, some jibs, some zero's and some gennakers.

 

Do you see the pattern emerging here?

 

Much like our little fleet in Auckland.

 

But no bi plane, shmy plane rigs, no f...n proas, no boom less rigs.... !

 

If the AC guys (who would have looked into all those stupid options) would have found any merit what ever, then you would have seen photo's of them trialling there Stupid XYZ rig, blah blah blah.

 

The fact that all the photo's you did see were of more or less convential rigs should answer your question !

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All true, except they didn't have a height restriction. Yes one tall mast will be more efficient than two small ones, but wouldn't two short masts mean more sail than one short mast?

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snip

 

When I read the 8.5 rules they do not exclude more than 1 mast so you could have TWO 12.6m air draft masts. So squid, they do not need to be SHORT, (except for the need to remain standing up)!!!!!!

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You are right that the trend is to shorter topmasts and stiffer as well, that is to do with the square tops and the high code zero loads, but I think the mast head rig idea is a step in the wrong direction.

JMHO of course !

 

Mnn, one major reason I would like to make it masthead is to eliminate extra side stays and runners, so knowing the section im using Tim would you think I could have the hounds say 300mm down and have no stays to the top to support the kite?

 

On lucifer we dont have a fractional kite, if its that windy youve got a bit on!!! DD also has no Frac kite, just a small flat genny for in the big breeze

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You are right that the trend is to shorter topmasts and stiffer as well, that is to do with the square tops and the high code zero loads, but I think the mast head rig idea is a step in the wrong direction.

JMHO of course !

 

Mnn, one major reason I would like to make it masthead is to eliminate extra side stays and runners, so knowing the section im using Tim would you think I could have the hounds say 300mm down and have no stays to the top to support the kite?

 

On lucifer we dont have a fractional kite, if its that windy youve got a bit on!!! DD also has no Frac kite, just a small flat genny for in the big breeze

 

 

Yeah but we would prefer a fractional for when it gets breezy for sure. the small flat genny is an old 18 chute fyfie tidied up for us which was all we could afford at the time, it does however work really well tight reaching in light to medium breeze so we have held onto it.

 

Bobbo

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Why can people never be happy with the rule that is set?? It is what it is, period.

If you make the rule so you have a taller rig than present, then you may as well just build an open class multi! its all about the close racing and having fun!

Rigs would be just the start of things that you could change in the rule.. what would it end up being like?? An open class multi, you have a choice....

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You are right that the trend is to shorter topmasts and stiffer as well, that is to do with the square tops and the high code zero loads, but I think the mast head rig idea is a step in the wrong direction.

JMHO of course !

 

Mnn, one major reason I would like to make it masthead is to eliminate extra side stays and runners, so knowing the section im using Tim would you think I could have the hounds say 300mm down and have no stays to the top to support the kite?

 

On lucifer we dont have a fractional kite, if its that windy youve got a bit on!!! DD also has no Frac kite, just a small flat genny for in the big breeze

 

I think the amount you will lose due to inefficiency of a masthead rig, would be more than offset if all your worried about is an extra set of topmast backstays ?

 

Just stick the hounds at 7/8 with a set of runners,

then yep you'll need topmast backstays, but so what ?

 

The fractional sails need 25 kts to come into their own but that has won Attitude the last 2 Coastal races!

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my old mast was a two spreader mast..........It had pre-bend. As neither side stay broke I have to assume that the mast inverted, broke then fell off the boat. we never saw the mast dancing, maybe we never looked but it would appear that two sets of spreaders did not stop the inversion.

This time we are going for a single spreader mast on advice from the expert, I have a big enough dork on the boat so we won't put one on the mast.

 

Strangely I have to agree with the Wolf on masthead rigs. Samin go by a Chico thirty if you want to step back in time.

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If the AC guys (who would have looked into all those stupid options) would have found any merit what ever, then you would have seen photo's of them trialling there Stupid XYZ rig, blah blah blah.
Maybe like a lot of people they had their heads up their asses and were to afraid to look out side the square!
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Ok - how about a biplane rig a la Shionning Radical Bay. Two full sized mains would be more sail than a main and jib???????

 

In the Americas Cup just gone those guys could have used any configuration that they wanted.

 

The wing mast had a jib, some zero's and some gennakers.

 

Alinghi used a more conventional rotating wing mast with a main, some jibs, some zero's and some gennakers.

 

Do you see the pattern emerging here?

 

Much like our little fleet in Auckland.

 

But no bi plane, shmy plane rigs, no f...n proas, no boom less rigs.... !

 

If the AC guys (who would have looked into all those stupid options) would have found any merit what ever, then you would have seen photo's of them trialling there Stupid XYZ rig, blah blah blah.

 

The fact that all the photo's you did see were of more or less convential rigs should answer your question !

 

Okay I can only resist this discussion for so long!

 

The AC boats had a very narrow band of expected conditions, ie light airs, and a relatively short evolution time period.

 

The NZ multihull fleet operates on mostly light to moderate conditions, mostly using full working sails. It has evolved a single or twin spreader rig, using high compression diamond wires and sometimes a forward spreader (dork) to control pumping. Having lots of highly stressed components keeps riggers well employed. A deep reef, with the head of the mainsail well below the hounds position, compromises this rig type without the addition of a lower forestay. Even then the high load diamonds have a great deal expected of them sideways in extreme conditions.

A few of the local boats have none rotating tubes, without spreaders, and low compression, high angle lower back stay.

 

The most evolved multihulls in the world have to be the ORMA 60s, which we are lucky enough to have one of here with G3. They all have no spreader rigs with lower stays. This gives lots of options over all wind ranges, especially in high wind condtions where the lower half of the mast is well supported by aft lowers, and the staysail or storm jib stay. A perfectly triangulated lower mast supporting the deep reefed mainsail.

 

A diamond stay working at 10˚ to the mast compared to a lower stay at 30˚ is putting a great deal more compression into the mast tube. The spreader roots, especially those not triangulated forward, are under huge load when the mast pumps. A lower stay is controlling directly the mast, using a low angle, so inducing much less compression.

 

With carbon masts replacing alloy (which has no place in the marine environment of course), alloying longer, stiffer panels in mast sections, expect to see spreaders disappear as Kiwi multihulls catch up with the French...

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Very nice post Tim C.

 

And excellent considering you are just a cruiser.

 

I think I did allude to the Orma 60 rig being the ultimate option and you as always have some valid points.

 

My rig has no issues at all. It is a Single Diamond at 5 degrees of rake, with Inferiors and Superiors. It has an inner forestay/Staysail when triple reefed. (And yes we have used that combination sailing in 50 knots).

It has Topmast backstays, and Runners to the hounds.

Bar none it is easily the lightest mast section out there at 31kg (bare tube weight).

I would argue it would also be close to the least windage of any mast.

 

I don't think you could build an Orma60 mast either lighter or less windage.

Also the Lowers approach only works properly if the section itself is quite big (other disadvantages), and the lowers need to remain tight.

My rig rotates perfectly, and frankly most NZ multi's have rotating rigs that don't work that well.

 

BTW, why do you not mention that every Orma60 has a boom!

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.

 

2. If you put two sets of raked diamonds on TWU will that stop the mast bending sideways (assuming the same rake as the first attempt) ?

 

and so the answer is....... drum roll....

 

Two sets of diamonds with no rake seems to work great.

 

I guess we will never no if it would have worked with 1 set.

 

Will see you at the start line next wednesday :)

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There is an article in an issue of seahorse on the rig for the ORMA 60 Sopra Group along these lines. Can't post my scanned copy as it is too big, but there is a reference to it on this website (about half way down the page):

http://www.linderson.com/index.php?opti ... &Itemid=85

Might be of interest to some of you guys.

 

SO not all ORMA rigs are the same, can't comment on how successful or not this one was though, Alinghi also had much the same arrangement. Certainly easier if you are looking at a canting rig than having to deal with the adjustable ratio of upper/lower tension...

 

If someone is interested in the article then PM me and I can email it to you, otherwise raid someone else's Seahorse back library about 5 years ago probably!

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4. Would you go to NZ Rigging for a multi rig ?

 

 

you might want to ask that question again :)

 

 

what are you going to do Mike? I saw the rig when they came into westhaven and I can't see any reason why it went other than the wall section being to thin but I'm not a rigger so I'm not sure. It will be very interesting to know why.

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I really feel for the guys. 2 rigs falling over on a brand new boat....and the boat was going really well to ! it looked fantastic.

 

but seariously, 1 set of tiny swept back spreaders was never going to be enough. Thats why we had our rig configuration changed.

 

I guess the borderline boys didn't get that memo.

 

hope they get it all fixed up asap, as it will be a really cool addition to the fleet!

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borderline will be back asap. we had a great day these things are f**ken cool. We were really happy with the way the boat felt and went, we've got heaps to learn about it, I have only sailed her six times. This drop did a bit more damage to the boat and sails than the first one, so it's going take bit of work to get it back sailing.

 

A big thanks to Matty, Phil, Clive, Bex, Beno and Simon for helping get the boat sorted out at the marina. it was awesome in no time it went from carnage to tidy thanks guys.

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borderline will be back asap. we had a great day these things are f**ken cool..

hey hurry up and get her back up to scratch ... we were on your heels matie! :-)

Clive.

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