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for 2 to 1 or not 2 to 1

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Alto-Tim View Drop Down
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Post Options Post Options   Quote Alto-Tim Quote  Post ReplyReply Direct Link To This Post Posted: 24 Aug 11 at 10:58pm
If you get less compression forces with a 2 to 1 compared with the 1-to-1,the issue of compression forces is due to the way you tighten the halyard before cleating it off.

So if you use a wire and a rack there is less compression forces due to the halyard tension.
Tension on the halyard at is applied by the kicker or the Cunningham.

So if you have high halyard tension will this mean the top of the mast will respond more to gusts
quicker because the top part of the mast is under tension?.

So by not having high loads on your halyard must mean the mainsail will power up
because the mast will be stiffer and not bend off so much in the gusts.

All these questions come about looking for more power out of the rig
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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: 25 Aug 11 at 12:34am
Its not just the static tension on the halyard, if any, its the effect of the downhaul loads pulling down on the halyard. Given a stable mylar sail one of the the main effects of the downhaul is mast bend, so in theory I suppose you ought to get more mast bend for a given downhaul tension/amount pulled down the mast.
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G.R.F. View Drop Down
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Post Options Post Options   Quote G.R.F. Quote  Post ReplyReply Direct Link To This Post Posted: 25 Aug 11 at 8:32am
Originally posted by Alto-Tim

All these questions come about looking for more power out of the rig

Ah, think I get it now this is an Alto rig right? The Mk2 Sail?

My thinking of  2-1 was the combination of a pulley at the head and the foot as mine has.

The Alto is underpowered, at least the 2nd generations were imv, it also badly needs a mast head kite and a proper jib.

The Solution would be for it to use a B14 rig, again imv.

But the design criterion was for it to be used by skilled helms and semi to unskilled crews and it was originally going to be a hiker, which is why it performs so well in strong wind in capable hands.

They really need to use the original main sail I'm still using, it wasn't much use on the original boat because they had a crap Gnav, but now it's got a Selden boom with the correct Gnav it works really well. Fantastic light wind performance yet depowers in stronger wind, maybe the designer might read this and take note, not that he ever takes much note of anything I blather on about or they wouldn't still have the silly cloth enclosed chute delivery system behind the forstay.


Edited by G.R.F. - 25 Aug 11 at 8:34am
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Alto-Tim View Drop Down
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Post Options Post Options   Quote Alto-Tim Quote  Post ReplyReply Direct Link To This Post Posted: 25 Aug 11 at 4:51pm

Ah, think I get it now this is an Alto rig right? The Mk2 Sail?

          Yes you are right there, I think it's all in the name.(Alto-tim)

          We have a standard set of sails for the Alto which works well in all wind conditions.

 

My thinking of  2-1 was the combination of a pulley at the head and the foot as mine has.

          ?????

 

The Alto is underpowered, at least the 2nd generations were imv, it also badly needs a mast head kite and a proper jib.

 

          Underpowered??, We have raced our Alto for a couple of years now. Depending what type of beer is for sale, we are 30/31 stone and the boat  goes well in all wind conditions.

          Having sailed a 59er for five years we found it underpowered., considering the 59er was built for heavy crews.

           And the mast head kite does not suit most of the courses sailed at clubs and definitely not any river sailing especially when the tide is out, nowhere to go deep,(and we broke two masts  - no not in the mud (in a F3).

 

The Solution would be for it to use a B14 rig, again imv.

 

          Don't know enough about the B 14 to comment.

 

But the design criterion was for it to be used by skilled helms and semi to unskilled crews and it was originally going to be a hiker, which is why it performs so well in strong wind in capable hands.

 

          I think you'll find that the hiking idea was very soon discarded in the very early days of the development.

          We have had loads of people test the Alto at different skill levels from novice to competent and found it a well-balanced well-behaved racing dinghy.

          I think any boat goes well in strong winds as long as you can keep it up and pointed in the right direction.

 

They really need to use the original main sail I'm still using, it wasn't much use on the original boat because they had a crap Gnav, but now it's got a Selden boom with the correct Gnav it works really well. Fantastic light wind performance yet depowers in stronger wind, maybe the designer might read this and take note, not that he ever takes much note of anything I blather on about or they wouldn't still have the silly cloth enclosed chute delivery system behind the forstay.

 

          I think the designer is open to very sensible ideas and is not blinkered, we have worked with Mike for two years.

          I think the front foredeck cover works well,  covers up the spinnaker, pleasing to the eye, practical plus economic .

 

This discussion came about over a couple of beers, about controlling masts bend and main creeping down.

Although my name is Alto Tim I hope coming on this forum doesn't mean to say I have to be talking about the Alto. I do keep looking outside the box only to find the Alto is the best well-behaved racing dinghy I've ever sailed.

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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 25 Aug 11 at 6:17pm
In RS400's a 2:1 is favoured.
It's normal to pre-tension the halyard as much as possible, so that the shackle stays right at the top of the mast, even with a fair amount of downhaul and leech tension. Until the leech and luff tensions exceed twice the preload, the head does not drop at all, even if the mast bend shortens the path the halyard takes inside the mast. In this case, a bit of stretch in the rope is actually good!
Even using a kevlar 1:1 halyard, the sail drops significantly as the load comes on.
The kevlar halyards tend to be a bit un reliable, 2:1's fail eventually too, due to chafe unless you cut a bit off every few months. It pays to be careful rounding off all sharp edges at the masthead, and make sure the shackle goes on the sail the right way round. If the shackle capsizes, the halyard running around the pin can undo it!
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oldarn View Drop Down
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Post Options Post Options   Quote oldarn Quote  Post ReplyReply Direct Link To This Post Posted: 25 Aug 11 at 8:41pm
Originally posted by G.R.F.

No idea what you mean re 2.1 how else do other systems haul a sail up the mast from down below?


On your <original,AltO you have a Superspar mast with a normal 1 to1 system, and I assume a three year old main halliard. Whether kevlar (most likely) or other I guess it was chaffed. I would stick with a 1 to 1 8platt pre-strethed terrylene and put up with some stretch on the first few outings. Much cheaper and at least the cleat is holding the whole halliard and not just the outer surface. 
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Post Options Post Options   Quote RS400atC Quote  Post ReplyReply Direct Link To This Post Posted: 25 Aug 11 at 10:09pm
Originally posted by oldarn

Originally posted by G.R.F.

No idea what you mean re 2.1 how else do other systems haul a sail up the mast from down below?


On your <original,AltO you have a Superspar mast with a normal 1 to1 system, and I assume a three year old main halliard. Whether kevlar (most likely) or other I guess it was chaffed. I would stick with a 1 to 1 8platt pre-strethed terrylene and put up with some stretch on the first few outings. Much cheaper and at least the cleat is holding the whole halliard and not just the outer surface. 

That will stretch a few cm.
May not matter in the Alto, except of course if your head is within a few cm of where you expect the boom to be!
You could always use good old wire.
The trouble with stretchy halyards is that pulling on the mainsheet or kicker effectively loses luff tension, like letting off the cunningham. So you pull on more cunningham to counter it, then you have too much, possibly even damage, when you dump the main or kicker at the windward mark.

If money is tight or you want to use what's on hand, you can always splice a cheap tail into a mast-length of dyneema, this can even save a bit of weight.
Also stretchy rope can chafe more, because it moves across the wear points more.
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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: 28 Aug 11 at 6:25pm
Conducted a little experiment today... My Canoe mast is a much lighter section than most, and although it is beefed up more than the standard tube I've still been suffering with the leech opening up too early no matter how much kicker I use. I've been mulling over beefing it up some more, but this morning I simply lashed the sail to the top of the mast to see what happened. I have to admit I am gobsmacked by how much difference it made: I estimate I could get my 15 stone of lard out another 8 inches out along the plank. So I suppose I am going to have to sit down and design a halyard lock of some description.
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Post Options Post Options   Quote ham4sand Quote  Post ReplyReply Direct Link To This Post Posted: 28 Aug 11 at 10:52pm
Clap always nice when something discussed is showed to help!
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Jack Sparrow View Drop Down
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Post Options Post Options   Quote Jack Sparrow Quote  Post ReplyReply Direct Link To This Post Posted: 28 Aug 11 at 11:06pm
Originally posted by JimC

Conducted a little experiment today... My Canoe mast is a much lighter section than most, and although it is beefed up more than the standard tube I've still been suffering with the leech opening up too early no matter how much kicker I use. I've been mulling over beefing it up some more, but this morning I simply lashed the sail to the top of the mast to see what happened. I have to admit I am gobsmacked by how much difference it made: I estimate I could get my 15 stone of lard out another 8 inches out along the plank. So I suppose I am going to have to sit down and design a halyard lock of some description.


Jim, have a look here: Blog link this is what I have on my Farr 3.7 and it works a dream, with none of the safety issues of mast top lashing I / we used to do on the Cherubs.


Edited by Jack Sparrow - 28 Aug 11 at 11:08pm
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