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 Post subject: mast rake/jib halyard
PostPosted: Mon Jan 20, 2014 7:17 am 
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Joined: Sun Oct 07, 2012 8:05 pm
Posts: 94
Location: New Hampshire
First let me make sure I've got the theory correct here, before I get to where I'm confused.

Going downwind, the straighter the mast, the more efficient is your rig for going downwind. However, going upwind, the more rake you have in your mast, the more efficient is your rig for going upwind. Hence, to maximize your efficiency, you change the angle of rake on your mast while on your water by adjusting the jib halyard tension using the Aussie jib halyard system.

Am I right so far?

However, there is no way to adjust the side shrouds while sailing, so your side shrouds are a constant length.

Now I realize that the Hobie 16 mast is set up with some rake, meaning that the mast is always desiring to fall towards the stern, limited by the shrouds and forestay/jib halyard. However, the Hobie 16 mast, besides leaning to the stern, leans towards the leeward side of the boat, resulting in the leeward shroud having slack.

Am I still making sense?

So going back to adjusting the jib halyard while on the water. When the mast is upright, you'd have minimal slack in the leeward shroud, as sailing dead downwind, where you would load both shrouds the same, is not a desirable course for a Hobie 16. However, when you put some slack into the jib halyard to introduce more mast rake, you're also introducing more slack into the leeward shroud.

Now as long as you stay on the same tack, this isn't much of an issue, as the loaded side shroud stays loaded and the slack shroud stays slack. However, when you tack, the mast will swing to the new leeward side, and the shroud loads will reverse.

So my question is, how much slack in the leeward shroud is too much for this shift in loading?

Best of luck,

Jim Clark-Dawe


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PostPosted: Mon Jan 20, 2014 8:12 am 
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Joined: Mon May 09, 2005 10:25 am
Posts: 2549
Location: Jersey Shore
I wouldn't get too fixated on how loose the leeward shroud is. The leeward shroud will always go slack when sailing upwind, even in light wind. This is because when you sheet in the main sheet and tighten the downhaul, you bend the mast which brings the mast tang closer to the mast step causing the leeward shroud to go slack.

There are countless discussions and theories about H16 tuning and jib halyard settings (the "holy grail" of H16 speed). In general though, loose shrouds don't pose a problem as long as they're not so loose that the mast slams around in chop or are at risk of allowing the mast to jump out of the step. Otherwise, you will always see some degree of looseness in the rig when sailing upwind.

sm


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PostPosted: Mon Jan 20, 2014 10:04 am 
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Joined: Wed May 05, 2010 8:28 am
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Location: Clinton Lake, KS
I ain't very good at it yet... but the effect the Jib halyard has on Jib Luff tension/shape seems like one of the very most important factors..


as long as you have enough rig tension to keep the mast in during a capsize.. I wouldn't worry about it to much.. What I try and do is setup the rig without any jib halyard tension, just resting on the forestay.. At that point grab the shroud in your fist and try to take up the slack by turning your hand in one movement to "shorten" the shroud.. I am looking to turn it right about 90 degrees or so... The ensures that if I loose rig tension from the jib Halyard while capsized/turtled, for whatever reason, the mast will stay in the base....

Beyond that.. don't really matter. as SRM pointed out.. Lots of pressures and forces are bending the mast and you always have a decent amount of slack in the leeward shroud...


The only real exception for me is if the winds are really really light.. and the water is choppy from power boats.. whatever.. Then I will crank on some rig tension just to keep the rig from banging around...


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PostPosted: Mon Jan 20, 2014 11:58 am 
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Joined: Sun Jun 08, 2003 7:21 pm
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Location: Thunder Bay,On
Ron that is more theory for a Hobie 14.You guys really should read Gavin Colby,s tuning guide.You will see he uses max halyard tension.Here is a nice rule of thumb,that will get you close ( remember the wind is always changing so close is good).btw this should work for most newer model 16's
Put the shrouds in pinned in third hole from bottom.Put jib tack third hole from bottom.Pull jib halyard till you take up slack in shrouds.Then pull on about another 70 mm on jib halyard.Mark it go out and sail.If the boat is feeling a little underpowered,pointing lower then most not able to trap in 10 + knts then crank on another 25 mm.From there set it and forget it.Remember there is no perfect setting.Close is what you want,you might have to either foot or point a little to adjust to the fleet.
The 16 really is a simple boat,you can really psych yourself out with the tuning aspect of it.


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PostPosted: Mon Jan 20, 2014 1:37 pm 
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Joined: Wed May 05, 2010 8:28 am
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Location: Clinton Lake, KS
This?

http://www.hobie-cat.net/download/manuels/tuning_16.pdf


What I was talking about above though was mostly rig tension with the jib halyard loose.. My last sentence in my previous post did make that a bit unclear... Once the jib is put and haylard tension is set, my rig is "tight"..

I just like to have the piece of mind should something go wrong with the Jib halyard and I end up upside down that I don't have to add dismasting to the list. So I pin the forestay often a wee bit lower than some...


I do generally sail with a pretty tight rig... (you pull on stuff harder to make the boat go faster... right... :lol: :wink: :oops: ) Most of the time rigg tension is set basically about like you have described Mike.. Pull the rig snug with the Jib halyard.... Then for most conditions a bit more.. Which on the aussie halyard was pretty close to an inch and a quarter by the scale I had on my mast .. a bit less if it was really light or really blowing.

I think even very small changes in rig tension make big changes in how the boat feels.. Which sometimes I adjust for conditions.. and other times.. my mood...

And yep... I am guilty from time to time of playing with the strings instead of just sailing the boat. :) :roll:


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