| Main sheet vs. Downhaul #11148 10/01/02 10:43 AM 10/01/02 10:43 AM |
Joined: Aug 2002 Posts: 74 Fulshear, TX SGalway OP
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Posts: 74 Fulshear, TX | I have been wrestling with this question in my head every since I read the post about diamond wire tension. I have recently been converted to catsailing from dinghies. I have learned 10x more about sail trim in the two months I have been sailing these beasts than the 10 years I was sailing dinghies. I guess cats react much quicker so it's easier to see the changes. Anyway, to my question...
Since I don't have a boom vang, I have to rely on the main sheet to keep my leech in check. This would mean in heavy air I would want tons of main sheet, flatten the leech. This would also mean that the main sheet is trimmng the upper portion of the sail (squaretop). Naturally this would lead to the downhaul trimming the meat of the sail. Except when I really heave on the DH and it bends the tip of the mast over and dumps load from the squaretop.
So here is the question, when I hit a puff, what is the quickest way to depower?
I would have to say NOT blow the mainsheet (as in a dinghy), this would power us UP. I would say NOT heave on the downhaul, too much line to go thru to get to the subject (16:1). I would say blow the traveler. Unfortunatly, every cat I have seen only has a 2:1 to bring the traveler back to weather, not enough even when it's only blowin' 15kts.
So what's the verdict? | | | Re: cat mainsail vs. mono mainsail
[Re: samevans]
#11152 10/01/02 12:08 PM 10/01/02 12:08 PM |
Joined: Aug 2002 Posts: 74 Fulshear, TX SGalway OP
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Posts: 74 Fulshear, TX | I should have prefaced my first post with the reason I am asking this. Depowering is VERY important to me, my wife/crew and I tip the scales at a whopping 275# and sail a P19mx. Puffs hit us in a major way!
V-15's, 420's, and FJ's (all the boats I am used to sailing) have a full batten across the top 1/4 of the sail. When you sheet too hard it also hooks to weather = slow. What I am getting at is also true on a dinghy if you haven't set your vang properly.
When you let the first foot or two (maybe three depending on your purchase) of main sheet out, you power UP the sail by moving the boom up and making the sail fuller. Let out a bit more on a dinghy and your vang has now taken the vertical load and your sheet is acting like a traveler. But on a cat the boom just keeps going up and up, continuing to make the bottom of the sail fuller, granted the top is now spilled. Hence I would naturally want to use the traveler with main sheeted tight to spill power, not gain power.
I would agree that when you heave on the downhaul HARD you bend the top of the mast to leeward and spill power off the top. This can go no lower than the shrouds though before bending stops. Now what to do with the rest of the sail? The leech is already tight from so much downhaul, so this is good, but I am still overpowered. I feel I would travel out.
Or do I just keep honkin' on the downhaul? Is there something I am not seeing? Thanks for the advice! | | | Re: cat mainsail vs. mono mainsail
[Re: SGalway]
#11154 10/01/02 12:35 PM 10/01/02 12:35 PM |
Joined: Jun 2001 Posts: 292 Long Island, NY Ed Norris
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Posts: 292 Long Island, NY | Howdy, Shannon,
As nearly as I remember Rick's Book, (from which every catsailor, pleasure-or-racing will benefit hugely), You want to depower in the following order, until you're only dumping inches up to a foot or so of sheet on the puffs, not armfulls.
1. Trap out (Never depower when you can go trapping instead. Why else go sailing, anyway!!)
2. Outhaul
3. Downhaul. (this works especially well on a Squaretop. The more downhaul, the more mainsheet tension is needed to close the top leach)
4. Travel out an inch at a time until you don't need to dump too much sheet on the puffs.
A flat, traveled out sail does far less work than a full, traveled in one; yet it slips through the air easier, allowing you to go faster. Believe it or not. Never "Pinch up" except in a puff. If your overall path is a pinch, depower in the above order until you're making max boatspeed.
Now, that said, I've seen some amazingly full P19 sails on older boats - but those were pinheads. Flat tops are relatively new, and many are cut for "prebend" rigging. Does your luff of your sail have a bulge in it? Lay it out flat on the ground and look down from one end... a big bulge (pull a string straight down the luff and measure, 2-4 inches is big) means you need to rig your mast for "prebend" - failing to do so can make it kinda hard to flatten - alternatively you'd need very loose diamond wires!!
Best luck and
Sail Fast,
Ed Norris
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