Main sheet vs. Downhaul

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?

Why releasing the main would power up? I agree with you that neither DH neither traveler are giving a quick and efficient enough response. From my own experience (Tiger with square top) I feel that pumping the main does the job: releasing it makes the top of the sail twisting and then the power goes down. As soon as the wing exceed 10 knots this is my crew who handles the main (except when chute up): he has two hands to do it, so much more power to pull the sheet.

You are making one of the classic mistakes when comparing cat to mono sails.

Most always, cat sails will hook, not flatten when sheeted too hard. it is easy to oversheet a cat and make it go slower.

The trick is to know when is too much.

Rick has some good tips on mainsheet handling in his book.



Downhauling on a cat, will bend the mast tip and flatten the top of the sail, spilling the wind. That is why you have a 16:1 downhaul(lucky you), so the crew can pump it during the puffs.

i may be wrong, but i thought:

cunningham depowers the middle of the sail.

outhaul depowers the bottom of the sail

heavily sheeting in will flatten the lower 2/3 of the sail

the traveller can be used to let air spill off of the sail to depower the whole thing.

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!

That's what we used to do in the F18 in a blow upwind. Crew with two hands on the main keeping the W hull skimming the water with constant adjustments while the helm puts all his/her faith in the crew and keeps it in a straight line. Takes a bit of getting used to though...

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

I have never sailed a P19 but on my I20 I usually use a puff to get more up wind when racing I usually need it. (or deeper when going down wind) when playing I also steer up unless there is some land or a ship in the way. a puff is a short bit of stronger than normal wind. when racing why give it away when playing who wants to yank on the main unles you need the upper body work out. sometimes going from point a to b on a beam reach I have little choice but to play the main sheet and a local expert here told me Sunday that the way to do that was to give it to your crew to work out their bicepts while you focus on the course and watch for wind. since you have had every sugestion I thought one more to complete the set would not hurt.

I LOVE THIS PLACE!!!!



Where else can you ask an honest question and get an honest answer so quickly, and best of all, from so many people!



You guys are great. Thanks for the advice.

Shannon,



Another thing you will notice is that, even though the main traveler is only 2:1 compared to the mainsheet's 8:1, the traveler is easier to play in and out than the mainsheet. Its easier and faster to ease the traveler an inch or two to flatten the boat than to saw in and out on the sheet, particularly if you can train your crew to do it for you by barely holding it in the cleet and keeping tension on it so it doesn't slip.



Its practically the only way to sail the 100 mile beam reach Ruff Rider!



Mike Beuerlein

N6.0 #282

Hi:

Kind of got a chuckle when reading your post (sorry). I see that you own Randy's P19MX now. I can speak to you from experience with the P19MX...I also own one that has sails designed by Randy. Start with asking Randy for the two "guides" that he has for "land-based" tuning, and on the water adjustments. Use this info as your base. I don't mind telling you that this boat will spank you if you can't keep her under control. Consider that there was a fair amount of sail area added to the MX rig. Min. crew weight (at one time) was over 300 pounds. You are light, and there will be times that she will become a handful. The big jib (and I love mine dearly) can become a liability when you are forced to go off the wind, in a blow, in a confined seaway. Ask Randy for those tuning guides, remember that the P19MX relies heavily on mast rotation. Once you get a handle on how to sail her, "HANG ON!!!!".

Talk to you again.

Dave

The methods used to "depower" depend on the exact conditions you are sailing under.

What conditions?

Are you racing, trying to maximize VMG?

or just sailing as fast as possible?

Steady heavy wind?

Steady moderate wind with heavy puffs?

Steady light wind with very heavy puffs?

Are the puffs wind strength and/or angle?

Is the water flat?

rough/choppy?

swells?



We have all given valid actions for certain situations.

If you are just surviving and are overpowered under all conditions you simply do, as Rick says, the opposite of what powers you up. You downhaul, outhaul, under rotate, travel down and sheet out.

If you are racing and trying to play the puffs for more VMG, maybe you travel down, the crew can pump the downhaul, and you can weather up a hair to gain ground during the short puffs(stairstepping).

You should use the right "tool" for the particular job.