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Proper Downhaul Tension on the Mainsail
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Author:  SteveH [ Wed Jul 29, 2009 7:43 am ]
Post subject:  Proper Downhaul Tension on the Mainsail
I recently purchased a 2008 Wave and I am relatively new to sailing. I am attempting to understand how to trim and shape the mainsail, but I am confused about tensioning the downhaul. I just sailed the boat for a week on the Florida coast and I had trouble getting both sets of tell-tales to lay correctly. To me, it seemed that I had too much curve along the leach and I could not find a way to correct it...the lower part of the sail appeared to have far more camber (deflection on a horizontal line from the luff to the leach) than the upper part. My boat has a track and traveller on the rear crossbar, but no adjustment on the mainsheet seemed to help.

I know that downhaul tension should be adjusted according to wind speed and it seems that this could be a way to address this issue of sail shape, but I really feel like I am guessing at this point. Any guidance on sail shape and downhaul tension would be greatly appreciated.

Also, are there any guidlines for the actual tension (given as a force in pounds, preferably) that should be applied to the tack for a given windspeed. With my experience level, I might be better able to adjust my sail using this approach than simply guessing at the heaviness of the wind as well as guessing at what would be considered light or heavy tension.

Thanks in advance for any help!
Author:  mmiller [ Wed Jul 29, 2009 10:20 am ]
Post subject:  Re: Proper Downhaul Tension on the Mainsail
There is no pounds of pressure measurement for downhaul.

I think it is easiest to judge by the horizontal wrinkles in the luff of sail. Downhaul to (just) flatten these wrinkles. More mainsheet tension requires more downhaul.

Too much downhaul can cause the top of the sail to twist off and loose power.

Light air... light downhaul.

Heavy air... heavy downhaul.

Down wind... less / zero downhaul.

Downhaul is easier to achieve with main sheeted hard.

The upper and lower tell tails will not always be flowing. Try using the traveler centered and less sheet tension to twist the main off up high. Traveling out and sheeting harder will close off the upper sail.

With no boom, it is typical to have the sail get really full when sheeting out. In higher winds, the traveler helps. You can ease the traveler out a bit and keep sheet tension on.
Author:  zzcoreyzz [ Wed Jul 29, 2009 12:47 pm ]
Post subject:  Re: Proper Downhaul Tension on the Mainsail
In heavy winds (15-20 and above) I focus on the upper tell tail and keep that true

In lighter winds (10 and less) I focus on the lower tell tail
Author:  SteveH [ Sat Aug 01, 2009 10:42 am ]
Post subject:  Re: Proper Downhaul Tension on the Mainsail
Thanks for the responses.

In the 2009-2010 Parts Catalog, I just noticed that there is a 6:1 downhaul kit for the H14 and H16. To me, this implies that the necessary downhaul force can be quite large. A few hundred pounds of downhaul force could be applied to the sail with relatively little effort.

On my Wave, I was a bit concerned about applying too much force. But, with the downhaul rigged as indicated in the Owner's Manual for the Wave, my mechanical advantage should only be somewhere in the 3:1 to 2:1 range (considering friction in the system). As a result, it seems that I should be able to really crank on the downhaul without too much concern about damaging the sail or the downhaul cleat. Is this correct?
Author:  mmiller [ Sat Aug 01, 2009 10:50 am ]
Post subject:  Re: Proper Downhaul Tension on the Mainsail
If using the stock setup on the Wave... yes you can pull just about as hard as you can. I usually have to sheet the main a bit to get the downhaul really tight. If you use a 6:1, you have to be more careful as to not damage the sail.
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