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-   -   main sail blown? (http://www.sailnet.com/forums/seamanship-navigation/100225-main-sail-blown.html)

flo617 06-06-2013 11:45 PM

main sail blown?
 
hello,

My sailboat does not currently have a boom vang. When I sail in light condition, all is well and I can point but in the slot on SF bay, holly crap! Even with two reefs I have a lot of weather helm and I am having a hard time depowering the sail even on a reach or a close reach.

When I let the sheet out a bit there is no way the sail will look right. the leading edge seems back inflated. There is so much weather helm that sheeting in feels silly at this point. I always thought that boom vangs were for downwind modes and that cruisers often can get away without it.

what I hate above all is the weather helm because I feel the rudder is taking some useless stress. I also hate looking at my sail like that.

Should I be looking at getting a new sail?

Florent

Columbia 29mkii #221

overbored 06-06-2013 11:55 PM

Re: main sail blown?
 
1 Attachment(s)
sounds like you should be getting a boom vang before you get a new sail. they are not hard to rig up. a bail on the boom and an attach point at the base of the mast. some line and a couple of blocks one with a cleat

CalebD 06-07-2013 12:12 AM

Re: main sail blown?
 
Ask 4 sailors and get 6 opinions.

For the generally pretty windy conditions you get in SF Bay I think you need a new, flatter cut sail before you need a vang. Either would be good but flatter sails work better in higher winds like you get, regularly.

I'm a happy customer of thesailwarehouse.com who has an office in Montery, CA. They are cheaper than most name brand lofts. Brand name is Rolly Tasker, made in Thailand or some such.

Minnewaska 06-07-2013 06:40 AM

Re: main sail blown?
 
What kind of foresail are you flying? If a huge genny that reaches far behind the mast, it could also be part of the issue. I suspected it when you said the main is being back winded.

flo617 06-07-2013 07:11 AM

Re: main sail blown?
 
oh no, I fly something like a 90%.

About the boom vang, I am embarassed to say that 2 years ago I drilled into the boom to bolt a fitting for the vang. I did not calculate right and although the angle is ok, the distance is only about a fifth of the boom length. I'm worried that would put too much pressure on the mast when tightening it up but I might be worrying for nothing.

Minnewaska 06-07-2013 07:22 AM

Re: main sail blown?
 
Quote:

Originally Posted by flo617 (Post 1040774)
oh no, I fly something like a 90%.

While the opposite of my supposition, maybe a 100 would better balance the helm? It can also have to do with where the draft is located and whether that is far enough forward.

In the end, I don't disagree with the vang issue, I'm only trying to throw alternatives out. But, if you really do have mismatched sails, a vang would be of little help.

Faster 06-07-2013 09:38 AM

Re: main sail blown?
 
It's likely that your boom is plenty strong enough for the vang position you're describing, and a vang is a good idea in any case, but primarily for off the wind work. Once your sheeted in hard on the mainsheet, there's little for the vang to do if you're hard on the wind. Unless, of course, it's windy enough that you're into 'vang sheeting' (using vang for luff tension, mainsheet for 'angle of attack' only.. something you might try one day but does require a flattish main to be successful)

That kind of persistent weather helm also points to mast rake and overall CE of the sailplan as currently set up. Perhaps you need to move the rig forward a bit..

Garhauer makes some nice vangs, and attaching fittings for reasonable dollar.. and will sell you just the fittings to fit your mast and boom if you just want a rope vang.

Alex W 06-07-2013 10:04 AM

Re: main sail blown?
 
A photo of your sail shape when close hauled would be helpful for this discussion.

Too much depth in the genoa/jib can also cause increased heeling and weather helm. My Pearson is tender and I'm having a new flatter genoa made now to reduce heeling (and weatherhelm).

GeorgeB 06-07-2013 01:57 PM

Re: main sail blown?
 
Flo, yes, you need to provide additional information and a photo or two. The indentation on the main's luff is a "speed bump" and is caused by the compressed wind coming through the slot between the main and jib. When the winds are up, it isn't much of a worry - you need to think of your jib and main as part of the same system, make sure the tell-tales on the leech of the main and luff of the jib are flying and you should be o.k. What kind of traveller do you have? lowering the traveller will help the weather helm. No traveller? (Or a short one?) then ease the main sheet and pull down on the vang. 20kt winds and old tired sails don't mix. You may be visiting your sail maker in the future (shop the off season and boat show specials). How is the rake on the mast? Shroud and stay tension? These will impact performance. A large percentage of the boats on the Bay have a back stay tensioner to correct a sagging headstay. When was the last time you cleaned your bottom. Are you located in Marina Village? If so, PM me and perhaps I can come over and check your rig out.

Barquito 06-07-2013 02:59 PM

Re: main sail blown?
 
So, to help the OP... and me, what would he look for to decide it the sail is blown vs. other tuning problems? Is not being able to keep the point of maximum draft forward even with increasing halyard/cunningham tension a reliable sign the sail is blown?


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