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matthewwhill 03-12-2013 10:49 PM

Weather helm question
 
So I was out today in my Kent Ranger 24 in 20-29 knot winds. I had the unreefed main and the 70% storm jib up. Did great, but.....

When the wind died down to 15 or so I was on a beam reach and tried to balance the sails with jib and main sheets so that the tiller wouldn't move. Even when the main was completely eased and the jib trimmed I got a bit of weather helm. How can this be? There is no part of the 70% that is aft of the boats center of lateral resistance. I was not heeled either (I gather that a heeled hull wants to head up due to asymmetry of wetted surface and aft shift of center of effort).

Flybyknight 03-12-2013 11:50 PM

Re: Weather helm question
 
One possibility:
Check your mast rake, and is it set too far forward?

blt2ski 03-13-2013 12:32 AM

Re: Weather helm question
 
I was going to say, not forward enough, as I moved my rake forward a bit, and it helped get rid of a lot of weather helm.

If you have not done a true mast check to see that it is not centered side to side, for and aft, correct tightness of the shrouds and stays, that would be my first step overall. There is good thread in one of the sections. I also have a tuning guide from Ullman that might help, it is in a pdf booklet form I can email you. PM me or use my handle at hotmail will get me that way. I will need to email it to you, I do not believe I can do this via pms.

I am sure it was a good day to sail. Got blown around going across the narrows bridge, then when I went to bellevue up 405, back to seattle via 520, also got blow around a bit. Should have been a good day on the lake!

Marty

tried to make a link to the rig tuning thread, but sailnets lovely blinken use of certain words putting in a link to a page in there store, F's me up! It is a sticky in "gear and maintenance" section............

poopdeckpappy 03-13-2013 12:40 AM

Re: Weather helm question
 
1.what kind of weight do you have in the bow area ? may want to redistribute it aft, too much weight in the nose of a small boat brings the CLR forward causing WH

2.Single reef and move traveler leeward will move CE forward

3. Mast rake could be to far aft, loosen BS and tighten FS

4. Add mast bend by tightening BS

Combo of 3 & 4 brings CE forward

smurphny 03-13-2013 06:52 AM

Re: Weather helm question
 
At 15 knots, I find reefing is necessary to get helm balance. Also, with a small jib and full main, the balance may be thrown out. You probably need to get the effort as far forward as possible on the main which can be accomplished in a number of ways: tightening the forestay, Cunningham, vang, outhaul, downhaul, easing twist, etc.

jameswilson29 03-13-2013 08:23 AM

Re: Weather helm question
 
You need less main and more jib up.

TakeFive 03-13-2013 10:27 AM

Re: Weather helm question
 
Quote:

Originally Posted by matthewwhill (Post 1001900)
...There is no part of the 70% that is aft of the boats center of lateral resistance.

Even with the main luffing, it still has friction with the air, so there is force aft of the center of lateral resistance. Reducing rake might reduce it, but I am not sure a state of zero weather helm would be safe or desirable.

zeehag 03-13-2013 10:39 AM

Re: Weather helm question
 
weather helm happens in most sloops i have ever sailed. is cured by owning and sailing a ketch with full keel and protected rudder.....

ok now for the slamming..LOL

RichH 03-13-2013 02:19 PM

Re: Weather helm question
 
With the mainsail fully eased, and a jib 'drawing' it is quite possible to develop what can be 'felt' as 'weather helm' under the following conditions relating to the jib --- jib 'shape'.

1. if the forestay is slack, the jib will develop a hooked-up leech and deeper draft toward the leech. .... a luffing or fully eased main 'can' supply the opposing or additive balancing force.
2. if the jib is 'overtrimmed' ... such as by a gorilla on the jib lead winch that causes the forestay to stretch/sag due to undue sheeting force and which results in a severely 'hooked up to weather' leech. --- this will/can induce the boat to 'skid' to leeward and the side pressure of the skid impacting on the side of the rudder can be erroneously 'felt' as weather helm .... only way to tell the difference is to look to see if the wake/turbulence from keel/CB/rudder is coming 'straight back' off the stern, if the wake is at a noticeable angle, you're probably skidding off to the lee. The overtrimmed portion = yellow; the unattached/flogging = pink .... in the below pic.
3. Jib foot too close to the boats center line and with the head of the sail 'tripped' with unattached flow and the head of the sail flogging .... usually happens if you forget to move the jib's fairlead car back FORWARD when at less than 'beating' and the jib becomes grossly 'over-twisted'. The foot of the jib is 'backwinding', the head is flogging, and only a small narrow mid-panel section is 'drawing' correctly.

http://i1086.photobucket.com/albums/...ps4c32fe13.gif

The only way to keep this 'all straightened out' is to use a FULL set of tell tales .... and watch the angle of the stern's turbulence wake.

All the relationships between CE and CLR go out the window when you develop undue 'dynamic' forces caused by 'cross control' or skids, etc. The CE vs. CLR is great ... for 'heaving to'; but, can be unduly influenced by 'developed dynamic' forces, especially in 'cross-controlled' situations.

tommays 03-13-2013 02:45 PM

Re: Weather helm question
 
Its all about knowing more about your boat which takes time and willingness to experiment

On My Cal 29 for example just easing the back stay will take the boat from hands free perfect balance to REALLY BAD and back to perfect in a matter of the seconds it takes to use the adjustment


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