Weather Helm - Sail Cut & Trim

Tim22

.
Jun 16, 2014
254
Hunter 310 Ottawa
Today I finally got out with the Doyle Rep. Wind was at 15knts gusting to 22 so we were reefed (both main and Jib). This was less than ideal as I had hoped to demonstrate the weather helm with full sails at 10knts. Nevertheless the Doyle rep identified the 2nd and 3rd full battens as being overly flexible thereby creating a deeper than desired belly with no sail trim control to reduce it. He is arranging for stiffer battens which should be ready next week.

In general he felt that reducing the sail area by 10% (+ or -) would not have any appreciable affect and recommended against this.

He was also happy with the rig, mast bend, rake, forestay tension etc.

I will report back once I have tried the new battens

Tim
 

Gunni

.
Mar 16, 2010
5,937
Beneteau 411 Oceanis Annapolis
Your halyard, vang, and outhaul should be able to shape the sail (and flatten it) regardless of what the battens are doing. Time for a second (non-Doyle) opinion. Quite frankly it sounds like a bad cut. Good luck.
 
May 17, 2004
2,099
Other Catalina 30 Tucson, AZ
Today I finally got out with the Doyle Rep. Wind was at 15knts gusting to 22 so we were reefed (both main and Jib). This was less than ideal as I had hoped to demonstrate the weather helm with full sails at 10knts. Nevertheless the Doyle rep identified the 2nd and 3rd full battens as being overly flexible thereby creating a deeper than desired belly with no sail trim control to reduce it. He is arranging for stiffer battens which should be ready next week.

Jackdaw: What do you think of the Doyle's Rep's evaluation of the battens in relations to Tim's problem and an evaluation of batten stiffness in general?
 

Tim22

.
Jun 16, 2014
254
Hunter 310 Ottawa
So the Doyle rep never did show up with the new battens!

Fortunately the UK sails rep from Toronto was in Ottawa, and having reviewed the problem with him I was persuaded to order a new sail and do a minor recut on the jib. UK has provided sails for many of the people at the club and all that I consulted were very happy so hopefully this will fix the problem. I will try to remember to post the results next spring after I've tried the new sail.

Thanks to all for the great suggestions. It made for some great sailing testing them all out.

Tim
 
Jun 24, 2014
14
Catalina 36 Mk II #2124 Crystal River
Wow, read this thread and loved it. Tim's last post made it feel like a TV next season cliff hanger!
 
Oct 29, 2016
1,915
Hunter 41 DS Port Huron
So I read this interesting discussion on main sail trim as it relates to weather helm / boat balance, what I failed to see is, how the boat responded to a reefed main?

Would a reduced main sail area remedy the issue? if so,
Would hull speed be achieved with the reduced sail area?
Would the boat flatten out thus reducing weather helm?
Just a couple of curious questions I have after reading the postings.
 

Tim22

.
Jun 16, 2014
254
Hunter 310 Ottawa
The hope is that by reducing the sail area in the roach by about 30 sq ft that the boat will heel less and have less weather helm. Because the reduction is in the top of the sail the effect should be magnified. In addition the sail will have the draft moved forward slightly.

In reviewing the mainsail recommendations from several lofts I discovered that the suggested size varied from about 275 sq ft to 308 sq ft. The current sail is at the high limit and the new one will be at the lower end. I'm not to concerned about reaching hull speed as the boat does this fairly easily and I expect that the increased speed generated by the larger sail size will be offset by less heel with the smaller one.

All will be revealed in the Spring!!

Tim
 
Jul 20, 2005
2,422
Whitby 55 Kemah, Tx
Tim:

The helm on my 1996 Hunter 376 has always been a problem until lately. First changed the rake to 10 inches (1 below Hunter min recommendation) from 18 that the PO had it at and that helped a lot. Next, realized in stronger blows that only reducing the main was still leaving a lot of sail out over the water via the jib due to the tall mast creating weather helm so now I reef evenly. I also pay more attention to my leach cord making sure it's not cupped. All that helped considerably, but I did something else that made steering a breeze on this boat, I modified the rudder.

I started to notice that the boat would be sailing perfectly under autopilot but when a small gust came it always rounded up overpowering the 'below deck' autopilot. I would have to jump up and take the wheel and it was heavy. All the boats I looked at for this year range had a odd shaped rudder that just seemed way too unbalanced, so this past summer I added two inches to the leading edge of the rudder. Not only is the rudder perfectly balanced so the helm can be steered with one finger even when power reaching healed over 25 degrees and doing 8 knots with 8 degrees of helm on a reach, but it also seemed to help balance the boat a little better (I think in the past it would be about 12 degrees weather helm for those conditions).

Just something to think about next time you are out there. Ask yourself, is the angle of the rudder bad (a lot of weather helm), or is it just heavy? Sometimes a heavy helm can be mistaken for a lot of weather helm.
 
Jul 26, 2016
94
American Sail 18 MDR
Two years ago I acquired a 1997 Hunter 310. As part of refitting I bought a new suit of sails from Doyle. The main is loose footed and full battened and the jib is 110% with the height of the clew slightly above the lifelines.

I am finding that the boat carries substantial weather helm at wind speeds as low as 9 to 10 knots and becomes excessive ( rounding up) at about 12 knots. In an effort to correct the problem I bought Don's very good book on sail trim and this evening, in 10 to 14 knots of wind we tested the various methods recommended to move the draught forward and reduce weather helm. Moving the traveller to leeward, tightening down the Cunningham, and adjusting the vang all made slight differences but not to the extent required.

I am now looking at the cut of the main sail and wondering if having it re cut a bit flatter and reducing the roach might help.



The boat is a B&R fractional rig.

I would be grateful of any suggestions that might help to resolve this.

Thanks
Tim
I think I got this right - weather helm - tendency to move towards the wind. To correct or reduce there are many things you can do. The simplest is to move the masthead forward or tilt the mast forward. Loosen the aft stay and tighten the forestay. Adjust shrouds as needed. This moves the center of effort forward as Iunderstand it, mast rake part of balancing the rig. It is possible the new forestay is longer than the previous one.

Remember also, the rudder not only steers but also brakes. Weather helm causes heel which makes rudder lift keel, adding to heel. Weather helm makes your boat slower. A perfectly trimmed boat has a minimum of weather helm and maximum speed through the water in all conditions within the designed expected foil interaction factors.
 
Last edited:

JRacer

.
Aug 9, 2011
1,331
Beneteau 310 Cheney KS (Wichita)
If your sailmaker is service oriented, he/she should be the one sorting out this problem. That said, bottom line is that there is too much effort being exerted behind the center of effort(perhaps not correct term). Normally, this is corrected with mast rake. if that can't solve it, its a problem with the size of the sails relative to one another, I think. I noted that you replaced the forestay, if it got longer in the process, that would rake the mast further aft and cause or exacerbate the problem you have described.
 
Jul 20, 2005
2,422
Whitby 55 Kemah, Tx
...A perfectly trimmed boat has a minimum of weather helm and maximum speed.
Have you ever heard the term Power reaching? Every boat has an opimum angle of heal for a reach and yes, there will be more that the slight amount of weatherhelm you have for optimum pointing. On my boat it is 23 degrees heal and about 8 degrees of weather helm. After that I need to reduce sail. If I reduce before then I slow down.

Most beer can racers are not that familiar with power reaching because they do not reach.
 
Nov 7, 2005
33
Hunter 26.5 DeGray Lake, AR
We need to go back to what Erwin said. If you have tuned and tuned the rig, and still have too much weather, MOVE the MAST FORWARD!!!
 
Jul 26, 2016
94
American Sail 18 MDR
"We need to go back to what Erwin said. If you have tuned and tuned the rig, and still have too much weather, MOVE the MAST FORWARD!!!"

That's too simple. It's more fun to tinker with everything else. No matter how ineffectual..
:deadhorse:
 
Jun 27, 2004
113
Hunter 34 New Bern, NC
Have you considered reefing the main when the wind speed goes above 12 kts. Many boats with large sailplans put their first reef in at this wind speed.
 
Oct 1, 2009
23
American Sail 18 American Sail 18 Everywhere
Get a copy of Royce's sailing illustrated. It helped me control weather helm*.You can also use the centerboard to control weather helm caused by wind pressure. It's the top o mast that when adjusted can increase or decrease weather helm.

* i attached it to the top o mast :^)
 
  • Like
Likes: Solarfry

Tim22

.
Jun 16, 2014
254
Hunter 310 Ottawa
It was a long winter and Spring. Launch was delayed due to flooding and once launched we were unable to exit the harbour due to high water levels. All this is in the past and on Tuesday we were able to test the new UK main sail.

The sail is about 10% smaller than the Doyle main with most of the reduction coming in the top 1/2 of the leach. Like the Doyle it is full battened. Wind conditions were near ideal at about 10 knts with gusts to about 16.

Upon hoisting the sail it was immediately apparent that the draft was not as deep as the Doyle, and that it looked to be slightly further forward. The foot seemed to be cut at a slight angle resulting in the clew being a few inches higher than the tack when not under downward pressure. Also, the sail is slightly shorter at the foot which allows for the use of a small block and tackle to better flatten the sail.

The boat handled the 10 knots well and produced a reasonable 6+ knots of speed. It developed some weather helm in the gusts but nothing so over powering as to cause it to round up. My initial impression is that this is a substantial improvement over the Doyle but I would like to do some more testing before declaring victory. (ie. the improvement justifies the cost!)

Tim
 
Mar 29, 2016
89
Cal 21 Sidney, ME
Reading this thread, I clicked on what is a B&R rig, which led indirectly to a very informative post by Jeff H, including this statement:
"Fractional rigs tend to give the most drive per square foot of sail area."
Unable to find a way to contact him directly, I'm posting here, since my Q also has to do with sail trim.
I don't understand why a fractional rig would yield more drive per sq. ft. I'd like this to be true since my boat has a fractional rig. I've read that the slot between jib and main is very important in producing drive. It seems to me a masthead rig will have more slot, thus more drive per sq. ft.. Or not?
Pondering this, I think I figured out why the upper of my four mainsail (leech) telltales is the hardest to get flowing: there's no slot above the point where the forestay connects to the mast, thus poorer flow over that part of the mainsail.
So much to learn about sail trim!