Sail Trim Versus Rudder Deflection

Jackdaw · Feb 21, 2016

3 degrees.

As little as 2, no more than 4. At this angle the tiller/wheel will have a nice 'feel', and the rudder is acting as a foil, adding lift. More and this and it starts to stall, as well as working as a brake. Slow.

If you need more than that, two things: Firstly a pure sail trim issue. Mostly your main. Second it MIGHT be a sailplan 'balance' issue. But that's another topic!

Davidasailor26 · Feb 22, 2016

Also keep in mind that depowering the main to reduce weather helm can and should be done with more than just the sheet. Increasing out haul tension, or decreasing vang (if off the wind) can also help.

Jackdaw · Feb 22, 2016

I just noticed that you posted this in racing, so I'll some racing related thoughts.

While racing to windward, the job of the main-trimmer is to keep the mainsail powered up, while controlling both excess helm and heel angle. While the latter can be done by watching the inclinometer, helm pressure is an on going discussion with the driver, which continuous adjustments being made while keeping the sail in trim.

While racing, mainsail trim is a FULL TIME JOB.

Foolish · Apr 18, 2016

The best part about singlehanding like I do is getting getting real feel for the sail trim / weather helm combination. I can instantly feel every slight change in wind and trim. In answer to your first question, weather helm should be no more than a 3 year old girl can manage, or just a few degrees as mentioned by others above. If you are flying a 155 Genoa, then that will have as great an impact on helm as the main, so it must also be considered in your equation.

Some time ago I learned to feel the boat not by weather helm, but by the knot meter. By watching it for every. 1 change in speed I know if I'm trimming right or wrong.

markwbird · Apr 19, 2016

It depends on the boat. While you definitely want to keep weather helm low, different boats handle differently. I crew on a J-105 and the helm is light as a feather when the boat is trimmed. I own an H-34 and the helm is heavy. I do not expect to get my H-34 trimmed so that the helm is as light as the J-105. I do trim the sails to reduce weather helm as much as I can to the point where the boat is fastest. I am only using about half of the main at that point (in heavy air) but the boat is fastest trimmed that way.

PaulK · May 13, 2016

If you really want the right answer, you will need a VMG readout from your instruments to tell you what works for your specific boat in various wind ranges and sea conditions. In smooth water and 10 knots of breeze you might get better results from strapping the sails in and not worrying too much about weather helm (the rudder angle) because the smooth water allows you to edge to windward regardless. If the wind picks up, even if the water stays smooth, your helm may have to go too far over to compensate and THAT may slow you down. That's the time to try dropping your traveler to leeward to see if your VMG readout improves when you do that. Choppy water in a nice breeze? Check the VMG with the sails strapped (and the helm over) and you'll probably find that easing the traveler helps because you need more power to keep moving through the waves. Each time you go out is a little different, but you will learn what works best in each situation by watching your VMG to the next mark.

Stu Jackson · May 13, 2016

A 155 in over 15 knots is a handful, even if racing. Makes you heel too much.

The traveler should be the first thing to deal with before you let out mainsheet. Why? Because letting the mainsheet out changes the trim of the main and increases depth making it more powerful, not less, while just adjusting the traveler changes the angle of attack only and with a flat main is the best thing to do first.

Buy Don's excellent book.