Trimming/Helming For Speed

Mudtimud · #1 12-15-2012

90 degrees on the run, 45 on the reach, trim in to the corner at close haul. These are what I learnt from the Basic Sailing Course on a dinghy.

During the practice sessions however, I realised that while travelling on the beam reach, I can achieve a sudden burst of power when I rapidly sheet in the main. Does this mean that I'll go faster if I keep sheeting in and out between 45 degrees to the corner of the stern degrees so as to enjoy constant bursts of speed?

On the close haul I cannot apply this speed technique as the main sail is already trimmed in all the way to the corner. But one advice I got was to alternate between bearing down and pointing out to allow the sails to power up and down whilst maintaining the close haul bearing.

The advice I get from my other friends, however, is to just simply maintain a fixed sail trim and and fixed bearing without sheeting in and out or pointing and bearing, and the overall average speed will be faster.

So which is it? Should I go with dynamic trimming/helming or just go with a fixed setting? Should I apply the same techniques on a dinghy and a 24 ft keelboat?

Minnewaska · #2 12-16-2012

Couple of things. First, the 90 deg, 45 deg, etc is conceptually correct. However, these are not the actual angles that always work best on all rigs.

There is a concept of gaining as much speed as you can on a close haul, then pinch in a bit higher, then fall off again as you lose speed, then pinch in again. I don't believe this maximizes overall boat speed, but it may improve velocity made good, if you are able to maintain a single tack or fewer tacks toward your destination/waypoint.

You must also consider your VMG when sheeting in too tightly . You may be moving through the water faster, but are undoubtedly heeled over further as well. Therefore, you've lost some of the efficiency of your keel, as it is at an angle and effectively shorter. You are likely slipping to the side as much as you are increasing forward speed, therefore, not really making additional progress toward your waypoint.

All boats are a bit different in this regard. Racers work incessantly on knowing the exactly balance. Cruisers usually set it and forget it. We retrim for shifts in wind direction or sustained changes in wind speed only, unless there are serious gusts.

jameswilson29 · #3 12-16-2012

There are no set sailtrim angles for top speed, certainly not only three. The only way to trim sails properly is with properly positioned telltales to show subtle airflow over the sail or following the sail, and your windvanes and wind indicators to show apparent wind direction.

With a speedo or GPS unit, and on an even more complex level - polar charts for your particular boat, you can experiment to determine which heading and which trim produces the greatest VMG (velocity made good) for a given course heading.

Pumping the tiller/rudder in light air is a form of sculling which is prohibited under the racing rules. In heavier air, it may provide a momentary boost in speed by pumping the sails, or to adjust trim quickly for gusts (which changes apparent wind) or momentary changes in wind direction, and is sometimes used by sportboats to induce a plane, as you can see in this video of a Hobie 33 reaching planing speed:

CodeXSailing - Hobie 33 during San Diego Delivery in Transit South Bound from Orange County - YouTube

From Ed Adams, "Sport Boats and Asymmetrics":

"The trimmer must constantly talk to the helmsman about the pressure on his sheet. As soon as the pressure softens, he must tell the helmsman to head up slightly until the sail is repressurized.

As the wind builds, there will come a point when, if you head up instead of down in a puff, the boat will start to plane. The apparent wind shifts forward with the added speed, and the asymmetric chute comes into its own again.

Once planing, sail as low as you can. But don’t let the boat drop off the plane. Your VMG (velocity made good) downwind is always better with the increased speed, even if you have to sail slightly higher to get it.

In planing and surfing conditions, a sportboat can accelerate so fast that your feet come out from under you. No winch can keep up with the almost instantaneous changes in the apparent wind. The trimmer has to sit down and trim the sail by hand; sometimes with two crew on the sheet in blast reaching conditions. The rest of the crew has to scrimmage the full length of the cockpit, using all the kinetics the rules allow to surf waves.

Pumping the sheet of so large a sail is sometimes out of the question. But you can pump the sail with vigorous steering. The spinnaker is so far in front of the boat when hung from a bowsprit, that by simply pumping the tiller you also pump the sail."

If you are cruising or sailing shorthanded, it is usually best to simply set your sails with the best trim possible, then steer according to changes in wind speed and direction. Once set, look at your speed indicators while you subtly ease or trim a sail to see if you can increase your speed by trimming. If there is a persistant shift in speed or direction, you may need to re-trim again. Many of the things racers do, such as tacking on the wind shifts (header), are not practical when cruising or daysailing, unless you have a large crew aboard.

Sailormon6 · #4 12-16-2012

In organized sailboat racing, the action you are describing constitutes "pumping" the sails, and is prohibited by the racing rules. If you aren't racing, it works, but it takes a lot of effort, and I doubt that you will find it worth the effort to pump the sails for long periods of time, especially as the size of the boat increases.

You will spend a lifetime learning all the little techniques for maximizing the speed of a sailboat, but I'll make two basic suggestions. When beating to windward, the sail trimmer should generally trim the sails to optimize the boat's speed and pointing ability, and the helmsman should then steer the boat to maintain the optimum angle to the wind, as the boat moves through each little lift and header. Doing so will keep the boat's speed maximized for the greatest percentage of time, while shortening the distance as much as possible between the leeward and windward marks.

When the boat is sailing on a reach, but less than closehauled, the helmsman should generally choose the point that he wants to steer toward, and then hold the boat on that heading, while the sail trimmer is actively trimming the sails in and out to maximize boat speed as the boat moves through the lifts and headers.

Notice that I used the word "generally", because those principles aren't carved in stone. They are general principles, to which there are occasional exceptions.

zz4gta · #5 12-16-2012

Pumping downwind can make a big difference. Depending on what class rules you sail by will determine if it's legal or not. One design, not legal, PHRF, it's legal.

Upwind, it doesn't make any difference. Sculling is different than pumping. Dinghy sailing and small keelboat racing is very similar. Roll tacks, pumping, weight placement, etc. are very similar.

smurphny · #6 12-16-2012

One of the things you can do to optimize your particular boat's speed is to get the polar data. A polar chart is sometimes an eye-opener as to your most efficient point of sail.