Monday, August 3, 2015

The D or "Dammit" Course Revisited

Tillerman just posted about planing RS Aeros and courses designed for planing singlehanders. This brought to my mind the D course I modified* for just that and the unintended but humorous results when I sprang the D Course on the unsuspecting Classic Moth fleet at their 2013 Nationals (hence the moniker "Dammit" course).


* Tillerman points out that what I've "designed" here is really a Harry Anderson course, a course that has been around for eons -  and he is right - but the D course is a Harry Anderson with modified reaching legs. (See Comments)


I still think the D course has potential. For hiking, cat rigged singlehanders the fastest planing angles seem to be just below a close reach, or a course slightly lower than 90 degrees to the wind. I remember as a PRO back in the 1980's running a Chesapeake Bay Olympic training event and the Europe dinghies had something similar, though if my memory serves, they ran their close reach into an extra mark about 1/2 way between the windward and leeward marks. When the southerly came up, on that reach, the Europes really scooted.

The D course has a curly-cue rounding at the leeward mark. A starboard rounding might be better but I have found that racers are so attuned to going around marks-to-port that they get confused when you change this up.

I offer up the D course details in the following PDF. I'm always interested in what other racers or RC thinkers may come up with in designing planing courses for hiking singlehanders. I think one of the keys is to come up with the angle to the true wind your singlehander is sailing when it is planing the quickest. Data anyone?




7 comments:

Tillerman said...

Around these parts this is called a Harry Anderson - named after sailing icon Harry Anderson. Apparently it's quite popular in college sailing and we use it in Laser frostbite racing in Newport. Some RCs have you rounding the pin instead of the RC boat. I've never seen it with a starboard leeward mark rounding - usually a gate or port rounding.

The Z course that we used for the RS Aeros NAs at the Gorge also had a starboard rounding but that was because the last leg was a broad reach rather than a run.

Tweezerman said...

Tillerman,

Yes, you are right but I'd call the D Course a modified Harry Anderson with tweaked reaching angles (and the reach mark set much further out than a typical Harry Anderson). The key is to try to get one of the reach legs at a tighter angle which I've done with the second reach leg. Any idea what angle to the true wind the RS Aero is hitting it's highest speed? I'm guessing it's about 95 degrees, maybe 100 degrees to the true wind though this would get step up to broader angles the more wind there is.

Tweezerman said...

Just want to add if you want to make the second reach somewhat broader:

For 10 degrees up from start line compass course the included angle at the reach mark would be 35 degrees and for 15 degrees the included angle at reach mark would be 40 degrees (angle between weather mark and RC boat or pin off RC boat).

Tillerman said...

I have no idea what the fastest reaching angle is for RS Aeros. But watching the RS Aeros competing in the Speed Freaks challenge in the Gorge a couple of weeks ago, it looked to me as if the faster boats were sailing quite a lot lower than 90 degrees.

Tweezerman said...

Tillerman,

I looked up Speed Puck because I've never seen one let alone used one. Besides speed it does give course direction over the bottom. If you know your true wind direction, should be a piece of cake to get an accurate idea of what your fast planing angles. On the D course, the second reach is designed to be the fastest one. As the wind picks up, the broader the fastest reach angle will become. This is because the righting moment of the skipper hiking off the back of the bus becomes overpowered. Also the faster you are going the more you suck the apparent wind forward and a broader angle may be better. As you get more data you may find three different angles that might be ideal depending on wind strength. As you get over low twenty knots it may be best to go back to the tried and true triangle with the reach mark at an included angle nearing 90 degrees. With the D course I picked 95 degrees from the true wind as a starting point but it seems the technology is there to nail that number down with some precision. Again more data and feedback would help. Have you found any numbers yet?

Michael O'Brien said...

The ideal reaching angle in an Aero depends on the wind strength. If the wind is stronger, the angle is much broader. If lighter, the ideal is more of a close reach. The key is that the angle has boats fully powered up and fully hiking without having to spill too much wind/power.

In strong breeze greater than 22 knots, the angle is probably about 120-140 degrees. When lighter, say 15 knots, it may be much closer to 110.

Tweezerman said...

Michael,

Interesting. Thanks for the input. A bit broader than what I would have thought. I think the practical upper limits of the D course, given that all the reaching legs are in the top half of the course, is both reaching legs set at 125 degrees to the true wind, making equal angles at the base, with an included angle at the reach mark of 50 degrees. With this course it might help to move the start line and RC boat down to about 1/3 the distance between the leeward and windward marks to give the reaching legs sufficient length. This would make the first beat longer than the finish beat.