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GPS Team Alpha Racing Explained

Created by hardie > 9 months ago, 20 Apr 2007
WA, 3831 posts
20 Apr 2007 9:49AM
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Hi My Little Fragile Speed Pets,

The following speel was taken off Mal Wright's Alpha Racing site, Elmo has given the address on the other site which I will also include here.

Alpha racing is a way of eliminating the Sandy point advantage and even things out, with the skill factor of gybing involved. Though going fast also requires skill.

The other thing I think will even things out is if we have a one hour category, as SA Boggy Lake beat WA and Vic, so another fair method of measurement, and a way of getting fit, one hour non-stop sailing.

What is Alpha Racing?

Alpha racing is a merging of GPS technology with the natural back and forth sailing done by most sailboarders around the world. It uses the power of GPS and computing to calculate your best average speed from any point through a gybe and back to the same point.

The goal is to return to a previous position achieving the highest average speed within the maximum distance specified for a division. This sounds rather futile at first but makes sense when you realise that having to return to a previous position enforces that the sailing is done predominantly square (or at right angles) to the wind. So why don't you just do a full circle on the spot. Surely you will achieve a quicker time. Yes, the time will be shorter but the average speed will be slow. The idea is to achieve the highest average speed. So to take the opposite approach, why don't you do a 2 kilometre loop? In this case the average speed could be very good but a result is only achieved within the maximum distance set for the division, and the result will not count. So it becomes a true test of speed across the wind, through a gybe and a return crosswind leg that in total covers no more than the maximum distance.

So what makes the perfect run? The perfect run will be to sail at roughly 90 degrees to the wind then gybe maintaining as much speed as possible accelerating out of the turn without losing too much ground, and return slightly downwind of the point where you started. Because the software can use any distance less than or equal to the maximum distance, it is best to return close to your incoming path for some of the return leg to ensure that your best average will be found. The software will look at all points within the maximum distance to find your best result. And sometimes the result will surprise you, being achieved over much less than the full distance.

There are only two rules in Alpha Racing:

1. You must get back to a previous position, the position being within a known tolerance. Because it is not always easy to know exactly where you have been or on what line you sailed into the gibe, a tolerance needs to be applied in the calculations. The term for this tolerance is the Proximity Distance. This proximity distance is specified to allow for slight errors of judgement in location.

This can be used to your advantage if you can judge your location accurately. It means that on the return leg you can get a better average speed by sailing slightly downwind of your original path. But don't overdo it or the run will not count! This will also help to avoid accidents or aggravation when there are many sailors sharing the same piece of water. If you are sailing in open water with no nearby landmarks to use, then on your return leg it might be better to cross over your incoming path within the maximum distance to ensure you have at least one valid result for that run.

2. All results must have a total distance covered that is less than or equal to the maximum distance. The software will only calculate results achieved where the total distance covered from start to return is less than or equal to the maximum distance. If you cover too much distance before returning to your original path, the software will not produce a result. To avoid the chance of a lost result, it is best to return close to your original path before you have achieved the full distance.

No other rules are necessary. As long as you are on a sailboard you can do whatever you like within these two constraints. You can gybe multiple times, you can cross your path multiple times, sail upwind and downwind, you can even tack! Whatever you like.

There are currently three proposed divisions defined as follows:

1. aRacing 250 - Maximum distance of 250m, Proximity distance of 50m
2. aRacing 500 - Maximum distance of 500m, Proximity distance of 50m 3. aRacing 1000 - Maximum distance of 1000m, Proximity distance of 50m
(Note that the proximity distance of 50m is still under consideration) There will be times when different division settings could be applied. One example would be at a contest location where it makes sense to increase the Proximity distance to allow more sailors on the course at once. This would make a very good alternative to speed sailing when the wind direction is too square for optimum sailing speeds. However, the event organisers should announce the distances and guidelines as part of the notice of race, and ensure that the implications of the settings are understood by the competitors and the marshals. It would also be beneficial to have two buoys placed at appropriate locations to assist the sailors. Incoming sailors would sail above the first buoy, around the second buoy and back below the first buoy.

What makes Alpha racing so versatile is that it does not require extraordinarily flat water. The course angle will be predominantly across the wind and the speeds are relatively moderate compared to true speed sailing. So it can be done anywhere and still be reasonably competitive. Even wave boards will do quite well on the short course on a windy day. And it may even be useful to use a wave to help achieve a gybe. In Alpha Racing, anything goes! To get started with Alpha Racing, download ALPHARACING.RSP and open it using RealSpeed version 1.803 or higher. This file contains the alpha racing divisions you need to analyse your tracks. You can open the default.rsp again later to return to your normal divisions, or RealSpeed will revert to default.rsp automatically next time you restart RealSpeed.

Then open one of your favourite tracks that contains some fast gybes. Typically a one-hour track is good for this. The following image shows an example of Alpha Racing results. Note that this set of divisions uses a Proximity distance of 50m so that it can show the results from normal sailing. Once we learn to sail specifically for Alpha Racing, then the Proximity distance can be reduced.

Note the Speed column is the average speed for the Alpha run. It is very difficult to get values over 25 knots for even the 1000m course, so the result displayed here is very good (taken from a very fast one hour track from Chris Diamond of South Australia). Another very useful value is the Min Speed column that shows the minimum speed, usually through the gybe. It is a very good result to achieve a minimum speed of 15 knots, and typically 10 to 12 knots. So the challenge is set! If you can achieve an alpha racing speed greater than 25 knots in any division then let me know and I will publish the results on my web site.
Download the Alpha Racing division file now -->


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