those with velociteks certainly have a good grasp of what the velocitek vmg function can do for you above the other gps varients ,they give you a realtime blow by blow account of what is and what isn't good relative to the race course and conditions on the day.

Polars whilst giving target speeds and angles cant take into account differing conditions ie wave patterns , tide , wind , shear and any other variable , polars are at best average performance targets based on historical data . Velocitek VMG is realtime and constantly updated and is the only thing you need to look at and whats more ITS DEAD SIMPLE .

There are ways of setting up vmg on other gps devices , but for a whole host of reasons this info can be totally irrelevant and the setting up impractical on the water .

What you guys need to consider is wether you allow VMG calculating GPS as Velocitek to be used on the race course or do you want to use data logging for later playback.

I have used many GPS units (garmin foretrex 201 - relegated to my bike, Garmin various handhelds and raytheon plotter on the cruiser ) and have found the Velocitek with its VMG function to be the most performance advantageous of the lot , infact I now have the S1 which has dual displays which you can set as you like , compass (in tiktak format or true ) , VMG , true speed .

speed alone is better than nothing as it help keep you on the pace

I think you will all agree that Rohan Veal has made good use of his sailing with Velocitek.

As for mounting , I've made a simple rotating bracket mounted on my spi pole with lines taken to my rotation spanner so it self tacks , prototype worked a treat from first day .

I definately think we should not use GPS units while racing. Just for logging and later analyzis. The game is racing, and a compass is all we should use, the rest is skill and experience. Having VMG, even with its limitations, available removes part of what I think makes the game interesting.

We had the A Cat north american championships at our club last year and one of the guys who is a sales rep for Velocitek (anyone can be) had 6 boats run the units during racing. At the bar later he was able to run all six tracks at the same time showing the race as it eveolved. Very cool. For the GC08 you might want to approach Velocitek and see what you can work out. Maybe all boats carry some Velocitek advertising in trade for them supplying a certain number of units. Possibly work out a reduced price for regatta participants to purchase units. The possibilities are endless, or they might just say no. Of course when we did it the units were half of what they cost now. Oh well, worth a shot? Ed

I think you can do that with any GPS, right, using GPSAR?

Indeed,

Every GPS able of tracking can be used in GPSAR and can do playback.

Is there any rule on GPS/VMG units during racing in any racing rules? (F16, Tornado, F18, ...).

Gill

I'm might be wrong but in the UK GPS and electronic compasses are a no-no for the A Classes but digital watches are OK. They are anti-gadgets because they'd like to believe in pure sailing.

Tornado class also limits you to an electronic compass + emergency communication (not to be used except in emergency or before/after racing).

Velocitek devices are OK to use in the A-Class and other classes unless the class specifies differently.

The A-Class Association clarified this last year and published on their website. The text is:

"Dear Piet,
As far as I am aware there is no general Racing Rules of Sailing prohibition of electronic equipment including GPS.
If a class association wishes to control the permitted or prohibited equipment then these should be specified in the class rules.
Regards
Simon Forbes"

The linky is:

http://www.a-cat.org/id113.htm

I think these devices are great and shouldn't be limited.

I like these words written by William Arthur Ward:
THE PESSIMIST COMPLAINS ABOUT THE WIND;
THE OPTIMIST EXPECTS THE WIND TO CHANGE;
THE REALIST ADJUSTS THE SAIL

Mark,

any chance of getting GPS units onboard to capture data on the top four or five boats every day at the GC-08? It is an extra effort, but it would be very good to have those logs next winter <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />

If it would be seen as an unfair advantage to have these units on some boats but not others the display can be taped off. As long as the unit is on the boat and turned on it is archiving the data for display later. Ther is some other outfit that will put their "bug" on each boat and collect all of the data from a regatta. I think this was done for the Key West Race Week. Sound a bit more involved but may be worth checking into. I think they give you a finished package that can be sent around ekectronically.

One thing about the Velocitek verses a regular GPS is that I think the refresh rate is faster and as someone said just the speedometer alone was worth it, it is for me.

Ed

hi

GPS unit now are very cheap, so why band them, if they help you go faster. Most f16 sailors are unable to get two boat training and these tools make up for this.

I do not worry about if the next boat has a gps.
I worry that the helm&crew are lighter then me and the sails are newer then mine, and the boats in better condition then mine.

John,

I dont think anybody suggested banning the use of GPS units for training or similar. But at a largish regatta it might be sensible to have a rule on GPS units and similar to make the competition be about sailing and skill. The tape idea came up becouse a couple of us would dearly like to see some GPS plots from the top boats at Mumbles GC'08. If we agree to race without GPS units, taping the display is just a way to not give anybody an advantage (which they dont need anyway, since they are in the top <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> ).

Rules are rules, if there would be a ballot on this issue I would never vote for it.

Basically I believe that banning GPS/log devices would hurt inexperienced sailor most because there is one less tool to be used to observe how your trim changes affect your speed when driving straight line. More experienced sailors don't need these as much because they know in advance how trim should be changed, also more experienced sailors tend to have better feel on their boat and speed. Bottom line is that knowing your speed is most important thing when developing your sailing skills and these devices cost lot less than a good coach, rib and a video camera <img src="http://www.catsailor.com/forums/images/graemlins/wink.gif" alt="" />.

In a race situation a beginner would have a hard time using the GPS in a meaningful way in my opinion. When surrounded by other boats they are the measurement on how your speed is. Having a GPS then is not really useful for a beginner in my opinion as he has more than enough to do with keeping track on what is happening around him and trying to get his boat going. A really experienced sailor would as you say not need the GPS to keep track of his speed, but for determining VMG and deciding on shifts, favoured sides etc. it could be useful. A beginner would not be in a position to really take advantage of this as he simply dont have the time to concentrate on this.

We have trained rather a lot with GPS units to try and find best trim. We have also raced with it in distance races but then mainly to find the fixed marks. Workes incredibly well in that configuration.

My personal opinion is that racing is a game and a large part of that game is determining shifts, favoured side, best trim, best VMG etc. etc. Sailing with a GPS removes some parts of the game which I wold rather keep. For training, I find a GPS useful, but a coach is infinitely better!

Speed is only one tool for following how you do, good part with it is that it's still there when others have pulled away and you are sailing behind. It doesn't take lot of time to look at it sometimes and combine this knowledge with how others are doing around you then it starts to be more useful. This data can be used for finding better trim between races which I see quite important for inexperienced sailors like me.

Anyway I understand your points on VMG and shifts but I still don't think that they are that important for good sailors mostly because sifts can be detected with land marks or compass and the VMG is only needed for sailors that don't know how their boat should feel.

The Velocitek may be able to help you pick shifts, but it won't take the shift into account when calculating the VMG. You have to do that manually by pressing buttons.

So with a shifting breeze, which is almost always the case, even if the wind strength stays steady and your boat speed stays the same, the indicated VMG will change, while the actual VMG stays constant.

What do you guys think about this thing?
I dont think that any device on the market has more features.
At €550 its not exactly cheap, but on the other hand a separate GPS and Tacktick adds up to the same amount.

http://www.nauteek.com/EN/index.php?page=3&prod=2

Hi guys, another cat n00b comes looking for knowledge...and hopefully another hull sometime soon.

After reading the discussion of measuring VMG vs. plotting polars, one would think those to be apples and oranges: VMG is measured with respect to a fixed point such as a mark, while in a polar we need to know course vs. that fickle wind direction. To plot decent polars, one should measure the direction and speed of the wind coming at the vessel. Wireless wind buoy? Seems insane, but the components would cost less than that Nauteek thing. Dealing with the difference in wind speed and direction between a buoy and a boat would be a problem though.

A question is, what would be more valuable in improving one's technique: Ordinary GPS showing VMG to a given waypoint, or a comparison of one's boatspeed to a polar?

VMG much better. Polars are better for yachts, and due to the masses of lead they drag around can be sailed close to their max and it is harder to drop away from targets.

Cats on the other hand can accelerate/decelerate due to a multitude of factors. Training with the Velocitek it is normal to see a +/-1.5 knot difference in boat speed. Yacht would be +/-0.2 knot from polars.

This is prob not technical enough for many of those on this forum, but just my opinion from sailing various types of boats and using various types of devices.