vosa, try uploading to this site, see how you go.www.ka72.com/

Join a team mate, join a team, they will get you over the 30 knots
read this post then put your name up.
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=59146

Hi Adrian,

I can't help with your Garmin as I've never owned one. One of the Double Demerits, Waiting4Wind uses a Garmin and if you catch up with him he may be able to give you some advice. From reading threads here the main issue with them seems to be getting them to talk to the computer and then getting the data off them. If you can manage to get the data off the Garmin you should be set.

Sounds like you had a great sail yesterday. The Demerits are happy to take on sailors of all levels. We are a smaller team so its very probable your results will count for the team score each month. As mentioned in the other thread a few members who live up at Port Macquarie started their own team. We are on friendly terms with the Marauders and are keeping in touch. However the Demerits need a few more sailors so we can improve our rankings on the scoreboard.

Hi All,

I finally got around to pulling the data out of Garmin Geko GPS (using easyGPS and saving GPS files of the tracks I was interested in), and putting it into KA72.com, and I have a few questions. If people could point me in the direction of where I can find answers (links) that would be appreicated.

First... here are the 3 days of sailing that I did:

* 21/12/09 - 30 Knot NE on Botany Bay: http://www.ka72.com/TrackRecalc.aspx?fid=3456
* 22/12/09 - 15 Knot NE on Botany Bay: www.ka72.com/TrackRecalc.aspx?fid=3458
* 24/12/09 - 35 Knot NE on Botany Bay: www.ka72.com/TrackRecalc.aspx?fid=3459

Can someone explain to me what the terms mean? I have made some assumptions, but some of them do not make sense with the data, so I am not sure if there is a bug in the data or my assumptions are wrong:

* I assume 2 second peak is the highest speed over a 2 second period. This should be one of the highest speeds I would have expected since it is the shortest interval? I expect this paramter is the highest peak speed you hit in the log, and would represent a short gust or something that you were able to hit momentarily, but is not a good measure of consistently reaching a high speed.
* 5x10 average has me a bit confused. I believe it is 5 10 second peak runs, since it then lists 5 individual 10 second speeds, and if I average the 5 individual speeds I get the calculated average. Also I assume the individual 10 second speed is the 5 highest average speeds over a 10 second period. I assume this parameter is a good measure of consistency in high speeds... so if this is good, you are not just a one hit wonder as such.
* Assume 1 hr is highest average speed over 1 hour (low for me as I had lots of rests!!)
* Nautical Mile is highest average speed over 1 Nautical mile of distance.
* 100m is highest average speed over 100m.
* No idea what Alpha is... maybe moving average???
* Total distance is obvious.

So the thing that has me confused is that the 2 second is lower than some of the 10 second speeds. Particulaly in the case of the 24/12/09 which has a 2 second of 23.75 knots and a 5x10 of 25.68 knots. Not sure why this is, but I suspect it may have something to do with the sample mode I had my GPS set to which was Automatic. This means it selects the sample interval based on many things including how full the memory is (which was close to full). KA72 says the sample interval is over 2 seconds for more than half the time which is not desirable. I have just forced the sample interval to 1s for future logs. Maybe this will fix up the 2s reading? I would have assume the 2s reading should be higher than any other reading, and the GPS recorded max speed of 28.3 knots. I assume if I had it sampling correctly I would have gotten closer to this reading with the 2s??

I find it interesting that I got 21 knots on the 15 knot day (in the one gust of the day that got to 15 knots... was mostly bobbing about), and 27 knots on the 30 knot day which felt heaps quicker, but was really only 6 knots quicker. I assume this is mainly due to much increased chop in higher wind. Because the 15 knot day was a short gust, the water was like glass. I suspect that 20-25 knots would be ideal for getting some good speeds.

Now I just have to work out how to get over 30 knots... not too far away!! :)

Cheers,

Adrian

Hi Adrian,

I'm by no means an expert of GPSes and how speeds and times are calcuated.

Firstly those pages you linked did not work for me so I can't comment.

Secondly your assumptions over the divisions seem to be largely correct.

The one you are confused about, the alpha 500 is explained here:
http://www.intellimass.com/RealSpeed/Alpha%20Racing.htm

I'm not sure why your 2 second peak can be lower than your 10 second speeds. It can't be right.

If you want, send me a PM and I'll reply with my email address. You can then email the files to me. I'll run them through RealSpeed and give you the results.

CYA

Karl

Good luck with it. Yeah the first seabreeze since Christmas Eve.

I'm heading out this arvo too but not to Botany Bay as I live on the northern outskirts of Sydney and its too difficult to get through all of the Sydney traffic to down to the bay.

vosadrian said...


Can anyone suggest a good fin for my JP FSW 92L for going for speed.. thinking a 28cm or so speed fin??? Maybe smaller?? Something suitable for 5-6.2m sails and aiming for 30+ knots of board speed.

Thanks again guys!!

I've got a 94L Carve and normally use slalom fins. With a 6.0 I use a 31cm fin and a 27cm with a 5.0. The 27 is a touch small in rough water, a 29 would be better for that size board. I wouldn't worry about a dedicated speed fin unless you have good flat water speed conditions.

Hi Adrian,
Check out this old forum, you're not the only one with a whistling fin.
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=49091&SearchTerms=fin,whistling
Cheers Gaz.

Thanks for the input guys.

I think I need to look at my setup, and technique most. I found the fin I was using was difficult to control in chop as I beared off. As I beared off, and hung more off the back of the board, rather than pushing against the fin, I found the fin hard to control, and would sheet out and stand on top of the fin to get the board under control. I think this is partially running too bigger fin, and partially the way I trim my gear. I still run similar gear trim to 10 years ago when I was right into it (had two kids which meant windsurfing was down to 5 sails a year for a while, and only just got new gear and getting back into it). I run short harness lines (not sure of length but seem shorter than everyone else), lowish boom. It works great for all round blasting, pointing well, early planing etc. but I think I need to lengthen the lines and get the boom up and allow the sail to get further away from me so I can hang more out from the board when on a broad reach. If I can get the control when bearing off, I am sure I will break the 30s with my current gear. I would also like to get a fin that I know is good for 35+ knots, and then I can lay all blame on my trim and technique and work on that. Currently I seem to have a bit of a wall at 30 knots I cannot get over.... having said that, I have not been into speed sailing in the past, so I am pretty happy with the results I have achieved for a newbie at this without having gear particularly aimed at speed (I bought the FSW for jumping and gybing, but have noticed that some people have got them cranking up towards 40 knots so thought why not give it a go!!)

I did find yesterday with my short lines, I got the best speeds when I put a bit more downhaul on, put the boom down about 2cm, and put the base forward 1cm from normal settings. I think this point towards control being my biggest issue.

Can anyone suggest a link with good trim tips for speed.... harness line length, boom height etc??

MobyDisc,

Is that invitation still open for me to join the demerits? If so I would like to take you up on it. I am not sure how much I can add, as I am generally a busy person with young kids etc. I had not sailed much the last few years, but I have been trying to get out a bit since updating my gear. I should get out atleast twice a month over the summer, and a couple times in autumn, but not much else. I tend to mostly sail Botany, but I occasionally go up to Lake Macquarie (is it Marmong), central coast (Nth Entrance) and other spots. Probably can't get to much social stuff, but I may be able to contribute to results from time to time. Not sure if my performance would be useful. Could I enter sessions I have already done?

Anyway, just let me know if you want me aboard.

Cheers,

Adrian