Hi All,
I have been lurking around here for a while, and I have had a Garmin Geko for a few years. I went out and bought a Paqua shoulder band, and today I had my first sail with a GPS. I found it very interesting to see the data that was available, but I have a few questions:
* I can see max speed and distance travelled and that sought of thing, but I see that most people here report the best 10 second average. I have the Geko version that can output RS232. Is there any software I can use to extrapolate this data?
* Is there any way to know if the GPS failed to get a signal at any time.. like if the band slipped so the GPS was under my arm and I missed some data?
* Is the data from my GPS comparable with others that seem to use a different unit?
Now some questions on how I did. Today I had my 09 JP FSW 92 with a (15 year)old Gorge Gear freeride fin, Gaastra Pulse 5.0m (wave) sail (about 30 knots). It was a good Noreaster in Botany Bay sailing from Kyeemah. I felt well powered up, and was overpowered (as in ran out of guts in the chop) a few times. I managed to sail 85km which I was well impressed with. I was aiming for 100km, but I saw lightning off to the West and decided to call it a day. I managed a max speed of 52.5kph, which I converted to around 28.35knots. Earlier in the day I was sitting on max speed of 50.5kph. Then I trimmed the sail a bit and got it to 52.2kph. Then the wind picked up a bit and I got 52.5kph.
* Is that speed OK for the gear? Was a bit of chop about (middle of bay rather than close to runway). The best run was a nice gust and I was in a section of water that had more organised chop and was able to find a nice line.
* Would I expect to go faster or slower with my lighter wind rig in about 20 knots of wind. My big sail is NP Hellcat 6.2, and I run a select freeride/slalom cross over fin with that. I am keen to get over 30 knots, but just want to know if I am heading in the right direction.
Thanks in advance for the advice guys. Any tips on beating 30 knots appreicated!!
Cheers,
Adrian
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,
Welcome!
There are a number of programs around that allow you to analyse your tracks:
1) Realspeed (http://www.intellimass.com/RealSpeed/Index.htm)
2) GPS Action Replay (gpsactionreplay.free.fr/)
3) GPSResults (tinyurl.com/3cmhzm)
4) KA72 (www.ka72.com/)
The data from your unit is comparable, however it will read a bit higher using software when looking at your 2 second peak. This is usually around half a knot or so.
28 knots isn't bad in chop, especially with an old dinged up fin. The only way to tell which is faster is to try it!
If you want to be really bitten by the speed bug, then put up a post on here asking which team to join -- you'll get snapped up in no time
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.
Thanks guys,
I will try and get the data off my GPS (I have done so before for bike use), and put it into one of those programs and get some stats. I will then join a team. Sounds like the demerits may be the go for me.
Went out yesterday also, but it was comparably marginal. Managed a few comfortable planing runs over a couple of hours. If I had not drive 45 minutes to get to the water I would not have bothered, but once out there, I decided to go out, and it was a nice day to be on the water even if the wind was not great.
Cheers,
Adrian
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
Well done, Adrian. You have it pretty much sussed out.
gpsteamchallenge.com.au/pages/guides has some helpful linkshttp://www.intellimass.com/RealSpeed/Alpha%20Racing.htm gives the info on alphas they can be a bit confusing and there have been many threads here about the intricacies but essentially it involves a gybe and getting back to within 50m of your start point with a maximum distance of 500m.
Garmins are very inaccurate on the auto setting so should be set to 2sec interval or 1sec if they can record to that frequency?
Good luck
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
Thanks Guys,
Karl I edited my post, and I think the links will now work. Putting <> around the links caused problems (habbit from my email program).
It seems to me that my understanding of the parameters is pretty much right, but that my long sample interval has caused some issues for the software to accurately determine the 2s parameter. I have now adjusted my GPS settings to those recommended by gps-speedsurfing.com for my Garmin geko. Basically I have it hard set to 2s interval. They say that 1s can cause some accuracy problems... I presume this is due to the interval being similar to the GPS sample rate resulting in some sample being recorded more than once.
I am hoping for a sail this afternoon (first possible NE since 24/12/09 due to the cyclone fallout that has been effecting the east coast). So I will do more logs, and see if I get better data.
Also hoping to get a descent go on my 6.2m hellcat(20knots predicted) and slalom fin which I believe has more speed potential than my wave sail and freeride fin which I was forced to use in the other 30 odd knot sails.
Thanks again!!
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.
I went out today with the new settings (2 second interval), and the results on ka72 make much more sense (2 second is higher 5X10):http://www.ka72.com/TrackRecalc.aspx?fid=3476
So I think I have it pretty well sussed now.
Wind was 20-25knots. Got a 2 second of 29 knots, so close to my goal of 30 knots!! I think I need a smaller fin. The 32cm Select S-Ride gets pretty hard to control when I bear off the wind alot. 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!!
Thanks Gaz 45!!
While I am at it with fins... I found this fin to whistle/squeal very loudly once going above about 20knots. So much so that I was wondering if other sailors would here me coming. Is this normal? Is there anything I can do to prevent it?
-- Adrian
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.
I have an '05 91FSW with which I use a 26cm Flying objects weed fin. 5.8 koncept slalom sail is about the limit. Good for speed in flat water (has hit 37 knots). I would probably go bigger at 28-30cm. Not so good for choppy conditions. By comparison the same board on the ocean with the stock JPcarve 29cm fin and a 5.8 combat wave sail hits about 26 knots. Flat water is the key and bearing away off the wind with a sail with the outhaul at least a couple of cm less than normal (full shape).
Also see these threads for getting 30+
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=57985
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=54581
You should also set the straps back and outboard. Make your adjustments incrementally.
Have fun!
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??
Hi Adrian,
Guy Cribb has a lot to say about how adjusting equipment and sailor trim to achieve good speed. I had a look at one of his cribb sheets the other day and there is much to be said there.
Other than that there are a fair few threads here discussing board and equipment trim.
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
