Steve101
N/A
A friend of mine have an ST60 Tri data (er I think) and it's always shows speeds about 2 knots less than the GPS. Any ideas?
Raymarine ST60
- Thread starter Steve101
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Gunfleet
New member
Tide? nm
PaulJ
Member
Has your friend calibrated his log? If you look in the book of words there is probably a calibration process that he can carry out by timing over a measured distance. Another thought that comes to mind is could the paddle wheel be installed "back to front" ?
Chris_Stannard
New member
There is a calibration process for ST60 instruments, which will be in the handbook. If your friend does not have one it can be downloaded from the Raymarine website, www.Raymarine.co.uk. If the GPS is also Raytheon/Raymarine it can be connected to the Tridata via seatalk and you can do an automatic cross calibration, but if not you have to do it manually.
The best time to do it is at slack water, which should be confirmed by observation on a buoy or other fixed mark. You can then set the ST60 to GPS speed, and check it by turning 180 degrees and making sure they still agree.
Good luck
Chris Stannard
The best time to do it is at slack water, which should be confirmed by observation on a buoy or other fixed mark. You can then set the ST60 to GPS speed, and check it by turning 180 degrees and making sure they still agree.
Good luck
Chris Stannard
Chris_Stannard
New member
I forgot to add the paddle wheel unit has a little arrow on it which must be facing the front, it should then click into place.
Chris Stannard
Chris Stannard
pkb
New member
Its odd that it "always" shows a speed difference of 2 knots since the log is measuring speed through the water and the GPS speed over the ground (SOG) and the difference between the two should vary considerably given variations in your course relative to the changing tidal flow.
Peter
Peter
JeremyF
New member
Press and hold down for 5 secs the 2 left-most buttons until 'User Cal' comes onto the screen. Press the left button about 3 times to get to the speed calibration screen. Right-most button increments the speed. Keep pressing until the speed is the same as the GPS in slack water, at around 3 - 6 kts of SOG. When aligned, press and hold the 2 left-most button until it reverts to normal mode.
Make sure the log is clean and directionally true before you start.
Jeremy Flynn
Make sure the log is clean and directionally true before you start.
Jeremy Flynn
Moose
New member
I did a Sea Trial, the other day on a Fairline Phantom 37, that I am taking delivery of tomorrow (I'm excited!!)
Anyway, this boat had a ST 60 Multi and I saw exactly the same thing, Comparing it with 4 GPS's the ST 60 consistantly read about 2-3knots lower.
Oh, and sorry to all the Yachties we swamped coming out of Chichester, obviously we had a skipper with us from the brokers, but it had the policy of aiming at every yacht he could see at 30knots and swamping them he said "Its there fault they are there" I felt embarrased sitting up on the Flybridge with him. This is surely a bad attitude that can easily be conveyed to other new boaty's like ourselves.
I can assure you that I will not be like him!
Moose
I want a boat!!!.........a nice big one that is really cheap and runs on air.
Anyway, this boat had a ST 60 Multi and I saw exactly the same thing, Comparing it with 4 GPS's the ST 60 consistantly read about 2-3knots lower.
Oh, and sorry to all the Yachties we swamped coming out of Chichester, obviously we had a skipper with us from the brokers, but it had the policy of aiming at every yacht he could see at 30knots and swamping them he said "Its there fault they are there" I felt embarrased sitting up on the Flybridge with him. This is surely a bad attitude that can easily be conveyed to other new boaty's like ourselves.
I can assure you that I will not be like him!
Moose
I want a boat!!!.........a nice big one that is really cheap and runs on air.
jimi
Well-known member
Clean the impeller. I did recently & scraping off all the wee barnacles helped considerably!
Jim
Jim
kdf
New member
Put it into a cup of Milton for a day - it will come back out like new
JeremyF
New member
How does that work kdf? Does Milton 'bleach' eat the weed and crud away then?
Jeremy Flynn
Jeremy Flynn
kdf
New member
Must do - mine had lots of dried weed and barnicles on it but these fell off after about a day in the milton. Then used the hose to wash everything out and its been great since.
John_Clarke
New member
Hull must be clean too
I have had a frustrating 2 years trying to calibrate my ST60 log. Despite cleaning the impeller each time I got very inconsistent results over a range of speeds - a different calibration factor was needed at different speeds. It also changed each time I tried to calibrate it. The log and impeller were returned to Raymarine for checking and were found to be in good order.
I now think that the problem has been a fairly thin carpet of fine weed and slim on the hull which has pushed the boundary layer of water away from the hull enough to put the relatively small impeller out of the main flow. At higher speeds it worked reasonably well as the carpet was flattened against the hull, but at lower speeds it gave far too low a reading.
I have scrubbed the hull from the transducer forward with a scrubbing brush on cords leading up on either side of the hull. Keeping tension on both cords and pulling from side to side did the trick.
I also made the mistake of not antifouling the transducer flange, thinking that because it is bronze it would not need it. The beard of weed on the flange was enough the jamb the impeller on some occasions.
I have never had this problem with other logs such as the ST30 which had an impeller with wider longer blades.
With a clean hull I now need a calibration factor of about 1.30
I have had a frustrating 2 years trying to calibrate my ST60 log. Despite cleaning the impeller each time I got very inconsistent results over a range of speeds - a different calibration factor was needed at different speeds. It also changed each time I tried to calibrate it. The log and impeller were returned to Raymarine for checking and were found to be in good order.
I now think that the problem has been a fairly thin carpet of fine weed and slim on the hull which has pushed the boundary layer of water away from the hull enough to put the relatively small impeller out of the main flow. At higher speeds it worked reasonably well as the carpet was flattened against the hull, but at lower speeds it gave far too low a reading.
I have scrubbed the hull from the transducer forward with a scrubbing brush on cords leading up on either side of the hull. Keeping tension on both cords and pulling from side to side did the trick.
I also made the mistake of not antifouling the transducer flange, thinking that because it is bronze it would not need it. The beard of weed on the flange was enough the jamb the impeller on some occasions.
I have never had this problem with other logs such as the ST30 which had an impeller with wider longer blades.
With a clean hull I now need a calibration factor of about 1.30