mickl
new user
Reged: 14/09/2005
Posts: 6
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Does anyone have recent experiance with the installation of the above?
Mine underreads (indicates 2kn when the SOG is 4kn), while I'm able to calibrate the untit to allow for this and Raymarine say it's OK, I'm concerned as to why it underreads. The paddlewheel is in front of the keel behind the depth transducer and replaced a Stowe paddlewheel which did indicate the correct speed.
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nimbusgb
regular
Reged: 22/10/2005
Posts: 474
Loc: UK
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Yup, my installation is exactly the same.I have a factor of about 2.5 entered to correct the unit. You can also calibrate using the GPS signal if you have it on the Seatalk bus. I connected my 125 gps up and it ended with near-as-damn-it the same factor so I have left it like that!
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ex_finn_sailor
regular
Reged: 18/07/2007
Posts: 526
Loc: Nottingham .. About as far as ...
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STW and SOG are only the same when you have no tide .. or am i teaching a grandmother how to suck eggs .. Have the ST60 Speed set to show STW and A65 set to show SOG then i have an idea of tidal flow ..
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There must be hundreds of sailors waiting for the dawn of a new day and as many watching the sunset on one departing .. Happy Sailing wherever you are ...
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tony_d
regular
Reged: 13/01/2005
Posts: 211
Loc: Sydney
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our st60 was calibrated when new but now 4 years later constantly under reads. But on a long cruise it gradually catches up and after a few hundred miles it reads correctly. Until the boat is back on its mooring and not used for a month. Cleaning the paddle wheel helps but does not completely fix the problem.
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maxi77
regular
Reged: 11/11/2007
Posts: 859
Loc: Kingdom of Fife
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By their very nature impellor logs operate in a region where the water flow is not stable, especially on a sailing boat. When a boat moves through water some of the water is dragged along with the boat so the log is always in water that is not actually stationary, logs are set up by the manufacturer at a guess point which is correct for some hulls and not others. hence the need to callibrate. Not only does the log perform differently on different hulls, it also performs differently at different speeds and commercial logs will have a multiple point correction. Then take a sailing boat, the flow pattern will change at hifferent heel angle and again at any heel angle at different speeds. This is why before GPS etc those on long passages used towed logs where the spinner operated in water which was not affected by the passage of the boat.
Thus on any liesure log the calibration point will be a compromise and the ideal point will vary from user to user depending on individual needs.
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Peter
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mickl
new user
Reged: 14/09/2005
Posts: 6
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Thanks for the many comments. It's interesting to read that others experience the same but annoying that I seem to have gone from something that, while old, appeared to be reading accurately to something that is less accurate. We're about to go on our hols (sailing) so will see if the speed undereading is consistent and hence it's ok to calibrate to SOG. Also, I plan to attend the Southampton boat show and will ask the Raymarine techies for their views.
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MoodyNick
regular
Reged: 29/04/2003
Posts: 6600
Loc: Lymington
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Quote:
.... will ask the Raymarine techies for their views.
Don't hold your breath. The majority of people on their stand are dealers, ie salesmen, from various independant outlets around the country. You can ask three of them the same question, and get three different answers.
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aka BigNick, in the past.
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