Misreading log

[yerffoeg]

The paddle wheel on my NASA log needs regular replacement (cost about 5 squid) because the magnets embedded in the plastic tend to corrode. Consider changing the paddle wheel. As stated above there is significant error on paddle wheel logs, even when correctly calibrated.

 

[Birdseye]

True I can live without it just like I live without a wind instrument, except for windex, but I find it useful to know STW for tweeking sails to see if I'm going faster or slower.

you can do the same thing with gps - tide varies but not normally in the short distance / time needed to check sail tweeks.

 

[FWB]

Take a look at Airmar CS4500 such as this one: http://www.p2marine.com/marine-electronics/airmar/airmar-cs4500-speed-transducer.shtml

No idea what they are like.

I have had an ultrasonic transducer feeding ST60 for 12 years now. Never had any problems and it appears to be very accurate.

 

[nigelmercier]

Take a look at Airmar CS4500 ...

I have had an ultrasonic transducer feeding ST60 for 12 years now...

Is it that model?

 

[FWB]

Is it that model?

Probably not. I think it's a Raymarine one, now made by Airmar. I think it was fitted in 2004 so that's ten years ago not twelve. It replaced a previous one which I think was by Echopilot and not that suited to the ST60.
Ultrasonic transducers aren't cheap but they are completely maintenance free, just like the depth sounder transducer.