GPS Log

[Mavis]

My last three plotters recorded trip and log data but they where all inaccurate and seem to randomly jump from one figure to another, and the thru hull speed paddles fair no better. Is there a reasonably accurate stand alone automatic GPS device which can record trip and overall miles travelled ? I have a few apps on my iPhone which can do this but I wanted something more permanent fitted to the boat.

 

[langstonelayabout]

I have had little luck with through-hull paddle wheel logs as my boats have always lived in high weed and barnacle growth areas. If I'm lucky I can get two weeks between paddle wheel scrubs.

I also have a small Garmin chart plotter fitted. It displays Speed Over Ground (SOG) in knots in the top left of the screen and has always proven reliable. It never gets covered in sea weed or barnacles...

So this spring, just before I launched, I got a local boatbuilder to remove the through-hull paddle wheel fitting and glass up the hole.

I no longer have problems with sea weed nor barnacles. The plastic through-hull fitting (that had cracked and was leaking slightly) is no longer there and isn't a potential problem when the boat pounds in large waves.

Works for me. (or have I missed something?)

 

[Fantasie 19]

My last three plotters recorded trip and log data but they where all inaccurate and seem to randomly jump from one figure to another, and the thru hull speed paddles fair no better. Is there a reasonably accurate stand alone automatic GPS device which can record trip and overall miles travelled ? I have a few apps on my iPhone which can do this but I wanted something more permanent fitted to the boat.

Garmin GPS 72H.. swear by mine....

 

[Mavis]

I had had two previous SH plotters and my new boat came with a RM classic C80 which yesterday showed 2,051.00 mile travelled and then later in the day showed 6,000 and something travelled. So not at all reliable or accurate. I do not want to buy a new plotter and hoped something simple (cheap) and reliable would be available which I could link to one or the other of my two existing GPS units on the rail.

 

[pagoda]

I had had two previous SH plotters and my new boat came with a RM classic C80 which yesterday showed 2,051.00 mile travelled and then later in the day showed 6,000 and something travelled. So not at all reliable or accurate. I do not want to buy a new plotter and hoped something simple (cheap) and reliable would be available which I could link to one or the other of my two existing GPS units on the rail.

I don't trust paddle wheels either that much. SOG is basically what I want most of the time, so GPS speed is OK.ditto log data stored to SD card for recovery later. If I suspect much tide is running I can cope with some mental arithmetic!

 

[ghostlymoron]

Almost every boat I've seen has a paddlewheel log. Surely they can't be that bad or no one would have them. My NASA one used to jam up fairly regularly and had to have the twiddler cleaned or replaced but my Raymarine one was completely reliable.

 

[Iliade]

Plotters: You should be able to set the refresh rate (i.e. turn off battery save mode) and the damping is also adjustable on my Garmin. GPS speeds are typically very accurate indeed, so if the numbers are jumping about look into the settings. Also enable EGNOS/WAGNOS or whatever the supplementary system your receiver will use is called.

 

[Iliade]

Logs: I would like to know my boat speed, but have never had a reliable speed log. I started out with a towed log, which kept getting eaten and would tangle hideously if recovered too late in the journey, then moved to a VDO turbine log which is grossly inaccurate, probably because it's well over 45 years old.
Any log close to the hull gets affected by venturi effects to some degree.

 

[macd]

Plotters: You should be able to set the refresh rate (i.e. turn off battery save mode) and the damping is also adjustable on my Garmin. GPS speeds are typically very accurate indeed, so if the numbers are jumping about look into the settings. Also enable EGNOS/WAGNOS or whatever the supplementary system your receiver will use is called.

In settings, damping is sometimes called 'speed filter'. The sampling rate remains unchanged, but a longer time setting (say, 60 seconds) gives a more consistent and useful SOG readout. It also has a similar effect on the COG displayed, reducing the likelyhood of spurious CPA alarms if AIS is integrated into the system. Unfortunately not all plotters have adjustable speed filters (presumably to promote bragging credentials based on momentary speeds).

 

[ghostlymoron]

I don't think that the venturi effect iS applicable to a boAt travelling through the water. It's probably more affected by the boundary layer effect.

Logs: I would like to know my boat speed, but have never had a reliable speed log. I started out with a towed log, which kept getting eaten and would tangle hideously if recovered too late in the journey, then moved to a VDO turbine log which is grossly inaccurate, probably because it's well over 45 years old.
Any log close to the hull gets affected by venturi effects to some degree.

 

[Fantasie 19]

I don't think that the venturi effect iS applicable to a boAt travelling through the water. It's probably more affected by the boundary layer effect.

Not at the speed I travel....