Do I need a paddlewheel log?

[AllanG]

I checked today and I have been exposed as a fraud, I actually have a paddlewheel!

My preference would be for a non paddlewheel sensor, but I stand by what I say about needing a speed through the water read out.

Thanks, Bandit, for checking, but I do agree that a paddle wheel sensor on a mobo is pretty ineffectual.

 

[Bandit]

I have not had many problems with mine, we get next to no barnacle growth here and she has a mid season scrub, it appears to work well.

I would still prefer not to have a paddlewheel sensor.

 

[burgundyben]

If you use your boat where there is any tidal flow, speed through the water gives you totally different info to a GPS which is speed over the ground and your position over the ground.

You don't want a paddlewheel which as you say are accurate only the day they are launched, but then foul up.

I have the a standard Raymarine Tridata with the speed transducer (electronic speed sensor) on the hull which has no moving parts (no paddle wheel). It appears very accurate to waves, hull fouling and resulting speed loss etc. This I use for my vessel performance and speed through the water and eventually my fuel and range calculations.

The only sensible range monitor in a motor boat is how many litres of the pink stuff to do a nautical mile Through the water.

After 6 months in the water I can see my speed reduce and fuel burn per mile increase until a scrub or a scrub and antifoul when it goes back to best reading.

Reading both Log speed and SOG from GPS gives you a good understanding of which way the tide is running as well during a trip. Around the CI's the tide generally is 1 to 6 knots.

What's the Point in having the best electronics, temperature sensor, fish finder, etc. If your electronics don't tell you the most basic thing "speed through the water".

Theoretically I agree with you. However, the practical application is a little different.

For example, while a paddlewheel and a GPS would allow me to know the tide, its would only be the case while running directly inline with the flow, or there'd be some maths to do. Secondly, I know what the tide is doing as I have done my passage plan.

I'm happy we've answered the question, no paddle wheel install required.

 

[longjohnsilver]

Like most people, we have one.
It always gets fouled up
But now it is now nice and clean - all nicely cable tied up in the engine room - been like that for 6 years.

I can think of a reason for using one though.
In tidal areas when you want the vectors and wind calcs to be correctly displayed on the plotters.

Maybe true Mike,but like you, ours hasn't got wet for years, serves no useful purpose for us.

 

[Jonmendez]

Just before you don't fit if, will you be having Radar? If so and the Radar has a MARPA capability then the other crafts speed, heading vector, CPA and TCPA will be incorrect as the system will be comparing theirs from radar information againct yours from the GPS. This set up in tidal waters gives incorrect answers. To be fair small boat log (boat speed through the water) and heading information is rarely accurate enough for it to be critical.

 

[vas]

Just before you don't fit if, will you be having Radar? If so and the Radar has a MARPA capability then the other crafts speed, heading vector, CPA and TCPA will be incorrect as the system will be comparing theirs from radar information againct yours from the GPS.

I cannot imagine Ben planning on installing a radar arch on a Fairey...

V.

 

[Hurricane]

I cannot imagine Ben planning on installing a radar arch on a Fairey...

V.

No, but John has a point.
And he also said "To be fair small boat log (boat speed through the water) and heading information is rarely accurate enough for it to be critical."
I would add that these paddle wheels are very inaccurate with even the smallest amount of growth that a GPS calc fed into MARPA would be better than the water wheel sensor anyway.

 

[John100156]

I agree that the paddle wheels may well be inaccurate, most systems are, but all this talk about fouling.... its takes a few minutes to pull it out and clean the paddle wheel, I tend to leave it out with the plug in, then just pop it back in if I'm going on a long trip as a secondary means of measuring speed over water.

Probably would not bother with a new boat, weighing usefulness against yet another hull penetration, but if you have one fitted, use it, just like a bow and stern thrusters....!

 

[henryf]

I think most boats have them as standard fit. When I took my Yachtmaster exam I set the speed up carefully running 2 ways and it did prove to be accurate. Obviously the tidal vector on the chart plotter takes info from the paddle wheel so that won't work. It will just tell you there is a huge tide running with the direction of travel.

Easy enough to pop out and clean up from time to time. Do we really need it with GPS, second GPS, radar (although to be fair that would pack up if the chart plotter went AWOL. I think it gives you a degree of comfort and given the number of through hull fitting we already have for toilets, air con, etc will 1 more make any difference? Particularly when the hole comes complete with an emergency cap.

If we are doing displacement speeds it's quite handy to brush up on basic nav & you have lots of time to check tidal flow etc.


Henry