log and wind solid state sensors

[rico]

No way, every time I take the boat for sailing (every other week or so), the speedometer doesn't work. Autumn and Winter here in the Adriatic are not cold enough to avoid weed growth, just enough in ten days to block the paddlewheel !

Cleaning the sensor means water inside, sprayed everywhere ! What a mess !

Lately I read of Echopilot log ultrasound sensor and I am tempted (no moving parts !). Does anyone have first hand experience on this system ?

I'll be glad to know how these new sensors (I read also of solid state anemometer) really perform compared to the old technology !

Thank you to anyone who can help !

Riccardo

 

[pvb]

A question...

What sort of antifouling do you use on your log sensor?

 

[qsiv]

B & G have been using ultrasound (they call it sonic) logs for ages. They work by measuring the doppler shift in echoes reflected back from the bondary layer and are very accurate, and no longer require two sensors as per the old.

A number of them output pulses that match those generated by paddlewheels so they are an easy swap out.

As for solid state wind - they have been around (but not at recreational prices) for some time. They use technology that was (I believe) originall designed for battlefield use on tanks and mobile howitzers. These tools need to know wind direction for accurate gunlaying and although they use lasers to measure wind speed at the target by measuring the wind shear, they also needed to know speed and direction at the tank. For some reason the felt that an ST50 wind sticking out of the turret didnt quite look the part, so they spent millions developing a vertical wand with 4 pitot-style tubes. Wind strength and direction are calculated by reference to the differences in pressure measured from the 4 holes. I hadnt seen much until recently - but at SOuthampton Furuno had a solid state wind device for their navnet system.

The stinkies think they will look so much 'neater' than the agricultural round and round jobs that we raggies use! The price looked high - and I dont see that it offers much improvement over the old for most recreational use. Sonic logs however sound brilliant!

 

[andy_wilson]

wind solid state sensors

Vetus do a wind instrument using a solid state sensor for speed and direction, utilising temperature difference to provide the signal.

I read somewhere fairly recently (PBO I think) of someone who had one fitted to his ketch on one of the masts to compare with the conventional setup on t'other.

Haven't seen the story re-visited since though.

 

[Metabarca]

Forgive the hignorance but who and where are B & G. I like the sound of this log as I have a weedy bottom too, out of sitting in the Adriatic!

 

[qsiv]

B & G - Brookes and Gatehouse, very much at the pricey end of the scale, and may not integrate with other systems.

There are some transducers that will directly replace paddlewheels in raytheon style systems - but I cant remember who makes them at the moment.

 

[tome]

I looked at fitting an Echopilot but the diameter is huge and I didn't fancy drilling such a large hole in the bottom.

 

[FlyingSpud]

I read a test on the echo pilot about a year ago, it has a transducer that was, I think, about 2.5 inches across, it was accurate but could not read speeds of less than 1 knot. A lot more expensive.
Does anyone make a traditional log paddlewheel that you can pull half out, then close a sea cock after it so you can take it out without shipping a ton of water? I't can't be than much of a problem surely. If they did, this would be cheaper and would involve a smaller hole in the bottom of the boat

 

[Rowana]

Many moons ago when I was in the Merchant Navy (When UK had a Merchant Navy!), we had a log that went through the bottom of the boat, but was pulled up before going into harbour. You could then close a sea-cock and pull the whole thing out into the engine room and fix it if required. If it got bent underwater, there was a method of removing the top-works, and using a new "tube", push the old one out through the bottom and re-connect the top-works again.

It worked on a pitot tube principle if I remember correctly.

Sounds like an opportunity here for someone!

 

[tome]

All transducers (Raymarine, Simrad, etc etc) seem to be made by the same company.

Latest versions of speed/log transducers (< 2 years old) have a flap valve so that when you withdraw the head, it shuts instantly and prevents the enema of old. Still leaks a little until you plug it, but a great improvement...

 

[willtaylor]

another question

I thought the point of the Adriatic (apart from separating Greece from Italy) was that it is agreeably warm.

 

[FlyingSpud]

Is that so, shows how out of date I am. I may have a look at that.

 

[HaraldS]

That company is Airmar. www.airmar.com
I think they are working on a standard size (52mm) replacement for paddlewheels, based on sonic, but when I asked them a year or so ago, it wasn't yet ready.