Trailing Logs

[bluet36]

I want to get a mechanical trailing log because I believe they are more reliable than electric logs, can be easily cleaned and I can fill in another hole in my hull!

My problem is I also have a towed generator and don't fancy having a big tangle following me across the worlds oceans. Older logs used to have a propellor which could be fitted on to the transom and have a cable drive (similar to a motorcycle speedo cable). Does anyone know where I can get something similar?

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[qsiv]

I cnt see how a log fitted to the transom of a sailing boat could ever be accurate - the flow is too disturbed and too prone to being out of the water - I know speedboats use such items - but they re relying on a well established high speed water flow parting cleanly from the transom or trim tab.

Certainly VDO used to have their mechanical sumlog - but I broke more of those than any other transducer type I've ever had. I dont see why a paddlewheel is inaccurate (unless you're at sea so long you get weed build up). I have a Walker as a backup - but I've had spinners taken by fish.

If you want the best solution then fit an ultrasonic transducer , and keep your existing log electronics - but be prepared to pay handsomely!

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[ean_p]

or use the one in your gps..........

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[qsiv]

Perhaps rashly I assumed that if I hadnt got sufficient power to run the instruments I might not have enough power to run the GPS. And yes, I do have a handheld or tw, and some batteries, but that is not a long term solution.

I feel that that sort of attitude is similar to the people who take along a sextant and ephemris as backup tools - and then rely on the GPS clock as their chronometer - it's fine til you actually need it.

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[byron]

<font color=blue>I really don't see why you need a Walker these days. Surely your trailed generator provides ample power to overcome the minimal power a GPS uses and your GPS will provide far more accurate figures unaffected by weed or anything else. Furthermore I don't subscribe to the "what if the GPS goes wrong" brigade. Aviators have used satnav/gps for 30+ years now without ado.. Any way its always handy to have a stand alone one for the unlikely even you lost power.

<hr width=100% size=1>http://www.alexander-advertising.co.uk

 

[Evadne]

I bought a Stowe electronic trailing log when I first got my boat in 1985, and I would choose the same type again (Stowe no longer exist) if it died on me. I had to replace the impeller after dragging it over some sandbanks (a story too long to go into here, involving slow sailing and a duff engine). The electronics needed a little attention as well when water got in one year but it is surprisingly simple and robust. I would never go to a through-hull impeller, because of the fouling problems. All you have to do with a trailing log is to haul it in to clear the odd bit of seaweed now and again. (You know when its fouled because the speed suddenly goes to <1kt). You also have to put up with larger cruisers in the solent motoring over to tell you that you have a line in the water.
Accuracy is ok over coastal distances (e.g. across the channel or Lyme Bay), although instantaneous speed in a sea is inaccurate because the impeller is in the wave behind you. In a F6-7 out at sea the speed varies wildly between 4 to 9+ knots but the distance logged is faithful.

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[vyv_cox]

<I would never go to a through-hull impeller, because of the fouling problems.>

Which ones are these, then? On average over the past 8 years, since I owned my current boat, I guess I have pulled the transducer no more than three or four times per season. This is one of those bits of kit that you fit and forget, unlike the many written accounts that I have read of trailing types in which there seems to be a problem every few hours.

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[PuffTheMagicDragon]

Fully agree

One came with my boat. I was a bit sceptic at first until I adjusted the nuts at the end of the impellor shaft. Surprisingly accurate, it is reassuring to hear the 'click' every 1/10 of a mile. Psychologically it means to me that it is actively 'working' not like the modern electronic devices that are loads more accurate but which go about their work in a silent, clinical manner. The only modification that I have made was to change the clip on the internal supply wires so that I can use ordinary 9volt batteries that you can find anywhere.

<hr width=100% size=1>Wally

 

[ianwright]

>I really don't see why you need a Walker these days<
No? Then let me explain,,,,,
My Walker gives speed through the water, my GPS speed over the ground.A few seconds with a pencil and paper will give me a spot on idea of tidal direction and speed. Qucker and more accurate than looking it up,,,,,,,,,,
,,,,,, but then I enjoy navigation and at 6 knots maximum have time to do it.

IanW.

<hr width=100% size=1>Vertue 203, Patience

 

[ean_p]

I think the gist of the post was distance covered....not speed through the water.......mmmmmm maybe still go for gps all things been equal.....

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[ean_p]

yeah like taking a good radio and or watch for time signals to use with your sextant......its all a shame when the chips are down......

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[byron]

<font color=blue>Ah! the voice of wisdom. Right-on Ian, hadn't thought of that.

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[owendo]

Try the people at Tolsbury Autonic ( I think) I have had one for some years now.
Fitting new batteries after 2 years increased my boat speed from 3 kn to 5 kn in one step !!!



<hr width=100% size=1>Mike Woodhouse
Vertue V17

 

[qsiv]

.. but as I recall most aircraft still have ADF units, which if one was given to scepticism might imply that they feel that there is a residual risk of GPS failure.

I also believe that despite the best endeavours of various governments there is something that purports to be an air traffic control system that monitors continuously the whereabouts of some aircraft part of the time. Provided the operators wear strong glasses I believe they can actually identify individual aircraft. I know this because an ex science teacher at a school near Havant is now reponsible for the smooth running of the computers.

I believe most pilots also carry the rather quaint circular slide rules (or else use the one on their Breitlings) as a further back up....

Surely the idea of a backup is that it should stand a chance of working when the primary device fails - without taking into account the reliability of the primary device.

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[quaelgeist2]

Autonnic Research, Tollesbury, that is

and personally, I cannot recommend their trailing log, which
a) is an electronic, rather than a mechanical log - the spinner sends electrical impulses to the main unti
b) has an unreliable main unit which appears thrown together, fiiting loosely (put mildly)
c) is promoted by a company (as above) which still has to discover the customer (and subsequently maybe service ?)

never worked properly in 2 seasons - thrown out for a proper through hull then.

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[owendo]

Each to his own!

My log has worked fine for 3 seasons with the exception when i did not bring it in when going astern.

I took it to the factory they repaired FOC while i waited.
Three of us have compared output while sailing an fount the resuls the same to withon .1 of a knot.


<hr width=100% size=1>Mike Woodhouse
Vertue V17

 

[quaelgeist2]

...That's good and how it should be !

Maybe I should have sailed there, too, instead of calling them and sending the unit.
Hindsight...

The fit of the unit was pretty bad anyway and the batteries hardly stayed in their case without moving away from the contacts.

Much success with yours, anyway.

chris

NB As to the accuracy - when mine actually worked for some length of time and I checked it at slack vs. GPS it appeared absolutely accurate, too.

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[alan12345]

Alan Williams at A.W.Marine now ownes Stowe marine electronics info@awmarine.com 02392 501207

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