question for the oldies - Walker Log

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oldvarnish

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I've still got my old Walker log and am quite fond of it and thought I might get it going again.

I've always wondered - is it possible for a Walker log to under/over read due to friction or something similar? My guess is that if you have the right spinner and the correct length of line attached to the correct unit then over a long distance (say 100 miles) then it must give an accurate reading, assuming it was calibrated properly when made.

If there were friction in the gears, then I can well imagine that the rotations of the spinner might appear as twists in the line, but over a distance that would sort itself out, wouldn't it?

So can a Walker log ever let you down?

(Ignoring tides and currents, of course - or allowing for them)
 
oldvarnish said:
I've still got my old Walker log and am quite fond of it and thought I might get it going again.

I've always wondered - is it possible for a Walker log to under/over read due to friction or something similar? My guess is that if you have the right spinner and the correct length of line attached to the correct unit then over a long distance (say 100 miles) then it must give an accurate reading, assuming it was calibrated properly when made.

If there were friction in the gears, then I can well imagine that the rotations of the spinner might appear as twists in the line, but over a distance that would sort itself out, wouldn't it?

So can a Walker log ever let you down?

(Ignoring tides and currents, of course - or allowing for them)
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They can under-read a lot once a big fish eats the spinner....
 
I used to use a walker log. a small patent log.
My limited understaning of Newtons laws. there had to e some loss due to friction. I think it was alowed for though.
I found it to be surprisingly acurate. They will under read a bit especialy if you are going very slowly. when drifting along in light airs it tended to hang limp vericaly down from the stern. there was allways a short period of time for the line to twist after streaming and setting the log. so it would not start to read acuratly right away. If they over read it is probabaly because the tide was up your jacksy.
The fish story was allways a good one.
Real story you had to check at least once a day and move the weight or the line would wear through and you lost your rotar.
The line was a specific line of a specific lenth for a particular unit. wrong line or wrong lenth wrong reading.
I dont have one but if i find one for sale would love to by for the sake of nostalga if not for real practical need though I would use it.
 
Not old enough to answer lol but having grown up and used them seemingly for years, as a latecomer to electronics.....
My only under reading experience was when averaging what turned out to be 9knots and despite there being a lead torpedo weight on the spinner line ahead of the spinner, I think the spinner was skipping . The boat was new to me and had a very long waterline so I was absolutely delighted but I had thought we were making 7kn through the water, so quite a difference..turned out that the spinner line had been shortened a bit too, so a one off experience that I was unable to repeat.
I still have two(!) excelsior iv and spare spinners and carry one to calibrate the through hull log occasionally.
Few drops of oil before/after use, afaik it's all bronze ball bearings inside so corrosion would be superficial and theoretically 'self polishing' though the older ones do rumble a bit at speed..
Does that help?
 
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My walker log is sitting here on the shelf as a book end. I think apart from when simply ghosting along, it was fairly accurate. But perhaps our expectations were lower.

But when I saw the new 'torque rope' used on a free flying asymmetric furling system, I did wonder if using that would have increased the sensitivity or accuracy, as the original ropes did use to kink slightly, especially when surging fast down waves.

But with the cost of such rope, I think it'll have to stay as idle curiosity!
 
I sailed on a yacht where the Walker Log was calibrated at different speeds across a measured mile. I am sorry but I cant remember if there was any significant error, I certainly don't remember applying corrections.

However, the error issue is not really relevant as DR and EP are only best estimates of the yachts position. Walker Logs were used at a time when opportunities to fix the yachts position were usually taken and plotted, thus resetting any cumulative error to zero again as the log reading was noted with the fix.

It would go wonky when sea weed got caught up in the log line.
 
I, sort of, remember a diagram in an old book.

I think the point was that the log could over read in big seas, as the boat and spinner moved up and down in the swell. Dunno if it was right, or not.

Pretty soon after I got a Decca, "with four waypoints", so that was that.
 
measured accuracy

I measured mine over quite a few miles and reckon it's within 1.5% of distance travelled, which is pretty good! The only times it under-reads is when going over 8kts when it skips occasionally. I lengthened the line which reduced this. Now I reckon it's better than my ability to hold a course so that along-track error after a night at sea (say 10 hrs without a fix) is much less than cross track error and about the same the random error in taking a sight.

Friction should not be an issue, at least not if cleaned and lightly oiled. It should turn really easily, and if it does then its friction will be nothing compared to that of the braided line.
 
From what I remember, the error was no worse than the error in tidal streams.
DR beating was always a bit vague though.
 
logs

I used a Walker's ship log, bequeathed to me by a grateful sovereign when I left the service and my ship went to the scrapyard.
It is impossible to judge accuracy because of current variations among other variables, but I have found an error of less than five miles after a 3,000 mile voyage.
Keep the taffrail unit well greased.
Set the log by easing out the log-line first and then tossing the impellor over outwards. Hand it by uncoupling the log-line from the meter, and then paying the line out round a stanchion or cleat as you haul in the impellor. That way you avoid kinks in the line.
Apart from the log, a grateful sovereign also left me a Walker's anemometer. This serious instrument also came from HMS Cumberland, the three-funnel one, which went to scrap in 1959, the year I drew my pension. It is now mounted on my present boat, aboaard which I live. Walkers sent me a new rotor, complimentary, about seven years ago. Nice people, Walkers.
 
ChattingLil said:
I have one that I don't know how to calibrate. Mine over-reads, substantially. EG showing 8knts when I know we can only be doing 4 or 5.
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I don't think we can be talking about the same things. My Walker 'knotmaster' trailing log does not read speed, only distance travelled. It's pretty much inconceivable that it could over read by a factor of two given the design unless I put it directly in a propellor wash - and the trailing rope is too long for this (4m?) even if I did use it while motoring.
 
jdc said:
I don't think we can be talking about the same things. My Walker 'knotmaster' trailing log does not read speed, only distance travelled. It's pretty much inconceivable that it could over read by a factor of two given the design unless I put it directly in a propellor wash - and the trailing rope is too long for this (4m?) even if I did use it while motoring.
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My Walker Excelsior Mk 4 has a slot in the housing of the rotating disk, which itself has a white segment so that the revolutions can be counted. This is then applied to a supplied chart of rpm to knots.
 
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