Knotstick - every boat should have one!

VicS

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It only displays speed through the water.... If thats what you want to know thats fine.

The Walker records distance which, once allowance has been made for tide, is more useful for navigation.

For navigation a simple GPS, costing not a huge amount more, would be more useful .
It'll always tell you exactly where you are as well!
 
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Ubergeekian

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Surfing the net this morning, as you do, I came across this: http://www.knotstick.com As the Walker Log is no longer made, I think this could be the next best thing. What do you think?

It looks interesting, but is only a speed measure and not a log. Also they'd probably sell more if the "products" link on their homepage wasn't dead.
 

ColdFusion

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It only displays speed through the water.... If thats what you want to know thats fine.

The Walker records distance which, once allowance has been made for tide, is more useful for navigation.

I'm aware of the Walker Log recording distance, but it is no longer made. The knotstick displays speed - a glance at your watch and you can easily calculate distance through the water.

For navigation a simple GPS, costing not a huge amount more, would be more useful .
It'll always tell you exactly where you are as well!

Yes, obviously, but what about when your GPS packs up or all your electrics fail or Uncle Sam turns GPS off or the MOD jams the signal or...?

As a back up (which is what just about anyone owning a Walker Log uses it for) I think the knotstick seems pretty good.
 

VicS

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I'm aware of the Walker Log recording distance, but it is no longer made. The knotstick displays speed - a glance at your watch and you can easily calculate distance through the water.



Yes, obviously, but what about when your GPS packs up or all your electrics fail or Uncle Sam turns GPS off or the MOD jams the signal or...?

As a back up (which is what just about anyone owning a Walker Log uses it for) I think the knotstick seems pretty good.

You want one obviously! ......You buy yourself one.

Walker logs turn up from time to time on the for sale board and ebay. Mine ( as good as new) will be for sale before very much longer. Keep your eyes peeled
 

Sgeir

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For the reasons above, it does not have the full functionality of a Walker log, but could still be useful if all else fails.

Just a thought; I was wondering about the extent to which water viscosity variation, from salinity and temperature for example, would affect the readings. Marginal probably?
 

sarabande

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I reckon, Sgeir, that as the force on the disc is a function of (primarily)water speed and (secondly, by a long way) drag, then the variability of sea water density being between 1020 and 1035 Kg/mcube, the disc sizes of between 4 to 15 cmsq (estimate) will have very little influence. The variability is <1.4% or less than a tenth of a knot at 6 kts.

The use of an elastomeric link to absorb variation due to snatch and surge of the disc and line is a neat idea.

It looks as if the instrument has been designed empirically, rather than from theory including Bernouilli and Reynold's Numbers.


I wonder how many they lose to predator fish in the tropics ?
 

photodog

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OK, as the Walker Log is no longer available (new) what do people use as a non-electrical back up to record speed and distance?

Its funny that, the Log ont he boat is hopeless... and relies on leccy.... In fact it simply doesnt work and I gave up on it 4 years ago....

With a GPS plotter... (2 now.. one down below and a independent one above..) hand held GPS, and my Iphone.... I simply havent felt the need for the log. Does that make me a bad sailor?

I reckon charts, Depth sounder, radar and compass will probably suffice if the GPS goes down...
 

vyv_cox

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Yes, obviously, but what about when your GPS packs up or all your electrics fail or Uncle Sam turns GPS off or the MOD jams the signal or...?

I have had a GPS almost since the very first ones became commercially available. My first was bought in USA, (an Apelco, whatever happened to them?) much cheaper at £1000 than anything available here. I have had numerous ones since and currently have a plotter, a battery powered hand-held and a telephone that has gps capability. Not a single one of the >10(?) that I have owned has ever failed. So it seems an unlikely event that three will fail.

In 25 years my boat electrics have never failed. I doubt very much that they ever will, but in the event I have two battery powered backups.

Apparently USA have guaranteed that GPS will not be turned off. So much equipment depends upon GPS nowadays that the consequences, even in USA, are too great to be contemplated. E.g. I was told by a Canadian airline pilot that GPS is their primary navigation system because beacons are too difficult to set and maintain in such difficult terrain.

Jamming is now quite sophisticated and could be applied specifically in a war zone, no need for it generally.

So taken overall, I think I will stick with GPS.
 

Ubergeekian

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In 25 years my boat electrics have never failed. I doubt very much that they ever will, but in the event I have two battery powered backups.

The Eagle Accunav Sport GPS which I bought 15-ish years ago for gliding and sailing became a paperweight after about seven years. Probably EEPROMs inside losing their memory. It's a shame, because it was far and away the best user interface I have ever seen on a handheld GPS, and had a few features which were particularly good for gliding, since the designers were glider pilots. My current Garmin 72 is good, but nowhere near that good. Mind you, two AAs run the Garmin for a day - the Eagle got through six of them in an hour and a half...

Apparently USA have guaranteed that GPS will not be turned off. So much equipment depends upon GPS nowadays that the consequences, even in USA, are too great to be contemplated.

I understand that the current plan is to make Galileo completely interoperable with Navstar GPS, so the same receivers should be able to use both constellations of satellites, and both systems would have to go down to lose the plot completely.

I'm perfectly happy to use GPS as my primary method of navigation.
 

panthablue

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I think it's a great idea. We have a trailing log, and a GPS. The GPS is great for telling us where we are, but to get the best speed out of the boat, the trailing log wins hands down.
 
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