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Old 03-08-2013, 12:43   #1
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Taffrail Logs - ?

Someone referred to "taffrail logs" under the general heading of what to do when the technology fails.

So I put it into google, and I saw it described as something tied to the taffrail and dragged behind the boat.

I get that -- but I'm not at all clear about how this tells you your speed.

Would someone tell me how to use this? Do you just learn by doing? How do you compensate for things like big waves when you need to know speed over ground?

I really like having backup plans. I'm really curious about this one.
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Old 03-08-2013, 12:50   #2
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Re: Taffrail logs - ?

You need to Google "Walker logs" which will explain all.

Personally I am not keen in having that out of the back of the boat whilst in coastal waters.

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Old 03-08-2013, 12:59   #3
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Re: Taffrail logs - ?

My dad was at one time the Mate on a RML pasanger ship called the Andes, this was back in the early 60's.
They had left Southampton on a voyage to NY, and he was down aft supervising the rigging of the walkers log. A young lady passenger asked him what they were doing, so he explained that they were spooling out the telephone wire, the other end being connected to the Southampton telephone exchange.
Soon after, the Sparky was complaining about all the passengers wanting to make telephone calls.
Nowadays, the spinners make for interesting table lamps, got a couple at home.
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Old 03-08-2013, 13:16   #4
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Re: Taffrail logs - ?

A KnotStick is an inexpensive alternative to a Patent Log. Waves, currents et al have no influence as the KnotStick/Patent log measure the yachts speed through the water only.
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Old 03-08-2013, 13:31   #5
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Re: Taffrail logs - ?

Quote:
Originally Posted by Pete7 View Post
You need to Google "Walker logs" which will explain all.

Personally I am not keen in having that out of the back of the boat whilst in coastal waters.

Pete

I completely agree about not trailing things in coastal waters, but I will probably be doing some sailing more in offshore waters, possibly a trip to the Tortugas in October. But I'm not looking for more technology. I thought taffrail logs were non-technological.
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Old 03-08-2013, 13:34   #6
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Re: Taffrail logs - ?

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Originally Posted by svHyLyte View Post
A KnotStick is an inexpensive alternative to a Patent Log. Waves, currents et al have no influence as the KnotStick/Patent log measure the yachts speed through the water only.

Thank you! That looks really interesting! I think I'd like to take the boat out to the Gulf just to play with that thing and see what it can tell me.
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Old 03-08-2013, 13:35   #7
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Re: Taffrail logs - ?

Quote:
Originally Posted by Rakuflames View Post
How do you compensate for things like big waves when you need to know speed over ground?
I am normally hanging on for dear life when they are that big, a second hand held GPS is a wonderful thing.

Quote:
Originally Posted by Rakuflames View Post
I really like having backup plans. I'm really curious about this one.
Half a coconut shell dropped in at the bow and timed past the stern followed by some maths will give you the speed. Alternatively when the quarter wave reaches the stern you are at hull speed. If it goes aft of the hull you are planning and probably have other things to think about, like what will happen when you reach the bottom of the big wave you have just surfed down.

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Old 03-08-2013, 13:44   #8
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Re: Taffrail logs - ?

I've got a Walker Log (came with the boat) never used it, and likely never will - but a thing of beauty (in a workmanwise way) so likely will never sell either!

Plan B on no log is GPS #1, then #2 (and possibly #3!) - after that it is into guesstimation. Not really that hard, boat unlikely to be doing 10 knots (at least mine ain't!) and will know if doing 0 knots (ignoring tidal drift as that can be done by time if you have a tidal atlas)......after that it is just about narrowing the window of guesstimation and navigating by DR around the unsures. But once you pick up a known position from shore (Radar would help) can reset your guesstimation starting point. In any event, most folks have an idea of how fast their boat sails within a knot or 2, just a matter of keeping a written log.

All that a long way of saying I would not bother with a Taffrail Log - IIRC (from internet writings!) the spinners seemed popular with large ocean critters.......
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Old 03-08-2013, 13:49   #9
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Re: Taffrail logs - ?

Quote:
Originally Posted by Pete7 View Post
I am normally hanging on for dear life when they are that big, a second hand held GPS is a wonderful thing.



Half a coconut shell dropped in at the bow and timed past the stern followed by some maths will give you the speed. Alternatively when the quarter wave reaches the stern you are at hull speed. If it goes aft of the hull you are planning and probably have other things to think about, like what will happen when you reach the bottom of the big wave you have just surfed down.

Pete

Thanks for the information! Been 'surfing.' Unfortunately, the person with me thought it was "fun." He acted like he was on the teacup ride at Disney when the boat tried to broach.

What I'm looking for is something that can help me judge how fast the boat is moving if the electronics have gone out so I can make better estimations regarding our true course. Having reliable speed information would help a newer person like me tremendously.
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Old 03-08-2013, 14:04   #10
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Re: Taffrail logs - ?

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Originally Posted by Rakuflames View Post
What I'm looking for is something that can help me judge how fast the boat is moving if the electronics have gone out so I can make better estimations regarding our true course. Having reliable speed information would help a newer person like me tremendously.
I think David summed that up pretty neatly with his normal down to earth approach. The big tides found on NW sides of continents make it all guess work anyway. Sometimes our log reads the same as the GPS and sometimes it doesn't. Now is it the tide, a bit of weed or calibration of the log?

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Old 03-08-2013, 14:05   #11
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Re: Taffrail logs - ?

A Walker Log is a way better way to get your distance covered through the water. Estimating distance covered by averaging speed through the water is fraught with inaccuracies unless you have electronics automatically sensing the speed and averaging it.

I've always trailed a Walker Log. Never lost one to the fishies though have tangled it in fishing lines once or twice. Getting the log line tangled up with other lines is a real motivator to make sure it never happens again. Have towed the log coastal cruising as well as passages probably going on 20,000 miles by now. Don't see why coastal cruising would be any different than open ocean.

The taff rail logs are a bit of an anachronism but they work reliably whether you have electrons or not. Assuming the Walker Log is accurate, it's also a great tool to calibrate your electronic log.
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Old 03-08-2013, 14:19   #12
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pirate Re: Taffrail logs - ?

Quote:
Originally Posted by Pete7 View Post
I think David summed that up pretty neatly with his normal down to earth approach. The big tides found on NW sides of continents make it all guess work anyway. Sometimes our log reads the same as the GPS and sometimes it doesn't. Now is it the tide, a bit of weed or calibration of the log?

Pete
LOLOL.... Yup... I remember doing 6kts with a nice heel going into the Solent... sat staring at the Needles for 4 hrs... made 1/2 a mile during that time... taught me not to try and clear the Shingles on a Spring ebb...
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Old 03-08-2013, 14:24   #13
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Re: Taffrail logs - ?

Quote:
Originally Posted by roverhi View Post

The taff rail logs are a bit of an anachronism but they work reliably whether you have electrons or not. Assuming the Walker Log is accurate, it's also a great tool to calibrate your electronic log.
Something that I have long wondered about: why do folks believe that the Walker log is so accurate? It does have the advantage of being in relatively undisturbed water, but is surely subject to fouling of both prop and line, errors due to yawing of the vessel and errors at lower speeds due to the "angle of the dangle" as it tends to sink away from the surface and its angle of attack changes.

Does anyone have access to any real calibration data?

Cheers,

Jim
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Old 03-08-2013, 15:28   #14
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Re: Taffrail logs - ?

Raku:I noticed that no one has answered your question regarding how speed is measured.
Of course there is a counter that is attached to a braided line that is attached to a towed spinner that reads out in nautical miles covered , but there is also a opening in the housing that enables one to count the revolutions of the spinning flywheel and when armed with a stopwatch the navigator could reference a diagram that gave the speed thru the water in knots.
I towed one across the Atlantic and they are very accurate ,totally mechanical devices that use no electricity, fool proof and work well in all weathers but speed is not accurate in drifting conditions or very slow speeds while the distance run still continues to work accurately
As noted, one does not want it to become entangled with a fishing line since the two lines will then be wrapped around each other thousands of turns...If contemplating a voyage RTW I would probably keep it aboard since the modern yacht is only 1 lightening strike away from the 18th century. PM me if interested in purchase of a lightly used one complete with original wooden box and spare spinners( sharks think they're yummy).
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Old 03-08-2013, 15:34   #15
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Re: Taffrail logs - ?

Quote:
Originally Posted by Jim Cate View Post
Something that I have long wondered about: why do folks believe that the Walker log is so accurate? It does have the advantage of being in relatively undisturbed water, but is surely subject to fouling of both prop and line, errors due to yawing of the vessel and errors at lower speeds due to the "angle of the dangle" as it tends to sink away from the surface and its angle of attack changes.

Does anyone have access to any real calibration data?

Cheers,

Jim
If I remember right you calibrate the log by lengthening or shortening the line. The trick is to match the log reading to the day's run. We used to enter the log reading at the end of every watch.
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