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Old 25-03-2010, 21:12   #1
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Purists Way of Measuring Speed

We have all heard of the timing the wood chip method but what are some other ways of measuring speed or distance without drilling a hole in your hull for a transducer and without buying a GPS? Does anyone still use a patent log? In short, is there an alternative to spending a ton of money on Raymarine instruments?
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Old 25-03-2010, 21:17   #2
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Every now and then I see taffrail logs show up on ebay.

They keep reminding me of stories of fish eating the spinner which is why they sell them with a spare.
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Old 25-03-2010, 21:28   #3
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Sheesh those things are more expensive than a Raymarine.
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Old 25-03-2010, 21:29   #4
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Any hand-held GPS will give you speed over ground.
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Old 25-03-2010, 21:53   #5
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Sheesh those things are more expensive than a Raymarine.
Not really, more expensive than a handheld GPS maybe, but still no batteries and no holes in the hull.

If you get one, make sure it has spare spinner.

The most comon manufacturer I found was Thomas Walker.

Searches on eBay that brought results with prices under $200 were "taffrail log" and "walker log".
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Old 25-03-2010, 21:57   #6
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I don't know about other places, but you won't have enough spares for that in the Caribbean where sharks, swordfish and a dozen other species will take it before you let the new one fully out again.

cheers,
Nick.
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Old 25-03-2010, 22:00   #7
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Any hand-held GPS will give you speed over ground.

And etreks are less then 100 bucks brand new...
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Old 25-03-2010, 22:00   #8
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2 in one boat speed instrument and fishing lure, you see problems I see solutions.
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Old 25-03-2010, 22:05   #9
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Drop something in at the bow. Scrap of paper. Passing seawead. Spouse. Time it to the transom. Do the math to convert from s/LOA to nm/h.

Note GPS SOG. Turn to reciprocal course. Note GPS SOG. Compute the average. That's speed.

As you pass that fully gizmo'd cruiser hail and ask his speed. If he knows what you are talking about, take that number and add a little bit. That's the speed of your trim well sailed boat.

That reminds me. "When my wife left me she took the anchor. If you see her tell her I want it back."
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Old 25-03-2010, 22:11   #10
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I never got the SOG argument...That's all Im ever interested in!..Speed through the water is irrelevant really.

So you drop in your floaty object and time your movement past it..Then what..you still have no clue as to what the current is doing with you.

It really boils down to a sextant or a gps
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Old 25-03-2010, 22:23   #11
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I never got the SOG argument...That's all Im ever interested in!..Speed through the water is irrelevant really.

So you drop in your floaty object and time your movement past it..Then what..you still have no clue as to what the current is doing with you.

It really boils down to a sextant or a gps
It's the Pacnorwest in us- we've all been in some pass (Cattle, Deception, Mosquito, etc) motoring with the throttle maxed out, water racing by the speedo at 10 kts!!....and not making any headway because we are heading straight up a huge ebb or flood. All because we didn't want to wake up a 4am to make slack water..or the wind died and we missed slack water, or we had to plan the tides, or we were lazy and forgot to check, or...

Yes, I like SOG
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Old 25-03-2010, 23:22   #12
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I never got the SOG argument...That's all Im ever interested in!..Speed through the water is irrelevant really
Nice segue from OP's question about SPEED to the old SOG troll.

While sailing, my instruments, and I have them all, are displaying SPEED and HEADING. Occaisionally I check POSITION, COG, maybe SOG. The interval varies from minutes in a river to a day at sea. Just to play along, SOG and COG are powerboat-thinking...purist sailors live in the moment. Heading and speed are what a sailor controls with trim and helm.
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Old 26-03-2010, 00:00   #13
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Nice segue from OP's question about SPEED to the old SOG troll.

.

Your the one that brought it up...

Like Geopowers stated so well...speed of water moving past your hull is really a worthless number...unless your charging batteries from it.
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Old 26-03-2010, 00:20   #14
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Your the one that brought it up...

Like Geopowers stated so well...speed of water moving past your hull is really a worthless number...unless your charging batteries from it.
Nope. Post #4 brought up SOG. Speed a worthless number? Wow. Look around your boat. See all that hardware? Rigging, sails, engine? That produces speed. It has only an indirect effect on SOG. That rudder, remember it, connected to your autopilot? It produces only heading. It has only an indirect effect on COG and position.
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Old 26-03-2010, 00:24   #15
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OK Missed that one..

Nope...all those things are to improve my VMG ... could care less about water speed...an extra 2 knots of water rushing past my hull does me no good in the wrong direction.....well unless Im just funin around.....
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