Are Speed Logs and Wind Speed Instruments Obsolete?

[44'cruisingcat]

Originally Posted by El Pinguino

Yes, thank you, I do know....

Which is why I wouldn't use either close inshore where I sail.

Well yes,their use does need to be governed by common sense...

And as I often do, I once again made the mistake of expecting that here.

[Don C L]

Originally Posted by 44'cruisingcat

Well yes,their use does need to be governed by common sense...

And as I often do, I once again made the mistake of expecting that here.

Hmm, a tad harsh, no? I'd say perhaps you assume too much in the negative about those participating here and you're willing to express it a bit too quickly.

[rognvald]

Yesterday morning, I was reading "Gypsy Moth Circles the World" by Sir Francis Chichester. While sailing in the Roaring Forties en route to Australia Chichester writes: "That day my speedometer packed up. At first I was surprised how much I missed it, but as things turned out it did not matter much, for I found my dead reckoning was as accurate as it had been when my speedometer was working. As a matter of fact, it was more accurate because the speedometer had been under-registering at low speeds. Perhaps this was because the little propeller of the speedometer's underwater unit was getting foul with marine growth. After I had got over the feeling of loss when the speedometer failed, it was quite a relief not to have it."(p. 79, paragraph 3, First American Edition, 1968). Not much has really changed in 50 years. Good luck and safe sailing.

[Terra Nova]

Originally Posted by rognvald

...I found my dead reckoning was as accurate as it had been when my speedometer was working...

Let's not discount the benefit that speed/log had contributed to this highly experienced sailor's ability to deduce his speed before its ultimate failure.

[Jim Cate]

Originally Posted by Terra Nova

Let's not discount the benefit that speed/log had contributed to this highly experienced sailor's ability to deduce his speed before its ultimate failure.

Very good point! Without the "training" his eyes and ears had from watching the speedo, his instinctive DR would not have any basis for quantification.

Jim

[Wotname]

Originally Posted by Terra Nova

Let's not discount the benefit that speed/log had contributed to this highly experienced sailor's ability to deduce his speed before its ultimate failure.

Originally Posted by Jim Cate

Very good point! Without the "training" his eyes and ears had from watching the speedo, his instinctive DR would not have any basis for quantification.

Jim

Surely this is speculative at best. His DR ability could have just as easily have been due to his celestial nav ability and/or the "feel" of the boat.

While not particular to DR ability, Sir Francis was an extraordinary navigator and developed navigational techniques that were considered "impossible" by the RN and RAF navigators of the day.

[El Pinguino]

Given that on much of his voyage any current he was experiencing would have been less than a knot working out a DR possy would have been quite simple... simply use yesterday's run to determine speed ... easy peasy.

He - like the rest of us on long sea voyages - would have only been interested in where he was and how far he had to go ...

[Jim Cate]

Originally Posted by Wotname

Surely this is speculative at best. His DR ability could have just as easily have been due to his celestial nav ability and/or the "feel" of the boat.

While not particular to DR ability, Sir Francis was an extraordinary navigator and developed navigational techniques that were considered "impossible" by the RN and RAF navigators of the day.

G'Day Wottie,

I'm surely not questioning his celestial or other navigational competence.. he was a whiz at those things. But from the short quotation above, I thought he meant that he could estimate his instantaneous boat speed without the instrument, not that he could estimate his day's run... these are quite different skills IMO. Boat speed varies constantly, or at least it does on our boat, so knowing that I ran 180 miles in the past 24 hours is one thing, but knowing that right NOW I'm doing 8 knots is another. If he did mean instantaneous speed, then having had the instrument to "calibrate" his senses would have been important. If he meant that he could do his DR for establishing an assumed position for his celestial calculations, that's another.

FWIW, I play a little game with myself to while away watch hours. I listen, look and feel the boats motion and estimate the speed through the water. Then I look at the knotmeter. Rinse and repeat, and repeat, and repeat. I am usually well within a knot of the correct speed nowadays. I could not have gained this skill without having the instrument to give me the real numbers for calibration of my senses.

Is it important to know boatspeed? I guess that's a personal matter, but it is to me. Others may care not, and that's fine.

Jim

[rognvald]

"Is it important to know boatspeed? I guess that's a personal matter, but it is to me. Others may care not, and that's fine." Jim Cate


Jim, as a person who has done his fair share of offshore sailing(I'm referring to you), how is SOG or STW important when passage-making if your fix at a 24-hour interval determines your real speed overall or average day's run? Unless you are racing and need to micro-manage, it seems like wasted effort. This does not mean that I advocate sailing the boat inefficiently but after a few days at sea, you develop a ROA- rhythm of advance(this is my term) that makes far more sense than a maniacal tweaking of sails and "knot watching" to achieve an extra 1/8 of a knot? And, with a GPS and your ability to plot a fix, how is it not possible to determine your actual speed over the last hour's run? Perhaps it is a personality type but there is also another side to sailing where your oneness with the wind and sea has, for some, a different meaning. Perhaps we're beating a dead horse and it's similar to why some Men like blondes and others brunettes. However, this is no place for trading secrets. . . "Hell hath no fury like a woman scorned." Good luck and safe sailing. Captain Rognvald

[Don C L]

Well, of course, again, if all the electronics goes dead for some reason then...

BTW who here has used the REAL knot logs of old? You know the wooden triangle on a rope with knots in it? I recall this from many years ago and I remember it being incredibly accurate. It would be fun to check against GPS now.
This site has a little info on it for those interested.
How do sea navigators measure their ships speed?

[rognvald]

Originally Posted by Don C L

Well, of course, again, if all the electronics goes dead for some reason then...

BTW who here has used the REAL knot logs of old? You know the wooden triangle on a rope with knots in it? I recall this from many years ago and I remember it being incredibly accurate. It would be fun to check against GPS now.
This site has a little info on it for those interested.
How do sea navigators measure their ships speed?

Don,
We have carried a towed manual speed log that works on the principle of resistance in the water that is remarkably accurate. We used it on our 25 footer with only a GPS and a sextant and sailed over 6k miles of cruising bliss. We had no depth sounder. Here's the link:
Knotstick Sailboat Speedometers Good luck and safe sailing.

[Jim Cate]

Originally Posted by rognvald

"Is it important to know boatspeed? I guess that's a personal matter, but it is to me. Others may care not, and that's fine." Jim Cate


Jim, as a person who has done his fair share of offshore sailing(I'm referring to you), how is SOG or STW important when passage-making if your fix at a 24-hour interval determines your real speed overall or average day's run? Unless you are racing and need to micro-manage, it seems like wasted effort. This does not mean that I advocate sailing the boat inefficiently but after a few days at sea, you develop a ROA- rhythm of advance(this is my term) that makes far more sense than a maniacal tweaking of sails and "knot watching" to achieve an extra 1/8 of a knot? And, with a GPS and your ability to plot a fix, how is it not possible to determine your actual speed over the last hour's run? Perhaps it is a personality type but there is also another side to sailing where your oneness with the wind and sea has, for some, a different meaning. Perhaps we're beating a dead horse and it's similar to why some Men like blondes and others brunettes. However, this is no place for trading secrets. . . "Hell hath no fury like a woman scorned." Good luck and safe sailing. Captain Rognvald

You keep saying things about "one with the sea and wind" and the like. I guess that i must just be missing something, for I've never experienced such a thing. I enjoy being at sea, but always with the knowledge that the sea does not give a damn about me or my boat. Romanticizing the "relationship" of sailor to sea is not part of my sailing experience. I fear that I'm more physicist than poet when sailing.

Now, as to why I like to know both STW and SOG and COG when passage making... Well, I do come from a racing background, but it was several decades ago. None the less, I do pay attention to trim and try to maximize boatspeed. You say that the only important thing is your 24 hour run... well, your 24 hour run is the integral of all the instantaneous speeds that you have achieved during that 24 hours, is it not? You can not have good noon-to-noons without good speeds throughout the whole time. I'm not sure what you mean by rhythm of advance, and why it is more important than sail trim and course management, and I seldom fall prey to maniacal tweaking, but I have a mental "polar diagram" for my boat , developed over the years, and when she feels sluggish, I'm there trying to get her back up where she belongs. And your hypothetical 1/8th of a knot ain't what I'm talking about, more like a half or even a full knot is what gets my attention. And that represents something like a 10 % increment, and to me that ain't trivial... a day or two on a long passage.

So, as I said, it is a personal matter. Your romanticized view works for you, my mundane and result oriented view works for me.

Jim

[s/v Jedi]

STW: I sure hope that my autopilot uses this to determine how much rudder to apply for corrections. A length of rope with knots tied in sure isn't gonna tell my AP the current STW. Now we're gonna hear how real sailors steer by hand again I guess, and we're back to the daysailors etc.

[rognvald]

"So, as I said, it is a personal matter. Your romanticized view works for you, my mundane and result oriented view works for me.' Jim Cate


Well said, Jim. However, it is true . . . I have always preferred the romantic over the mundane. Good luck and safe sailing. Captain Rognvald . . . lost forever by the music of the wind and sea.

[Wotname]

Originally Posted by rognvald

....... Chichester writes: "That day my speedometer packed up. At first I was surprised how much I missed it, but as things turned out it did not matter much, for I found my dead reckoning was as accurate as it had been when my speedometer was working. As a matter of fact, it was more accurate because the speedometer had been under-registering at low speeds. Perhaps this was because the little propeller of the speedometer's underwater unit was getting foul with marine growth. After I had got over the feeling of loss when the speedometer failed, it was quite a relief not to have it."(p. 79, paragraph 3, First American Edition, 1968)......

Originally Posted by Jim Cate

G'Day Wottie,

I'm surely not questioning his celestial or other navigational competence.. he was a whiz at those things. But from the short quotation above, I thought he meant that he could estimate his instantaneous boat speed without the instrument, not that he could estimate his day's run... these are quite different skills IMO. Boat speed varies constantly, or at least it does on our boat, so knowing that I ran 180 miles in the past 24 hours is one thing, but knowing that right NOW I'm doing 8 knots is another. If he did mean instantaneous speed, then having had the instrument to "calibrate" his senses would have been important. If he meant that he could do his DR for establishing an assumed position for his celestial calculations, that's another.

FWIW, I play a little game with myself to while away watch hours. I listen, look and feel the boats motion and estimate the speed through the water. Then I look at the knotmeter. Rinse and repeat, and repeat, and repeat. I am usually well within a knot of the correct speed nowadays. I could not have gained this skill without having the instrument to give me the real numbers for calibration of my senses.

Is it important to know boatspeed? I guess that's a personal matter, but it is to me. Others may care not, and that's fine.

Jim

Well Jim, it isn't often that I disagree with you but...

Sir Francis seems to be talking about his ability to deduce his dead reckoning rather knowing his boat speed at any given moment. As I understand the term "dead reckoning", it working out one's position using methods of deduction (of historical data and time) rather than using observations of immediate data. Thus I can't see how this could extend to him knowing his current boat speed at any given moment.

Further, it would seem pointless to me to even attempt it as there would be no way he would know if he was correct or not, given that he had no way measure his instantaneous speed once his speedometer stop working.

Just as your "little game" would be pointless if you had no independent way of knowing the boat speed in order to confirm your estimate; well not pointless, it would be a useful way of whiling away the hours