How Necessary is a Knot Meter ?

[bobconnie]

Personaly I am a old fashion guy who likes simple stuff ! I use a hand held GPS, paper charts, still take noon sites and even a star shot once in a while ! I use a taff rail log for speed and distance recording, if it stops spining, ya pull it in and clean it !! they work fine for me and something less to worry about ( but I still carry a lead line also!!) every other speed gauge Ive had was impossible to get to so I use a rail log !simple ! I know most of ya will think Im nuts but i aways find my way home LOL I must admit my wife Connie has her lap top with the Capt soft ware, and I do ck my Plot with her as offen as needed(depends how close we are to land) I just like the old stuff and Its CHEAPER LOL Just my 2 cents Bob and Connie

[Celestialsailor]

Holy crap!!!...Ton of responses...
Astrid:- both were Standard Horizon...Taffrail log??? You're as salty as they get girl!
Thinwater:- Thanx man...I agree 100%. Now i have a little more confidence.
AuroraGH:-Even after I clean them, they won't spin for the first mile it seems and still dose not address it's inaccuracy's.
Ziggy:- Thanx...same page.
Bash:- Yup...I'm just moved from Alameda at Nelsons to Antioch. Good comments.
Kettlewell:- You telling me I don't have to spend $300. You da man!
Don Lucas:-Thankyou for seconding the motion that indeed...it is useless.
Ex-Calif:- point taken
Rover-Hi:- I have 3 GPS's. They are cheaper than most knotmeters
mrohr:- Yes, but my GPS does that
mikereed100:-barberhauler?

,,,Whewww!!!

[SkiprJohn]

Really not necessary with GPS unless you are curious about being in a certain current or want to know about a tide shift and how its effecting your speed through the water. In the days before GPS I lost my Walker knot log to a shark (or long line) coming from Hawaii about the 15th day out. From then on it was guessing the speed to do navigation all the way in to the Puget Sound. I could have used a chip log but guessing by the wake or how the boat was acting was pretty accurate.

[delmarrey]

I've been w/o one for 8 years and will be reinstalling with my new electronics. I like to know how fast a current is running under the boat, whether I'm moving or anchored. If I'm at a dock and the current is fast, I'll know what to do when she's untied.
Also, I can adjust my sails by the knotmeter, obviously the faster is spins the better the sails are trimmed, no matter what the GPS says!

[Jim Cate]

Necessary??? Of course it isn't necessary, but most sailors who are interested in sailing performance will make good use of one... as several posters have pointed out. The GPS speed is not very useful as a trim monitor due to longer averaging times plus the usual jitter in low speed situations.

But really, it sounds like you are looking for support in the idea of not having one, so for goodness sake, don't buy one! Nothing bad will happen to you as a result.

Cheers,

Jim

[Bash]

Knotlogs work poorly on boats with dirty bottoms. Of course, boats with dirty bottoms work poorly on oceans. One advantage of having a knotlog is that when it starts under-reporting STW, you know it's time to clean the bottom.

Here's a tip for keeping your knotlog functional: after you clean it, hit it with a healthy spray of McLube Sailcoat. Let it dry! Microorganisms hate the taste of that stuff.

[four winds]

Coincidentally, it was just two days ago that I noticed the pin that holds the impeller wheel in the hull. (I've been removing unused wiring left over from upgrades and drawing a wiring diagram.)

I didn't know it could be pulled and cleaned from inside the boat. It's an older Standard with digital readout, that has worked for a day or two after the diver cleans the hull in the past, but I haven't turned it on in a while.

Dumb questions of day. I can't find the manual online, yet.

Does it pull straight out after removing the pin?
I guessing water comes in. Don't think I have the plug, so need a substitute. Any suggestions for that, like the wood cone bungs?

I'd like to leave it out and put a plug in if I can find one, so it can be used reliably. Can't learn anything from it if I can't keep it working.

[Celestialsailor]

Originally Posted by delmarrey

I've been w/o one for 8 years and will be reinstalling with my new electronics. I like to know how fast a current is running under the boat, whether I'm moving or anchored. If I'm at a dock and the current is fast, I'll know what to do when she's untied.
Also, I can adjust my sails by the knotmeter, obviously the faster is spins the better the sails are trimmed, no matter what the GPS says!

You're going to laugh but before backing out of a slip I spit off the stern to watch which way the current is set.

[Bash]

Originally Posted by Celestialsailor

You're going to laugh but before backing out of a slip I spit off the stern to watch which way the current is set.

I'm guessing you have an upwind slip?

[delmarrey]

Originally Posted by Celestialsailor

You're going to laugh but before backing out of a slip I spit off the stern to watch which way the current is set.

Yeah, I'll laugh. I don't have a slip. I use a side-to dock on a river that flows both directions, that I share with others most of the time. So, it's a bit like parallel parking. And if I drift, I'll drift into the boat down stream if it running too fast.



.

[David M]

I have a knot meter that has no moving parts. It sends out a signal that measures how fast it took particles to displace from one point to the next. It is accurate to 0.1 knot. It's actually not using the Doppler shift. I also have a bottom tracking acoustic Doppler current profiler which measures the boats speed and direction over the bottom. It does not use GPS to do this. Both instruments are required for what I do.

I think for pleasure boats a knot meter it is pretty much unnecessary, unless you want to use it as a fun meter, where faster is more fun.

If you want to know how fast the current is running then stop the boat and let the sails luff for 30 seconds. Then see what the GPS is telling you. Guestimate the drift caused by windage. You don't need to use the difference between your knot meter and GPS to determine current velocity and direction in order to determine set and drift.

[Geoduck]

Well, if'n ya want them knots to be tied right, ya better git one - pilgrim!

[rebel heart]

Originally Posted by roverhi

If your GPS goes tits up, how are you going to DR without some idea how far and how fast you are going. To me, it's as important as a depth sounder for a back up should the real world ever intrude on my life. It's also invaluable in experimenting with trimming the sails and optimizing boat performance. The knotmeter reacts instantly while the GPS is a lagging instrument and next to worthless for that.

For a DR it doesn't matter how instant it is; you're talking about hourly averages anyway. I always error on the side of caution but most everyone knows their speed by looking at their wake long enough, and if the GPS packs in you can always take not-too-complicated measurements if you couldn't just eyeball your speed and be fairly accurate. Barring crazy stuff I can usually get boat speed within half a knot if it's a vessel I'm familiar with in daylight.

And it's not like the knotmeter is some super reliable piece of gear. I've had more problems with them than GPS, easy.

[MarkSF]

Originally Posted by four winds

Coincidentally, it was just two days ago that I noticed the pin that holds the impeller wheel in the hull. (I've been removing unused wiring left over from upgrades and drawing a wiring diagram.)

I didn't know it could be pulled and cleaned from inside the boat. It's an older Standard with digital readout, that has worked for a day or two after the diver cleans the hull in the past, but I haven't turned it on in a while.

Dumb questions of day. I can't find the manual online, yet.

Does it pull straight out after removing the pin?
I guessing water comes in. Don't think I have the plug, so need a substitute. Any suggestions for that, like the wood cone bungs?

I'd like to leave it out and put a plug in if I can find one, so it can be used reliably. Can't learn anything from it if I can't keep it working.

I think it's a bad idea to leave it with anything other than a properly threaded plug in it.

[four winds]

I agree, that would be for just long enough to clean it.

I would look for a new proper plug.

So the impeller threads into the housing? And turns out for cleaning, not pulled straight out?

I'm still looking for the paper manual, I think I have it somewhere.