"Knots"?

[Welti]

Originally Posted by Calif.Ted

In practical terms it's usually about 1.5 knots downcoast, more during a winter storm from NW, however the California bight sometimes called the Catalina eddie creates a whirlpool most noticeable below Palo Verdes Point. From points downcoast the current is reversed and upcoast as you approach Catalina.
https://en.wikipedia.org/wiki/California_Current

Interesting! So, does it reverse in winter? It isn't clear to me.

Second question: does installing a paddlewheel necessitate a haul out? I would think so.

[ChrisJHC]

Originally Posted by Welti

Interesting! So, does it reverse in winter? It isn't clear to me.

Second question: does installing a paddlewheel necessitate a haul out? I would think so.

Installing - yes.

Once installed, you can pull it out while in the water.
You will get about a half-bucket of water in the bilge when you do it (depending on how quickly you plug the hole).
Many people - particularly racers - pull theirs whenever they’re not using it.

[Cynara]

You can throw all the tech at a you want. That is why we recorded our estimated position every hour. The more accurate your tech the more accurate your estimated position is. Generally if you are using a GPS that makes it pretty accurate

[Lodesman]

Originally Posted by ZITIBOAT

A knot is a measure of nautical miles period!

Oh the irony!

Surprised none of the other grumpy old pedants jumped all over you for this. With all the yelling and the patronizing tone, you should have checked your work before hitting "post".

It's impossible to tell from reading it, whether you omitted a couple words, or don't know what you're talking about

The nautical mile is a unit of distance. The knot is a unit of speed - specifically nautical miles per hour.

Just yanking your chain, btw.

[Jim Cate]

Just yanking your chain, btw

IMO, that chain richly deserved a good big yank. So, well done!

Jim

[marcvilleneuve]

Originally Posted by wingssail

As a racer and a sailor who grew up before GPS was invented I have always (since 1970's) had knots (STW) displayed on any boat I was sailing, it gives me the accurate performance of my boat which is my primary interest.

For a racer STW is really the information that will confirm your real performance or how fast you are against your sailboat polar speed for a specific wind.

Here on the St-Laurence River we race with a current of 2-5 knots. For this reason I often make the calculation SOG - STW to evaluate the current.

So both values are USEFULL.

[Greatest Lakes]

I have my STW and SOG displayed side by side. They often disagree. For accurate navigation, SOG is more pertinent to me as that is what actually matters for arrival time. STW has limited usefulness at this point, but still tells you where some currents are and it never hurts to have a backup.

[Gone Gypsy]

All of the references are for STW measured by a paddle wheel with numerous mentions of the difficulties maintaining a paddlewheel. We are looking at new electronic kit for our boat. B&G offers an ultrasonic measure of STW. They use this for true wind and the myriad of calculations in their derived opposite tack lay line. Is ultrasonic speed accurate or just as troublesome (perhaps in different ways) as a paddlewheel?

[Don C L]

Originally Posted by Welti

Good information! For my boat, I do not have a paddle wheel. I would like to at least have an estimate (ahead of time even) for currents where I am sailing. I know there are tide tables, but where can I find a current prediction/map? I mean, I have looked in Navionics and one or two other apps that I have and don't see it. Perhaps it is a Premium feature?

There is a website, let me see where it is… UCSB had one that showed the currents in the channel but I can’t find it now. Google currents in Santa Barbara channel and you’ll get quite a bit.

[Night_Sailor]

I have a paddle wheel knotmeter. I have never used it. In fact I'm contemplating glassing it over.



SOG is all that matters unless your instruments all die, in a lightning strike or nuclear war.

[Adelie]

Originally Posted by Night_Sailor

...


SOG is all that matters ....

There are plenty of folks that disagree.

Racing you need STW.
If you want true wind speed and direction you need STW.

[Tanqueray]

Originally Posted by billreilly

Without a paddle wheel there is no way for your sailing instruments to calculate true wind, so not having a paddle wheel is a big mistake.


If anybody is sailing without a paddle wheel then I suggest they install one.

I sail on an inland ocean (Lake Michigan), so no tidal current to worry about.

I have a paddle wheel, but not hooked into my chart plotter. I do have GPS SOG and that is used to calculate True Wind.

Greg

[Don C L]

When you maximize your STW with knowledge of sail trim, you’ll be maximizing your SOG. And STW is what you can measure fairly easily without either a computer via gps or a chart and some math and ded reckoning skills. To say SOG is all there is seems a bit odd to me. I don’t check my SOG when trimming.

[Hasbeen]

I had a paddle wheel speedo & on a few occasions towed a walker log. I have crossed the Coral sea 6 times, & sailed well over 30,000 nautical miles around the pacific islands.


In tropical waters I don't think I ever got more than 4 hours without a bit of seaweed stopping the things working.


Life would have been so easy if sat nav had been available at affordable prices in the 60s & 70s.

[wingssail]

Originally Posted by Hasbeen

I had a paddle wheel speedo & on a few occasions towed a walker log. I have crossed the Coral sea 6 times, & sailed well over 30,000 nautical miles around the pacific islands.

In tropical waters I don't think I ever got more than 4 hours without a bit of seaweed stopping the things working.

Life would have been so easy if sat nav had been available at affordable prices in the 60s & 70s.

I am a little surprised to hear that you had so much trouble with your paddle wheel, (and others who reported so much hassle with them).

I've had this type of speed sensor on my boat for 38 years and it is typically reliable. I pull the unit out if the boat is not being used for a period of time (like over a week) and occasionally use a bottle brush to clear away growth around the paddle, but gennerally mine work, day in and day out, year after year, and I rely on it for performance measurement even when not racing.