Speed Wheel

[Fair_Skies]

I am wondering,with all the GPS tech if should bother to replace my paddle wheel for speed inputs? Seems like it is just extra work to keep clean and maintained.

Thoughts?

[Sailmonkey]

I use ours all the time to determine the amount of current we’re in, as well as incremental changes in speed based on sail trim.

Seeing as you posted this under powered boats, I’d not worry about it if I had a power boat, unless I was specifically concerned with currents.

[Fair_Skies]

That's kinda what i was thinking. I am on the fence if I care about current enough to manage the maintenance of a paddle wheel, with all the other things service. I am leaning towards, if currents are going to be an issue for navigation on a power boat, I should be able find reasonable current tables for the area before I chart the course.

[Suijin]

I agree on a powerboat speed through the water is of negligible value. If you have wind instruments, speed through the water is necessary to get a true wind reading, but that's largely only an issue for sailboats.

And yes, general current rarely exceeds 1.5 knots. And if you're heading somewhere where it is considerably more, like Wood's Hole MA, or some cut somewhere you should be well aware of it before you're in it staring at an instrument going "whoops".

[Fair_Skies]

Originally Posted by Suijin

I agree on a powerboat speed through the water is of negligible value. If you have wind instruments, speed through the water is necessary to get a true wind reading, but that's largely only an issue for sailboats.

The True wind calculations are still a bit fuzz to me. I guess it is because I have heard it explained differently and some conflicting ways several times. Is True Wind the wind velocity and direction adjusted for the vessels actual speed and direction over ground. If so, wouldn't GPS Heading Sensors and Gyro/Fluxgate Compasses provide correction data electronically?

[slug]

The paddle wheel measures speed thru the water

GPS measures speed over the bottom

[Sailmonkey]

Originally Posted by Fair_Skies

The True wind calculations are still a bit fuzz to me. I guess it is because I have heard it explained differently and some conflicting ways several times. Is True Wind the wind velocity and direction adjusted for the vessels actual speed and direction over ground. If so, wouldn't GPS Heading Sensors and Gyro/Fluxgate Compasses provide correction data electronically?

True wind can be calculated accurately enough for powerboat purposes without stw, I personally wouldn’t worry about it.

[JPA Cate]

Fair Skies,

Depends on where you sail. Knowing the difference between the speed through the water and the speed over the ground allows you to re-calibrate your arrival time at your destination. It is also helpful when you try to account for drift. It is up to you whether you care enough about either to figure it out. It is pretty basic piloting.

Ann

[Pizzazz]

While true wind is less important for powerboats, water speed is still important for radar wrt to powerboats.

The easiest way to understand all the winds is that the instrument measures the apparent wind that passes by the boat. If you (vector) subtract boat speed through the water from it, you get true wind which is wind felt by a floating object in the water that is moving with the water. This state is also called sea stabilized in radar speak which means that if you are tracking another boat on your radar you will be able to accurately measure its speed through water (useful at times).

If you subtract the speed relative to land or ground (called GPS speed) you will get ground wind which is useful when close to wind and for port/marina maneuvering. In radar speak this is called ground stabilization and it is really useful for navigating close to land. GPS speed is also preferable if you want to know when you will get to your destination.

SV Pizzazz

[rsn48]

I just checked to make sure I was in the powerboat section here. I live on the British Columbia Vancouver Island coastal area. Generally I listen to broadcasts from the VHF, use programs on my Android including C Tow and Windy for wind conditions and predictions. I get updated on my weather app of heavy winds in our area.

I don't know about where you are but currents here can go crazy, definitely above 1.5 knots and if you don't know what you are doing it is those currents that can kill you here.

[AlanT]

Originally Posted by rsn48

I just checked to make sure I was in the powerboat section here. I live on the British Columbia Vancouver Island coastal area. Generally I listen to broadcasts from the VHF, use programs on my Android including C Tow and Windy for wind conditions and predictions. I get updated on my weather app of heavy winds in our area.

I don't know about where you are but currents here can go crazy, definitely above 1.5 knots and if you don't know what you are doing it is those currents that can kill you here.

Agree. I am south of you in the South Sound. Tacoma Narrows is 3 miles from me by water and currents run 4-5 knots through there every day. Also comparing my Speed through the water (paddle wheel) with my speed as shown by the GPS helps me navigate the eddies and makes me faster and more efficient.