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speedo's


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My echelon is playing games with me. It decides when it wants the speedo's to work. they will work for a while then just stop. Or one will work and the other wont.

I have no idea about these things so any help would be appreciated.

Cheers

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The speedo's use a water pickup off the transom called a pitot. As the water coming off the boat boat's bottom passes over these "pitot's" it creates pressure. This pressure is translated to the speedometer. The higher the speed, the higher the pressure and the higher the boat's speedometer registers on the needle.

The bad news is these tubes can become clogged by debris. This is very common in the spring and fall when there is more debris in the water. When the tubes become clogged they can totally stop registering speed, or partially loose pressure and only display part of the boat's actual speed.

When you have trouble just try to clean off the pitot's to make sure they are seeing accurate water pressure at speed.

Here's a pic of them on my boat. They suck and clog all the time so I developed this. There is also an updated pitot tube from SkiDim here that is supposed to be much much better than the older airguide pitots.

DSC04156.jpg

Edited by martinarcher
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I put the new style on my Echelon and new rubber hoses from them to the brass equalizer tubes, which are all the way in the back corners of your boat on the hull. While they do work much better, I still rely on RPM for more accurate speed.

If you do upgrade, you'll have to cut off the top ear with the third mounting hole in it to get them to lay flat against your transom. No big deal and very easy to do.

Last resort, and much more accurate is if you have a GPS in your car, just move it to your boat while you are using it. That is the most accurate, and the way that I calibrate my speedoMETERS. :biggrin:

Good luck.

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Also maybe noteworthy that the GPS will not be accurate if you are boating on a river with a current. That is, you may be actually moving at 20mph, but if you are going upstream against the current it might feel like 24 mph. Conversely, if you are going downstream 20mph may feel like 16mph. Just something to think of.

That said, I pay zero attention to my speedo's (which are all over the place) and go by RPM's exclusively. With my Echelon (265 merc, 13x13 prop) my speedo is 100:1 ratio to RPM. That is, 30 mph = 3,000 RPM. 42 mph = 4,200 RPM. Etc. If we are boarding and have the wedge down, different story. But either way it's easier for me or my wife to rely on RPM. But we don't boat on a river.

With the availability of GPS, the old pitots are obsolete equipment (at least to me). I'll never bother with mine, and if someday I do it will be with a GPS speedo or speed control GPS set up.

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Also maybe noteworthy that the GPS will not be accurate if you are boating on a river with a current. That is, you may be actually moving at 20mph, but if you are going upstream against the current it might feel like 24 mph. Conversely, if you are going downstream 20mph may feel like 16mph. Just something to think of.

That said, I pay zero attention to my speedo's (which are all over the place) and go by RPM's exclusively. With my Echelon (265 merc, 13x13 prop) my speedo is 100:1 ratio to RPM. That is, 30 mph = 3,000 RPM. 42 mph = 4,200 RPM. Etc. If we are boarding and have the wedge down, different story. But either way it's easier for me or my wife to rely on RPM. But we don't boat on a river.

With the availability of GPS, the old pitots are obsolete equipment (at least to me). I'll never bother with mine, and if someday I do it will be with a GPS speedo or speed control GPS set up.

Good reminder. With my GPS speedo I had to remind my driver to knock off 2 mph when going up river and add 2mph when going downstream. 2 mph doesn't sound like much, but when your learning inverts crashing at 22-23 feels a lot different than 20-21. LOL.gif

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  • 1 month later...

I ran with using RPM for a while, but my wife couldn't keep the speed steady with that; then I bought the NL2 from these guys: http://www.nauticlaugic.com/nl2.html

It works great, and both my speedo's work everytime (unlike rairly before). Highly recommended. I did a write up of the install if you search my name.

Good luck,

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The new style pitot tubes work much better than the older version. They are inexpensive and easy to install and calibrate. That way, you will pretty much always have a working speedo that will be river compatible for correct speed. Two nice Airguides are a horrible thing to waste as they are some of the most accurate and repeatable units available. I have noticed that my Airguides are more accurate than any of the newer boats and we are pretty anal about accurate speed. You do have to remember that if something does clog one of the pitot's, the higher reading unit is always the correct one (unless they both get clogged, which is rare with the newer style pitot tubes since the concept is completely different on how they work, venturi v. pressure).

Edited by Woodski
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