Electronic Paddlewheel Spedometers

[79Merc80]

Does anyone know where to get these? I had a digital one htat also gave water tempreture in the late 80's and an anolog in the mid 90's, but can't find any now.

Please help.

 

[Beefer]

Re: Electronic Paddlewheel Spedometers

If you really want to know your speed, a speedometer on a boat isn't the answer. Get yourself a GPS, and you'll have an accurate reading. I removed my speedo, and won't miss it.

 

[Boatist]

Re: Electronic Paddlewheel Spedometers

Many depth finders / Fish finders have them or they are an option you add to the depth finder. The paddle wheel gives speed of boat thru water.
Also Most fish finders with transom mounted transducers also have built in Temperature sensor.
GPS also gives you very accurate speed over ground.

Many GPS/Fish Finder will give you speed thru water and speed over ground.

 

[5150abf]

Re: Electronic Paddlewheel Spedometers

Ya the paddles and add on pitots aren't normally very accurate, I had a fish finder with one and it never worked right.

You can get a hand held gps on Ebay for cheap if you look or as the others said , alot of fishfinders have them.

I hava a Garmin 178c color gps finder tha tells you all kinds of stuff, speed, voltage, water temp, it even tracks your milage, lots of options but the paddle isn't the best one.

 

[JimS123]

Re: Electronic Paddlewheel Spedometers

Paddle wheel speedometers are usually part of a depth finder / temp combo. You'll be hard put to find a stand alone system. If you do chose a combo, be advised that although they read consistent numbers, they are not too accurate. Paddle placement is very critical and the numbers can be affected by wash from sponsons or even heavy waves that cause the boat's attitude to change.

A GPS is cheap, but it shows ground speed. If you boat in waters that have a current you won't get true boat speed.

A brand name old fashioned pressure gauge / pitot tube speedometer is actually very accurate if installed correctly. That means proper pitot placement and a tube that is tightly sealed, no water intrusion and no kinks. The downside is that the lower end starts at about 6 or 7 mph, so if you need to know idle speed you won't get it.


If I go up and down river at cruise speed and average my GPS speed, its withing 1 mph of my pitot, which shows the same results going both ways. My paddle wheel is off by about 5 mph. Below plane at 8 mph, all 3 show the same results.

I use the paddle wheel to set the kicker speed for trolling, the tach to set the cruising speed and the GPS to find the fishing hole offshore.

 

[H20Rat]

Re: Electronic Paddlewheel Spedometers

A GPS is cheap, but it shows ground speed. If you boat in waters that have a current you won't get true boat speed.

A brand name old fashioned pressure gauge / pitot tube speedometer is actually very accurate if installed correctly.

The pitot on my tube is MORE accurate than the gps at measuring the speed my boat is traveling over the water. GPS is +/- 4mph. (Current)

 

[Silvertip]

Re: Electronic Paddlewheel Spedometers

The pitot on my tube is MORE accurate than the gps at measuring the speed my boat is traveling over the water. GPS is +/- 4mph. (Current)

I sure hope you are not implying that pitot/paddle wheels are a more accurate indicator of speed of forward motion (true speed) of your boat because that is simply not true. Current has zero effect on the accuracy of GPS speed. To prove this, take your boat to a river with a known and relatively constant flow. Fire up the gps, point the boat upstream and drop the anchor so the boat stays put. Note the speedo and gps readings. The boat speedo should show whatever the speed of the current is. In this example your statement about "speed over water" would be somewhat true -- however the water is passing the boat but your true speed over the earth is zero since there is no forward motion. Repeat the test going downstream -- this time with no anchor and engine off. The GPS will now show the actual speed of the current and the boat speedo will show zero. Here, the boat is being carried over the face of the earth by the current but you definitely are not moving "over the water. In this test you are indeed moving over the face of the earth but not "over" the water. Only the age of the gps and the method it uses and ability of the computer affects GPS accuracy (and whether the military has mucked with the offset). The boat is moving over the face of the earth at whatever speed the GPS indicates. Pitot and paddle wheels are very inaccurate since they rely on water moving over them to calculate speed. Hence going down stream at an indicated 30 mph is actually 35 MPH over the earth in a 5 mph current. Conversely going upstream, 30 mph indicated is only 25 mph over the earth since you are fighting the current.

 

[JimS123]

Re: Electronic Paddlewheel Spedometers

OK, go where there is a 4 mph current and turn the motor off and don't anchor. The GPS will show 4 mph and your gas mileage will show infinity....LOL.

I think the real intent of a speedometer is to see how fast the boat goes...period. If you do use a GPS, just check it twice and take an average.

 

[ziggy]

Re: Electronic Paddlewheel Spedometers

I think the real intent of a speedometer is to see how fast the boat goes

imho, the only good reason to have a speedo is to figure out where your at when piloting your boat... time/speed/distance, any two of the three and ya can figure the unknown.

fwiw. i boat inland. my boat don't have a speedo. if i do feel the need to know how fast i'm going. my handheld gps has one that is very accurate for speed over ground which is what ya use to pilot if need be..

 

[H20Rat]

Re: Electronic Paddlewheel Spedometers

I sure hope you are not implying that pitot/paddle wheels are a more accurate indicator of speed of forward motion (true speed) of your boat because that is simply not true. Current has zero effect on the accuracy of GPS speed.

I knew I would get one person riled up! I didn't emphasize the 'speed over water' part much, probably should have. Many boaters have absolutely no concern about actual speed. If i'm trolling in a river at 5 mph, with 3mph of current, a gps is absolutely worthless. It will read anywhere from 2 mph, to 8 mph, and everywhere in between depending on the boats attitude in the current. A paddlewheel is the only useful and accurate instrument in this example.

Other boaters may have absolutely no use for speed over water, they are using the boat for navigation and the distance between point A and point B is an absolute, best measured with a GPS.

So i notice you have a plane in your avitar... If you had to give up pitot speed, or gps speed, which would it be? (no pilot that wants to live very long would say they would prefer to have gps speed only. Landing approach speed might be 80 knots. Gps says 80 knots. But the problem is you stalled out a mile back because of the 40 mph tailwind. Your wings only saw 40 knots.)