My knot meter is rarely working anymore. If i dive below the boat and spin the little paddle wheel manually, it doesn't show a reading. There is power to the instrument, and the depth meter seems to be working properly. The equipment is Raymarine brand. My question is, how can I service the transducer? What else could be wrong? I have a plug to insert in the through-hull from the inside if i pull the transducer. Thanks in advance.
Knotmeter transducer
- Thread starter aquaholic1
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There are little'critters' that like to live in the little space around the paddle wheel (at least in the northeast area). They are about half the size of mosquitos and are shaped a little like shrimp. Have the dummy plug ready in one hand and then remove the transducer plug and switch quickly to minimize the amount of water that comes in. We have the Admiral hold a basin upside down over the area to contain the water spout. Clean the paddle wheel and the slot it lives in and then reinstall the transducer the same way you removed it. If it still does not work, then it is either the transducer 'guts' (replace it), or the cable from the transducer to the display (replace it). Possibly the connection of the cable AT the display. Good luck.
Knot Meter
The knot meter tranducer consists of a paddle wheel that has magnets in the wheel and a coil in the base. As the magnets pass through the base they create small voltage spikes . The speed of these spikes are registered on the head unit , thus giving you a speed readout. Check all your connections first, then do what the previous post suggests. You can buy replacement paddle wheels if needed.
The knot meter tranducer consists of a paddle wheel that has magnets in the wheel and a coil in the base. As the magnets pass through the base they create small voltage spikes . The speed of these spikes are registered on the head unit , thus giving you a speed readout. Check all your connections first, then do what the previous post suggests. You can buy replacement paddle wheels if needed.
The most likely fault....
is probably the cable connection. The next most likely is a cable that as been damaged. I would inspect those items first since you have already confirmed that spinning the paddlewheel does not produce a reading. Do the other functions of the display work? For instance maybe water temperature? I have never heard of a paddle wheel going bad, but I suppose anything is possible. If you can borrow a display head from someone else you can isolate the fault to the head or the transducer/cable. If you have a separate repeater does that show any readings? And finally if you have a Rayteon radar you may be able to have it display the Seatalk data that is on the bus and determine if the transducer/head is outputting anything.
is probably the cable connection. The next most likely is a cable that as been damaged. I would inspect those items first since you have already confirmed that spinning the paddlewheel does not produce a reading. Do the other functions of the display work? For instance maybe water temperature? I have never heard of a paddle wheel going bad, but I suppose anything is possible. If you can borrow a display head from someone else you can isolate the fault to the head or the transducer/cable. If you have a separate repeater does that show any readings? And finally if you have a Rayteon radar you may be able to have it display the Seatalk data that is on the bus and determine if the transducer/head is outputting anything.
Water temp gauge
Does anyone know how the water temp gauge works on the Autohelm ST50 speedo? My temp gauge has shown the same temp for years. Where is the sensor? Is it within the totally sealed part of the transducer head? My speedo works fine after I clean it, either diving under the boat or during a haulout.
Does anyone know how the water temp gauge works on the Autohelm ST50 speedo? My temp gauge has shown the same temp for years. Where is the sensor? Is it within the totally sealed part of the transducer head? My speedo works fine after I clean it, either diving under the boat or during a haulout.
Temp Readings
The temperature part of the speed log is encased inside of the sending unit. It consists of a trermistor, which is a resistor that changes value according to temperature. Thus, as the value changes the readout changes. You usually have to replace the entire unit. However, check your connections first. I have seen a paddle wheel go bad, which is a rareity.
The temperature part of the speed log is encased inside of the sending unit. It consists of a trermistor, which is a resistor that changes value according to temperature. Thus, as the value changes the readout changes. You usually have to replace the entire unit. However, check your connections first. I have seen a paddle wheel go bad, which is a rareity.
Change out the entire unit? $$
Well, I guess I don't need to know the water temp that badly. Around here in the NorthWest, the water temp doesn't change too much. It is always cold. It only gets much warmer along Canada's sunshine coast. A few degrees won't make too much difference here. If you fall in, you will die from hyperthermia without waiting too long anyway. A few degrees difference in water temp will only let you live a few extra minutes longer. ;d ;d ;d *cry *cry *cry Since the speedo part is working, I guess I will wait until that dies before I spend the dollars to replace the entire unit. In the mean time, I will just stick my toes in the water to test the temp. By the way, I think the temp and speedo use the same set of wiring. So if the speedo is working, I assume the temp wiring is ok too. Thanks for the info.
Well, I guess I don't need to know the water temp that badly. Around here in the NorthWest, the water temp doesn't change too much. It is always cold. It only gets much warmer along Canada's sunshine coast. A few degrees won't make too much difference here. If you fall in, you will die from hyperthermia without waiting too long anyway. A few degrees difference in water temp will only let you live a few extra minutes longer. ;d ;d ;d *cry *cry *cry Since the speedo part is working, I guess I will wait until that dies before I spend the dollars to replace the entire unit. In the mean time, I will just stick my toes in the water to test the temp. By the way, I think the temp and speedo use the same set of wiring. So if the speedo is working, I assume the temp wiring is ok too. Thanks for the info.
JC- the temp and speedo wiring use the same cable
but different pins on the connector. It is possible that one of the temperature signal pins is not making god connection. It would be worth checking the cable connection. One way to tell if the connection is open is to power down, unplug the connector to the display head and then power back up. If the temperature reading is the same value as with the cable connected, you probably have a bad connection. Reconnecting and with power on wiggling the connector may show an intermittent temp reading.
but different pins on the connector. It is possible that one of the temperature signal pins is not making god connection. It would be worth checking the cable connection. One way to tell if the connection is open is to power down, unplug the connector to the display head and then power back up. If the temperature reading is the same value as with the cable connected, you probably have a bad connection. Reconnecting and with power on wiggling the connector may show an intermittent temp reading.
GPS
I gave up a long time ago trying to keep the knotmeter working, I've had the plug in for quite some time and just use my GPS. No fuss, no cleaning, and no Chiness fire drill everytime you have to yank it out!
I gave up a long time ago trying to keep the knotmeter working, I've had the plug in for quite some time and just use my GPS. No fuss, no cleaning, and no Chiness fire drill everytime you have to yank it out!
Placement
I guess I'm fortunate in that the pickups on my H34 are placed just ahead of the keel and are accessed by a pry-out on the v-berth sole just inside the doorway. Evidently this was done by a PO or dealer, not the factory.
I guess I'm fortunate in that the pickups on my H34 are placed just ahead of the keel and are accessed by a pry-out on the v-berth sole just inside the doorway. Evidently this was done by a PO or dealer, not the factory.
The original transducer on my 35.5 was located under a cutout in the Vberth. A real pain in the ass to get to. Also it was not located inline so port and stbd tacks would give inaccurate readings. I made a cutout in the main salon under the table with a floor mounted screw out deck plate. Removal is now a breeze.(like I said, 10 seconds to remove and plug)
Alan: Is it like a flapper valve?
This valve of yours that will close when you pull the transducer plug, is it like a one way flapper valve? Where does it go when the plug is in the boat? By the way, who is the maker of that unit? Is it by Ray Marine?
This valve of yours that will close when you pull the transducer plug, is it like a one way flapper valve? Where does it go when the plug is in the boat? By the way, who is the maker of that unit? Is it by Ray Marine?
David, I'm with you.
I gave up on my knot meter this summer when I bought a gps. My transducer wouldn't go more than 2 weeks at a time without having to be pulled and cleaned. The gps is more accurate anyway as is it is not affected by tides or currents.
I gave up on my knot meter this summer when I bought a gps. My transducer wouldn't go more than 2 weeks at a time without having to be pulled and cleaned. The gps is more accurate anyway as is it is not affected by tides or currents.
GPS is ok, but....
Sometimes you need to know how the tides or currents is impacting your progress.
Sometimes you need to know how the tides or currents is impacting your progress.
Paddle wheels
Someone mentioned you can replace the paddle wheel. I have to move mine to get it to work every time I go out. Even if I clean it, if I anchor for an hour or two, I need to "reset" it. Once I do that it works fine the rest of the trip. It does seem very eroded, wonder where I can just get a new wheel. Anyone know where you can just purchase a wheel?
Someone mentioned you can replace the paddle wheel. I have to move mine to get it to work every time I go out. Even if I clean it, if I anchor for an hour or two, I need to "reset" it. Once I do that it works fine the rest of the trip. It does seem very eroded, wonder where I can just get a new wheel. Anyone know where you can just purchase a wheel?
Mine is Not that hard to remove
I have a Hunter 37.5 and the transducer is in the floor of the V-Berth and it is offset as Alan mentioned. It's not that hard to pull out and replace the unit with the plug and vise versa. I just put my left hand over the hole as I remove the transducer and then put the plug in with my right hand. I don't think I have a flap but still don't get that much water in the bilge. BE CAREFUL AND INSURE THE TAB IS ALIGNED PROPERLY OR NEITHER THE PLUG OR THE TRANSDUCER WILL BE WATER TIGHT. Both the plug and the transducor only fit one way. I'm sure you all know how I learned this. Anyway, I remove the transducer every time I leave the boat. These subtropical waters produce microrganisms very efficiently. And by the way, my water tempurature reads 62 degrees.. anyone believe that Galveston Bay is 62 degrees in August?
I have a Hunter 37.5 and the transducer is in the floor of the V-Berth and it is offset as Alan mentioned. It's not that hard to pull out and replace the unit with the plug and vise versa. I just put my left hand over the hole as I remove the transducer and then put the plug in with my right hand. I don't think I have a flap but still don't get that much water in the bilge. BE CAREFUL AND INSURE THE TAB IS ALIGNED PROPERLY OR NEITHER THE PLUG OR THE TRANSDUCER WILL BE WATER TIGHT. Both the plug and the transducor only fit one way. I'm sure you all know how I learned this. Anyway, I remove the transducer every time I leave the boat. These subtropical waters produce microrganisms very efficiently. And by the way, my water tempurature reads 62 degrees.. anyone believe that Galveston Bay is 62 degrees in August?
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