removing speed transducer - help

jsalley · Sep 17, 2012

Unscrew the collar with one hand, have the plug ready with the other hand. Then quickly remove the transducer and insert the plug. You'll get a small gush of water, but with practice you can get it down to only a cup or two. I remove my transducer after every use of the boat, as it seems to attract sea creatures after only a couple days in the slip.

Silvio · Sep 17, 2012

Yep, what jsalley said.

Mine has a flapper inside the fitting that actually closes off after the first rush of water and keeps it to just a trickle until I put the plug in. I suggest you use two hands, one to grip the fitting and the other to unscrew the cap. Don't over tighten when you install the plug or replace the paddle wheel.

I also store mine with the wheel removed, keeps me from having to clean it so often.

Also I usually rub a bit of vaseline on the threads of the cap before I re-install it, others may disagree but I find it helps.

truckman · Sep 17, 2012

As everyone else said its easy to pop in the bung and very little water comes in. I do however leave the transducer wheel in the boat. In over 3 years I have not had one little critter grow on it. I painted the wheel and surrounding area with transducer bottom paint and reapplied once during that time.

Silvio · Sep 17, 2012

iSailor,
Grip "B" in your photo and unscrew "C".
If you unscrew "A" you run the risk of breaking the bedding of 5200 loose and having to re-bed the fitting. The cap "C" is just like the screw on cap on your plug.

Albanach · Sep 18, 2012

Silvio said:
iSailor,
Grip "B" in your photo and unscrew "C".
If you unscrew "A" you run the risk of breaking the bedding of 5200 loose and having to re-bed the fitting. The cap "C" is just like the screw on cap on your plug.

As per Silvio's advice above and perhaps 'wiggle' the "B" part while pulling on the ring. It may have seized a bit, if it hasn't been removed for a while, and if the o-rings were not greased with vaseline or similar, when installed. Once you grease the rings, it will almost shoot out when collar "C" loosened.
Btw, I am just trialling transducer paint covered with Nappy rash cream. Each on its own lasts about 3-4 weeks before fouled.

Albanach · Sep 18, 2012

Albanach said:
As per Silvio's advice above and perhaps 'wiggle' the "B" part while pulling on the ring. It may have seized a bit, if it hasn't been removed for a while, and if the o-rings were not greased with vaseline or similar, when installed. Once you grease the rings, it will almost shoot out when collar "C" loosened.
Btw, I am just trialling transducer paint covered with Nappy rash cream. Each on its own lasts about 3-4 weeks before fouled.

PS: Suggest withdrawing the transducer quickly, don't hesitate, this will allow the inside flapper valve to close over. Also, put some Vaseline or white Teflon lubricant on the dummy plug's rings. Messier, but easier.

onecoolair · Nov 9, 2012

iSailor said:
UPDATE: finally got around to removing it today. I was a little shocked at how much water gushes in , but then quickly inserted the dummy plug and all is well.

I found several little crusty critters all around the impellor and once removed it solved the issue.

cheers,
Matt

Be careful while cleaning not to damage the little magnets embedded in the paddle wheel impeller.

c130king · Nov 11, 2012

Not to change the subject...

But can these transducers be re-calibrated? I think mine is off...I just don't think my boat is really doing 8+ knots of boat speed. I trust the SOG but I don't trust my Boat Speed.

Thanks,
Jim

jsalley · Nov 11, 2012

c130king said:
Not to change the subject...

But can these transducers be re-calibrated? I think mine is off...I just don't think my boat is really doing 8+ knots of boat speed. I trust the SOG but I don't trust my Boat Speed.

Thanks,
Jim

The calibration is done on the head unit if it's a Raymarine. The button sequence is in the manual.

Witzend · Nov 12, 2012

Be careful to account for differences in speed readings between GPS and your water transducer due to currents.

c130king · Nov 12, 2012

My 310 is in Gulfport, MS. If it sits for more than a few days I get enough growth on the transducer wheel that it won't spin...reads 0 boat speed.

So I pull it out and use a stiff toothbrush to clean it off. Works good. I have a "plug" that keeps the water from coming in...but that water flow is no big deal. No need to rush things. Might get a couple of cups of water.

But now my boat speed frequently shows 7.5 - 8.5 knots of boat speed when the SOG shows around 6 knots. Guess I need to read that book on how to recalibrate it.

But the good news is that I sailed 22 days in September, 25 days in October and have 11 days so far in November. What a life...

Cheers,
Jim

Silvio · Nov 12, 2012

I found a new one secondhand for $60 shortly after I bought our boat. I think new isn't much more than that, maybe in the $100 range. Easy to replace, be careful pulling the wire to not scrape the outer coating off. Look here http://www.p2marine.com/marine-electronics/airmar/airmar-st850-speed-transducer.shtml

Witzend · Nov 12, 2012

iSailor said:
We took the boat out yesterday and still get a zero speed reading. Assuming that the wheel has been damaged, I guess the entire tranducer needs to be replaced? Anyone venture a guess on $$$?

Thanks,
Matt

Hey Matt, don't bother, just use GPS.

onecoolair · Nov 12, 2012

c130king said:
My 310 is in Gulfport, MS. If it sits for more than a few days I get enough growth on the transducer wheel that it won't spin...reads 0 boat speed.

So I pull it out and use a stiff toothbrush to clean it off. Works good. I have a "plug" that keeps the water from coming in...but that water flow is no big deal. No need to rush things. Might get a couple of cups of water.

But now my boat speed frequently shows 7.5 - 8.5 knots of boat speed when the SOG shows around 6 knots. Guess I need to read that book on how to recalibrate it.

But the good news is that I sailed 22 days in September, 25 days in October and have 11 days so far in November. What a life...

Cheers,
Jim

I pulled my knot meter paddle wheel to clean it off...maybe guessing 8 years ago?. Put the dummy plug in and haven't had to clean it sense. I Just use the gps and that's good enough.

joker460 · Nov 13, 2012

I had an intermittent speed transducer, or so I thought. It turned out to be the connector at the instrument in the pedestal. Easy to fix.

removing speed transducer - help

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