ST60+ Knotmeter Issue>>>Thoughts?

Mar 20, 2004
1,753
Hunter 356 and 216 Portland, ME
you might also be having the transducer binding when it's in the thru hull - the tabs that hold the wheel are pretty flexible and if bent in only slightly can cause the paddlewheel to stick
 

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
8,020
Hunter 430 Waveland, MS
The housing is plastic so there shouldn't be any corrosion issue
My housing is also plastic but the backing plate/flange that holds/screws the housing to the hull is ( I hate spellcheckers "ferule" ) is called a "ferrule" and mine is made of brass. If you don't have your ST60+ manual, try....

https://raymarine.app.box.com/s/2ji2raqp5to75zaikekcbam5en93u0sz/1/402195283

The install picture will show you how it is supposed to look when you dive the boat.

I pulled and cleaned mine yesterday for the weekend sail. Yukky with algae.:eek:

I noted my sea water influx was slight since the " flexible rubber back flow flapper" was intact. When i pushed on the flap with a brush handle...

Here come da water...:eek:

Thus proving my flapper was serviceable and NOT fouling the wheel. You might do the same.

I looked at the wheel and it and its axil looks pretty durable and simple design.

Remember the Display is just a fancy Digital Volt Meter. Try the Green wire check too.
Jim...
 

Rick D

.
Jun 14, 2008
7,204
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Not-Meter Follow Up

OK, so I have tested the speed transducer three times since this thread and each time, the knots show on both the display and on the remote on the chartplotter. I took some canned air and ran the impeller to a steady 18 knots indicated for a while, and it was stable. Today, I donned my fins and mask and dove on it (when it was 99 degrees F and 30% humidity). Besides feeling refreshed, I found no obvious issue with the paddlewheel. It spun freely and indicated at the station OK. There was no flap hanging down and the area around the through-hull seemed clear (although I did clear a small piece of growth off the flange in front of the wheel). So, the next step is a real world test. I have been out a couple of times but didn't want to install the transducer until I dove on it. So, I am faced with dead-ends all over. We'll see if the issues continue or not. Look for a follow up installment, or if you have had an epiphany, please post it!
 
Oct 2, 2008
3,811
Pearson/ 530 Strafford, NH
I was told once that an air bubble could be caught by the paddle wheel and keep it from turning. Mine sometimes needs to have 6 knots of water under the keel before it wakes up. Then its good at any speed. However I did find that my paddle wheel was for high speed not the low speed wheel. I was happier when I didn't know.

All U Get
 

Rick D

.
Jun 14, 2008
7,204
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Interesting!

I was told once that an air bubble could be caught by the paddle wheel and keep it from turning. Mine sometimes needs to have 6 knots of water under the keel before it wakes up. Then its good at any speed. However I did find that my paddle wheel was for high speed not the low speed wheel. I was happier when I didn't know. All U Get
Interesting! OTOH, the last fail, I ran it for 35KM / 5 hours and it did not respond. Geesh. Good for the hunt and I'll add it into the bag. Thanks.
 

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
8,020
Hunter 430 Waveland, MS
It spun freely and indicated at the station OK. There was no flap hanging down and the area around the through-hull seemed clear (although I did clear a small piece of growth off the flange in front of the wheel)
Ok did it look like the install diagram from your ST manual , with only one half of the wheel protruding below the intact backing flange/nut on the thru hull?

Did you reset/calibrate it per manual?

Jim...
 

Rick D

.
Jun 14, 2008
7,204
Hunter Legend 40.5 Shoreline Marina Long Beach CA
It did look correctly orientated. Have not done a calibration yet tho since it seems to be a go/no-go situation and the velocities of wheel spin seem intuitively on target as to the speed read. However, maybe next visit I'll do a factory re-set if for no other reason than why not!
 

JamesG161

SBO Weather and Forecasting Forum Jim & John
Feb 14, 2014
8,020
Hunter 430 Waveland, MS
It did look correctly orientated.
I am not trying to be a pest, but it is the amount of wheel exposed to the "current of water" flow by the wheel.

A fully exposed wheel, to the flow of water, will NOT spin.

Only half of wheel should dip below the ferrule and expose itself to water flow.

If the wheel protrudes into the water flow beyond its install point, then No proper Spin!

Obviously this protrusion can't be perfectly mid way on the wheel axis.

So...

You must adjust by....

Calibration...

But if...

The wheel is too much out below hull surface line then erratic behavior and no calibration

Jim...
 

BarryL

.
May 21, 2004
1,116
Jeanneau Sun Odyssey 409 Mt. Sinai, NY
Hey,

I had a similar problem last year. In my case the paddle wheel would spin freely by hand, but had some resistance and didn't register in the water. I bought a new wheel (which came with a new pin, o rings, etc.) and that solved the problem. After seeing the difference in how easily the wheel spun on the new shaft vs old shaft I used some sandpaper on the old shaft and now the old wheel works too.

My suggestion is to buy a new wheel and / or lightly sand the old shaft. The new wheel would spin when I blew on it, the old wheel would not (before sanding the shaft).

Barry
 

Rick D

.
Jun 14, 2008
7,204
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Thanks!

I am not trying to be a pest, but it is the amount of wheel exposed to the "current of water" flow by the wheel.

A fully exposed wheel, to the flow of water, will NOT spin.

Only half of wheel should dip below the ferrule and expose itself to water flow.

If the wheel protrudes into the water flow beyond its install point, then No proper Spin!

Obviously this protrusion can't be perfectly mid way on the wheel axis.

So...

You must adjust by....

Calibration...

But if...

The wheel is too much out below hull surface line then erratic behavior and no calibration

Jim...
Not a pest! Thanks for the thoughts. It did look correct in terms of the area of the wheel that was protruding. I'll check it out next time I'm there. Thanks again for the suggestion.
 

Rick D

.
Jun 14, 2008
7,204
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Good Idea

Hey,

I had a similar problem last year. In my case the paddle wheel would spin freely by hand, but had some resistance and didn't register in the water. I bought a new wheel (which came with a new pin, o rings, etc.) and that solved the problem. After seeing the difference in how easily the wheel spun on the new shaft vs old shaft I used some sandpaper on the old shaft and now the old wheel works too.

My suggestion is to buy a new wheel and / or lightly sand the old shaft. The new wheel would spin when I blew on it, the old wheel would not (before sanding the shaft).

Barry
Although it seems to spin freely, that sounds like a good idea. I'll order one. Thanks.
 
Oct 2, 2008
3,811
Pearson/ 530 Strafford, NH
You could also try putting the plug in and out several times to clear the tube. I did that until I skinned my knuckles and got a blister. I also tried cussing and spitting, but my wife came and took the tool box away and I was sent to the time-out chair.

All U Get