Knotmeter stopped working

[ctjeanneau]

So, I face another newbie challenge. The knotmeter stopped working after a month and a half in the water. I am assuming it is just algae and  other crud built up on it. Is there a simple method to pulling this and not sinking the boat?
Thanks in advance.

[rc sail]

Hi Ct,
many congratulations on your new DS. Sorry to hear you have the gremlens
challenging your new vessel.
Your Knot meter, as you know, has the head-end (and paddle wheel) probably
impeded with algae or sea life. This head-end unit (paddle wheel) for your
knot meter should be located in the bildge in front of your keel. There
will probably be two thru hull head end units (one for
the knot meter and second for the depth). Hopefully you should also have a similar
looking unit which is free standing and serves as a plug. With the "plug" in one hand and
unscrew and pull out the head end of the knot meter and quick replace with the "plug" unit.
There should be no more than one or two pints of sea that will come in during this
replacement adventure.
Also with the paddle wheel out of the hull you should be able to spin it by hand/finger
and have someone at the knot meter confirm the unit is providing a signal and speed.

If and when you haul out via travel lift/slings you should also pull this paddle wheel
and replace with the "plug" prior to haul out. If the lifting sling covers the paddle wheel
during haul out it will be damaged and require replacement.

Please keep us up to date with the adventures with your new vessel
RC

[rapide]

Watching water come shooting up through the hull of your new boat can be a bit breathtaking. But as rc points out, once you gain proficiency there is not a lot of water that actually comes in. We always put an old towel around the sending unit or plug before we swap them. This keeps the water from shooting somewhere it should not. Also, we are on the gulf coast, so we put the plug in whenever the boat is docked. Since we sail every week this is a lot of in and out but the sending unit stays clean.

[Don Reaves]

The transducers for my Raymarine speed and depth have a small piece of plastic that automatically moves into place to help block the flow of water when you pull the plug. But you should still put the blank in to stop the water completely. I never get even a pint of water during the operation.

If you're still concerned that something might go wrong, and don't want to pull the transducer, you can clean it from the outside. A light-duty scrub brush might be all you need to use, other than a dive mask.

Don

[so36idavid]

You might think about hiring a diver to periodically clean the bottom and inspect the zincs etc. If you have a regularly contracted diver (i.e. once every month or two), then usually they won't mind swinging by and cleaning your paddlewheel if it sticks. Sometimes I find that getting the boat up to speed clears the paddlewheel if it's been sitting in the slip for a while.

If you do pull the paddlewheel I recommend lubricating the O ring with either silicone grease or lanolin.  I once had a paddlewheel that wouldn't reseat properly and that was drama. A little lubrication on an O ring goes a long way.

David

[MalcolmP]

The video below gives an idea, note though is removing the blank - then putting back in the paddle wheel sender. It is also a different type to those normally used by Jeanneau which will most likely by Airmar units. These, as mentioned by others, have a small flap valve which normally reduces the water flow considerably.  An old towel is a great idea to stop the salt water running into the bilge. Also have a look at the blank before starting the job - it will be marked with the direction it should face and this is also ensured by a notch that only locates at the fore and aft position.

[tedp]

Interesting video, Malcolm. I always feared making a hole in the hull, but it seems to be a straightforward procedure.

I once had the same problem with the paddle wheel being stuck. Together with someone else I dragged a line under the hull, keeping it tight by hand. Dragging it back and forth a few times cleared the paddle wheel.

[hoppy]

My Raymarine never had the flap, so it was always a fun time taking out the log. It's a freaky feeling seeing blue light through the hull. I had a new spare RM log with a flap, so over the winter when I replaced all through hulls I swapped the log through hull over as well. I'll be curious to see what difference the flap makes

[allegria]

Hello All,

While you have the transducer out, you can apply a coat or 2 of special anti-fouling paint on it.
The wheel itself can be removed easily and cleaned thoroughly. You can then paint around it as well.
This will save you many pulling out the transducer... Mine was left over in the water over 18 months without any locking after that treatment...

Look for "transducer paint" online.

Happy sailing,
Allegria

[sailbleu]

Try turning the log 180° while sailing , that could clear out all the junk.
Regards

[ianqv]

Top suggestion from Sailbleu!!

Right.... I'm going to the boat this weekend and I have to clean my paddle wheel.
I will pull the transducer out and video the water flow for a few seconds.
Honestly.... its nothing to worry about!

Video to follow.

Regards

Ian

[MartyB]

I do the right hand to remove, left to install plug. Then again, maybe it should be left to remove, right to install......your mileage may vary!

Another option if you do not want to remove the plug, is a long handled brush that can reach the bottom where the plug is. OR, make a 6-9" wide rig about 12 or so long, then rope on the ends, and you put under the boat at the bow, and slowly pull back to the keel while moving the rig side to side. This will clean the bottom and sometimes to usually also clean the transducer wheel.

Marty

[rene460]

Hi ctjeanneau,

A few more suggestions to help give you confidence.

I use three car wash chamois (plastic) cloths, Vaseline and a two litre container.  Two of the cloths are used to block the limber holes through the frames and contain the water that does come in to one compartment.  I check that the plug has a nice coat of Vaseline around the o- rings and threads before I start.

I use one hand to unscrew the nut and pull the transducer, and the other to block the hole while I pick up the plug.  There is no water flow in until the transducer is almost fully removed so there is no nene to panic.  Mine has a flap which usually reduces the water inflow but not completely, but sometimes hardly reduces it at all.  I check the orientation arrow on the plug shift my hand and insert the plug.  Once it is mostly seated there is no further water flow.  Push it down, hand tighten the nut, push it down again and take up any further slack.  Remember it is only plastic.  Blocking the hole after I pull out the transducer means I am not under pressure of watching water flow in while I pick up the plug.

I then mop up the water and squeeze it out into the container.  Finally wring out the two cloths that block the limber holes.  Never more than a litre enters in total.   I leave the bilge totally dry.  I keep two cloths in the container with the Vaseline so they cannot block the limber holes if really needed in earnest, and are ready for next time, and use the third for general drying of seats and decks etc.

I have found that the paddle wheel rarely blocks with daily sailing, but sometimes in as little as a week, sea weed can start and even a little wriggly worm will take up residence, so, like rapide, I remove the log every time I leave the boat for more than a day or to.  It is not difficult.  Keeping it clean and the seals lubricated means the calibration holds well and the job continues to be easy.  The only issue for me is that the space around the log on an SO30i is tight and it requires a bit of a squeeze to get in position to work with both hands below my feet.  Cleaning the paddle wheel from outside will always be a compromise, but sailbleu's idea of rotating it half a turn a few times works well if you are in weedy waters and often pick up a weed as you sail (also learnt by experience).  As your paddle stopped only recently, I would guess it has been removed often and should come without too much trouble.  Give it a try.

rene460

[ianqv]

Ok Chaps,
As promised, here is my "how to" video! lol.... I know, don't give up my day job!!
But, it really does show how EASY it is to do.



Regards

IanQv-Speilburg

P.S If anyone is still looking to actually hire people to do this, I'm available 24/7 especially in the med or Caribbean!!

[so40gtb]

I have lost two Airmar paddle-wheel sensors, one on our prior boat, a SO34.2, and one on our SO40. Neither had any evidence of fouling and both turned freely upon removal, though one of the webs on the SO40 sensor was bent, probably by improper sling placement during annual launch or haulout. Both were replaced with no issues thereafter.

I also suffered a failed depth sensor on the SO34.2. I replaced it with an Airmar sensor-and-sleeve model, so that a future failure would not require thru-hull removal and replacement, which is not fun.

--Karl

[ctjeanneau]

Boat and Cpt. survived the cleaning process - thank you to all who commented. 
The crud and seaweed we're hanging down for 4inches,nasty, but all is good and working now.
Now if I could direct your expertise to my next problem....please see the post on algae in water tank.....arrgghhh.

[ianqv]

cool - glad you are all sorted!

We'll have you replacing the stern gland whilst afloat next! I've done that twice now......
now that isn't for the faint hearted!!!!!!!!

Best Regards

Ian