NASA log paddle wheel

[MJWB]

Mine is now knackered. The little magnets have all but gone. Whilst one can manage without it, I'm a firm believer in knowing speed through water as well as over the ground. The other factor is that I inherited a replacement when I bought the boat, so I might as well use that brand new part. That said is it straightforward to replace old with new when next I lift the boat for winter?
Many thanks.

 

[Rappey]

Plan B could be to buy the nasa electro magnetic transducer . No moving parts !

 

[MJWB]

Plan B could be to buy the nasa electro magnetic transducer . No moving parts !

Yep if I didn't already have the unit I'd look at that but I inherited a new replacement part. Assume the previous owner suspected it was on the way out.

 

[Rappey]

I've had a seafarer, smiths and nasa paddlewheel log, all virtually the same. I found none of them seemed to last more than a few weeks before stopping and it wasn't worth the incoming water to keep pulling them each time I went out so didn't have a log for many years.
The electro magnetic log readings slow as the transducer weeds up.

 

[Bodach na mara]

Nasa impeller is tricky to replace the first time but easy after that. You can buy the impeller kit ( impeller and shaft) from Nasa and also from an instrument spares agent whose name I have forgotten. I usually buy 2 to save on postage costs.

To replace the impeller, withdraw the unit from the mounting tube and get the cap on the tube if you are afloat. Hopefully there will be enough slack in the co-ax cable to get to a comfortable place for the next step. Using a thin probe on one end of the shaft and a socket or something else with a hole on the opposite side press out the shaft far enough to get pliers on the opposite end. Pull out the shaft. Replace with new impeller and shaft. Replace unit in mounting tube.

Sometimes the shaft needs a LIGHT tap to persuade it to move.

 

[jerram]

Buy a replacement impeller it come with a new bearing pin no need to replace the unit one tip paint the sml metal insert in the impeller with nail varnish it will stop the metal rusting and failing out if you need to replace the unit do not shorton the cable and use a good coax connector

 

[Refueler]

Its actually easy to replace the magnets ... they are small Rare Earth Magnets you can buy of eBay ... the strength of magnet is not critical as all it does is pass a sensor in the body to create a pulse.

I assume as others - that OP has replacement impellor and pin ... nothing hard about fitting .... just be careful not to damage the plastic around the pin when driving it out / putting pin back.

 

[Porthandbuoy]

Regards fouling. I coated my paddlewheel with Coppaslip grease at the start of this season and it is still working. Usually the little critters jam it after a few weeks.

 

[MJWB]

Many thanks everyone. That's very helpful and boosts my confidence.