Hull Sensor - ID ?

[seaboy]

Can anyone ID this sensor fitted in hull.

Thanks

 

[tillergirl]

Looks like a Nasa paddlewheel for a log. The little (what d you call them) thingies for pulling out the paddlewheel for cleaning. If you google a Nasa paddlewheel you will see some images.

 

[seaboy]

Thanks,
Have seen some.
Problem I have, its dribbling water from what appears from the white nut. I have my bilge auto-pump working to control the levels.
Is there a ‘O’ ring to seal or rely on the nut closing the seal around sensor.
I’m afraid to tighten the gland incase of further leakage etc.
Think I will get a blanking cap first and hopefully change over quick enough ?

 

[tillergirl]

There will be two 'O' rings on the paddlewheel (from memory). That volume of leak suggests the 'O' rings have failed. Yes, the blanking insert first. Lubricate the 'O' rings

 

[seaboy]

Thanks,
I've since found the actual hull connection is the source of the leak.
Either the previous owner/owners did not correctly fit the connection to the hull or being plastic has become brittle or cracked.

Next question, can I fit a bronze item in the place of the plastic version ?

 

[KompetentKrew]

Surely it depends on the model of transducer, if the manufacturer makes one?

I don't think I'd chose bronze by default - they're a lot more expensive if I recollect. I think Airmar has a page about this on their website.

I think that a plastic transducer mount will be perfectly adequate - I don't think you'll find it has "become brittle or cracked" simply because of old age; if it's damaged it'll be because it's somehow had a knock. Even if it did deteriorate due to old age - which, I repeat, I don't think it will - you'll get 20 years out of a plastic one.

 

[tillergirl]

Next question, can I fit a bronze item in the place of the plastic version ?

Unlikely. Nasa don't do a bronze one and I don't think an Airmar one will fit. Buy a replacement direct from Nasa ..... or get completely new kit. Bronze one ain't cheap!

 

[Stemar]

The fitting instructions for my log sensor say to fit the through hull with silicone sealant, tighten the nut down (not too much, you don't want to squeeze all the goop out and let it cure. Then put GRP over everything - I used Isopon p40, making sure there's enough clean thread for the sensor to screw on. Slather the sensor with silicone grease before fitting.

Pro tip - make sure the sensor's the right way round

 

[seaboy]

Thanks guys

I've replaced the skin fitting with another Nasa fitting and paddlewheel to be sure.
The old fitting sealant used by one of the previous owners was reasonably soft, but appears the hull was drilled and skin fitting fitted on top of the AF at that time 'maybe the source of the leak'

i followed this post from 2016 and used PU40 sealant rather than the Sikaflex for the reasons explained in the link.

Nasa Log Skin fitting failure

??

 

[KompetentKrew]

i followed this post from 2016 and used PU40 sealant rather than the Sikaflex for the reasons explained in the link.

Nasa Log Skin fitting failure

I won't necrobump that old thread to add this information, but there's a broken link in comment #6 by @l'escargot - if anyone would like to read also the older 2004 thread then this is it: NASA Log skin fitting cracked!!!

It took me a few attempts to find this.