Mystery Airmar Triducer Circlip

[doraymefa]

I have an Airmar DST800 Triducer Multisensor with a plastic low profile P617V housing. When clearing the paddle wheel this weekend I noticed a loose circlip which fell off the set up into the bilge.
l can not locate the circlip in the installation instructions and the unit appears to work fine without it.
Can anyone help explain where it should sit? With thanks.

 

[Martin_J]

That circlip looks like the one that's (usually) within the through hull. It holds the plastic tube in place within the through hull fitting, that in turn holds the flap.

 

[yotter]

Yes, it looks like part of the flap valve that should shut to slow the inrush of sea water when the log is removed.

 

[Martin_J]

Just found a couple of photos I took showing a dismantled through hull next to a complete one...

 

[Martin_J]

And a close up..

 

[Martin_J]

It's a bit fiddly getting it back together even when on the saloon table... I'd say impossible whilst on the water unless you can bung from the outside and haven't lost the smaller parts.

 

[doraymefa]

Thanks Martin, that explains the significant inrush of water when I take the Triducer out!
This is probably one for the winter. I will just have to be quick when changing between Triducer and Blank when necessary.
You have reassured me that it is not part of the structure of the main body.