NASA log paddle wheel installation

awol said:
What a fuss! Just bond drainpipe to the hull over the log and long enough to be above the waterline. Cut and join the electrickery bit. Sorted!
Click to expand...


I'm now having images in mind of people coming out of B&Q with lengths of drainpipe .... thinking about how long to get it above W/L .... and how to extract sender with it in place !!

Some boats - the sender head is a number of feet below W/L ... with many boats - the cabin sole itself is below W/L ...
 
Alfie168 said:
Does the new EM sender work on paddlewheel driven clipper instruments or does it need a complete replacement head and sender?
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The EM sender comes in a couple of 'flavours' one of which works with the existing clipper and duet heads (EML-3 IIRC). The sender comes as a transponder with a new through hull that is slightly larger than the 'old' through hull. It also has a control module that reads and converts the signal to a pulse output. The control module can be hidden behind a panel.
NASA EML-3
 
alahol2 said:
The EM sender comes in a couple of 'flavours' one of which works with the existing clipper and duet heads (EML-3 IIRC). The sender comes as a transponder with a new through hull that is slightly larger than the 'old' through hull. It also has a control module that reads and converts the signal to a pulse output. The control module can be hidden behind a panel.
NASA EML-3
Click to expand...

Interesting you mention slightly larger through-hull .. is that about 1mm more in diameter ? Reason I ask - the paddle wheel Nasa tube is slightly less diameter than many others .. ie Echopilot ....

So maybe Nasa has upped the through hull tube on this EM to same as others now ?
 
Corribee Boy said:
Webby, your log tube is now indestructibly bonded to your hull and cannot, in any way, leak, snap, or fail, no matter what you do to it in the next three years.

Is that the answer you wanted?:)

BTW, my tube didn't fail at the flange - it developed capillary cracking further up the tube, allowing water to track from outside to inside the boat, despite the grp collar. The plastic had been turned to something with the strength of Wensleydale cheese, which failed when I prodded it quite gently.
Click to expand...

To what do you attribute this plastic failure if it was a part of the tube that had not been in contact with the sealant?

- W
 
Refueler said:
Interesting you mention slightly larger through-hull .. is that about 1mm more in diameter ? Reason I ask - the paddle wheel Nasa tube is slightly less diameter than many others .. ie Echopilot ....
So maybe Nasa has upped the through hull tube on this EM to same as others now ?
Click to expand...

The paddlewheel skin fitting is 42mm, the skin fitting for the EML is 51mm/2 inch. Not sure if that matches other manufacturers.
 
alahol2 said:
The paddlewheel skin fitting is 42mm, the skin fitting for the EML is 51mm/2 inch. Not sure if that matches other manufacturers.
Click to expand...

Most Airmar fittings are 2" diameter. Airmar supply the transducers offered by most brands of instrumentation. And their plastic isn't degraded by polyurethane sealants!
 
webcraft said:
So maybe the NASA plastic spontaneously degrades... do you know how old it was?

- W
Click to expand...
Age unknown. It could have been quite old but the weak area was close to the hull and so the sealant could be the cause, rather than age. It’s also the area most likely to be damaged by leverage on the tube.

I now think the weep was a warning that the tube ( not the flange or sealant) was failing and the only thing that my attention sealed, was it’s fate.
 
Rhylsailer99 said:
I'll re fit a new one soon as they're only £11 ISH on eBay
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For us, it is not the cost of the fitting, it is the cost of the unexpected haul out.

I am pretty sure the leak has been there for years, but has probably got worse after nearly two years on the hard.

And in our case I am pretty sure it is sealant failure.

I can't leave it though now I know about it as we will be leaving the boat unattended for several months on its mooring.

I am now convinced CT1 will not damage the plastic, but worried about the method of glassing in and possible damage caused by the hardener. I may just not bother as the present one has survived 18 years without being glassed in. It is in a place where it cannot get accidentally nudged.

And frankly I am pissed off that NASA appear to have created such a minefield.

- W
 
Refueler said:
Which imho is not so good ... but there it is .. I haven't tested Polyester based on my Nasa sitting in the box and tbh - do not wish to ;) ..... but because Epoxy is quite safe as long as both components are well mixed .. that's my GoTo .....
Click to expand...

And herein lies the reason for the "minefield" that the forum has created (in your words). The manufacturer has specified a fitting method, some people think their instructions are "not so good".

NASA fitting instructions state: "encapsulate the whole assembly in G.R.P. "

That seems rather clear to me, use GRP. They do not state epoxy must be used, neither do they state the polyester must not be used, so logic would suggest either can safely be used. So i don't see anything wrong with using epoxy, as you suggest, but i also don't see anything wrong with using polyester, hence the P40 the OP has suggested long ago.
 
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Wouldn't you prefer to stay on the side of safer ? If you and pvb prefer to risk Polyester - that's your choice.

Personally based on Epoxy is generally advised for repair / addition work in GRP hulls because of its non--reaction with materials and also its superior strength .. as I am sure you as Yard guy knows well - I prefer the Epoxy route.
 
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