What NASA say about installing their paddle wheel through-hull

I really can't see what all the hoo ha is about. Just do whatever NASA recommend in their instructions. It's not as if they're expensive or difficult to apply. Most sailors have some mat and resin in their toolbox.
 
ghostlymoron said:
I really can't see what all the hoo ha is about. Just do whatever NASA recommend in their instructions. It's not as if they're expensive or difficult to apply. Most sailors have some mat and resin in their toolbox.
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The hooha is that NASA specificaly said to Paul not to use polyester resin, to use epoxy.

Then in the next sentence they say P40, which contains polyster resin, is OK to use.

I presume you can see the inconsistency in that?

- W
 
webcraft said:
The hooha is that NASA specificaly said to Paul not to use polyester resin, to use epoxy.

Then in the next sentence they say P40, which contains polyster resin, is OK to use.

I presume you can see the inconsistency in that?
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The inconsistency is, of course, unforgivable. But it's worth remembering that Nasa is a tiny company, with limited resources, and they may not have people who really know the facts about their products. They claim to manufacture everything in the UK, but they obviously don't make the stuff themselves, as they only have about a dozen employees.
 
pvb said:
The inconsistency is, of course, unforgivable. But it's worth remembering that Nasa is a tiny company, with limited resources, and they may not have people who really know the facts about their products. They claim to manufacture everything in the UK, but they obviously don't make the stuff themselves, as they only have about a dozen employees.
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If, as now seems to be the case, they don't really know the facts about their products then suggesting all will be well if we follow their installation instructions is inconsistent with that.

Anyway, CT1 to seal the fitting in, no more than finger tight, then glass in with epoxy resin and chopped strand mat or woven roving seems to be the way to go.

I'll let you know when it fails!

- W
 
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webcraft said:
If, as now seems to be the case, they don't really know the facts about their products then suggesting all will be well if we follow their installation instructions is inconsistent with that.

Anyway, CT1 to seal the fitting in, no more than finger tight, then glass in with epoxy resin and chopped strand mat or woven roving seems to be the way to go.

I'll let you know when it fails!

- W
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My preference would be to use epoxy rather that polyester because it will make a stronger bond with the hull moulding, Important because one of the weaknesses of NASA' fitting seems t be that the outer flange is easily broken off.
but
Note that the chapped strand mat used for polyester resin is not suitable for use with epoxy.
 
All things considered we'd all be better off if they made the hull fitting out of a polymer that doesn't react badly with common marine sealants and thick enough that it doesn't routinely need reinforcing with a fillet of bog. Every other sensor maker seems to cope with this.
 
I checked mine on Sunday. I used P40 to glass my NASA log in 2006 and it's just fine. I still have the very tin of P40 and it still works fine as I used some the other week (new tube of hardener though).
I've got a feeling the P in P40 stands for polyester. I've got a feeling that somebody at NASA is confused as GRP paste, which is what they specify, has always been polyester. That's what GRP boats have traditionally used and epoxy is a bit of a latecomer and epoxies like Araldite don't like UV one bit.
 
PaulRainbow said:
Latest reply from NASA :

"We have used P40 before it’s a styrene based GRP body filler. It is suitable for glassing in the skin fitting."
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I seem to recall that polyester resins usually contain styrene. Not my specific area of expertise and remembering from decades ago.

Just a thought, is their tech. dept. headed up by someone called Jim Trott? Ref. to Vicar of Dibley in case you thought it was a serious question. :D
 
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webcraft said:
The hooha is that NASA specificaly said to Paul not to use polyester resin, to use epoxy.

Then in the next sentence they say P40, which contains polyster resin, is OK to use.

I presume you can see the inconsistency in that?

- W
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So why not just follow their printed instructions and use silicone sealant and fibreglass mat with resin. It's not arduous and takes a few minutes.
 
ghostlymoron said:
So why not just follow their printed instructions and use silicone sealant and fibreglass mat with resin. It's not arduous and takes a few minutes.
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a) the printed instruction don't say that

b) They have said:

Use Epoxy, not polyester
or
Use P40 (which IS polyester)
or
Use proprietary body filler

What would you suggest the OP uses ?
 
My paddle wheel log hasnt worked for a couple of years now. Its coming out and the hole will be glassed over on the next refit.

For the short coastal hops we do ,rarely more than a day, I think I can live without it and one less hole in the hull is good.
 
PaulRainbow said:
a) the printed instruction don't say that

b) They have said:

Use Epoxy, not polyester
or
Use P40 (which IS polyester)
or
Use proprietary body filler

What would you suggest the OP uses ?
Click to expand...
I cut and pasted what it says in a previous post and there's nothing about P40, proprietary filler or epoxy v polyester. So my reply to your question is "none of the above"
 
I've fitted a couple of these and also reinforced one with epoxy and glass fibre mat. The latter was after a talk given by a club member about a cruise he undertook to the inner Hebrides in his Drascombe when his log tube flange became detached and water rushed in through the inch and a half hole. I and several others examined ours and carried out remedial strengthening. I thought I would share my knowledge not get into a bad tempered argument about alternatives to the published method of installation.
 
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