What NASA say about installing their paddle wheel through-hull

A further anecdote... I went down to the boatyard today to arrange a lift-out to install the new through-hull and the yard owner told me he had personally broken one of them by over-finger-tightening it. He said he only used fingers and it cracked all round the flange!

- W
 
In no way a reflection on this thread, or any from any previous fora, but I have to ask what would happen if Mr. Webcraft would ask an anchor question?
 
jamie N said:
In no way a reflection on this thread, or any from any previous fora, but I have to ask what would happen if Mr. Webcraft would ask an anchor question?
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I reply to a lot of anchor threads because I know a lot about anchoring. I don't generally start them or ask questions. We all have different areas of expertise.

I know very little about the reactions betrween plastics, polyurethane, hardeners etc, and I have to replacve a leaky N ASA through-hull.

The thing some people seem to be missing here is that a disturbing number of people have experience of these through-hull fittings failing in a catastrophic or potentially catastrophic manner. It therefore seems to be quite in order to enquire as to the best way of fitting them and the best materials to use.

I now understand that PU mastics and sealants are not a good idea, that CT1 is probably an ideal material because unlike conventional silicone sealants it is designed for underwater use, is much more adhesive and does not shrink on curing. It is safe for use with plastics.

And that if glassing in epoxy resin and chopped strand mat OR an epoxy putty such as JB Water Weld or similar sould be used, NOT a polyester based filler like Isopon P40

It has taken this number of posts to arrive at this conclusion due to a lot of uncertainty on the part of many posters and a tendency of others to assume we are all materials scientists. However, I now feel I can make a good job of it and pretty much eliminate the possibility of catastrophic failure at some point in the future.

Now, what do you want to know about anchors? :p

- W
 
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webcraft said:
I reply to a lot of anchor threads because I know a lot about anchoring. I don't generally start them or ask questions. We all have different areas of expertise.

I know very little about the reactions betrween plastics, polyurethane, hardeners etc, and I have to replacve a leaky N ASA through-hull.

The thing some people seem to be missing here is that a disturbing number of people have experience of these through-hull fittings failing in a catastrophic or potentially catastrophic manner. It therefore seems to be quite in order to enquire as to the best way of fitting them and the best materials to use.

I now understand that PU mastics and sealants are not a good idea, that CT1 is probably an ideal material because unlike conventional silicone sealants it is designed for underwater use, is much more adhesive and does not shrink on curing. It is safe for use with plastics.

And that if glassing in epoxy resin and chopped strand mat OR an epoxy putty such as JB Water Weld or similar sould be used, NOT a polyester based filler like Isopon P40

It has taken this number of posts to arrive at this conclusion due to a lot of uncertainty on the part of many posters and a tendency of others to assume we are all materials scientists. However, I now feel I can make a good job of it and pretty much eliminate the possibility of catastrophic failure at some point in the future.

Now, what do you want to know about anchors? :p

- W
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As an expert with anchors and new knowledge of adhesives, which would give an anchor the best grip on a rocky bottom? OB1, CT1 or StixAll? :D
 
webcraft said:
So JB Water Weld would be good?

Do you think one stick would be enough?

- W
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Yes JB - would in my mind be an excellent choice ...

Here's similar product round my through hull :

el2q4K7m.jpg


I have a similar stick in my tool box always ... so why not buy a number of sticks ... and keep one or two as repair items ?

I know when I tried a temporary repair of my leaking through hull tube - I used two sticks ... it was a near success - but with water seeping in while working - it was impossible to seal completely ... but if working out of water - then it will do the job well.

I also used similar to plug a burst core plug in my engine before a 10 day cruise ... on return to mooring - that epoxy was still sealing that plug well. But of course fitted a new plug.
 
PaulRainbow said:
Is JB weld GRP ?

No, it is not. NASA instructions state to encapsulate in GRP.

You are correct in the other thread, "this forum is creating a minefield".
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Think its splitting hairs now ...

GRP as you well know is Glass Reinforced Plastic ... just resin with glass fibres mixed in .... whether its matt with resin then applied or the tinned variety as a filler.

JB Weld and Epoxy sticks are basically Plastic Metal ... resin with powdered binder ...... which really will do the job more than well enough.

I suggest that the advantage of the sticks - is the faster setting time over conventional Epoxy resin ... which can be a problem if quick turn-round needed. As with my lift out to rebed - I had only a couple of hours ... so Epoxy stick was a good choice as it has set sufficiently by time lift back in time came.
 
Richard10002 said:
Milliput has come to my mind as something that says it sets under water. Just googled it and it's described as an epoxy putty. I wonder if it would be OK for this purpose - it comes in sticks and has a shelf life of 2 years.

Milliput Products - We have a range of epoxy resins to suit many applications, including modelling, diy, and car and household repairs
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Most catalyst form resins will set under water ........ that's not the limiting factor though ... try and get it to 'grab and adhere' under water ...

You still need in most cases a dry time to apply and work into shape etc. before allowing it to immerse.
 
Richard10002 said:
Milliput has come to my mind as something that says it sets under water. Just googled it and it's described as an epoxy putty. I wonder if it would be OK for this purpose - it comes in sticks and has a shelf life of 2 years.

Milliput Products - We have a range of epoxy resins to suit many applications, including modelling, diy, and car and household repairs
Click to expand...

The point of using GRP is to reinforce the otherwise flimsy plastic tube, i don't think Milliput is the answer here.
 
Refueler said:
Think its splitting hairs now ...

GRP as you well know is Glass Reinforced Plastic ... just resin with glass fibres mixed in .... whether its matt with resin then applied or the tinned variety as a filler.

JB Weld and Epoxy sticks are basically Plastic Metal ... resin with powdered binder ...... which really will do the job more than well enough.

I suggest that the advantage of the sticks - is the faster setting time over conventional Epoxy resin ... which can be a problem if quick turn-round needed. As with my lift out to rebed - I had only a couple of hours ... so Epoxy stick was a good choice as it has set sufficiently by time lift back in time came.
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In the other thread, you said "The Minefield to be honest has been created by this forum .................... "

You are almost correct, "The Minefield to be honest has been created by Refueler .................... " would be correct.

NASA say use GRP, the OP has suggested using P40, which is GRP, you said in the other thread use epoxy and glass, which is also GRP, yet here you are, suggesting using something else.

Make your mind up please and stop confusing people with your random suggestions. Just follow the damn instructions.

Edit: in post #29 the OP states "I have some P40 left, so plan to use that. "

So, he has the correct material to do the job, but you suggest going out and buying a material that is not recommended by the manufacturer is OK ?
 
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Paul,

I fail to understand why you are so aggressive in your style of posting. Refueler is trying to be helpful and sharing his experience, as are you. I have some JB WaterWeld on order anyway from when I first discovered the leak, so would not be going out to buy it.

I would prefer to use epoxy resin and choppped strand mat, but I do not have any and am absolutely hopelessly messy when it comes to using it. I would probably end up with it too far up the threads. I may try to persuade a friend who does GRP professionally to do it for me.

Reinforcing the tube and holding it in the hull is indeed the idea, but if the polyester resin used weakens the plastic in the tube when epoxy would not then maybe epoxy putty would be better than P40.

- W
 
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webcraft said:
Paul,

I fail to understand why you are so aggressive in your style of posting.
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How do you arrive at "aggressive", i've just stated a few facts.

Reinforcing the tube and holding it in the hull is indeed the idea, but if the polyester resin used weakens the plastic in the tube when epoxy would not then maybe epoxy putty would be better than P40.
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Now i'm baffled!

NASA say to use GRP, you have some GRP. NASA do not state that you should use epoxy, or that polyester will eat the plastic, seems like they would mention that, if it were the case. But, you think it will be better to use a different material, because Refueler claims that polyester will eat the plastic tube.

I suppose if Refueler know better than NASA you should follow his advice, in which case, i'll bow and and leave you both to it.
 
I emailed NASA:

"Your paddle wheel fitting instructions say to "encapsulate the whole assembly in G.R.P." but:

a) Is polyester resin suitable for this ?
b) Would polyester resin harm the plastic ?
c) Could Isopon P40 be used ?"

They replied:

"Don’t’ use a polyester resin, use an epoxy resin.
No problem with Isopon P40."

So there we have it, or do we ?
 
PaulRainbow said:
I emailed NASA:

"Your paddle wheel fitting instructions say to "encapsulate the whole assembly in G.R.P." but:

a) Is polyester resin suitable for this ?
b) Would polyester resin harm the plastic ?
c) Could Isopon P40 be used ?"

They replied:

"Don’t’ use a polyester resin, use an epoxy resin.
No problem with Isopon P40."

So there we have it, or do we ?
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erm, doesn't P40 ue polyester resin?

- W
 
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