NASA log paddle wheel installation

[Dipper]

I fitted mine about 26 years ago. I can't remember exactly how I did it but I must have read the instructions because there's a mound of what looks like some form of epoxy putty going halfway up the fitting on the inside. It's as solid as a rock. The flange was still on the outside of the hull at the launch last April so that hasn't fallen off yet. I think it's important to support the tube at least halfway up and not just at the base.

 

[Refueler]

I've just launched the boat after a few unexpected bills. Cheaper to use PU now, avoid a lift-out and redo it with silicon at my leisure in two or three years when she comes out of the water again. I will be glassing it in though, just in case the PU eats the plastic. I think I will be OK for three years, don''t you?

- W

Regardless of what you read from others - PU does NOT eat plastics ...... just make sure you have the Exterior Grade which is Seawater Proof ...

Just for info : PU glue is a common glue used in modelling ... particularly for Foam Sheet based models ... where even the solvent in Contact Glue will eat through. Its used for all plastics such as cowlings, canopies, extras .. due to its excellent bond strength and light weight ... and its SAFE use on plastics.

 

[Dipper]

I think I will be OK for three years, don''t you?

As one of the doom merchants I would say that providing it is well bonded onto the hull that wouldn't be a problem. That will take over the function of the flange and nut.

 

[webcraft]

Regardless of what you read from others - PU does NOT eat plastics ...... just make sure you have the Exterior Grade which is Seawater Proof ...

Just for info : PU glue is a common glue used in modelling ... particularly for Foam Sheet based models ... where even the solvent in Contact Glue will eat through. Its used for all plastics such as cowlings, canopies, extras .. due to its excellent bond strength and light weight ... and its SAFE use on plastics.

I am talking PU sealant, not glue, eg Sikaflex, CT1 etc as used for all my other thru-hulls.

Which others on here seem to be saying will make the NASA through-hull brittle and cause the flange to fall off.


- W

 

[pvb]

I am talking PU sealant, not glue, eg Sikaflex, CT1 etc as used for all my other thru-hulls.

Which others on here seem to be saying will make the NASA through-hull brittle and cause the flange to fall off.

Nasa specifically advise against using conventional mastics (eg Sikaflex, which is polyurethane based), and say only to use silicone sealant. Why would they say this. unless in their experience PU had been found to attack whatever grade of plastic they use? Feel free to use whatever you like, but don't grumble later if you get a problem.

 

[Refueler]

I am talking PU sealant, not glue, eg Sikaflex, CT1 etc as used for all my other thru-hulls.

Which others on here seem to be saying will make the NASA through-hull brittle and cause the flange to fall off.


- W

I have actually maintained in all posts PU Glue ... not sealant. Problem with Sealants - is that they are designed to do a different job and that can mean introduction of other chemicals ..

Your later posts only say PU ... so I apologise for assuming glue ...

 

[webcraft]

Nasa specifically advise against using conventional mastics (eg Sikaflex, which is polyurethane based), and say only to use silicone sealant. Why would they say this. unless in their experience PU had been found to attack whatever grade of plastic they use? Feel free to use whatever you like, but don't grumble later if you get a problem.

I am curious as to how long 'later' might be. And I hadn't planned to grumble. Using mastic now will save me nearly £300 that I do not have, and I can redo it with silicon at my leisure in a year or two when the boat is out of the water in the natural course of events.

Interestingly, NASA say 'proprietor silicon sealant' without naming any specific products.

Has anyone here sealed their NASA through-hull with sika or similar?

- W

 

[pvb]

I am curious as to how long 'later' might be. And I hadn't planned to grumble. Using mastic now will save me nearly £300 that I do not have, and I can redo it with silicon at my leisure in a year or two when the boat is out of the water in the natural course of events.

Have you asked Nasa for their advice?

 

[webcraft]

Have you asked Nasa for their advice?

I'm going to give them a ring before I do the job, but I doubt they will do more than refer me to the instruction sheet.

My sealant of choice is CT1, which claims to contain no petroleum products and is specifically recommended for bonding plastics.

- W

 

[Rhylsailer99]

After reading all this have I messed up using sikaflex 291i
As I installed one a few months ago.

 

[ghostlymoron]

After reading all this have I messed up using sikaflex 291i
As I installed one a few months ago.

Yes . It's always best to stick to manufacturer's instructions partly because they presumably base this on knowledge they have of the materials used and second to not provide a get out if anything goes wrong.

 

[webcraft]

After reading all this have I messed up using sikaflex 291i
As I installed one a few months ago.

I would not worry too much as I am sure hundreds of these have been installed using mastic type sealants. I would glass it into the hull as per recommendations and leave it for a few years. At least with it glassed in there is no possibility of a disaster.

Perhaps ring NASA and see what they say?

- W

 

[webcraft]

Yes . It's always best to stick to manufacturer's instructions partly because they presumably base this on knowledge they have of the materials used and second to not provide a get out if anything goes wrong.

I don't think an insurance claim against NASA if your boat sinks is going to stand much chance. If they contested it (a certainty I would think) you would have to prove the flange failed and prove what sealant you used.

- W

 

[Rhylsailer99]

I would not worry too much as I am sure hundreds of these have been installed using mastic type sealants. I would glass it into the hull as per recommendations and leave it for a few years. At least with it glassed in there is no possibility of a disaster.

Perhaps ring NASA and see what they say?

- W

I had 3m 5200 left over and used that to seal it in place over the top inside the boat.

 

[Refueler]

I had 3m 5200 left over and used that to seal it in place over the top inside the boat.

Oh Dear ... you'll be Hung, Drawn and 1/4'd for using a Polyurethane Adhesive / Sealant !!

 

[Refueler]

One of the factors to bear in mind when fitting the tube ... is later on.

I know I am not only one who has fallen foul of the 'sealant' only method ... the Echopilot tube I have as I said was fitted based on recc'd - instead of my following my 'preferred' way. Echopilot say to use "bedding sealant and to not overtighten the nut" .... no mention of glassing or other fixing. (So much for Manufacturer's instructions !! )
That's fine until the time you want to remove the sender and find as I did that the tube moves slightly breaking the seal ... then its cure the leak. Even if you regularly extract the sender - eventually it will happen.
Nasa's recc'd to glass the tube is not a bad route to take as then the tube is fixed and you can then extract sender with a lot less risk of breaking seal.
Its also less risk of twist and damaging the flange as some have had.

 

[Corribee Boy]

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.

 

[alahol2]

My sealant of choice is CT1, which claims to contain no petroleum products and is specifically recommended for bonding plastics.
- W

I installed a NASA log about 14 years ago. Used CT1 as the sealant then epoxy filler to cover the fixing nut and a way up the thread. This spring I had to remove it in order to replace with a NASA electromagnetic speed transponder. The through hull was rock solid and has never leaked since installation.
The new through hull was fitted in exactly the same way but the sealant is now called OB1.

Very pleased with the EM transponder by the way, it's still working fine. By now the paddlewheel transponder would have stopped 2 or 3 times and required cleaning.

 

[Refueler]

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.

As shown in another thread ... my Echopilot developed a crack in the sender itself .....

>>>>>>>
So I try all sorts but no real success ... so today I pulled the log ... braved the water geyser !! to check the crack in the log body. Just to make sure that wasn't letting water past the O rings.
Through hull blanked - still leaking so it is the through hull.

Decided to seal the crack with waterproof PU ... it expands to fill all cracks etc. 0 then you sand it to form.

With PU in the crack ... let it foam and set ... then sand back ..

<<<<<<<<

Holding fine .... whether I swap out for the Nasa Clipper gear I have new in box depends how it is when I lift out for winter ...

 

[Alfie168]

I installed a NASA log about 14 years ago. Used CT1 as the sealant then epoxy filler to cover the fixing nut and a way up the thread. This spring I had to remove it in order to replace with a NASA electromagnetic speed transponder. The through hull was rock solid and has never leaked since installation.
The new through hull was fitted in exactly the same way but the sealant is now called OB1.

Very pleased with the EM transponder by the way, it's still working fine. By now the paddlewheel transponder would have stopped 2 or 3 times and required cleaning.

Does the new EM sender work on paddlewheel driven clipper instruments or does it need a complete replacement head and sender?