Which Sikaflex to bed new thru hull fittings?

I used the 291i about 2 yrs ago to bed in all my through hull fittings, and have noticed the sikaflex has gone soft. I can't understand why this has happened, it was solid, and now it has broken down, and went soft.
It is a mystery to me, and a bit worrying.
 
I've started to avoid using Sika in the yard and on my boat so much and have taken to using Arboseal Butyl Glazing Tape instead.
If you don't need the adhesive quality, ie, the fitting is bolted down, then the Butyl Glazing Tape provides a far better seal over time, much cleaner to use and when you come to remove it there's no mess.
 
Javelin said:
I've started to avoid using Sika in the yard and on my boat so much and have taken to using Arboseal Butyl Glazing Tape instead.
If you don't need the adhesive quality, ie, the fitting is bolted down, then the Butyl Glazing Tape provides a far better seal over time, much cleaner to use and when you come to remove it there's no mess.
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Interesting. I've got some through-hulls to install, and since replacing all deck fittings using butyl tape with great success, I have been strongly considering this option myself. Can't find much relevent info on the web though, so may I ask how successful your job has been? How long have you been using butyl below the water-line?
 
PlankWalker said:
Great stuff, but I cant find a chandlery that stocks it?
Click to expand...

It wasn't imported (from the US) for a while, but a fe places have it now, and it's fairly easy to find by mail order.

Javelin said:
Not good on teak though
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Possibly not a major issue on through-hull fittings, but why not, as a matter of interest? A quick google turns up one person saying "don't use it", without giving reasons, and a lot of people saying "use it".

Polysulfide adheres well to teak (a special primer improves adhesion), and is unaffected by harsh teak cleaners, making it the best choice for bedding teak rails and trim. The black caulking between the planks of a teak deck is invariably polysulfide. For this application, a two-part polysulfide gives the best results. Polysulfide is the slowest curing of the three sealant types, often taking a week or more to reach full cure. Because it will adhere to almost anything, polysulfide has a maddening propensity to get on everything, so neatness is called for in using this sealant. Polysulfide sealants will have polysulfide printed on the package, or sometimes Thiokol--the trademark for the polymer that is the main ingredient of all polysulfide sealants regardless of manufacturer.

http://www.boatus.com/boattech/casey/sealant.asp​
 
I have used Sikaflex 291 for every type of sealing job above and below the water for more than 20 years. I have never found a problem with it, except that it is quite expensive and doesn't last for ever once the tube has beeen opened. A couple of years ago I tried PU40 from Toolstation. It appears to be the same, or very similar, stuff and works just as well at about 40% of the cost.

Several people reported softening problems with the Sikaflex 291i version, possibly a faulty batch?
 
vyv_cox said:
I have used Sikaflex 291 for every type of sealing job above and below the water for more than 20 years. I have never found a problem with it, except that it is quite expensive and doesn't last for ever once the tube has beeen opened. A couple of years ago I tried PU40 from Toolstation. It appears to be the same, or very similar, stuff and works just as well at about 40% of the cost.

Several people reported softening problems with the Sikaflex 291i version, possibly a faulty batch?
Click to expand...

Important to check it's still "within date". I understand from a friend that if "out of date" the result is just as reported above - i.i it goes soft.
I contacted Sika on this as I had a tube a year out of date - and expensive to throw away if still usable. Sika-man said categorically that Sika would not recommend its use at all.

I am not an expert, merely passing-on a report from a guy who (as a window installer) should know what he's talking about.
 
After many threads on various aspects of this over winter I used PU40 sealant which was recommended by a number. its cheap and available from Toolstation among other places.

I found that on Jeanneau it was not possible to assemble valve in final position so had to undo thro hull fitting, tilt the whole fitting and assemble valve with loctight, including rt angle tail etc and then as last operation tighten thro hull fitting in a position where valve can be easily operated. PU40 allowed me to overcome this cock up on my part some 16 hrs later!

Other mistake I made was not cutting thro hull fittings to length silly me thought length was standard. All now project into boat far more than the old ones.

See also old thread on loctight to use as some set over 24 hrs and one is almost instant set - not ideal.

Search facility on these forums is really good for info.
 
I've used PU40 on skin fittings. It's only drawback in this application is that it is a sealant/adhesive rather than just a sealant.This will make it more difficult to remove if ever I have to. Much cheaper than Sika though. FWIW, I've always just used PTFE tape on the threaded joints and have had no problems with them unscrewing themselves.
 
Bolted deck fittings we use Butyl rubber tape, though some of the guys still stick with Sika or Saba
Bonding / sealing jobs like windows we use SABA Sabatack and the anti UV one I can't remember what its called.
Teak deck caulking we use Saba
Skin fittings we use Saba or Sika
For flexing joints like Keel/hull joints we use Arbokol 1000

Not sure If I would have the confidence to use Butyl tape below the waterline but I guess it would be fine - certainly good above it.
 
yodave said:
How about CT1? It has the added advantage of being able to cure underwater.
Click to expand...

On the advice of someone on here I used CT1 to seal a NASA log tube and a bronze skin fitting. After 2 years in the water I inspected them and am happy to report both units are sound and satisfactory.
The original NASA log which I replaced had been sealed with Sikaflex (can't say which version as it was done by the previous owner) The log tube had failed and the flange detached around half it's circumference. Furthermore the unit had not been glassed in with epoxy on the inside as recommended by NASA. Lucky I made a thorough inspection.

Thanks to whoever advised CT1. I wouldn't use anything else now.
 
Javelin said:
I've started to avoid using Sika in the yard and on my boat so much and have taken to using Arboseal Butyl Glazing Tape instead.
If you don't need the adhesive quality, ie, the fitting is bolted down, then the Butyl Glazing Tape provides a far better seal over time, much cleaner to use and when you come to remove it there's no mess.
Click to expand...

+1. Yes yes yes. Butyl tape is the way to go. Do not use sicklyfecks
 
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