Will Sikaflex Set in Cold Weather ?

[Jon magowan]

My boat (10m Bavaria) is coming out of the water this week (7th December) for the first time in my ownership. I plan to change the two through hulls that the surveyor recommended changing.
I have two Tru Design fittings and a tube of Sikaflex295i to do the job.
Im worried about whether it’s a good idea to do this during the cold snap we’re experiencing at the moment. The forecast temperature in Plymouth over the next week or so is single figures, so consistently less than 10 degrees Celsius.
My question is, will this temperature seriously compromise the integrity of the Sikaflex curing ?
Im sure Sikaflex will advise waiting for warmer weather but just how crucial is that ?
Also, as a total newbie to all these, can someone explain why we don’t simply use epoxy for a job like this ?

 

[penberth3]

My boat (10m Bavaria) is coming out of the water this week (7th December) for the first time in my ownership. I plan to change the two through hulls that the surveyor recommended changing.
I have two Tru Design fittings and a tube of Sikaflex295i to do the job.
Im worried about whether it’s a good idea to do this during the cold snap we’re experiencing at the moment. The forecast temperature in Plymouth over the next week or so is single figures, so consistently less than 10 degrees Celsius.
My question is, will this temperature seriously compromise the integrity of the Sikaflex curing ?
Im sure Sikaflex will advise waiting for warmer weather but just how crucial is that ?
Also, as a total newbie to all these, can someone explain why we don’t simply use epoxy for a job like this ?

Er, have you read the Sikaflex data sheet???

 

[lustyd]

295 cures with atmospheric moisture so yes it eventually will. They specify 10C minimum temp though

 

[lustyd]

Far more importantly, that’s the wrong goop for the job.
https://trudesignplastics-com.s3.am.../docs/57/6389b4fd615839f67ea01c49a9b9c545.pdf

 

[ShinyShoe]

They do indeed say >10C. If it wasn't in a critical area I'd chance it.

Thickness to cure matters.
Time matter
Temp matters
(All on the datasheet Sikaflex®-291i | Sika Industry https://industry.sika.com/content/dam/dms/nz01/m/sikaflex_-291i.pdf )

If it's a thin area can anything be done to make that area warm for a few hours?

The reason for sikka and not epoxy is epoxy has no flex.

 

[ShinyShoe]

Far more importantly, that’s the wrong goop for the job.
https://trudesignplastics-com.s3.am.../docs/57/6389b4fd615839f67ea01c49a9b9c545.pdf

Interesting that says let cure for 2hrs before fitting valves. How long should you wait for colder...

 

[lustyd]

All on the datasheet Sikaflex®-291i

Being pedantic, OP said 295 so that’s the wrong data sheet but you did select the product TruDesign specify and one approved by Lloyds and therefore insurance.

 

[lustyd]

Interesting that says let cure for 2hrs before fitting valves. How long should you wait for colder...

The air is also “drier” in winter so yes very probably longer. I would and did go for overnight before moving on to valves when I did it in May.
Don’t use Sika for the valves!

 

[Jon magowan]

Very sorry, my mistake. It’s Sikaflex 291i that I’ve got, as per Tru Design recommendation.

 

[lustyd]

In that case I’d go for overnight. If the boat is staying out wait for it to not be freezing, it’s fine to leave a hole for a while just don’t launch before fitting so do something to prevent that happening.
If you don’t have some, buy stilsons which are enormous pipe wrenches. This is vastly preferable to the grinder method which I found ineffective, time consuming, dirty, and got the fitting hot enough to boil the old sealant.

Stilson will remove the old valve easily and the nut and will be useful to push the old skin fitting around to break the old sealant. Standing on the old skin fitting usually pushes them out.

 

[thinwater]

Charles Stilson invented and patented the modern pipe wrench in 1869. A Stilson wrench is a style, not a size.

Yup, good approach, if there is room. This is the sort of thing they are made for.

 

[lustyd]

Yes good point. I bought two sizes when working on my through hulls. I was saying Stilson since in the UK it’s easier to find info with that term

 

[Jon magowan]

Thanks everyone.
Great input as usual !

 

[lustyd]

if using the collars make sure you measure and cut the through hulls before installing. Be prepared with something good to cut them with that “plastic” is very tough. A good hacksaw blade, grinder blade or multi tool will do it but even then I was surprised how long it took. Useful to plan a way to cut them square too

 

[thalassa]

I've used Loctite 55 sealing thread cord in January. Instant result, still not leaking after seven years. And the remainder of the buy didn't go off...

 

[thinwater]

Yes good point. I bought two sizes when working on my through hulls. I was saying Stilson since in the UK it’s easier to find info with that term

Interestingly, even though Stilson was an American, the style is now simply called a pipe wrench, with Rigid being the premier manufacture. Other pipe wrench styles (chain and strap wrenches, for example, are identified by type. Aluminum handle wrenches have taken over the pro market, because they are SO MUCH easier to use all day.

 

[justanothersailboat]

"the air is also drier in winter" - I know the theory but the experience of my last couple of boatyard days says no.

For what it's worth, my sika 291 has been setting up well this weekend and last. (it's not so easy to get out of the tube at one degree c though)

 

[lustyd]

"the air is also drier in winter" - I know the theory but the experience of my last couple of boatyard days says no.

For what it's worth, my sika 291 has been setting up well this weekend and last. (it's not so easy to get out of the tube at one degree c though)

Less humid and its humidity that cures it rather than water. Arguably you’d want it slow enough to cure through before it seals the moisture out so really I have no idea what’s best

 

[Neeves]

I'm not entirely sure of the application, or I'm sure of the application but not the fine detail.

If you fit the skin fitting and the yacht goes back in the water the Sika is viscous enough to offer a water tight seal, once skinned, and as long as you don't try to operate the valves nor knock them. Once in the water the temperature will rise, the water is not freezing, and the Sika will continue to set off, slowly. A few days later I have always tightened the through hull, maybe a quarter turn, to compress the set Sika. You want to tighten, and not everyone agrees it is useful, when the Sika has set off - as the set Sika will now hold the fitting when you turn the flange. If you are impatient you might break the seal if the Sika has not set right through. If the tube is at 1 degree C it WILL be difficult to work with, just stick the tube in the sun, or warm water.

I have heard of people actually fitting through hull fittings - in the water. Its a bit wet but apparently works. I fitted a new transducer between tides without issue (in warm Sydney) and because of the thickness of hull fittings I am sure the Sika did not set off between the tides - but cured - under water. Loctite also works with water and will also set off under water, not only atmospheric water, and is sufficiently strong set under water as in the atmosphere. Adhesives Test - Practical Sailor.

I only ever knew Stilsons as Stilsons, not as pipe wrenches. Many devices can be used as and called pipe wrenches but they are not Stilsons. Mine are made in China and I have a small one maybe 300mm long and an even smaller one 150mm (length can be increased with a suitable piece of steel pipe). I know of really big ones - but never had the need to use one. I find them a bit coarse for hull fittings and prefer a Plumbers wrench, this sort of thing https://www.aliexpress.com/item/100...ab7cd244bebba4bcad0e0bac463&afSmartRedirect=y.

Jonathan

 

[lustyd]

A few days later I have always tightened the through hull, maybe a quarter turn, to compress the set Sika. You want to tighten, and not everyone agrees it is useful, when the Sika has set off

I strongly disagree with this guidance, the TruDesign fittings are extremely difficult to hold still so any attempt to tighten the nut is more likely to break the seal than improve it. The nut at this point is very likely also covered in Sika anyway, and underneath a collar.

That plumbers wrench is useless for removal of the large nuts on through hulls but a useful tool for holding the hoses still.