Mistake when installing thruhulls (Trudesign)

[Usangi]

I've just come back from the boat after installing Trudesign thruhulls, and suddenly realised I made a mistake. I hope it's not too serious as I'm very constrained by time (and energy!) before the boat needs to go back in the water.

Am using Sikaflex 291i, and was following the Trudesign instructions But then I decided to put the sealant on top of the washer and threads above it to secure the nut. I then tightly wound the nut down with my fingers, thinking I would then put another turn on with a spanner the next day. And so I've just realised that I won't be able to put this turn on now that the nut is bonded to the threads and washer. Very silly and my erroneous thinking was the more sealant the better!

I used a liberal amount of Sika, and I finger-tightened the nut pretty tightly. While not ideal, would this likely be enough for the thruhulls to be watertight?

 

[lektran]

Thats exactly how I just installed my new triducer and was as per the instructions. I can't imagine it being a problem.

 

[LittleSister]

I've just come back from the boat after installing Trudesign thruhulls, and suddenly realised I made a mistake. I hope it's not too serious as I'm very constrained by time (and energy!) before the boat needs to go back in the water.

Am using Sikaflex 291i, and was following the Trudesign instructions But then I decided to put the sealant on top of the washer and threads above it to secure the nut. I then tightly wound the nut down with my fingers, thinking I would then put another turn on with a spanner the next day. And so I've just realised that I won't be able to put this turn on now that the nut is bonded to the threads and washer. Very silly and my erroneous thinking was the more sealant the better!

I used a liberal amount of Sika, and I finger-tightened the nut pretty tightly. While not ideal, would this likely be enough for the thruhulls to be watertight?

I think it's very likely to be fine, but do (a) give the through hull a fairly brutal pull this way and that to make sure it is genuinely secure, and (b) check carefully for leaks when launching. There is the potential for either the fitting to be only loosely fitted, and (something different) for inadequate sealant between faces to allow water to pass between the through-hull and the hull.

Paradoxically, the more sealant you put on, the more likely it is that either of these situations could arise. The thickness of sealant in one place around the fitting may have prevented your hand tightening squeezing the parts together adequately to take up (a) any potential movement or (b) close up any air gaps in the seal.

It's a shame that you didn't tighten it down with a spanner at the time. In my view you need maximum compression available before the sealant sets (assuming its a setting sealant) and that in such cases the idea of leaving it a bit loose and tightening more later is a load of cobblers. You also need only enough sealant to actually make the seal (it's weaker than your fittings and hull in any thickness), plus just enough so that you can see that a small surplus has squeezed out of every visible edge so that you know you have complete coverage where it matters.

I'm also agin the use of highly adhesive sealants, except in specialist applications, having been the victim of previous owners' applications of the stuff for no apparent reason on various boats. Using it on through hulls is fine, in my view, only if you think your through-hull will last forever, and also never need its size or position changing for any reason.

Because you've (I think) used high adhesive sealant, if you find you can move your fitting at all when putting strong side loads on it, or that it leaks significantly, you will need to destroy the fitting to extract it from the hull - ask for advice on here how best and easiest to do that if you haven't done it before - and fit a new one. Good luck with cleaning off the old adhesive sealant - you'll need it!

If you have just a tiny leak - no more than a weep - don't worry about it (though do check it doesn't soon get worse), as it will eventually seal itself with crud and stop.

 

[Tranona]

Much more important is the seal between the skin fitting and the hull as this is the path for water into the hull.

 

[LittleSister]

Much more important is the seal between the skin fitting and the hull as this is the path for water into the hull.

That's true, but my concern is that excessive sealant inside, combined with the lack of adequate tightening, may perhaps have prevented an adequate seal being formed there (and also that the rigidity of the structure should be achieved by the fitting being tightly clamped to the hull, not by any appreciable thickness of sealant).

 

[Usangi]

Thanks so much for your replies (and the reassurance!). @LittleSister Thanks also for mentioning about the possibility of a small weep clearing itself up.

Fingers crossed it'll all be dry when dropped in.

I'm now heading to the boat to put the seacocks and other fittings together. I am using Loctite 5331 for all of this. Any tips or advice? For instance, amount of sealant I apply? Or anything else?

BTW, I've already dry-fitted them to ensure the handles end up in the right place.

 

[dankilb]

I'm now heading to the boat to put the seacocks and other fittings together. I am using Loctite 5331 for all of this. Any tips or advice? For instance, amount of sealant I apply? Or anything else?

I had one (of 6) of our new TD fittings leak at the joint between the ball valve and the skin fitting with 5331. I had followed their instructions to apply to something like 1/3 the circumstances of the thread. Upon removal there was barely any visible sealant remaining.

I reinstalled with a liberal smear of sealant around the entire female thread of the ball valve.

This was a 1 1/2” fitting so watch out for the bigger threads.

 

[Usangi]

I had one (of 6) of our new TD fittings leak at the joint between the ball valve and the skin fitting with 5331. I had followed their instructions to apply to something like 1/3 the circumstances of the thread. Upon removal there was barely any visible sealant remaining.

I reinstalled with a liberal smear of sealant around the entire female thread of the ball valve.

This was a 1 1/2” fitting so watch out for the bigger threads.

Thanks, very helpful. And do you know if it’s ok to hand tighten the ball valves? This is how I dry fitted them so the handles would be in right place.

 

[Never Grumble]

Thanks, very helpful. And do you know if it’s ok to hand tighten the ball valves? This is how I dry fitted them so the handles would be in right place.

I replaced a couple of mine with TruDesign this year, I presume you have marked the skin fitting so it goes back in the correct orientation i.e. same place as when you dry fitted. I used 291i which I believe is one of the listed adhesive sealants to use between skin fitting and valve, I did them up by hand, that seemed tight enough to me. Also the skin fitting you haven't been able to tighten down if you tighten the valve onto that too much I would have thought there could be potential for you to ruin the seal with the hull if it turns. Good luck.

 

[dankilb]

Thanks, very helpful. And do you know if it’s ok to hand tighten the ball valves? This is how I dry fitted them so the handles would be in right place.

Yup hand tighten is the idea. The 5331 does cure to a ‘hand tool breakable’ adhesive bond (nothing like as strong as Sika 291) and does not need to rely on being a tightened all the way.

With these the trick is to move them as little as possible. I counted the number of turns it took to get my handles in position ‘dry’ so there was less risk of having to back off half a turn. That way the sealant stays in the threads.

 

[Fr J Hackett]

Why would you want to put either sikaflex or locktite on such fittings the question that occurs to me. At some point in the future they will need to be either maintained or replaced and I forsee a post asking how to remove bonded through hulls without damaging the hull and / or existing holes and fittings. Through hull fittings don't require such treatment.

 

[Usangi]

I replaced a couple of mine with TruDesign this year, I presume you have marked the skin fitting so it goes back in the correct orientation i.e. same place as when you dry fitted. I used 291i which I believe is one of the listed adhesive sealants to use between skin fitting and valve, I did them up by hand, that seemed tight enough to me. Also the skin fitting you haven't been able to tighten down if you tighten the valve onto that too much I would have thought there could be potential for you to ruin the seal with the hull if it turns. Good luck.

Great thanks. I will tighten as I did for dry fitting, I.e. hand tighten. And yes, marked hull so handles should end up in right position

 

[Usangi]

Why would you want to put either sikaflex or locktite on such fittings the question that occurs to me. At some point in the future they will need to be either maintained or replaced and I force a post asking how to remove bonded through hulls without damaging the hull and / or existing holes and fittings. Through hull fittings don't require such treatment.

I did quite a lot of research and many (including Trudesign themseleves) recommended Sikaflex 291i on thruhull fittings and loctite on everything else (valve to thruhull etc).

And it seemed reasonable advice.

I’m just hoping my mistake with the thruhulls won’t lead to me having to pull the boat out again soon to replace. If so, I do anticipate a lot of cursing and questioning of my decisions!

 

[Fr J Hackett]

I did quite a lot of research and many (including Trudesign themseleves) recommended Sikaflex 291i on thruhull fittings and loctite on everything else (valve to thruhull etc).

And it seemed reasonable advice.

I’m just hoping my mistake with the thruhulls won’t lead to me having to pull the boat out again soon to replace. If so, I do anticipate a lot of cursing and questioning of my decisions!

Having over the years ( many) fitted and removed many through hulls from bronze to nylon I have used Sikaflex as a sealant between hull, hole and fitting but never found it necessary to use it or locktight on the internal threads other than a small smear of seakaflex between flange or washer of the nut and the hull. None ever failed and were simple to service and or replace.

 

[Usangi]

Having over the years ( many) fitted and removed many through hulls from bronze to nylon I have used Sikaflex as a sealant between hull, hole and fitting but never found it necessary to use it or locktight on the internal threads other than a small smear of seakaflex between flange or washer of the nut and the hull. None ever failed and were simple to service and or replace.

I’m completely new to this so I am sure your way is very sound. I’m perhaps misunderstanding you here but you don’t use any sealant between the thruhull and the ball valve? This is where I plan to use loctite. I’ve read about a lot of leaks here if not enough sealant is used or if not smeared around both male and female threads?

 

[Fr J Hackett]

I’m completely new to this so I am sure your way is very sound. I’m perhaps misunderstanding you here but you don’t use any sealant between the thruhull and the ball valve? This is where I plan to use loctite. I’ve read about a lot of leaks here if not enough sealant is used or if not smeared around both male and female threads?

No I have never and never heard of anyone using sealant between (on the threads) through hull and valve although that is not to say that some do. Loctite is not a sealant and its use will make removing the valve from the through hull in the future difficult.

 

[dankilb]

No I have never and never heard of anyone using sealant between (on the threads) through hull and valve although that is not to say that some do. Loctite is not a sealant and its use will make removing the valve from the through hull in the future difficult.

They don’t seal without thread sealant. It’s a parallel thread!

Loctite 5331 is a pure silicon plumbing thread sealant. Commonly used. Recommended by Tru Design. Easy to remove.

 

[Fr J Hackett]

They don’t seal without thread sealant. It’s a parallel thread!

Loctite 5331 is a pure silicon plumbing thread sealant. Commonly used. Recommended by Tru Design. Easy to remove.

I was mistaking it for what the name of the company is wore well known for a locking product for threads as opposed to a sealant. Parallel or not with several turns threads will be water tight. However if the suppler recommends it then why not. But I reiterate there is no need nor is it advisable to use anything other than a counter nut or locking washer to use anything to, secure such fittings and I take the point that the lactate product mentioned does not do that, my error. An alternative if it was found necessary would be thread seal ( teflon tape).

 

[Wansworth]

What did boatbuilders use say backin the 1950s seems very complicated these days

 

[Fr J Hackett]

What did boatbuilders use say backin the 1950s seems very complicated these days

Wooden boats not so many through hulls but I guess a few twists of hemp or other caulking and some soft red lead putty.