tru design through hull installation dilemma

Matwill

Matwill

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Hi Guys,

Im installing a tru design through hull however i have an issue with installation space, i can install the outlet elbow or the ball valve onto the through hull, but not both at the same time, its out by about 5mm on the elbow when it turns on the aft side.

I was thinking i could 5200 the nut and washer in place, then screw in the through hull directly into the ball valve from the outside of the hull, the issue i see would be a radial squeeze of the 5200 rather then just doing it normally which would be to use the nut to pull it

Would my idea work? What do people think.

1624898683785.png
 
the threw hull is not the issue, its the collar, ball valve and elbow assembly that is too long when its not flush against the hull.

Getting it off later isnt an issue since you can grind off the outer face of the through hull which costs about 6 bux and it will come out.
 
This is a common problem when fitting Tru Design in place of metal fittings as they are not all dimensionally the same.

No reason why your plan should not work if the adhesive is fully cured. Presumably you are going to seal the skin fitting to the hull in the same way. Only thing to watch is that the ball valve needs to be tight on the skin fitting so it does not move when you operate it.
 
I would either not use the collar as I understand many do and shorten the through hul, you are only looking at 5mm and will gain space when you start fitting. If you want to use the collar shorten this by the same
 
How about mount the skin fitting first in the normal manner. Then screw on the ball valve and collar without the hosetail on it. You could then trim 5mm off the thread of the hose tail to gain your clearance. Safer to trim the hose tail than anything on the sea side of the valve.
 
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Bouba said:
What about a thru hull with a 90 degree bend
Click to expand...

yes there was a smaller version of this there before i pulled it out, i particularly wanted the tru design with he collar since this through hull is in the bilge in the middle of the cabin and if the boards came up and you accidently stepped on it and it broke off I would have a very bad day.

If my plan doesn't work or I'm not happy with it ill go back to a bronze fitting.
 
We had one that was a little easily stood on when boards were up, made a small cover that went over, easily lifted when needed
 
Bouba said:
What about a thru hull with a 90 degree bend
Click to expand...
If you want to protect something like this from abuse like getting trod on, then a block of wood and a pipe saddle around the bit labelled 'yellow brass' will prevent the thru hull seeing any excessive leverage.

If you prefer the collar, you could make a thinner one.
 
Matwill said:
yes there was a smaller version of this there before i pulled it out, i particularly wanted the tru design with he collar since this through hull is in the bilge in the middle of the cabin and if the boards came up and you accidently stepped on it and it broke off I would have a very bad day.

If my plan doesn't work or I'm not happy with it ill go back to a bronze fitting.
Click to expand...

I had the same thought about mine but when I contacted Trudesign they were very certain that an uncollared fitting was more than strong enough to stand on. I think they said the collar was a requirement for the American market but wasn't really necessary.
They were very helpful and their website has a lot of information.
 
CJU said:
I had the same thought about mine but when I contacted Trudesign they were very certain that an uncollared fitting was more than strong enough to stand on. I think they said the collar was a requirement for the American market but wasn't really necessary.
They were very helpful and their website has a lot of information.
Click to expand...

Indeed, I enquired about adding collars to our existing trudesign fittings. Basically the answer was "don't bother", they're more than strong enough without and the collar was simply introduced to allow new-builds to pass ABYC requirements, and thus allow boat-builders to spec. TruDesign more easily.
 
Matwill said:
Hi Guys,

Im installing a tru design through hull however i have an issue with installation space, i can install the outlet elbow or the ball valve onto the through hull, but not both at the same time, its out by about 5mm on the elbow when it turns on the aft side.

I was thinking i could 5200 the nut and washer in place, then screw in the through hull directly into the ball valve from the outside of the hull, the issue i see would be a radial squeeze of the 5200 rather then just doing it normally which would be to use the nut to pull it

Would my idea work? What do people think.

View attachment 118030
Click to expand...

I have recently installed TruDesign valves and had exactly your issue. I made the valve and tail up with sikaflex and allowed that to set. I bedded the nut down with sikaflex then with a helper screwed the through hull in from the outside into the fitting. Finally the nut was tightened down. I decided not use the collars which would have made it impossible to tighten the nuts.






Bouba said:
What about a thru hull with a 90 degree bend
Click to expand...

It was mainly to get rid of the elbows on the outside of the valves like that, that I was replacing the fittings. TruedDesign specifically state not to use elbows outside the valves below the waterline.
 
So i went down to the boat again today and did some tests, if the through hull is about this length then I can install it with the collar on, - if not I can install it with the collar off if i shimmy the valve down as i install the nut

IMG_20210630_073005885.jpgIMG_20210630_071135704.jpg
 
The 42DS aft. head installation has a similar problem. There's a 90 degree elbow on the skin-fitting and a straight hosetail, whereas you have the opposite. I imagine you could use the same arrangement but it wouldn't solve the problem as you'd still be unable to screw on the valve. :D

I came across some of these at a good price in Spain but wasn't convinced they could be fitted. However, the guy pointed to an identical 42DS in the yard and explained how to fit it. I had a look at that boat and could see the new skin-fitting. He explained the process and it is pretty much what you are suggesting.

1) Dry fit everything and trim off a small amount from any threads where clearance is going to prevent installation
2) Assemble the elbow, valve and hosetail using the proper sealant (they used a Soudal product)
3) Dry fit other end of elbow and skin-fitting to allow adjustment of the valve into correct position and leave to set
4) Dismantle, apply sealant to elbow and skin-fitting (hull & threads) before tightening in final position.

It sounds easy enough to do step by step but you do need a person outside rotating the fitting to screw it onto the elbow and then hold it as the person inside spins the nut home. I imagine it will then be a bit fiddly adjusting the assembly whilst tightening down the nut. The guy in the yard said it wasn't difficult as long as you can keep the skin-fitting steady whilst tightening. He said the hole should be snug and to use plenty of sealant. The final tightening is done with the nut internally and the skin-fitting held to prevent radial movement. That part is just what you'd usually do and should seal as long as there's excess sealant prior to pulling the fitting inwards for the last part.

You would obviously change the order to suit if fitting the valve without an elbow on the skin-fitting. I'm not using a collar and have a large amount of spare thread. No chance of standing on anything in my case as it is all inside a box under the base of the loo.
 
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