Replacing seacocks

[coopec]

On another forum people asked me in bewilderment why my through hulls were SS. Everybody it seemed was using TruDesign. When comes to replacing mine it will be more than likely I'll use TruDesign.


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How does TruDesign compare with Marelon???

What Marelon Is

 

[Tranona]

There is a lot of confusing information on this thread. Replacement with all DZR fittings and ball valves is the simplest and most effective approach. They will not dezincify or fail provided they are exercised regularly to prevent deposits building up on the ball - this applies to all ball valves. The main alternative is TruDesign composite valves which will also last indefinitely. They are direct replacements in terms of hole and thread sizes, but physically the bodies are larger which may make installation difficult in confined spaces (but not in the ones in the photo). They are generally a bit more expensive than DZR. Marelon are also composite but are a very different design and not direct replacement requiring different size holes in the hull. For this reason (and high cost) they are not common in the UK. Blakes are the most common cone type valves and are also made of DZR (and have been for over 30 years). However they not direct replacements, only available in 2 sizes (3/4 and 1 1/2, not the 1/2" the OP needs for at least one) because they were made for use with Blakes sea toilets and they are well over twice the price of DZR ball valves. TruDesign valves should not be confused with the plastic valves used in waste tank systems which are totally different material and construction.

Post#2 is good advice as is subsequent advice to grind the outer flange off, pull the whole assembly out from inside and replace with all DZR or TruDesign

 

[bobgarrett]

I agree trudesign fittings are better and replaced those through hulls and sea cocks where there was room for these last year but where they are too big I am not using dzr. The problem is the cold for the sealant with relaunch scheduled for next week. I may have to delay...

 

[Plum]

If you are going to replace your seacocks with the metal ball valve type, in my opinion it is only a matter of time before they fail again. Despite greasing from below, my seacocks would eventually become stiff and then seize, even with regular exercising. I can’t speak for plastic seacocks as I’ve no experience of them. As Birdseye already commented, Blakes seacocks seem to last forever as it is so easy to strip them down for service. Also, as they are bolted into position, you can be sure your skin fitting will never budge.

Hmm. Not in my experience. I used DZR ball valves from ASAP Supplies and they are still perfect after 15 years with zero maintenance.

Www.solocoastalsailing.co.uk

 

[Boathook]

Good quality ball valves designed for the job and operated on a regular basis have a long life span and as far as I could see the tru design is one of them.

 

[vyv_cox]

If it is too cold for sikaflex 291i for sealing a skin fitting and sealing between skin fitting and sea cock what sealant is suitable?

The product leaflet says ambient temperature and suggests 10 - 40 C. I doubt if a few degrees below 10 C would make a significant difference.

I use Sikaflex 291 or Puraflex 40 for just about every sealing job on board. Some of my skin fittings have been in situ for very many years without leaks or other problems. I guess that several were installed at less than 10 C.

 

[wingcommander]

Just done mine with new through hulls . I found easiest way was to use a step drill cone from outside. The flange will usually spin once your through, if not a gentle tap will remove, then simply pull away inside. No damage at all to fibreglass surrounding. I would double up on the jubilee clips also if not already considered

 

[tompug]

Hi again,
So I was able to unscrew the old fittings out of the hull without too much trouble. But it turns out that they were countersunk in on the outside. A good 5-6 mm depth in a hull thickness of about 10mm. This gives me two problems. One, it doesn't leave much hull thickness, which I don't like so much. Two, the replacement fittings I can find have different head dimensions, so I can't just swap in a new one anyway (I am planning to put in TruDesign, but the DZR ones I find also all have wider heads than the ones taken out). I am thinking that the best approach could be to build up the countersinking and install a normal domed fitting on top. I am not sure how best to do this though. Is it enough to just use epoxy filler?

 

[bignick]

An alternative to rebuilding the grp on the outside would be to epoxy a large grp backing pad on the inside of the hull. I wouldn’t just put epoxy filler on the outside as that wouldn’t add as much strength as you would think.

 

[Spirit (of Glenans)]

As the gate valves are probably brass not bronze or DZR there is a fair chance the skin fittings might also be brass. I'd change the lot either for DZR or bronze, or plastic Marelon fittings. Careful angle grinding from outside the hull is probably the easiest way to get them off.

I found that the best technique to use, when removing them with the angle-grinder, is to attack the circumference of the hole, from the outside, so that you detach the flange from the cylindrical part of the through-hull without damaging any GRP.

 

[Bandit]

Gate valves and brass fittings have no place on a boat in salt water, it is a disgrace, they look quite old and they are leaking.
When you remove the fittings you may well find some components crumble. Gate valves apart from seizing you can often turn the handle but the gate does not open or close.

I would replace all the fittings, skin fittings,ball valves, tails and bends with DZR. Label all with a plastic tag and cable tie stating date. do the whole boat , inspect and check them each year and replace after 7 years. That way you can demonstrate proper maintenance.
Obviously do it with the boat out of the water.