Let's revisit through hull installations

[Eastward ho 24]

Just orderd the groco, based on their reputation. Although it has a chrome plated brass ball. The bucks have a hard chrome plated bronze ball with stainless handles. The bucks seems to use superior materials designed for salt water use as compared to the groco which seem to be just a plain old run of the mill bronze valve. But oh well went with the mainstream.

[Scout 30]

Originally Posted by CarinaPDX

I can't imagine going back to the tapered seacocks. They require cleaning and greasing during haulouts, and eventually the bronze-bronze contact causes wear (fixed by carefully machining the surfaces). A modern ball valve is made of bronze, with a chrome-plated bronze ball in a Teflon seat. No lubrication is required. (And PLEASE stop using "brass" to describe "bronze" - they are two entirely different metals. Brass doesn't belong on the outside of a boat, and especially not under water. OTOH bronze things that have rested on the bottom of the Med for 4000 years are often brought up intact.)


Greg

Tapered seacocks do not need to be machined when they wear. They simply need to be lapped which is not difficult. Cleaning & greasing them is also quite simple. This type of seacock is strong & reliable and I can't imagine replacing them.

[OZwingle]

My goodness, quite the discussion.
My primary seawater intake, a Buck-Algonquin seacock is failing after 8 years. It is a proper seacock with a ball valve and triangular base flange. According Buck-Algonquin the ball is chrome plated brass. The ball valve stem and handle are stainless steel. The handle will turn 1/4 revolutions before engaging the ball. The stem and nut turn with the handle. Thus, it is not possible to fully shut the seacock. I suspect that the bass ball is corroding in contact with the stainless steel stem. Post-mortem testing when we haul the boat will reveal what is going on. Reading up on the technical specifications across manufacturers it seems that "marine" ball valves are made with brass or bronze or stainless steel as the core material of the ball.

I have not used 5200 for quite a while. It is a very good permanent adhesive, and the best choice in certain applications. I have been using polysulfide bedding compounds (LifeCaulk) both on deck and underwater with good success, that is no leaks are 8 years and yet easily removed for maintenance.

Regarding TruDesign: These are the "go-to" through hulls here in NZ. Very well designed and obviates corrosion issues. But, be mindful about the technical specifications. E.g: A nominal 1" through hull with skin fitting and valve has a 3/4" internal diameter:

http://trudesignplastics-com.s3.amaz...2782bdd860.pdf

Rand
s/v Velic
Whangarei, NZ

[rbk]

Not 100% sure but if I had to take a guess at why brass is being used in place of bronze for valve balls, would be that the chrome adheres better to brass than bronze. Seen a lot of chrome played bronze flaking, too much copper in the alloy? If the chrome stays intact the brass should never be an issue especially with he ptfe seals it should stay coated for some time as long as barnacles done take hold and start scratching up the seals and chrome.

[Eastward ho 24]

I can’t say I’ve been around a while but just from armchair surfing the web. I haven’t heard of groco ball “ ul marine” valves failing. But I have heard of the bucks seizing up. I assume that’s what’s so long lived on the taperd cone valves bronze on bronze seat with a lot of surface area and room to tighten if necessary. I just epoxied in the groco backing blocks, filled the through hull mounting holes , and put the adapters on. Seems like a better trade off to me to just be able to unscrew the ball valve every year and replace it. And if in a far off place have an extra onboard just plug the hole and change it in the water.. if my memory is correct I think the bucks use a chrome plated bronze valve and groco uses a chrome plated brass valve. The latter would seem a weaker link but appears not to be. Hopefully when properly bonded there should be no issues.i was stopped at the marina and asked if I was 5200 the through hull apaullingly ( which I am) It seems odd to me that the reasoning for not using 5200 is for ease of removal, but no one deters from 5200 for the sake of sealing failure ( it is a sealant adheasive) My reasoning is I don’t want it to be easily removed. I figure after replacing all the through hulls if they do need to be replaced in 30 yrs I don’t mind it being a major job vs 30 yrs of well slept nights. But I’m still green so I’ll live and learn hopefully more living though.

[HopCar]

Originally Posted by rbk

Not 100% sure but if I had to take a guess at why brass is being used in place of bronze for valve balls, would be that the chrome adheres better to brass than bronze. Seen a lot of chrome played bronze flaking, too much copper in the alloy? If the chrome stays intact the brass should never be an issue especially with he ptfe seals it should stay coated for some time as long as barnacles done take hold and start scratching up the seals and chrome.

You may be right about the chrome but I think the primary reason to use brass is that it is much easier to machine to a tight tolerance and a smooth surface. As you pointed out, the chrome prevents the brass from coming into contact with seawater.

I sold hundreds of Groco ball valves and ball valve seacocks. Never heard one complaint about the balls failing.

If someone doesn’t like the CP Brass ball, they can buy the Groco BV series of flanged seacock. It had a stainless ball and stem. It even has a heavy bronze handle.

[kupo2kupo]

NahanniV,

Thanks for describing your approach. I replaced all our underwater seacocks last year with Groco flange adapters, used Groco backing plates, but did not bolt through the hull. I noted your carefully worded sentence:

"[*]Thread the thru hull into the flange and screw it in gently."

That seems different to what most instructions say. Most instructions, including MaineSail's, stress to keep the mushroom stationary, and thread the flange on the mushroom. That makes sense as it seems to allow for better control of the critical bond line between mushroom and outside of hull. But, there are situations where there is not enough space to turn the flange on the inside (I did run into this). I felt that it was difficult to control for no air bubbles in the sealant between mushroom and hull when turning the mushroom, given the consistency of the Sikaflex 291.

My question: How did you control the bond line between hull and mushroom, avoiding any air bubbles in the sealant, while turning the mushroom? Do you or others have input?

Originally Posted by NahanniV

I replaced all the seacocks (some were gate valves) on my boat with the Groco Flange adapter system.
Backing plates cut from 1/2" phenolic sheet (cheap, available, easier to work).
Bronze flat head machine screws countersunk into hull with SS nuts/washers on the inside.
I used 5200 to put it all together including bedding the backing plates. I hope they will be there for the life of the boat and you CAN get them off with a bit of heat if needed.

I used a much simpler/faster approach than others have suggested, installed the backing plate, thru hull and flange in one step. But I needed a helper.

This is what I did:

• ...
• Thread the thru hull into the flange and screw it in gently.
  ...
  

****
Fill over the Machine screw heads with waterproof filler.
****
Screw on the valves and tailpieces with pipe dope applied to the threads.

[hsi88]

Sorry to be late to the discussion, but I had an additional question. Are all these through-hulls safe in freezing weather? As in the air temp can be sub-zero(F) for up to a week at a time and the boat is frozen in ice. The reason I ask is I keep my boat in the water(ice) during the winter (near Baltimore) and this last cold snap has one of my current petcocks leaking (very, very slowly) now that it has thawed a bit. Can't tell yet if its the hose or the petcock itself (with the handle closed). But I am certainly worried with spring still 6 weeks away (according to Punxsutawney Phil).

[Cheechako]

Originally Posted by hsi88

Sorry to be late to the discussion, but I had an additional question. Are all these through-hulls safe in freezing weather? As in the air temp can be sub-zero(F) for up to a week at a time and the boat is frozen in ice. The reason I ask is I keep my boat in the water(ice) during the winter (near Baltimore) and this last cold snap has one of my current petcocks leaking (very, very slowly) now that it has thawed a bit. Can't tell yet if its the hose or the petcock itself (with the handle closed). But I am certainly worried with spring still 6 weeks away (according to Punxsutawney Phil).

Not sure, hoses definitely might fail in those conditions too. You really need just a touch of heat on your boat.

[rbk]

That brings up a great feature of the groco’s and I’m pretty sure the BA’s as well, is you can close the valave and drain for in water winter freezing conditions.

[Cheechako]

Originally Posted by rbk

That brings up a great feature of the groco’s and I’m pretty sure the BA’s as well, is you can close the valave and drain for in water winter freezing conditions.

What about the cockpit drains?

[rbk]

Don’t close them or like most northerners have a full enclosure and or tent/winter cover. My cockpit sees no water when at anchor or dock.