Bronze thruhulls. Are they worth it?

[Cadence]

Originally Posted by Chotu

I recently inherited some bronze “above the waterline “ thruhulls.

I have plastic ones installed now.

Is there any reason I should be using bronze?

They are far more expensive, but weigh like 5 lbs each. The plastic ones weigh a matter of ounces and have been doing fine for 5 years.

Can’t help but to think the bronze ones are indestructible though.

Which would you use on a boat where every pound counts?

If it ain't broke don't fix it.

[Manateeman]

Hi. The Tru Design is a thru hull, a ball valve and a support collar. The support collar is not attached to the hull. The collar can spread an interior load but a portion of that load is transferred directly to the thruhull . If the exterior portion of the thru hull is compromised, or the whole assembly becomes loose and the assembly is below waterline, the failure will be very difficult to correct. You have a thru hull without an interior nut. The valve and the thru hull cannot work without each other. If the head portion of the thru hull becomes damaged, the system can fail without evidence from inside the vessel. With a flanged bolted seacock or a Groco adaptor, the thru hull can be removed entirely and the valve still functions.
Flanged seacocks and Groco adaptors can be bolted to the hull, or a backing plate.
Comparing the two is like apples and oranges. Is bolting a traditional triangle flange seacock or Groco adaptor overkill or are you ok with a collar supported ball valve. Your boat, your decision. I regret my decision to use Forespar flanged seacocks. I will switch to Stainless Groco adaptors and stainless ball valves bolted to TIG welded interior backing plates. I’ll pass on Tru Design.
Mark a 316 stainless loving manatee.

[Chotu]

Originally Posted by Cadence

If it ain't broke don't fix it.

Might just be my favorite post in the thread.

Scope creep gets me all the time.

[Searles]

Just remember, never put or fit bronze or brass or stainless steel through hull fittings in an aluminium boat below or above the water line ,stainless maybe used with caution in a steel hull , in alu hulls weld in pre threaded stubs heavy wall and fit synthetic valves ,welded in stubs of 316 ss maybe used in steel hulls ,

[Manateeman]

Captain Searles. Sorry but I’m not sure what you are saying. I have an aluminum hull and I want to switch from Marelon to 316 stainless Groco adaptors with Marelon thru hulls and 316 stainless ball valves. The stainless adaptor parts will be isolated from the hull reinforcement plates. The thru hulls, Marelon. One alternative is to weld a standpipe, flange it on top above the waterline. Are you saying only plastic or Marelon valves can be used below or above the waterline ?
I’m not sure what you are saying in your post.
Mark

[CarlF]

I have 15 Forespar Marlon 93 Series above and below the waterline. No lubrication, broken handles or other problems in 10 years. The Series 93 also passes the ABYC test.

The Series 93 are an entirely different design from the regular Forespar seacocks - the regular ones do swell, stick, and break their handles. I wouldn't use them above the waterline - or anywhere else. I don't know why Forespar doesn't take them off the market.

But the Series 93 are great.

[Jhclay]

My shipwright used TruDesign when replacing a dodgy holding tank outlet thru hull and valve.

[Searles]

Sorry if I created confusion, salt water ,some saline fresh water,act as an electrolyte ,no matter how well you try to isolate or insulate through hull fittings or valves if they are not of compatible materials ,corrosion will occur ,how much ,and how acceptable this is is up to the boat owner . Heavy coats of epoxy under fittings will slow this down ,Mother Nature is always trying to breakdown our pride and joy to basic elements

[Manateeman]

Captain Searles Thank you for the reply. I’m very interested in the opinion of fellow boatbuilders. I understand the mixed metal issue. We used multiple coats of epoxy on our aluminum hull and are very careful about the electrical. So far, nothing amiss. Our mistake was Forespar flanged ball valves which stick and break handles. I don’t consider the new Forespar or the Tru Design as seacocks because the valve is not bolted to the hull or a hull fixed backing plate. I’m not the only boatbuilder with this opinion but that’s another story.
I think at this point I have two options. Fabricate standpipes that reach above the waterline and use industrial valves on top, either plastic or 316. We’d insulate the valve. The second option is to fabricate a plate which will bolt to our existing welded seacock plates and then use Groco 316 stainless plates and valves. We would stay with Marelon thruhull. The Forespar flanged valves and the Groco adaptors have different bolt patterns.
Naturally! Under no circumstances would I use the new “supported” style valves.
We have a seachest, but there are some places I prefer a closer opening. I have one motorized 316 valve and it’s working out ok . Time will tell. Anyway, could you please ask your fellow boatbuilders for their opinions. I sincerely appreciate your response and hope you are passing along your knowledge as I noted your sea service as well as your fine vessel.
With kindest regards, Captain Mark, a Merchant Marine manatee.

[Q Xopa]

I havent got or know of anyone using them, but full Ceramic ball valves sound like they'd be the 'ducks guts'. No corrosion, aging isdues. Very abrasion resistant etc.

Just a crazy thought.

[Cadence]

Originally Posted by Chotu

Might just be my favorite post in the thread.

Scope creep gets me all the time.

I guess, I'm not the only one that read the OP.

[barnakiel]

Above waterline I use brass. I think brass is stronger than plastic (unless you have marelon plastick cocks.


Below, well, bronze is the king, imho.


b.

[Manateeman]

Captain Q XOPA. Thank you for the suggestion. Ceramic is great for some chemicals but the price is out of sight. But...your suggestion got me thinking industrial valves ! So I found a 316 stainless ball valve with a nice flange on one end and female pipe on the other. Jamesbury series 6f.
But...your suggestion was read by my beloved who asked if ceramic was the same coating we had applied to the inside of our turbo. It was not, but it was a great
idea. You can hard coat ( it’s a specialty coating ) just the inside of the valve body and the inside of the ball. Then you have no seawater in contact with the stainless. You end up with a valve that is ballistic but not too expensive.
How to describe it...a cross between a ceramic and a stainless with all the benefits of both. I’m done with snap off Marelon ball valves and no way unbolted (supported) valves ( pretend seacocks ) are going in my vessel. I thought I’d have to weld standpipes but your post has pointed to a great idea.
My sincere appreciation.
Mark, a dry bilge manatee.

[Mike Banks]

Underwater I use bronze. Plastic is OK, but debris can harm it. I use plastic only for outlets above the waterline, bronze below.

[barnakiel]

As asked via a PM:


Our below water thru-hulls are bronze, valves are bronze (old) brass (new).


There are NO, repeat NO bronze valves to be had in Canary Islands chandleries, nor have I seen any on the EU continent. I know they can be had in the UK, specialist stores in Germany and Netherlands, possibly denmark, Finland or Sweden.


In the Med and below, all you can buy is brass.


Next stop Budget Marine shop on Antigua where you can have Grocco's.


Our above water fittings are mostly brass now, except for the ones that came with the boat (and hence it was 1980 and Sweden, bronze).


Bronze is the thing, no saying, but what do you do when you are Med based?


BTW Nearly all underwater fittings on Bavas, Benes, Jeanneaus, Lagoons, etc. I have seen were brass, not bronze.


Cheers,
b.