Bronze thruhulls. Are they worth it?

[Andreas W]

I am old fashioned and would not use anything else but bronze. I don't trust any plastic for such an important function and high degree of reliability required, and in such a harsh environment.
Well, having said that, I don't trust plastic hulls much either.

[Cheechako]

Depends on the plastic. I had a plastic one break right off once trying to get a hose off the barb. UV degradation I think. It was not ABS, looked more like nylon type of thing. Bronze is king!

[blubaju]

Originally Posted by sailorboy1

the bronze may be stronger, but the plastic ones never corrode

Correct, but plastic ages

[sepharad]

I have Bronze Blakes that are between 30 and 40 years old. No leaks, no breaks, apparently bullet proof. The son of the previous owner and builder was very proud of the sea cocks when he sold me the boat. I can't blame him, but weight was not an issue.

[gonesail]

Originally Posted by Cheechako

Depends on the plastic. I had a plastic one break right off once trying to get a hose off the barb. UV degradation I think. It was not ABS, looked more like nylon type of thing.

what I was going to say. UV turns plastic into powder given enough time. if the barb cracked on the inside you could have a problem

[NorthCoastJoe]

Just to be funny ... If a few pounds is going to hurt, what happens after you come back from eating ashore and weigh a few pounds more? I can't talk too much I got rid of my head and holding tank to save weight and problems, went with a Air-Head. Sell the heavy ones on craigs list or a marine consignment store.

[Mike OReilly]

The only thru hull that has ever given me grief is was a newer plastic one. All my bronze ones are 43-years-old and still going strong.

[stormalong]

Originally Posted by Manateeman

Hi. Few boatbuilders are honest about blunders but I made a whopper building my personal boat. Marelon flanged seacocks. Removing them and switching to Groco will be a lot of work and money.
It’s an aluminum hull. We fabricated 1/2” plates pre drilled and tapped to bolt the flange and TIG welded them. Nothing wrong with the Marelon thru hull...no nut needed. Forespar now states the valves should be lubricated and exercised.
They have no fitting on the side of the valve. There have been numerous reports of the valves freezing open and the handles breaking off with hand force.
The stem of the ball is where it breaks with surprisingly little forewarning.
I’m going to replace them with Groco adaptors bolted to a plate. You can then buy ball valves with a lubrication fitting. You can change ball valves while leaving the adaptor in place. There are ways to do this in the water...bit unnerving but possible. I just dive and plug. We tried hot water, heat gun and lubrications on a frozen open valve with no luck. I’ll soon have some Marelon valves for sale cheap.
Mark, a PADI manatee.

The older Marelon seacocks had a problem with handles snapping off. Forespar claims to have upgraded them.

You do not want bronze in contact with an aluminum hull. The aluminum will be eaten up by electrolysis.

I have all Marelon in my 35 year old boat. Thirteen below the waterline. I have replaced a few over the years, mostly due to upgrades. The originals were not the flanged type. A few because of difficulty operating. Never had a handle snap off. Four above the waterline. Three original and one I added about 25 years ago. Just changed a hose on one of the originals - still plenty strong. I put a lot of stress on it and it was fine.

[davenrino]

My Brother's fishing boat sank when a plastic thru-hull for the wash down pump broke. Bronze for me.

[bcboomer]

Trudesign have a range of thru hulls and valves that don't stick and don't need any maintenance.

[kas_1611]

Apart from our engine room seacock, which is now DZR Brass (with the green handle and a clear CR embossed in the metal) all our seacocks were replaced with Marelon plastic versions a few years ago.

Why? We discovered all our original seacocks were fresh water, domestic plumbing brass ones with the Red handle. Serious danger of them corroding and failing without notice.

I lube the Marelon ones every spring with Molydbenum grease and give them a good clean every autumn. So far no issues but you do still need to be watchful for any corrosion in the metal parts (the screws mainly) but these are easy to replace without removing the entire seacock and shouldn't suffer any serious corrosion as they are not exposed to seawater directly.

[IslandInfedel]

For me I have bronze chain plates on the side of my hull, bronze exhaust, bronze porthole trim rings, so my one above the waterline throughhull that wasn’t bronze got swapped out for a nice shiny bronze one.

Above the waterline I don’t think it matters too much, for me it was strictly cosmetic

One point I will add, the marelon one I replaced, the nut was cocked around heavily, after a good chunk of time trying to peel all the junk off the nut, I just tried the recommendation of someone at the dock, a flat head screwdriver and a swift hit with the palm of my hand, it split/shattered the marelon right off, that would not work with bronze, that said marelon won’t corrode, so I wouldn’t really say one is stronger than the other, just depends on the type of damage it takes.

[nrwian]

I used the Tru Design sea Cocks from New Zealand on my Alloy boat . Better design , better made and cheaper than the Marelon Forespar ones . They use a support collar so very strong . There range is increasing all the time . Worth a look .

[onavegador]

As bcboomer and nrwian I installed on my cat Truedesign seacocks replacing the old bronce ones what showed degradation due to elecrolyse. Valves can be opened and closed easy, as I close them every time when I leave the boat unattended for some days.
IMHO Bronce is ok but the new materials (Truedesign for me) has also its merits and would use it w/o hesitation.


fair winds

James

[Clivevon]

Another vote for Tru Design from New Zealand. I have 10 on my boat fitted 6 years ago. No problems at all so far.