Bronze thruhulls. Are they worth it?

[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?

[Simi 60]

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?

Above the waterline I reckon you could use whatever you like.
I'd use plastic
On a composite boat I'd actually glass in a fiberglass tube as part of the boat.

[sailorboy1]

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?

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

other than that I personally never would have cruise boat where such small weight differences matter driving the decision

[FAST FRED]

The bronze thru hulls are the best if you are cruising to remote areas.
With minimum effort/no expense the tapered sea cock can be brought back to new.

If you are cruising Miami , plastic would be great , exploring , bring tapered plugs.

[Sailmonkey]

What type of plastic are you talking about?

Something like Marelon is great, those abs plastic mushrooms are junk.

Also, if these are in an area where contact with a dock may be possible, the bronze will be fine, after some sun baking the plastic tends to become brittle. Our marelon deck drains became brittle after 40 years of sun exposure [emoji3]

[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.

[s/v Jedi]

Originally Posted by Sailmonkey

What type of plastic are you talking about?

Something like Marelon is great, those abs plastic mushrooms are junk.

Also, if these are in an area where contact with a dock may be possible, the bronze will be fine, after some sun baking the plastic tends to become brittle. Our marelon deck drains became brittle after 40 years of sun exposure [emoji3]

Exactly, we use Forespar Marelon fittings and seacocks above the waterline, Groco bronze below waterline.

[rslifkin]

I use Marelon for everything I've installed above the waterline. I've got some original plastic ones of unknown material as well that I should probably replace just to be safe. In my case, all but 1 of my above waterline thru hulls are in the boot stripe, so they get painted over. That keeps the UV off the outer part of the mushroom which likely helps longevity a lot (and is why the 34 year old ones aren't crumbling like some I've seen on other boats).

[Pegu Club]

When we did our refit we installed all new Groco bronze Seacock ball valves and thru hull fittings on half inch backing plates. Weight is not a consideration. The Groco seacocks have a grease fitting so lubing is easy, with minimum maintenance they will out last me. Imo real bronze fittings below deck are the only way to go.

Fair winds,

[Chotu]

As always, probably should have put more information.

I just have the cheapo plastic ones installed. They are about 12 inches Above the waterline, inboard, underneath the bridge deck where there is no direct sunlight.

For the bilge pump outputs,, they are much higher than that. They are almost at bridge deck level.

No sunlight, not near the waterline. So I’m wondering if I should look at using bronze since I already have them.

None of these thruhulls are below the waterline. They are far away above the waterline. I don’t have thruhulls below the waterline.

And sailor boy, when you are making a boat, every single pound counts. Just like when you were making an automobile. Or an aircraft. These are vehicles. And high-performance catamarans are extremely sensitive to overloading. The less waste I have in the actual building of the boat, the more payload I get to carry. Better for cruising far away.

[rslifkin]

For well above the waterline and out of the sun, I wouldn't even bother replacing them with better plastic. Just take a look at them occasionally and make sure the plastic isn't getting weathered.

[Manateeman]

Hi. Sorry. My bad. I thought you were asking about valves below, or very close to the waterline. I just don’t see how you lubricate a valve without a fitting. You can pull apart a three piece ball valve. Done all the time in industrial settings. I guess you will be ok above the waterline because there will not be the grinding paste of dead barnacles to destroy the valve seals. Maybe a tiny bit of Tef -Gel. Yikes ! My friendly manatee is wacking my hull for that suggestion. There are some three piece plastic ball valves used in the chemical and food sectors which might be lighter than Forespar but not as strong.
Mark

[Chotu]

Originally Posted by Manateeman

Hi. Sorry. My bad. I thought you were asking about valves below, or very close to the waterline. I just don’t see how you lubricate a valve without a fitting. You can pull apart a three piece ball valve. Done all the time in industrial settings. I guess you will be ok above the waterline because there will not be the grinding paste of dead barnacles to destroy the valve seals. Maybe a tiny bit of Tef -Gel. Yikes ! My friendly manatee is wacking my hull for that suggestion. There are some three piece plastic ball valves used in the chemical and food sectors which might be lighter than Forespar but not as strong.
Mark

Above the waterline thruhulls don’t have valves.

They are just a hole your sink or marine air conditioning plumbing exits from.

[Pegu Club]

Above the waterline, Marelon/Forespar would a good choice. Any hole in a hull should use quality fittings just as a matter of good practice.

Fair winds,

[s/v Jedi]

I have had a cheap plastic valve break off with the hose discharging inside the boat instead of overboard. I would ban these from the boat.

Also, we do use the Forespar Marelon seacocks on thruhulls at the waterline, not if higher up.