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Emerald Sea · 24-04-2013, 08:19

From everything I have read on this string and previously on very similar subjects, the lesson (and my recommendation) here is to have all your thru-hulls changed out every 3-5yrs pending the seawater environment your in, whether they need to be or not. There is too much risk at stake considering that corrosion occurs irregularly, imprecisely and cannot be quantified based on a simple visual inspection. The cost of failure far outweighs the replacement cost of these fitting.....and you'll sleep better at nite.

Steve
L450

**s/v Jedi** · 24-04-2013, 09:32

Quote:

Originally Posted by Emerald Sea

From everything I have read on this string and previously on very similar subjects, the lesson (and my recommendation) here is to have all your thru-hulls changed out every 3-5yrs pending the seawater environment your in, whether they need to be or not. There is too much risk at stake considering that corrosion occurs irregularly, imprecisely and cannot be quantified based on a simple visual inspection. The cost of failure far outweighs the replacement cost of these fitting.....and you'll sleep better at nite.

Steve
L450

You could do that, or change to proper bronze thru-hull fittings...

**roverhi** · 24-04-2013, 11:04

If you are rich and like to throw away good money, that would be a viable option. Bronze lasts a loooonnnggggg time in salt water. I've got one original seacock that is 43 hers old. Pulled it last year and it was sitll in excellent condition so reinstalled it. Inspect the through hulls when the boat is hauled paying close attention to the pink disease (electrolysis), remove and inspect maybe every ten years or so. It's usually the through hull not the sea cock that suffers.

Brass is plenty strong, btw. It's the chemical composition that allows the zinc to be used up like the zincs on the prop leaving a honeycomb of the other metals that is its downfall in saltwater.

Quote:

Originally Posted by Emerald Sea

From everything I have read on this string and previously on very similar subjects, the lesson (and my recommendation) here is to have all your thru-hulls changed out every 3-5yrs pending the seawater environment your in, whether they need to be or not. There is too much risk at stake considering that corrosion occurs irregularly, imprecisely and cannot be quantified based on a simple visual inspection. The cost of failure far outweighs the replacement cost of these fitting.....and you'll sleep better at nite.

Steve
L450

**estarzinger** · 24-04-2013, 13:25

I have an aluminum hull and bronze is not a good idea, so I have marleon ball valves on welded in aluminum 'thru hulls'. I did some load testing similar to Mainsail's and concluded that the 1 1/2" mareleon's were 'more than strong enough' (both the handle and the fitting), while smaller ones (like he tested) were not satisfactory. So, all mine are 1 1/2" and if the hose is smaller then they are bushed down at the hose barb. I have not had any of the mareleon fail, and re the question above, that includes in ice cold water.

Bronze is certainly better, but I would certainly much rather have mareleon than brass. And as an aside,

Beneteau

uses brass. Those do need to be inspected very very closely after about 10 years.

Celestialsailor · 25-04-2013, 00:04

I stopped using RC Marelon valves a long time ago, only due to the handles snapping off when the internal swelled up over time. As stated above from others, there is a difference between the brass EU through-hulls and Groco bronze fittings.

goboatingnow · 25-04-2013, 03:49

Just as a point. The EU RCD doesn't specify the particular material in underwater fittings , merely that such fittings must last at least 5 years , EU manufacturers are using both bronze , DZR brass and sometimes ordinary brass in this regard . The particular clause in the RCD is being rewritten for the next update ( which of course will bring lots more rules with it as well)

Hence one should not assume that the fittings are not bronze nor brass. A quick email to the dealer or beneteau will usually get a response. In my case the fittings are ( were) bronze.

Dave

Benz · 25-04-2013, 04:24

Quote:

Originally Posted by nimblemotors

Is it that important to use through hulls?? Do you need the water pressure?
Can I just run a tube up from the side for water intake?

You can absolutely run a tube up the side, if you figure out a way to fix in so it doesn't flap in the wash. But there's a better way to do through-hulls, and I'm not sure why it's not done more. If instead of a removable skin fitting you glass in a fiberglass tube--very strongly--and then at the top you install the seacock of your choice (like Evans did with his aluminum boat--this also works with FG). Need to change the seacock in the water? dive under and hammer a wooden plug in while you do. If desired, you can chamfer the outer hole and put in a flush plastic strainer grating with two small BRZ screws. If you run aground and it gets crushed, NBD. There are lots of commonsense easy things that manufacturer's don't do, and it always amazes me to see the expense and shenanigans they go through instead just to save a little time.

**s/v Jedi** · 25-04-2013, 06:09

Quote:

Originally Posted by Benz

If instead of a removable skin fitting you glass in a fiberglass tube--very strongly--and then at the top you install the seacock of your choice

This is exactly what Dashew did: with a Forespar OEM valve on top (the one that tested okay @Main Sail Youtube channel

On thread locker: it might well isolate the metals... why didn't they test that?

CaptainMurph · 25-04-2013, 06:21

I changed out all the thru-hulls on my past boat, and am doing the same with my "new" boat: Bronze thru-hulls coupled to Marelon seacocks.

I have no concerns on corrosion and have the advantages of the Marelon with the flange screwed to 1/2 maine plywood backers glassed to the hull.

This seems to be a good combination.

Murph

S/V Amalia
1965 Cal 30

boatsail · 25-04-2013, 06:24

Right now I am removing and glassing over through hulls. It's not really the through hull worried about, but the hoses that are more likely to fail given that is the weak link.

boatsail · 25-04-2013, 07:27

the end of this video shows why I don't like through hulls of any sort.

Kenomac · 25-04-2013, 07:50

Before we bought our Oyster, we were looking at the Jeanneau 54DS... a lovely boat until you start looking at recent survey results. Several of them had already required that their through hulls be replaced, even though the boats were only 5-6 years old. Not a good sign when you consider that the manufacturer chose to save a little money in this area.

We kept looking.