Through Hull Corrosion

[crashley]

I recently noticed that I have a through (thru) hull with rather severe corrosion on my 2012 SO 409. It is the shower sump thru hull which is right next to the head intake thru hull under the bathroom sink (2 cabin 1 head version). When I discovered it the hose clamp closest to the thru hull was totally corroded and loose (the screw was gone). I replaced the clamp prior to taking the pictures below. I assume there must have been a small leak in the fitting which caused the lower hose clamp to disintegrate. The good news is that the corrosion appears to be on the inboard side of the shut off valve, so if I leave it closed it shouldn't be a problem. The ironic thing is that I have the head plumbed for fresh water so the head intake thru hull (the good one) is not even used. I'm considering swapping the hoses so the shower sump goes to the non-corroded thru hull and replacing the end of the corroded thru hull at some point. It looks like there is a fitting at the hose end that unscrews from the body of the valve, but it is so corroded that I may have to replace the whole valve next time I'm hauled out. Anyone have any comments?

Bad one (shower sump output):



Good one (head intake):



Both of them together:

[ianpowolny]

We had a similar problem with our engine sea water intake and gallery drain sea cocks. We changed them as I couldn't determine the internal condition. We went with TruDesign thro hull and valve. They are working well so far.

Ian

[vasko]

Clean it thoroughly first and after revealing the color of the truhul decide does it need changing...

[MalcolmP]

Looks like that jubilee clip may have been leaking. I would advise at least taking off the pipe and inspecting the tail piece for corrosion - esp pinking. Easy to replace.

[jdl01]

Hi Crashley,
Are you certain that is your shower drain? Our 379 has the same plumbing layout and the shower drain is above the waterline, with the head sink drain and toilet inlet being side by side below the sink in the vanity.

[crashley]

Thanks for all the suggestions. I will remove the hose to inspect the internal condition. A little nerve racking while in the water but I will have some wooden plugs handy in case all goes wrong.

I'm pretty sure it is the shower thru hull but I will check again. I think our sink outlet is above the water line.

[MalcolmP]

Jun 24, 2017 17:05:30 GMT crashley said:

Thanks for all the suggestions. I will remove the hose to inspect the internal condition. A little nerve racking while in the water but I will have some wooden plugs handy in case all goes wrong.

I'm pretty sure it is the shower thru hull but I will check again. I think our sink outlet is above the water line.

You might invest one of the various marine goo's which would be eaier to use than wooden bungs if you did get a fracture.

example: www.stayafloatmarine.com/

On my 2008 boat I have changed the seacocks but not the through hulls, expect the holding tank outlet, which all remain fine. The weakest link as far as I have found is the tailpieces which are quite thin and can dezincify and become brittle.

[crashley]

Thanks for the tip, MalcomP. Would you recommend replacing the metal tailpiece with a plastic one? Also, do you know what brand the valves are?

[MalcolmP]

Although I really like proper "plastic" fittings such as Trudesign which I have on my large holding tank outlet, I don't really like plastic tails that are more generic. When I changed out our valves I used a proper DZR ones and tails there are quite a few makers but check they confirm that are dzr.  There is much more info at: coxengineering.sharepoint.com/pages/brassandbronze.aspx

[crashley]

Hi dli01. Here is a picture showing that the bathroom sink uses the upper thruhull on my SO 409. The lower ones are the head intake and the shower sump output.

[crashley]

I meant jdl01.

[crashley]

So I removed both hoses from the thru hulls and was surprised to find no water in either of them (see photos), as the thru hulls are below the waterline and have been open before. Who’d a thought. The one that was more corroded was in a difficult location so I used an Xacto knife to help get the hose off, which left a little scar in tail piece. (Actually it looks worse in the photo than it did in real life.) The other tail piece also looks worse in the photo, although I was able to pull that hose off without a knife. I had to add about 6 inches to the shower output hose so that it would reach the “good” thru hull. As I mentioned earlier, the corroded thru hull is the head intake one and since I’m plumbed to use the boat’s fresh water I don’t even need it. The tailpieces didn’t look that bad in my mind so I think I’ll be able to wait a couple more years before replacing them all with non-metal ones. Forespar seems to make some good Marlon versions. It seems that Raritan markets the TruDesign versions in the USA. I’ll see what the yard recommends or has available when I get it done.

[vasko]

The one with the copper colour do not look good to me ...

[vasko]

also - are the new jubilee clamps SS 316 marine grade ? 

[crashley]

Good question on the clamps. I did buy them at a marine store but I suppose that's no guarantee. The copper colored tail piece is the original "bad" one. I keep that seacock closed.

[Allegria]

Hi Crashley,

Personally, I would look at removing the seacock/valve as it is badly corroded and could spread to the rest of the valve.
I would then to cap it off. The through hull itself looks fine...

Cheers,
Allegria

[crashley]

Allegria, the actual valve looks worse in the photo than it does in "real life". The next time she's out of the water I'm replacing all of the metallic thru hulls and valves with good plastic ones. I think it would be difficult to remove the valve in the water, but I suppose I could block the thru hull from outside with a wooden plug and get it done (anyone have any advice on this?). I believe the thru hulls are metal but I agree they look pretty good.

[so36idavid]

crashley,

You're not alone in this, this board is replete with problems with Jeanneau thru hulls. I think I have one original left on my boat. 

Plastic thru-hulls are not beloved in the industry, you don't really see high end boats being delivered with plastic thru hulls. I don't know why, I'm sure they're perfectly good. The point is that you don't have to go plastic, good quality bronze thru hulls should be just fine. 

David

[MalcolmP]

Jul 6, 2017 19:11:14 GMT so36idavid said:

crashley,

You're not alone in this, this board is replete with problems with Jeanneau thru hulls. I think I have one original left on my boat. 

Plastic thru-hulls are not beloved in the industry, you don't really see high end boats being delivered with plastic thru hulls. I don't know why, I'm sure they're perfectly good. The point is that you don't have to go plastic, good quality bronze thru hulls should be just fine. 

David

David

I agree there is a lot said about thru-hull quality etc, but it does seem the main issue is not the thru-hull itself but in the quality of the final tailpiece to pipe - which are quite thin and tend to dezincify quite quickly.

The properly engineered plastic thru-hulls, like the Forespar and Trudesign  are building up a strong reliably reputation, but I accept there are a lot of conservatives in the industry. The Trudesign promo video below is a bit lengthy but impressive - not just about shear and impact strength but also chemical and flame/ heat attack. I am converted after having the main 2" one on my holding tank for past 2 seasons, works like a charm.

[so36idavid]

Cool video!