Sea Cocks - should they be bonded?

[Nick_H]

I did a bit of exploring behind all the removeable panels during my last trip to the boat, and was a bit concerned by these

Its clear from the upper photo that there's been water in here at some stage, as there are dried salt crystals on the inside of the hull. I can obviously clean them up and check how sound they are, but should they be earth bonded? Could this be a cause of the deterioration?

They are just below the waterline.

 

[PilotWolf]

Not the answer you are after but I hope that the electric screwdriver isn't there because you ve just used it to remove the panels... those seacocks are something you might want/need to get at quickly!

W.

 

[drewstwos]

I think not ...mine are not because they are not linked to anything that has a current through it. it is the action of a current passing between dissimilar metals that causes disintigration. they are isolated by the non conducting hoses,

Just make sure they are free to move into the shut off position. and are readily accessible.

Hope this helps

Drew.

 

[Renegade_Master]

Hi I have had experience of ageing sea cocks which become very brittle (the brass tends to turn pink is the sign) and as a result dangerous.

I put a post up last year when just after I bought my P560 (circa 94) I lifted her out and to my horror when checking the function of the sea cocks, I thanked god it was out of the water cos two of them broke off as they where turned off, and two upon investigation looked turned off but did'nt if you see what I mean.

Had em all replaced. Now whether it is practical to earth bond them all others will have to say.

 

[jfm]

Hmm, might think/change mind some more, but to state the obvious, the effect of bonding them would be that they become part of the circuit that is protectable by your anodes. For them to be actually protected they need to be in the right place on the periodic table relative to the anodes, and I dunno if they are (they look like phosphor bronze or summink?)

If not bonded they become their own little separate world, corrosion-wise, not part of your boat as it were. They might as well be on my boat. In fact my seacocks are as relevant to corrosion on your boat as you seacocks*. I think that's how they are intended to be. Mine aren't bonded.

(My sterngear is however differently relevant to your corrosion, as we are plugged into the same shorepower. Now my head is starting to hurt)

BTW which seacocks are they? If the big pipe is your exhaust it looks port side so this is somewhere on your port quarter, right? In the crew cabin? They look aircon-ish or summink

(* My boat is in the neighbouring berth to houghn's, for those not aware)

 

[DAKA]

Seacock 1

Has a rubber hose that has a steel wire coil in it to help retain the profile around tight bends.
The steel will have bonded with your seacock leaving it in this condition.
I would be concerned what it is bonded to the other end.

The height of the water line in the tray looks like it has come from leaking exhaust hoses above and perhaps these need checking .

I would attempt to isolate the end of the steel wire coil, a clean cut would help, bound with tape, silicone on the end would also help isolate.
I would be replacing the old seacock asap if I found the exhaust was not the source of leaking while underay.

Seacocks 2 and 3
, I would not bond the plastic pipes .

 

[Nick_H]

Yep, port aft quarter, in crew cabin. The smaller ones are just cockpit drains, don't ask me why they would have holes below the water line just for cockpit drains, but they have. Can't remember what the bigger hose is, looks the right size for raw water exit for the genny?

Daka, thanks that's useful, i'll check if the reinforcing wire is in contact with the sea cock.

 

[Divemaster1]

Don't think you generally need bonding of electrically isolated metal thru-hulls and seacocks.

As far as I can se, exceptions are;
- where fittings are below bilge water level to protect against stray current corrosion.
- where you have conductive metal reinforced hoses running from seacock..

Funnily enough all my seacocks are bonded ... but then again, the boat is Italian /forums/images/graemlins/wink.gif

 

[Deleted User YDKXO]

Agree with DAKA. Water is more likely to have come from leaking exhaust flange above. None of my seacocks are bonded either
Are you sure those are cockpit drains? I thought the whole point of a self draining cockpit was that it could drain above water level.
Word of warning on checking seacocks. I paid a boatyard in Majorca to check every seacock on my boat last year. First time out afterwards, I got an alarm which I eventually traced to an overheating gearbox (mine are raw water cooled). When the botyard checked the seacocks, they managed to break the lever on the gearbox raw water outlet seacock such that it was stuck closed even though the lever was in the open position and it was'nt immediately apparent either because the lever was still relatively stiff
Moral of the story. Don't force seacock levers

 

[jfm]

Raw water exit from genny might go to exhaust not to a seacock imho. I mean main engine exh elbow. The black pipe in your pic could be raw water inlet to genny or to airco? Dunno really

Mine similarly has seacocks on bathing platform locker drains, totally pointless I agree. I'd much prefer it if they just drained overboard with no pipework that requires a seacock. By using pipework I reckon they are creating a risk and then managing it with a seacock if you get my drift

There seems to be consensus that they shouldn't be bonded. Seems correct to me

DAKA raises a very good point ref potentially connecting things thru the spiral wire in hoses. I think the yellow pipe in your pics has metal wire, not just the black pipe. Worth keeping in mind...

 

[Nick_H]

Yep, they're definitely cockpit drains. I think its a form over function thing so you don't get yellow stain lines down the boat from an open drain point above the waterline. There's no evidence of a leaking exhaust flange, as any water would have had to run a metre or more along the exhaust hose from the flange to reach this point.

jfm, I can't think what else the bigger pipe can be other than the genny exit. Its not the inlet, as I know where that is, its not the aircon, they're all on the other side. I don't think its unusual for the genny raw water to exit through a sea cock, it did on my last boat as well.

To put the question another way, is there any potential downside in bonding all the sea cocks? If not, for the sake of an electrician for half a day I may get them done anyway for peace of mind.

 

[jfm]

Ah, didn't know that. My genny raw water discharges into the main engine elbow.

I dont think you have an exhaust leak. Water and general area would be black if you did. (I think maybe they meant the spigoted joint with the massive jubilee clip in your pic, which is not actually a flanged joint)

The downside to bonding them is that they enter the fray in terms of mix of metals. You now have temet shafts, PB props, rudders, and wotever-metal seacocks, plus zinc anodes. I dont know of the seacocks would be protected by the anodes or if they would harm something else

Going back to basics you have anodes becuase you have mixed metals in water, connected. Eg you have metal A on the props and metal B on the rudder or shafts, and they are connected by the boat electrics or construction. Absent protection, one of them will be the anode relative to the other and dissolve. An anode is adding metal C, so it corrodes in preference to A or B

But if a seacock is made of one one metal you dont need an anode. Of course if the ball is different metal from the body you could have some local anodic corrosion and an anode would help in theory. If there is seawater inside the handle metal joins the mix but better to eliminate that by making the inside dry. But I dont think it's worth the bother grounding them. And would be > 1/2 a day. He has to reach the forward toilet seacocks too, and run wires. And then he will attach the wires to the seacocks under the nut that holds the handle or what? Hence the wire will move when the handle moves. Doable, but a bit messy and pointless? All imho

 

[mjkinch1]

Well my main seacocks for the engine are earthed, but all the others (holding tank, loos, aircon etc) are not.

When my boat was serviced teh guy commented on the slight pinking of the main seacocks, and suggested I get it earth tested at some stage. They fitted new seacocks last year and just re-earthed them (or re-bonded)

Interesting to see this is not the case with all the boats, I wonder why?

 

[jfm]

Now you mention it, my main engine coolant seacocks might be eathed and the others not. Will look tomorrow!

 

[jfm]

I'm on the boat and it turns out all my engine room seacocks are bonded (genset, airco, etc, not just the engine raw water intakes) and the earth wires are then taken up to the strainer units and indeed the exhaust elbows, so everything in there is bonded. With pretty chunky (like 30amp plus) green cable. My front (toilet) seacocks aren't bonded.

So I walked onto your boat houghn (there's a guy on there with F, she said he is casing it up to install internet) and looked in your engine room and none of the cocks or strainers are bonded, not even the engine raw water intakes.

So now I'm confused....

BTW the bonding is done with a special fitting. Metal strap around the bottom of the body of the seacock, and a set screw to tighten it and then attach the bonding wire. I think it is a plumber's fitting used for bonding heating pipes, cos they all have attached those yuk stamped metal tags saying "Earth wire attached for safety, do not remove". They're quite a neat way to do it imho

 

[Hurricane]

You've got me looking as well.
Got my pics from the factory out and here's something of interest.

Looks like one is bonded and one isn't.

I'm going to ask Princess some questions. I checked my photos of the engine room as well and I cant actually see if they are bonded or not. I'll let you know what they say.

Mike

 

[Nick_H]

Mike, that's not earth bonding on the one sea cock, its a switch to turn on the poo pump when you open the holding tank discharge sea cock. By the way, I also dug out my survey report by Paul Homer, and he suggests they should be bonded.

It would be very interesting to hear why Princess don't bond any of the sea cocks

jfm, yes broadband being installed today, i'll give you the access codes for when you're in port. I think i'm going to look into this (sea cocks) a bit more. Frances mentioned they started the flybridge mods yesterday, does it look any different?

 

[Bajansailor]

I am not going to get into the debate as to if seacocks should be bonded to the anodes or not - I will just say that our bronze seacocks / ball valves are not bonded, and they seem to be quite happy 15 years later.

I would suggest though that you should compile a plan showing the location of all your skin fittings (hopefully with seacocks) that are located below the waterline.
Ensure that they are all reasonably accessible.
If they are 'out of sight', they are too often 'out of mind'.
On your 'to do' list, turn every seacock off / on on a regular basis, eg once a week, or whenever you visit the boat.
Especially the ones that have to be left on all the time.
If you get shells growing inside the seacock such that it cannot be closed when needed in anger, it is not much use......

 

[jfm]

[ QUOTE ]
jfm, yes broadband being installed today, i'll give you the access codes for when you're in port. I think i'm going to look into this (sea cocks) a bit more. Frances mentioned they started the flybridge mods yesterday, does it look any different?

[/ QUOTE ]

Hang on a minute, I'll just go and look...

 

[jfm]

status of heatwave

Sorry for thread drift here but answering a question of fellow forumite. They've removed bbq and seat base and put bbq in new position but not fastened it there yet. All services for bbq come thru deck under helm seat, not bbq, so no big hole to fill in case you decided not to teak the deck (Jun is available for that whenever you want, I checked last night). 4 big M12 studs sticking up where bbq used to go. sort of GRP-ed in, will need lower ceiling removal to gettem out. The position of bbq on port side (just between the 2 white lights) is perfect. The gap walking thru to forward or aft staircases feels just right imho.

I imagine they now have to remove saloon ceiling to re-route services to bbq (H&C 15mm pipe, waste, and a load of wires)? They haven't done that yet.

They have unscrewed the refrig compressor and plate unit around its flange in starboard side fridge locker but not done anything else there