Hull bonding system

[CRYSTAL]

Hi Nigel,

I noticed that the newer models of Bavs have a zinc Hull Anodes installed and connected to the A/C earthing side (only). My 2007 B33 does not have one - would you recommend to install one or just leave is as it is? The only thing below the WL is the Saildrive which has it's own zinc and the two seacocks.

thanks,
Hratch

[Odysseus]

The subject of galvanic protection is still not understood by most of the sailing population, The big issue is when you are in Marinas.

I have fitted an isolator on all on my boats after seeing the effects of stray current damage to a power boat stern drive in Plymouth after only 1 season. I have grounded out the 12v and 240v system through the engine and saildrive to the stern of Odysseus, one side is Zinc the other magnesium, they hang down on 2 mtr wire.

Go to this site (I have no conection to them) and have a read, then get worried!!! Although UK is not bad foreign marinas are bad, every season I have my alarm go off when boats plug in and have show people that their system is at fault, I usally get a blank look.

Safeshore.marine@virgin.net.
 
 Tel 01977 513607...Mobile 07711 849426  or fax to   01977 515245  (Safeshore Marine UK) Put this into Google
SAFESHORE MARINE GALVANIC ISOLATORS

[CRYSTAL]

Thanks for the site, very nice indeed.

Did you say that the saildrive is grounded along with the engine?

Hratch

[Odysseus]

Yes as some saildrives have a gasket between engine and drive, also 12v system is grounded on a 6mm cable that runs through the boat to the stern there it splits into 2 and goes to 2 through hull bolts above the waterline which have the zinc and Magnesium anodes  on, salt or fresh water.

Odysseus

[CRYSTAL]

Hi, on a diff topic:

what's your opinion on Marlone plastic Seacocks? there are two types: 1 is a complete unit with the tail pipe and also found the pieces separately - thru hull / valve / etc..

Do you know anyone who switched to these? Seems to be a 'perfect' solution and the specs are very high especially noncorrosive.

R,
Hratch

[Odysseus]

I have not used the Marlone valves but expect them to be as good as they get regarding corrosion, however remember all Plastic swells in water, not by much but it has been know to make turning the seacock difficult. I am sure it will be on Utube some place!!!

There is a thread on this site about changing seacocks, if you have the right tools there is not any problem. I would use a cone drill from the outside, just cut it off. photo posted on the thread.

Back to the question, if I change mine I would look seriously at Plastic.

Odysseus

[Symphony]

Couple of observations. There is no need to bond the seacocks as they are not connected to any other metal. It is possible that some seacocks are not made of DZR but of plain bras which may dezincify, but not through galvanic action. Marelon seacocks can be used. They are made of a material that does not swell in seawater - however they are physically bigger than DZR valves (and more expensive) so difficult to justify.

The saildrive is isolated electrically from the engine and has its own anode, as may some props. If you moor in a marina and connect up to shorepower it is advisable to fit a galvanic isolator to the shorepower circuit.

[CRYSTAL]

"The saildrive is isolated electrically from the engine and has its own anode, as may some props. If you moor in a marina and connect up to shorepower it is advisable to fit a galvanic isolator to the shorepower circuit."

Just want to clarify on your above comments please:

You are suggesting to use a Galvalnic Isolator but this will require Hull Bonding anode (if not fitted already) with the A/C earth along with the DC ground connected onto it and leave the saildrive with its own anode ONLY.

[Nigel]

You are suggesting to use a Galvalnic Isolator but this will require Hull Bonding anode...

A GI is a good bit of kit if you use shore power, no need to alter any bonding.

[CRYSTAL]

Thanks Nigel, what if there is no bonding? How would you install the GI without any Hull bonding?
If need be, should I install a HB and only connect the AC earth or shall I connect the DC ground from the engine as well?

cheers,
Hratch