Good afternoon James,
bonding all the metallic items that are in touch with seawater helps fighting galvanic corrosion.
This concerns mainly the items under waterline, but also the fuel tank and freshwater pumps and ...etc...
Bonding the mast will not prevent local galvanic corrosion, like a screw fitted in aluminum, or an aluminum painted mast which gets blisters because stainless steel/bronze/chromium/aluminum are in touch, in a salty environment
Only removing salt of these masts will prevent galvanic corrosion: at every opportunity, you should remove the salt from your masts (and guardrail, and furlers).
The last Super maramu I've inspected was 14 years old, and her painted masts showed absolutely no blisters, especially in the bottom area where several kinds of metals are in touch. Again, the secret is: flush your masts to remove salt.
Bonding the masts could help removing static electricity (which enhances corrosion). The downside is: should an electric wire (positive or negative, from a worn out nav light wire) touch the mast, this would bring power to the bonding and make electrolytic corrosion.
Beware of the quality and wear of your electric wires, everywhere in the vessel.
Enjoy fair winds.
On Sunday, May 10, 2015 6:07 AM, "j.lochhead@... [amelyachtowners]"
Thanks Oliver & Bill,
Fantastic response but I think my question was a little missleading. I am not so concerned with lightning. (well I am concerned but am off the belief that if it is going to get you a little wire is not going to help much)
What I am more worried about is corrosion. My understanding of the bonding system is not just to be able to determine if there is a leak, but also to protect the important componets (mast, thru hull fittings etc) from corrosion by bonding them to the zinc annodes. I might be wrong but is the bonding system not connected to the rudder annodes?
I am sure that the thru hulls should be bonded (it even looks like perhaps at one point mine may have been) I would also think that bonding the masts, handrails, headsail track etc would help prevent corrosion. I have recently removed and refitted all the mast fittings and reapplied tef-gel. Even so there was some signs of corrosion starting on the mast. Also there is some corrosion on the headsail track where a stainless bolt passes though it.
This may well be just a case of deteriation on a 30yr old boat, but wouldn't bonding these items help?
Mahiti Maramu #147