Dear Daniele
Nobody dared to comment on this subject, but I make an attempt.
First it needs to be said that lightning protection is a separate system described earlier on this forum, and not to be confused with bonding, which means connecting all metal underwater parts with cables to a zinc.
It appears that very few boats have lightning protection as standard, and therefore the cables are often assumed to be part of a bonding system, particularly in the USA, where bonding is much more frequently used than in Europe.
Nautor does not use bonding, because the underwater components used are corrosion resistant and insulated from each other by the GRP hull. The exception is a bronze propeller on a stainless shaft, here a galvanic couple is created, but by adding a zinc protection is provided for the propeller.
ABYC in the USA has published a great number of standards, among them one for bonding systems, and it happens that yacht owners refer to this and suggest that it is a must to bond. There are also experts in yachting magazines promoting this view.
It can be noted, however, that ABYC also has a standard for unbonded systems, and in Europe there is, as far as I know, no standard for bonding. This possibility is only mentioned in the passing in the RCD ISO standard for electrical low voltage systems.
As long as everything is in order there is no difference if underwater components are bonded or not, provided the unbonded ones can take care of themselves. But, if something goes wrong with a bonded system, for example an electrical leak occurs, then all the bonded components are affected.
ABYC means American Boat and Yacht Council, RCD Recreational Craft Directive
Best regards
Lars
|