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From: Tom MacNaughton
Date: 13 Mar 2008
Time: 13:26:37 -0500
Remote Name: 66.252.37.33
Unfortunately somehow many years a myth got started that lightning protection on boats was somehow different from any other lightning protection and people should direct the conductor down inside the boat. If that is done certainly anything metal, electrical, or biological is another conductor that the electricity could get to, which is not good. However, if you don’t provide any path for lightning to get inside the boat, metal tanks are probably pretty safe. Just to be perfectly clear on this, if you install a lightning system, the lightning conductor must ALWAYS be led outside the boat on standoffs that prevent the rig, the fittings, and the hull, let alone the people and their gear inside from being struck. I’ve got to say that in boats under around 30’ we tend to use polyethylene jugs for water storage rather than having a complex water system. Given that, you’d think we’d be unreservedly in favor of polyethylene tanks. However the stresses on tanks are greater the bigger they are and I think I would want to do some pretty heavy duty tests to make sure they were up to the job. I remember seeing a polyethylene tank awhile back in a stock boat that looked terribly flimsy. I think it is probably like anything else. There are probably very bad tanks out there and very good ones. They’d have to be pretty thick walled and have secure baffles and cleanouts to be much good in anything but pretty small sizes. So far I haven’t seen any that I would use in my designs but there may well be some great stuff out there I haven’t seen yet.