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post #1 of 5 Old 08-06-2011 Thread Starter
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Bristol 32- Deck Stepped Mast - Lighting Protection

Lately with several nearby boats getting hit with heavy electronic damage, and fortunately nobody was hurt, I have gotten more concerned about our deck stepped mast.

A good friend of mine swears that the boat has to have a grounding strap in the construction somewhere, but I have not found it yet. Any suggestions? Perhaps someone knows a good source for construction information about this boat, since the yard in Bristol, RI has been converted to a yc/marina.

There is a cast aluminum deck plate with four or five bolts and an offset mahogany panel for the head to port and the locker to starboard. The door to the head has a 3" x 4" (approximate) mahogany post. I have not been able to find any signs of lightning protection straps, copper tubes, cables in this area under the cabin sole.

This also leads me to another question, our keel is fiberglass encapsulated, so how could they have used the keel as ground? I am hoping that these issues were worked out when they built the boat, but somehow I don't think they had the same standards for boat certification that they have now.

I've thought about running a protected #5-6 copper cable down from the step, to an new bronze thru hull bolt which clamps onto a new heavy copper plate (about 2 sf ft) that I would fiberglass to the outside of the hull.

Any constructive thoughts you might have would be appreciated.

Please, no flamers here

Last edited by rkgleason; 08-06-2011 at 06:10 PM.
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post #2 of 5 Old 08-16-2011
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The first generation Bristols with deck stepped masts did not have any grounding wire from the mast to the keel. You could run a wire from the mast heel through the cabintop down to the keel easily enough.

Good luck with your project.

Restoring a 1971 bristol 29

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post #3 of 5 Old 08-16-2011
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Many builders do not endorse the process you have been given for lightning protection, even today. There is not conclusive evidence that grounding the mast does anything. The only thing that the down cable to a bolt to a plate on the outside MAY do is direct the strike and blow a hole in the hull. You would be better to leave things as they are...

you might review the recent post:

Lightning Damage.. HELP

lots of good info
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post #4 of 5 Old 08-17-2011
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"Lately with several nearby boats getting hit with heavy electronic damage, and fortunately nobody was hurt, I have gotten more concerned about our deck stepped mast"

There may be some valuable info in your opening statment did thay all have "protection" ? JMHO

There is no right way to do the wrong thing
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post #5 of 5 Old 06-26-2012
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Re: Bristol 32- Deck Stepped Mast - Lighting Protection

I just finished a repair that involved removing two 1 1/2 sea cocks in the head on my Bristol 32 with a deck stepped mast. The valves appeared to be bonded with wire but I noticed that not all the valves on the boat were. When I traced the wire it led from chainplates port and starboard, down to the valves. It looks like an attempt at lightning protection to me. otherwise, why connect the chainplates. I'm in Seattle where thunder storms are not common. They happen of course, but not like other parts of the country or even eastern Washington east of the Cascade mountains.

I disconnected the wire. The way I see it, there are better paths to ground in the marina than my boat if the big metal stick in the sky isn't connected to the water via wire and thru hulls. The wire wouldn't carry the charge very well anyway.

Jim
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