CLYDE DISCUSSES NEWPORTER LIGHTNING PROTECTION

[bob mitchell]

          To help you get a handle on the ground plate: it should never be painted.  It is made pithy; this is the wisdom of the plate—it is rather small but equals many square feet of copper sheet for proper grounding.  It is attached to the lead keel with bronze bolts to insure electrical connection.  It is one of those things that is treated like a zinc anode (no paint, make sure it’s there and sound on all haul-outs) but is not a sacrificial metal—bronze in on the high end of nobility, zinc is on the low end.  Therefore, its presence is one of the reasons the zincs dissolve.  I have Jamestown Distributors ( http://www.jamestowndistributors.com )  in my Favorites list for the main purpose to window-shop.  Search for Dynaplate.  It lists four sizes, the standard size (memory again) is what I think was used.  Personally I’d go to the next size.  Standard size is $77.33 and the next size is $123.73; standard equals 12 sq. feet, D8 (next size) equals 20.  Prices go to over $400.  Standard amounts to $6.44 a sq. foot and D8 is $6.19.  The $400 one is just over $4.00.

 

Now to its hook-up.  Going to the print “_0019.pdf” the strap is under the nut of the third bolt from the after end.  This is (should be according to the print) just ahead of the number 23 frame.  That frame is home for the #23 Bulkhead—the ‘wall’ between the doghouse and main cabin.  The strap leads to the port side and a heavy (single strand, I think) wire goes to the lag piercing the bottom of the chainplate for the port lower mizzen shroud (going up into the bottom surface of the solid blocking acting as a mount for the chainplate).  The print calls for the strap to be under the washer for the bolt.  I think I’d like to have it between two washers under the nut.  But the principal here is that the strap must remain stationary while tightening the nut.  The top washer of two may have less friction against the bottom washer than the single washer has against the wood of the apron.  I would suggest that you find the wire on the chainplate (make sure it’s there).  In the boats I rigged the spring stay (between the mast heads) was used as an antenna and was therefore insulated from the rest of the rig.  Radios of today do not use that type of antenna so present springstays should not be insulated.  Go to my picture Ning thing ( http://newporter.ning.com/photo/photo/list ) for my working drawing for the springstay, right hand column, third row down, to see the insulators.  I mention this only because with the insulators the two masts are separated electrically, so there must be a wire from one of the main chainplates to one for the mizzen.  My guess is the main lower aft shroud.  Come to think of it, I may be wrong on which chainplates are used: The lowers do not connect electrically with the uppers, and the uppers are the one you want to use for lightning protection.  I did not do that work so I don’t know, so you may even find that all the chainplates are wired together (or at least one upper of both masts).  I have been struck by lightning many times, but never in a Newporter (which may only mean I’ve never been near lightning in a Newporter).  One strike did much more damage than the cost of even the most expensive Dynaplate.

 

[bob mitchell]

     Here is a photo of the actual connection of the mast ground wire to the 8th of 9 keel bolts ( moving from forward to aft). The 8th bolt sits right behind the forward engine compartment bulkhead, and of course under the front of the engine. The problems with this arrangement is that the mast ground wire is uninsulated and in the bilge (which often has water in it in old Newporters). The wire may even serve as a ground for other electrical equipment on the boat. In short, there is ample opportunity to pick up stray electrical current. Two main consequences ocurr. Because the ground wire is fastened to wood gussets and frames with copper staples, if those members get wet there is electrolytic action which destroys the fasteners and the wood (see other photo) The second is that the ground in the bilge makes the whole boat a giant battery if there is water in the bilge and stray electrical current, including those external currents often produced in a marina by other boats. Not to mention that the iron floors that support the engine are right there on top of all the electrolytic action and the bronze keel bolts.

          This fall I visited John Barlow, who has with out a doubt the finest, most well equipped, garage kept Newporter I have seen (Western Way).  His ground had been redone with insulated wire and the ground plate is on the bottom of the boat, and not connected to the keel. So the wiring is well out of bilge water - which is how I plan to set up my grounding system.