Conference unifix::sailing

    Is your mast stepped on deck or keel?   It might make a difference.
    
    In general you want that lightning to get to ground by the most direct
    route possible.   Think of it as a high velocity water stream.
    It will try to get to where it's going by the shortest unobstructed
    route.  This means no sharp bends (sweeping curves are better),
    and not a lot of intervening connections (they will inevitably go bad).
    
    The bottom line is that you are taming a very powerful force 
    (potentially speaking :^) )and if your wiring is not making it
    easy, this force will find its own path.   This self seeking is
    what causes severe damage.  

     The mast is deck stepped.
    
     I was thinking about running the cable from the the back stay because
    the dynaplate is mounted aft. This way i wouldn't have to fish the
    cable through anything, and it would only have to be about 3 ft.
    long.

	When running for lightning protection, are you trying to dissipate
the charge to help prevent lightning, or trying to take care of a direct 
hit?
	The stay might disipate the charge ok.  For direct hit protection,
a method that was described to me was to run a piece of copper pipe, thick
wall I think, directly from the base of the mast (thru the deck and a short
lead bolted to the mast) directly down to a dynaplate in the hold directly
under the mast.  You probably have a post which ends a bulkhead directly
under the mast.  You could attach the pipe to the bulkhead such that it
goes up thru the deck just outside of the mast mount plate.  The placement
of the dynaplate might be obvious considering where the bottom ends up.
The location may be obvious, but the access may not.

	Use a larger size dynaplate.

	This was just a thought that was related to me.  Your milage
may vary....

	Dave

    I have no experience in this per se, but wouldn't you be concerned
    about the electrical resistance of the backstay being sufficiently low?
    In most systems the mast is the primary conductor in this case the
    resistance might be high enough to blow the back stay away and you
    could arguably lose the rig.  Wouldn't the effort to snake a good
    conductor be offset by this risk?
    
    Hope this was just an idle concern.  Good luck.
    

RE:.0 by USMFG::RNICOLAZZO "Better living through chemistry"

> I just finished installing a Dynaplate and am not sure about the placement 
> of the mast grounding wire. 

GROUND THE MAST!  The backstay will not do as good of a job protecting you 
and your boat as the mast will.   Hmm... Didn't we just finish going through
this a little while ago?

Anyways,  the backstay will have over 100 times the resistance of the mast,
which means that a given lightning strike buildup over 100 times more voltage,
vastly increasing the chance of damage or death.


Phil

    Crusing World mag July issue has a very indepth article on this
    subject.
    
    They recommend using AWG #8 wireand:
    
    	1. Ground each stay--fore, aft, upper shroud, and lower shrouds.
    
    	2. Ground the engine, gas tank, all electrical equipment.
    
    	3. Run a #8 wire the full length of the boat connected to the
    	   Dynapalte and then connect all of the above to this wire.
    
    	   Where possible, connect the grounding wires fron the standing
    	   rigging to the plate directly.
    
    	4. Ground the mast.
    
    Paul

I'm surprised that the Cruising World article didn't mention that an 
external metal keel is even better for grounding than a Dynaplate -- 
more area. One minor problem with using #8 wire -- it is expensive and 
tends to be sold only in large quantities (like 500' spools). I would 
think that soft copper tubing could be used instead. Connecting the 
tubing would be easy -- flatten the end with a vise and drill a hole. It 
has been pointed out that the heat from the current of a lightning bolt 
might be enough to melt soldered connections. Better both a mechanical 
connection (crimped terminals on wire) and a soldered connection.