Lightening concerns with unstayed mast

Started by Owly055, February 06, 2017, 11:58:32 AM

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Owly055

   The boat I've pretty much decided on........ I don't have the specific one picked out at this point, is the Searunner 31.   They are far from roomy, but as a solo sailor that isn't a huge concern, and particularly when sailing in Mexico, Central America, and the South Pacific, where weather will often make the huge amount of exterior space more attractive than the interior.   I have some ideas as to how to make the wing areas far more useable.

     For a junk rig conversion, an unstayed mast is both desirable and pretty necessary.   That means that the mast will have to drop down to the keel (more or less), and will have to be moved forward, though I cannot move it as far forward as I would like due to structural and space considerations, in fact it cannot actually rest on the keel, but will have to be offset to one side about 10", putting it right next to the keel.   This places the mast just forward of the forward main strength bulkhead and centerboard case, which forms the strongest structure in the boat.   It will probably be offset to port.

     All that is neither here nor there........just background.    One of the considerations I have is lightening.   On most boats, the shrouds provide an excellent path at least as far as the chain plates, which depending on how they are located and attached can lead the energy to the sea or at least close to it.   A cable dragging over the side in lightening storms could be as real life saver..... or at least prevent a lot of damage.   In many cases lightening will blow holes in the hull.  The chain plates take it inside, and it follows the inside of the hull the water line and blows holes through.  In any case, nothing good comes from lightening striking boats.
     The searunner of course has a plywood hull, which is no better or worse than fiberglass, but the mast step is the logical place for lightening to blow through the hull..... right next to the keel.... OUCH!!   Logically it makes sense to have a metal plate there to prevent this.  Perhaps a  1/4" stainless steel plate replacing a section of hull directly beneath the mast, and ideally very well electrically connected to it, providing a ground plain.     A lightening rod on top of the mast, and a straight path downward to the ocean.  Electrical equipment should be far aft, and the ability to completely disconnect any antennas and move them well away from the equipment they serve might make sense.

     Considering the parts of the world I want to sail in, lightening strikes are almost inevitable.   Sailboats over all have a rate of around .5 percent per year....... that is one out of 200.   Large boats with tall masts are more vulnerable, but multihulls are said to have double the incidence as monohulls, or one out of every hundred.   The odds of strikes are far greater in some areas than others.  Of course most that are struck are anchored, or moored, or in a slip..........but that's where most sailboats spend most of their lives, so it's kind of a worthless statistic.    Frankly I don't consider 1% odds per year of taking a strike very favorable at all.    Many people go a lifetime without ever taking a strike, but that doesn't mean that I'm going to be one of those necessarily.    I've had a number of extremely close calls with lightening on shore, in two cases striking within a few feet of my pickup.    Two friends of mine were hit in a brand new car.......... It totaled the car at least as far as insurance was concerned, another was sitting in the cab of an excavator that was struck, taking out the computer system that ran the electronic diesel engine.   A father and son who were friends of mine were killed on horseback in Wyoming........ and the two horses and dog also.   I'm not terrified of lightening by any means, but I'm respectful of it.

                                                            H.W.