There is no way to prevent lightning from striking a boat. There are techniques that can be used to increase the chance that you will not be injured and the boat will not be sunk by a lightning strike. However, even using these techniques, the boat's electronics
and electrical equipment
will still be at risk of damage.
and wood sailboats are a real "hard case" when it comes to lightning protection/mitigation. The best that can be done is to tie everything metal together and provide as much grounding as is practicable.
The major risk during a lightning strike is when the lightning seek a path to the sea that goes through you or the hull
of your boat. This is known as a "flashover" event. Lightning will take ALL possible paths to get from ANY metal object above the waterline to the sea. To prevent flashover events
all metal objects aboard should be connected to a common seawater ground. This includes stays, shrouds, air terminal, mast, poles, sail tracks, lifelines
, stanchions, anchor(s), anchor
, through-hulls, electrical
components, electronic equipment
, RF grounding plates, engines, etc. As an example, the recommended wire size for the connection from the masthead located air terminal should be #4 GA tinned copper. However, an old stainless steel
backstay would work as good or better. For the other connections #8 GA tinned copper or equivalent should be adequate.
The purpose of the #4 Ga wire is to ensure that as direct and uninterrupted path as possible exists between the masthead and seawater ground. This is much better then letting the mast rise to tens of thousands of volts relative to other metal object in the cabin
or to the surrounding seawater. This rise in potential would most likely result in a flashover event that could injure someone or blow a hole in the hull. The goal is to ensure that flashover events
don't occur by keeping all metal objects at the same electrical potential. And to do this it is necessary to bond every metal object together.
Some common sense is required when making these connections. If an anchor
is laying on a already grounded anchor roller then it too is grounded. However, the bitter end of the anchor chain connected to that anchor should also be taken to its own ground. That way a flashover event is less likely to occur between the pile of chain and seawater that includes someone in the v-berth and hull of the boat.
And, yes, if time and circumstance permits, isolating electronics by disconnecting the antenna
and power connections can't hurt the electronics. But, it may be safer to not be holding on to a random piece of wire when that big bright bolt from the sky hits.
BTW, if you use low inductance connections to connect the above items together you will by default have a very good RF ground system. Low inductance connections can be made using copper or stainless steal tape and braid. The stainless will last longer.