Sparky gives electrical advise
Good question... I don't see any dedicated grounding of the mast on the electrical plans. That doesn't mean it's not there, but I don't see it.
So...Let's attach a ground wire to the inside bolt of any standing rigging chainplate. A shroud for example. Make the ground connection on the engine block or the negative bus terminal. A bare wire end in contact with a bronze through-hull fitting,(under the hose and hose clamp), can also be a ground. Let the fish have the fireworks.
Or... Wait until your rope halyards get really wet in a squall and enjoy an evening of St. Elmo's fire.