There is very little one can do to protect against a lightening strike. Insurance companies plan on one boat in a thousand being hit. Your odds are good.
Your mast being the highest thing around is, from my understanding, somewhat misleading. Lightning does not look for the highest thing - it looks for the easiest path to ground. This means that when a cloud is ready to discharge it will do so. If that happens 200 feet away from your 50 foot mast, it won''t seek out your mast, but go straight in to the water.
In Lake Michigan we have had the Mac race run for over 100 years through all types of weather. T storms are very common in our area and are a common part of the race.. No one has ever died in a Mac race from any cause. In addition, we run a 200 mile alternative race at the same time with the same results. That means almost 400 boats out on the lake each year going through whatever weather is thrown at them, and no one has died from anything - including lightning.
I agree, it is frightening and I don ''t like being out in it. But I just tell myself that the odds are bigtime for me. I am safer cruising on my boat, than vacationing in my car.