Um... in a 17' boat faced with a serious squall I might elect to hit the beach. That is what I would have done in my Bandit 15. It was a centerboard boat and while we endured some hairy situations with her, if the s**t hit the fan I'd be off the boat.
We, the wife and I, spent a pleasant interlude on a canoe trip, under a bridge which was over the Little Miami River, during a severe thunderstorm and I can testify that seeking shelter is a whole lot better than the lightening strikes.