The question was raised whether it is permitted to board a boat on Shabbat in order to perform a misva. This was an actual issue for Jews in Turnberry, who wanted to cross the inter-coastal waterway via ferry in order to reach Shul on Shabbat morning.
The Halacha clearly states that is prohibited to board a boat on Shabbat, even for the purpose of performing a misva. This is so even if the non-Jew at the helm is not working specifically for the Jews on board. The only exceptions to this rule involve cases in which the Jew boarded the boat on Friday, in order to "Koneh Shevita" (establish dwelling) before Shabbat.
SUMMARY
It is prohibited to board a boat on Shabbat, even for the purpose of performing a misva.
