The ONLY way to enter off a boat is the way the Captain instructs you too. I have only been on half a dozen shore dives, so extremely inexperienced with those. All of my dives have been boat dives, with Captains from the states to Bora Bora, from big, fancy outfits, to small, dinky familly outfits. They all have their preference and they will instruct you, so just listen and pay attention.