• For insurance reasons no 'fire' is usually allowed on a BBQ so the BBQ is usually a hotplate.
• You are usually completely exposed to the weather on a yacht BBQ because it is on the outer side of the yacht for safety. Yes, I have had people holding umbrellas for me as I cook, fighting torrential rain.
• It's usually really small. If you have a BBQ on a yacht for a large number, 10+ pax, you're going to have to be creative. Even the galleys are usually tiny.
• A BBQ on a yacht is a closed door. You can't just run to the shops to top up on something, what you have with you is it.
• It's always moving. It's a yacht on the water after all. Get used to everything rolling about, and potentially your guests being sick all around you.