A friend of mine bought a boat, renovated it, parked it at a marina and used it as his first air bnb. Is this a cheaper way to begin an air bnb then buying a house? Or does marina cost/mortgage on the boat end up being being more expensive?

Well on my opinion you have to factor in the Cost of maintenance; Insurance; and moorage. Moorage can depend on length of the vessel. Tax wise you have exemptions on business but certainly a home you will have Taxes a boat you pay licensing fees. However a house is Real Property and a boat is a vehicle vessel. Meaning you can pull mortgage on a home and it may go up on value. A vessel drops in value. I would do my homework and start visiting Marinas Moorage places and Marina Boat Maintenance place that cleans the bottom. It all depends what works for you and what your goals are. Just saying in my opinion. Good Luck on the BNB. 👍

Marina cost is like 400 to 800 i believe.... I think it's a cheaper way but don't know fersure since I've never started one