No. There are no guaranteed fast ways to sell a boat. You should be very careful of anyone making high claims like that. Your sales of boat depends on.
a) Market condition, b) The demand of the type of boat you are selling, c) Condition of your boat, d) Price of your boat.
To speed up a potential sale, it is recommended that you can do a pre-sale inspection of engines and machinery. This kind of inspection does not need to be very professional, but a simple precheck done by an engineer checking few key aspects of important machinery. You could also lift up the boat and check the bottom of the boat. Such a report or a video will give confidence to a potential buyer to make a decision. People who are interested often like to see more details to ensure they are not taking risks. Clients are however always suggested to hire their independant surveyor before making a purchase.