We have an underway requirement at our yacht club that you must take your boat out twice a year under its own power, first half / second half of the year, this is supposed to eliminate or at least reduce the number of slip queens and derelict boats in the marina. There are who try to skirt the rules, which amazes me, because, come on, how hard is it to use your boat two times a year?
Anyway, the boat in the photos, an old 36' Uniflight aft cabin belongs to a person in our club, this is their home and is a really cheap place to live. The engines in this boat are seized and every year struggle comply with the underway requirements. So, they mounted a 20 hp Yamaha engine to the swim step and they get a few friends to take the boat out twice a year to comply. It takes 3 people to make this happen, one to operate the outboard, one to relay information to the 3rd person at the helm. (left -right-stop, go etc.) They have to take the boat early in the morning before the wind builds or they have no control of the boat and top speed is about 3-4 knots WOT.
That said, if you try, there are calculations used to determine minimum horsepower to achieve hull speed of a given hull. I had a 34' CHB trawler and remember the minimum HP for that boat was 40hp, but the boat was equipped with a 120hp Lehman, you need the extra HP to overcome current, wind and sea state.
be safe, try to get the engine(s) running or have the boat towed.