90 hp is enough for just about anything that's 17.5 ft. in terms of speed it's hard tellin not knowin, my 15ft aluminium boat goes somewhere between 25 to 30 mph with a fourty horse motor. sure i'd love to have more speed but i don't really need it. i've gone up to 50miles in a day which was alot, but it only took about 7 to 8 gallons of gas where i hear that alot of the big outboads get 2.5 to 4 miles per gallon which can add up big time. unless you want to pull waterskiers you're fine, for all i know it would work well enough for that. good luck.