It really depends where you fish. If you fish South VI and the Race Rocks/Sooke area and its super moon currents you really want a 9.9HT on that 17 or at least an 8ht. We get some nasty nasty current. Remember it is not just your fishing motor it is your back up emergency motor. There are times the outer Secretary rips are so fast that in my boat with a 9.9ht wide open you are still going backwards or at best side to side but not forward and you need to start up the main to get you forward a few hundred yards where the 9.9HT will hold its own - just, at near wide open. I have trolled through the inside Secretary gap when the current and rip has it resembling a boiling raging river and that's with moderate wind. Granted it is not that often you get those conditions. One of my buddies finds the 8 HT is sufficient on his 16 Double Eagle for South VI both for safety and fishing but that is a smaller lighter boat. One of my older fishing buddies who has passed away, had a light weight 15 hp two stroke on his 17 foot glass boat. That is not to say that some don't get away with smaller motors but more is better and safer as long as the boat can handle the weight. A bigger motor does not have to work as hard, will last longer and be less likely to fail when you need it most and have to push it hard.