Re: outboard capacity
redlinj, what types of water do you plan to use the boat - small lakes, big lakes, rivers, ocean? How do you plan to use it? Are you a speed and adrenaline guy or are you more budget conscious?
That general rule that you quoted is, as Home Cookin' mentioned, just a general rule - partly based on performance and partly based on resale value. It's often easier to sell your boat when it's got the biggest motor on it because depreciation has knocked out a lot of the initial cost. Some boats have a narrow range of power, meaning there is a minimum HP needed to propel the weight of the boat and occupants and it's not too far off from the maximum HP rating of the transom.
Your boat has a very wide range, meaning that you could hang something even smaller than the 88hp or go all the way up to 200hp. I have a 90hp (the maximum hp rating) on my 16.5' Alumacraft and it goes in the mid-to-upper 30s with gear and people. That's plenty fast for me and I'm on a lake that is 35 miles across. When I'm fishing and going from spot to spot, I don't go much past half throttle. Some guys need to hang a 200hp on the back and gun it from spot-to-spot. It all depends on what you want to do. For me that's a lot of money to spend on something that I don't need. Don't forget that a different prop can change how a motor works for you. If the 88hp goes 33-34mph but struggles to get on plane with 4-5 people onboard, you can drop the pitch on your prop and it'll carry a heavy load much better - setting you back $150 for a new prop instead of $15k or more for a new motor.
So a lot of your "optimal" question comes back to what your intended uses are and how much you're willing to spend. Obviously 88hp pushes that boat just fine and based on going 33-34mph you could probably even drop down to a 60hp or 70hp if desired. Anything between that 60/70 and 200hp is optimal depending on how you choose to define it.
The "optimal" power is whatever the boat is rated for. That way, you won't be wanting more.
