Comparing apples to oranges here but I just purchased a Honda 115 for my fishing boat and the marina I bought it from put on a 19 inch prop. On the Honda website I used their calculator and it also recommended a 19 inch prop calculating the dry weight of the boat along with passengers and full fuel. The boat jumped out of the water like a Orca but top speed was only 2 mph faster then my Honda 90 and rpms at full throttle was 4,000. I went to the Marina where I bought the motor and they then calculated a 15 inch prop.
I gained another 2 mph but the rpm's rose to 6,400 rpm. We then went with a 17 inch prop and I gained another 4 mph, the rpm's dropped to 6k where it should be.
Calculations might get you close but sea trials tell the truth.
As you can imagine it was much easier changing props on a fishing boat then it would be a 3288. What are your rpm's and speed now?
Man - you talk about opening the proverbial "can of worms" here. Ask 10 boat guys about props and you get 10 different answers.
I would suggest you try to get your hands on the Propeller Handbook by David Gerr (International Marine pub.). He wrote this great workbook a few years ago to try to make sense of this complicated process.
As is the case with all boaters, we are our own worst enemies when it comes to efficiency, speed and comfort. While the 3288 is not TOO heavy, if you have owned the boat for a while it probably has gained some weight. The placement of that weight will change the center of gravity and the naval architect designed the width, dead rise, keel and engine power with a specific center of gravity in mind. See where we are going here??
What are you worried about, or trying to accomplish. You might get more speed from better trim tab performance. You could get better attitude while on plane with some weight redistribution. You should get better fuel efficiency by using high performance components in the engines. There are fixes available that are quicker, and cheaper than pulling the boat and doing trial & error with propellers - particularly since you have two of them.