It is not a larger load issue, boat is stock and just me in it for the test runs. Have used the prop calculator and the prop that came on it is one of the recommendations along with the prop I just put on is there as well.
Not sure if it is fair to say the dealer messed up, I like to think they did but in all fairness it may have been setup for the person who originally bought the boat. The original 13.8 X 13 prop works well, great acceleration, top speed of 18mph and a cruse speed of 5mph at 1800 rpm makes for a cheap day. Had the engine checked by a boat mechanic, (Not Mercury) and he stated there was no lugging of the motor, he actually thought the rpm gauge my be off a little but we confirmed it was not.
Guess what I need to decide is, do I want a boat that is better equipped for 90% of my running and lacking for 10% of my running compared to vise versa. I will cruise for 4hrs following the coast line at 5 to 7 mph, at sunset cook it home before dark. Going with a 14 X 13 three blade may literally buy me an extra 10 minutes of cruise before turning around per trip. It will cost me a lot more gas as cruise speed will be at 3000 rpm compared to 1800rpm with three blade plus another couple hundred dollars.
Think I will give Mercury a call. Thanks for the numbers.