I have just bought a 115hp Merc 25" shaft and have it on a 1903 Trophy. We have just ben out to sea and found it very hard to get to the plane with 3 people and fuel. Went out with just driver and it got to the plane faster but still slow. The motor came with a 13 3/4" x 18" pitch prop. I have read some reveiws and with a similar boat to the trophy they were using 13? x 15" props. Anyone can maybe give me experience on this matter?