HobbyKing Princess Prop Upgrade

[Xcessive Carts]

I have a 37" Hobbyking Princess V-Hull boat, running the stock 36-60 size 1604kv motor,Seaking 180a ESC and 4s
40c Lipo. I would like to upgrade the prop to gain a little more speed. Cant find any info on the stock prop other than that is a 12x48mm. It is close to the Traxxas Spartan prop. Any help guys?
Here is a link to the boat,
http://hobbyking.com/hobbyking/store...arehouse_.html

[Xcessive Carts]

Not sure of prop shaft size, but it is smaller than my Traxxas Spartan prop shaft.