no offfense but....
I had a 9.5 hp as my side kicker for trolling... trolling which does not have to be at the other end of the lake all the time .
I ran a 3 gal tank on the 9.5 ahd found that even trolling during several days was adding up at today'S 7-8$ Cdn per gallon (gas here today is now $1.78/L) . Presumably a 25hp trolling will be a thirsty animal.... twice my 9.5HP !!
I retired the 9.5hp and installed a nice 1 cyl Merc 4hp as my new kicker.
see picture
Merc as my $100 kicker and a good carb job proved to be perfect for trolling at minimal cost fuel wise on my last trip..
a small 1960's 3hp JW or 4hp will also troll cheap all day
both are good safety insurance when the bigger engine fails on you .