Guess you can use these charts as a guide or starting point:
[A]
[SIZE=13.5pt]basic guide lines for the different types of hulls:[/SIZE]
[SIZE=10pt]DEEP-VEE - INBOARD - SUBMERGED PROP- 3.5cc - 1337/3, 1640, 1938, X438
DEEP-VEE - INBOARD - SUBMERGED PROP- 7.5cc - X445, X447, X645, X646
DEEP-VEE - INBOARD - SUBMERGED PROP- 11 cc - X447/3, X448, X452, X646/3, X648, X548
DEEP-VEE - INBOARD - SUBMERGED PROP- 15 cc - X455, X455/3, X457, X457/3
DEEP-VEE - INBOARD - SUBMERGED PROP- 22 cc - X460/3, X465, X665, 1465, 1662
DEEP-VEE - INBOARD - SUBMERGED PROP- 25 cc - X460/3, X465, X665, 1465, 1662
DEEP-VEE - INBOARD - SUBMERGED PROP- 30 cc - 1470, 2167/3, X467, X470, X670, 1567[/SIZE]
[SIZE=10pt] [/SIZE]
[SIZE=13.5pt]Prather Suggested Prop Usage Chart[/SIZE]
[SIZE=10pt]Prather Props - [/SIZE]
[SIZE=10pt]Use the following prop usage chart to match the proper prop to your boat and engine. In many cases more than one prop is recommended. The 1st prop recommended is the smallest followed by one or two larger props. The 1st prop recommended is generally used for low nitro or where high R.P.M. is needed. It's also great for breaking in new motors. The 2nd and 3rd props are for higher nitro fuels (50% to 60%) or where a higher strut height is used. Propellers are supplied 'as cast' and must be balanced before use. [/SIZE]
[SIZE=10pt]Order Prather props now[/SIZE]
[SIZE=12pt]Engine Size: 3.5cc = .21, 7.5cc = .45, 11cc = .67, 15cc = .90[/SIZE]
[SIZE=12pt] Prop # Diameter Pitch
215 1.60" 2.5"
220 1.72" 2.6"
225 1.84" 2.8"
230 1.90" 3.0"
235 2.00" 3.2"
240 2.12" 3.3"
245 2.25" 3.5"
250 2.30" 3.6"
255 2.40" 3.8"
260 2.52" 3.9"
265 2.61" 4.0"
270 2.74" 4.2"[/SIZE]
[SIZE=10pt]Inboard Deep Vees[/SIZE]
[SIZE=10pt]3.5cc - 215 - 220
7.5cc - 230 - 235
11cc - 245 - 250
15cc - 255 - 260 - 265[/SIZE]
[SIZE=10pt]Outboard Deep Vees[/SIZE]
[SIZE=10pt]3.5cc - 215 - 220
7.5cc - 230 - 235
11cc - 240 - 245[/SIZE]
[SIZE=10pt]Outboard Tunnels[/SIZE]
[SIZE=10pt]3.5cc - 215 - 220
7.5cc - 230 - 235
11cc - 240 - 245[/SIZE]
[SIZE=10pt]Inboard Outrigger Hydro[/SIZE]
[SIZE=10pt]3.5cc - 220 - 225 - 230
7.5cc - 240 - 245 - 250
11cc - 255 - 260 - 265
15cc - 265 - 270[/SIZE]
[SIZE=10pt]Scale Hydro[/SIZE]
[SIZE=10pt]11cc - 245 - 250 - 255[/SIZE]
[SIZE=10pt]Large Gas Powered Boats[/SIZE]
[SIZE=10pt]20.0cc and up - 270 - 275 - 280[/SIZE]
[SIZE=10pt]Inboard Cats[/SIZE]
[SIZE=10pt]3.5cc - 220 - 225
7.5cc - 235 - 240
11cc - 255 - 260
15cc - 260 - 265[/SIZE]