Does the Dolphin Fin fit the Yamaha High Thrust trolling motors? We get asked that question all the time. Yamaha 8.0HP and 9.9HP High Thrust motors have propellers that are roughly 12 inches in diameter and as a rule of thumb, that is bigger than we recommend but the Yamaha is the exception to the rule. The Dolphin Fin will either bolt directly to or clamp on to the 8.0 and 9.9 high thrust Yamaha outboard motors and work perfectly. We have done hundreds of these and it always works great.