Hi All,
I've got a dilemma with my new fishing boat that I'm wondering if anyone else out there has had experience with. I recently purchased a 1996 Crestliner 1750 Fish Hawk (guessing 1,400 lbs with the engines and gear). It's an aluminum boat with a side console and a 40 HP Yamaha four stroke, long shaft (20") outboard that I mounted-up a couple of weeks ago. Since there are some lakes in my region that have a 20 HP limit, I also mounted a 2007 Yamaha 20 HP four stroke long shaft (20") off to the side. I connected the steering and have a second remote control so that each engine could be operated independently from the helm. The 20 HP is mounted about 8" higher than the main engine, since the transom rises on either side of the main engine location. The 20 HP is low enough in the water to submerge the cavitation plate and the bottom of the boat's hull rises enough at that point to fully expose the lower unit to the oncoming water. However, when I tilt the engine up only enough to where it would be pushing the boat forward (so that the cavitation plate is paralell to the plane of the hull) as opposed to being at a negative angle and pushing the transom upward (since I know there's not enough HP to push the boat onto plane), the prop begins to gulp air (cavitate), causing the engine to rev up and down and to bounce around. When I tilt the engine back down to a negative angle, the cavitation stops, but the upward force at the transom again consumes and wastes a great deal of my forward thrust.
I'm not out to win a race and don't have unrealistic expectations for the 20 HP. It achieves about 7 mph in its current configuration. In theory, a wider anti-cavitation plate would probably reduce the gulping of air. However, there's probably no better substitute for dipping the lower unit deeper into the water. Which finally brings me to my questions. Has anybody out there experienced this same problem with their kicker motor/mounting configuration? And, has anybody had any experience with an aftermarket kit (if available) to extend a 20" shaft to a 25" shaft?
Any shared experience will be greatly appreciated.
I've got a dilemma with my new fishing boat that I'm wondering if anyone else out there has had experience with. I recently purchased a 1996 Crestliner 1750 Fish Hawk (guessing 1,400 lbs with the engines and gear). It's an aluminum boat with a side console and a 40 HP Yamaha four stroke, long shaft (20") outboard that I mounted-up a couple of weeks ago. Since there are some lakes in my region that have a 20 HP limit, I also mounted a 2007 Yamaha 20 HP four stroke long shaft (20") off to the side. I connected the steering and have a second remote control so that each engine could be operated independently from the helm. The 20 HP is mounted about 8" higher than the main engine, since the transom rises on either side of the main engine location. The 20 HP is low enough in the water to submerge the cavitation plate and the bottom of the boat's hull rises enough at that point to fully expose the lower unit to the oncoming water. However, when I tilt the engine up only enough to where it would be pushing the boat forward (so that the cavitation plate is paralell to the plane of the hull) as opposed to being at a negative angle and pushing the transom upward (since I know there's not enough HP to push the boat onto plane), the prop begins to gulp air (cavitate), causing the engine to rev up and down and to bounce around. When I tilt the engine back down to a negative angle, the cavitation stops, but the upward force at the transom again consumes and wastes a great deal of my forward thrust.
I'm not out to win a race and don't have unrealistic expectations for the 20 HP. It achieves about 7 mph in its current configuration. In theory, a wider anti-cavitation plate would probably reduce the gulping of air. However, there's probably no better substitute for dipping the lower unit deeper into the water. Which finally brings me to my questions. Has anybody out there experienced this same problem with their kicker motor/mounting configuration? And, has anybody had any experience with an aftermarket kit (if available) to extend a 20" shaft to a 25" shaft?
Any shared experience will be greatly appreciated.