Posts: 3480
Location: Elk River, Minnesota | Hiya!!
Just want to make sure I understand the set-up correctly... The motor in the highest hole. If I understand correctly the motor is mounted about 3" off the lowest point of the transom?
If so, then I would agree that a pitch change is likely in order. In your case, you have a boat that is heavy, and with a 250 on it, I believe you are maxed on HP. A general guideline for pitch change is for every inch in pitch change, you can expect a change of 150 to 200 rpms (down in pitch -> up in RPM and vice versa) There is a limiting factor to this as well as getting too much pitch, the motor just does not have enough in it to turn it. For example, on my rig, I can run an 18 pitch prop and reach my max of 5500 RPM, but if I go to a 20 pitch, I can't reach 4600 RPM... The motor just does not have enough in it.
Also, I'm wondering if your new motor has the same gear ratio as your older motor. If they are different, that would explain a bit as to why you are not seeing somewhat the same performance out of the motor...
In your specific case, if you have a 19 pitch Rev4 (as suggested above), I feel that would be a good call as well. It should increase your RPMs by around 400 or so, but you may see more than that. Now...if it gives you those 400 rpms and your motor is mounted in the lowest position, moving the motor up a couple of holes will give you about 200 more rpm. This is a tricky call though as I believe you may have a setback on your boat so you might lose too much handling if you get too high. My gut says you'll be alright. The only way to know is to try it and see what happens. In many cases, you can be at higher motor heights...just because you have the 4th fin in the water with the prop, increasing handling significantly because you have more surface area contacting water with thrust.
I'm betting the 19 pitch will be really close.
Steve |
