Posts: 3507
Location: Elk River, Minnesota | Hiya,
I would completely disagree with the fin and the 5000 rpm.
What a jack plate is designed to do is allow the user to raise or lower either manually or hydraulically, which would position the motor at an optimum running height. Combine that with a motor that is propped correctly would put the fin totally out of the water, rendering it useless. All you would have is a motor with 4 holes in it which just reduced the value of the motor by putting something on that is no more than a band-aid to a set-up issue. THE only time to add a fin is when a boat is well underpowered and the motor needs help lifting the rear of the boat and keeping it there...those are the rigs that see a speed gain (maybe a mph or two at most as a general rule) as the lack of power of the motor does not lift the rear of the boat, let alone raise the bow. In most cases, a fin will slow the boat as adding the fin increases drag as it contacts the water.
With the 115 in question here, the fin will never be needed...especially when it is a running a good steel prop.
The Etec 115 is designed to run at a max WOT rpm range of 5500 to 6000 which for best overall performance, the motor should be propped in such a way that a light load would allow the motor to reach 6000 rpm's. This allows for extra people and gear to be loaded on without having to change props. If the motor is propped and below 5500 rpm at full throttle, the engine is working harder than it should, thus lowering the useable life of the motor....which eats up gas as well as the motor is not being allowed to reach is maximum in the power band.
Steve |
