2520 XLD Twin Engine Alignment

[Antidote]

My engines are set with one inch of toe out. The engines are mounted 38" on center. The leading edges of the lowers measure 38 5/16." The trailing edges of the lowers measure 37 5/16." Can anyone tell me if that is proper for Parkers with twin Yamahas? I plan to try running at cruise with the Port engine disconnected from the tie bar to find the neutral the engine seeks.

 

[warthog5]

Thats a Good idea.....

There is also a school that says the prop wash should meet 75ft behind the boat.

I bet you get better fuel mileage when alignment is with the least drag...IE: disconnect and let it seek...like your talking about.

 

[Antidote]

Running the engines at the best economy cruise of 3500 rpm 4 bars of trim and the tie bar disconnected the engines actually took a toe in position. With the bar shortened as much as I could the holes were still a 1/2" away from each other. I am assuming because the engines are mounted 2 1/2' behind the transom on the bracket, the water flow has reversed direction and is rolling away from the centerline of the boat. Another factor may be the distance they are mounted apart from each other. They are 38" on center apart. Currently the engines are parallel and the wake meets about 25-30' behind the boat which suggests they need the additional 1/2" of toe in.

 

[Antidote]

Today’s test and results are as follows. Full fuel, filled the transom cooler with water. The transom live well and fresh water tank also full. Two adults on board. She is just about as heavy as a full day of fishing. 3 blade
props, 4 bars up of engine trim, full trim tabs down, 4500 RPM, 36 MPH, disconnected the tie bar. I adjusted the tie bar to match the natural neutral at these numbers. I am happy that I have found the sweet spot. Incidentally, after the test I measured and the engines are perfectly parallel. Here is a picture of the wake.

Then I ran her same set up except 3500 RPM 25 MPH and here is the wake.

In both cases the anti cavitation plates are on top of the water.