[Fr. Frank]

Peter B,
I switched the lower units turning the props inboard instead of outboard- if you decide to try this the engine toe will have to be changed from 1/4" toed out (what is normal) to 1/4" toed in to compensate for the pressure the prop direction places on the engine. Your steering tie bar should be adjustable. The theory is the 1/4" of slack is taken up when running making them close to dead straight. If you don't do this, it will be squirrelly.
S

I rigged twin engines on boats from the mid-70's through the mid-90's, and I never rigged counter-rotating engines to rotate inward. Never. In fact, I have only seen this done once in my life, and that was when the 30' Rybo Runner was brought to me to correct it's handling problems after repowering at a different marina.

Left-hand engine rotates left, right-hand engine rotates right. To do the opposite sets up greater lower-unit drag as a result of the confluence of water pressure each motor applies to the other. This is the result of what is called "P" factor, which is the sideways thrust exerted by a rotating pitched propeller. You want to point that thrust away from your submerged running surfaces as much as possible.

Mount the motors on the transom bracket and align the front and back vertical edges of the lower units as measured below the cavitation plate to be 1/4" closer at the front edge than at the back edge with a standard 24" motor separation. This is toe-in. Add 1/4" of inward toe for each 6" of motor separation over 24", as measured at the leading edge of the lower unit below the cavitation plate. The toe-in IS NOT adjusted for distance behind the transom, but motor mounting height IS.

For identical rotation engines, i.e.; both RH rotation, the amount of toe-in is increased slightly. Start with 3/8" to 1/2", and then increase by 1/4" increments.

Because the outer motor in a turn has to travel farther in the turn, regardless of whether your motors or rotating inward or outward, you always must have toe-in, never toe-out, or else you are wasting power by working the engines against each other in every turn.