Re: Should I keep the outboard locked or on release
JB: The older big Chrysler engines without power tilt/trim had a manual lock. Turn the lever under the steering snout to lock or unlock it. If kept in lock position and if functioning correctly, if you hit something and the engine popped up, when it dropped down, the plate automatically engaged the tilt bar and locked again. Kept unlocked, the engine was free to tilt under reverse power. Engines with power tilt ONLY and no trim did have a lock that used hydraulic pressure (actually, lack of it) to engage while the engine was in running position. This also automatically released when a submerged object was hit at speed and reengaged when the engine dropped.
Smaller engines like 9.9 and 15 had a roughly circular plastic lever inboard, next to the starboard mounting clamp. The lock was a little different but functioned the same. These smaller engines also had a bar between the clamps to hold the engine out at an angle for shallow water operation.