Reverse gear may be preferred
I'd suggest putting the tranny in reverse, not just leaving it in forward. On our '85 Universal, if the boat is sailing and left in forward, the propeller can still spin the prop forward, grinding the plates in the tranny. Putting it in reverse locks the prop against forward spin, so it can't damage the tranny. The reason is that when the gears are in forward, the plates are designed to keep the prop moving at least as fast forward as the engine, but there's nothing but the plate friction to keep the prop from spinning ahead of the engine, wearing the plates away and leading to tranny slip.