it should turn. always.
Do you have power steering?
did you ever see it steer?
has the outdrive recently been apart?
actuator or torque amplifier box could be seized, helm cable could be seized, steering wheel shaft could be seized, worm gear in sterndrive could be seized, sterndrive can be assembled wrong (exhaust housing not shimmed correctly), trucourse shaft going out through the intermediate could be seized (there's a grease fitting there not too many people know about).
those are just the common and likely causes
need to start doing some visual inspection and basic troubleshooting. watch what flexes while someone steers. or tries to.
starting a boat that you haven't heard run should wait until you check all fluids including power steering reservoir. Maybe it's empty - can toast an expensive p/s pump pretty quick
if you loosen the 4 bolts on the top of the outdrive, does it free it up?took out drive apart greased every thing all gears work individually but once mated back together turns very stiff.
replace the cablehow do i get cable loose
if you loosen the 4 bolts on the top of the outdrive, does it free it up?
if so, the outdrive is probably a mix and match lower and upper that were not shimmed properly (and *maybe* correct gear ratio). There are shims under the top exhaust housing cover. Add more shims until there is 5 to 15 thou free float of the upper gearbox within the exhaust housing of the drive.
per "Shimming Upper Gearcase Vertical Movement" pg 7-1-20 in the manual
also grease the swivel bearing through the hole in the front of the drive - usually need a small grease gun tip like for u-joints
replace the cable