Hello!
Just a hypothetical question. If somewhat large freight liner (lets say built in last 10 years typical roro in decent shape) with twin screws would decide to put port side full ahead and starboard side full reverse, would it damage the hull? If so, how much of power would be needed? Would it make difference if this manouver would be done in full speed or dead in water? Unheard of?
by design should have no effect. (watch the cavitation though)
No. If such a simple and possible scenario would damage or fracture the hull, that hull design would never have made it past the drawing board. While maybe not typically done at full power, or not for very long, going ahead on one shaft while going astern on the other on a twin-screw ship is probably the most common way to maneuver, especially when you don’t have a tug assist.
I’ve never done a sea trial where we tested full split like that (that I recall), but we definitely went from full ahead at full vessel speed to full astern bell (crash stop). It works just fine, but as @jimrr hinted, the cavitation might rattle your teeth a bit.
Very common maneuver, but generally at a managable speed, especially without a assist. And with some engineers you give shit about. Speed is not your friend in most cases. Never heard of fracturing hulls that were built right in the first place.
annual sea trials involved a crash stop, I never liked doing that AT ALL !!! amps went to max, vibration, stress/strain … while in a way it’s nice to know your ship can do that I’d rather wait until it HAD to be done (like never) and THEN take your chances on breaking something.
with a rhib or work boat, … something, no prob !!