For a MODU not on an international voyage, an approved substitute for an impulse projected rocket-type line throwing appliance is a __________.

Correct Answer: Option B — shoulder-type line throwing gun

Title 46 CFR 108.597 allows a MODU not engaged on an international voyage to substitute an impulse projected rocket-type line throwing appliance with a USCG-approved shoulder-type line throwing gun. This provides a compact, reliable means of establishing a line connection during emergency towing or vessel transfer operations.