Which instrument may a towing vessel, engaged in towing exclusively on the Western Rivers, use in place of a magnetic compass?

Correct Answer: Option B — Illuminated Swing Meter

46 CFR 27.205 allows towing vessels operating exclusively on the Western Rivers to utilize an illuminated swing meter in lieu of a magnetic compass. This instrument provides a precise indication of the vessel's rate of turn, which is critical for navigating the narrow, winding channels typical of the Western Rivers system.