Towing & Ship-Assist · Towline — Catenary
The catenary (sag) in a towing hawser is valuable because it:
- AActs as a spring, absorbing shock loads as the tow surges instead of snapping the line taut✓ Correct
- BReduces the towing vessel's fuel consumption to zero
- CKeeps the towline permanently out of the water
- DEliminates the need to match towline length to sea state
Explanation
The weight of the hawser forms a sag (catenary) between tug and tow. As the tow surges, lifting the catenary absorbs energy gradually, cushioning peak loads. Too little catenary (short scope, or in shallow water) transmits jerking shock loads that can part the line.
Authority: Bowditch (Pub. No. 9); towing seamanship references
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