3208 Marine Engine Marine Towing Caterpillar


Marine Towing
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1.1. Towing Procedure
2.2. Intermittent Back Driving
3.2. Continuous Back Driving
4.1. Securing the Propeller
5.2. Wrapping the Propeller Shaft
6.2. Securing the Companion Flange

The vessel should be towed under the following conditions:

  • The vessel is disabled.

  • The vessel can not continue to maneuver.


NOTICE

Reverse rotation of the propeller shaft can cause engine damage. To help prevent reverse rotation of the propeller, secure the propeller. Lock the propeller shaft, when possible.


During towing, the propeller of a vessel will rotate through the water. This rotation is called back driving.


NOTICE

Rotation of the propeller shaft without proper lubrication for long periods of time will damage the propeller shaft bearings. If pressurized oil cannot be supplied to the propeller shaft bearings while the vessel is being towed, the propeller shaft must be secured in order to help prevent shaft rotation.


Towing Procedure

Under the following conditions, back driving is permitted for most marine transmissions:

  • The towing speed does not exceed the normal maximum propulsion speed of the vessel that is being towed.

  • The marine transmission is properly lubricated.

Intermittent Back Driving

Perform the following items for short trips and for towing purse boats in seining operations.

  • Ensure that the marine transmission is in NEUTRAL while the vessel is being towed.

  • Start the engine. Run the engine for at least three minutes. Perform this procedure during every 24 hours.

  • Maintain the marine transmission oil level at the normal propulsion level or maintain the marine transmission oil level at the "FULL" mark.

Continuous Back Driving

Perform the following items for these continuous back driving circumstances: long trips, delivering a vessel by towing and towing a vessel home on a trip that will last more than one day.

  • Ensure that the marine transmission is in NEUTRAL while the vessel is being towed.

  • Start the engine. Run the engine for at least three minutes. Perform this procedure during every 12 to 14 hours.

  • Maintain the marine transmission oil level to the input shaft on the centerline of the engine.

Securing the Propeller

There are several ways to help prevent the propeller shaft from rotating. The correct method depends on the turning force of the propeller and the construction of the propeller shaft tunnel. Use the method that is best suited for the vessel.

To minimize the force on the propeller, tow the vessel at a slow speed.

Wrapping the Propeller Shaft

  1. On small vessels, wrap a heavy rope around the propeller shaft.

    Note: The number of wraps that is needed will depend on the mass of the propeller and the mass of the propeller shaft.

  2. Secure the rope in the opposite direction of the shaft rotation.

Securing the Companion Flange

  1. Remove one or more bolts from the coupling on the companion flange.

  2. Bolt a chain to the companion flange.

  3. Wrap the chain several times around the propeller shaft.

  4. Secure the loose end of the chain at a right angle to the propeller shaft. Secure the chain in the opposite direction of the shaft rotation.