Alongside towing ("on the hip") is a common method of handling a barge or another vessel, docking, undocking, and transiting waterways. The tug will usually make up at the bow or the stern of the barge with its centerline inclined at an angle toward the barge to compensate for the offset position of the tug. The tug will make fast with several lines, usually a minimum of three,a head line, a spring line (also called a tow strap), and a stern line.
The operator must allow for the tug and barge to "crab" sideways a bit because of the offset position of the tug. This will vary according to the draft of the barge as well as which end of the barge is forward (with the stern forward, the tendency is less because of the skegs).
Deep-Notch Towing Pushing "in the notch" is getting to be common practice in offshore towing when weather and sea conditions are good. (The notch is the indentation at the stern of the barge into which the bow or stem of the tug fits to permit pushing.) It is probably the most efficient way for a tug to propel a barge and is faster than conventional towing since it reduces both the drag of towing gear and the barge's tendency to yaw or sheer.
Tugs and barges navigated in this fashion are suitably renforced in the area of contact and have special gear to secure them together. The tugs are also well fendered.
The deeper the notch, the more weather the tug and barge can with stand in pushing. When sea conditions are too rough, the tug will be obliged to take the barge in tow; towing gear is prepared usually in advance for this.
Since weather and sea conditions are an important factor in this type of operation, pushing is often seasonally limited.
Towing astern, the most common method of navigation for tug and barge units is employed in all oceans in all seasons. A tug may use either a hawser or tow cable. As a rule, hawsers are made of some synthetic fiber, nylon, other synthetic lines (such as those that float, such as polypropylene, polyethylene, and some blends like polydacron) are used by small tugs.
The tow hawser must be protected against chafing, either by securing a towing board to it or a piece of chain where it passes over the stern of the tug. It is shackled to a chain, wire rope pendant, or bridles secured to the bow of the barge.
Towing with a cable is much the same except that the cable is wound on the drum of a towing winch instead of secured to the tow bitts as a hawser is. On most tugs, these winches are nonautomatic and do not payout or recover cable when the load increases or decreases. Since the cable has little elasticity, a length of chain or nylon shockline is usually attached to the barge's bridle to help absorb some of the occasional heavy surge loads that the cable's catenary may not compensate for.
The tow cable must also be protected against chafing, either by shackling it to a steel spool that slides back and forth across the tow span or securing it to a metal "shoe" where it crosses the stern of the tug.
Multiple Tows are handled by oceangoing tugs. If the tug has a double-drum towing winch, the various barges are usually connected to separate tow cables and the forward barge rides over the bight of the after barge's cable. With hawser tugs, or tugs with a single drum winch, the barges are usually connected by means of an intermediate hawser. Most of the complications in multiple tows stem from the rigging and maneuvering while making and breaking tow.
Making and breaking tow are the processes involved in connecting up and getting underway with the barge, entering port, taking the barge "on the hip" or "on the head" (pushing), and docking it.
Making Tow If the barge is alongside a dock and must be maneuvered clear, the tug will usually "hip up" on the bow of the barge and connect its cable or hawser to the barge's bridle. Once the tug and barge unit is clear of the dock, the tug will drop the barge astern on a short hawser until it is clear of confined waters and then slack the cable or hawser to the desired length.
