Assistance Towing Endorsement
Assistance Towing - Towing
Towing
Towing is a dangerous undertaking. In any towing situation, the most important concern is the safety of people on board. The safety of the craft itself would be an important concern, but passenger and crew safety is always primary. If you have any doubt that you can perform the tow safely, then call the Coast Guard or private towing agency. Stand by the disabled vessel until the professionals arrive. You may be able to assist a vessel while waiting for help by putting a line across and keeping the other vessel’s bow at a proper angle to the seas. You could also provide support in many other ways, especially when it comes safety.
On a calm day towing another vessel is fairly straightforward. The towing vessel generally passes a tow line to the disabled vessel. A lighter line that floats, such as a water ski towline, can be passed first and used to pull over the actual towing line. Heaving lines can be used to pass towlines to a disabled vessel.
Quick way to connect a towline to bow eye
When approaching a vessel that is dead in the water (drifting) do not run too close to the disabled vessel, especially if there is wind or current. If you approach a burning vessel, always approach from the windward side so that the flames are blowing away from you. If you buoy a long line, towing it astern, take a turn around the stern of the disabled vessel, being very careful not to foul the line. A person from the disabled vessel can use a gaff to retrieve the line as it approaches. You can use the wind and current to your advantage with this maneuver. This method may be easier than using a heaving line and relying on throwing and catching. To “ease” a line means to pay out line to remove most of the tension in it.
The towline can be attached to the towed vessel’s forward cleats or bitts, making sure that they are able to handle this load. These bitts or cleats should be attached with adequate through bolts, washers and nuts. These should be reinforced with a sufficient backing plate. Wood or self-tapping screws should never be used.
Remember that bitts and cleats are found on deck whereas bollards are found on docks. For a sailing vessel, wrap the towline around the mast, unless the mast is stepped on the deck. If the mast is stepped then it will likely pull out. Keep in mind that any item of hardware that fails could cause the towline to snap like a slingshot, putting anyone in its path in jeopardy. A snapped towline can cause severe injury or even death. If the towed vessel is trailered, it will have a bow eye that would be an excellent place to attach the towline. However, be careful not to tow at sharp angles on a bow eye as it may snap under improper alignment of the tow.
Towing Lines
The best line for towing is nylon, double-braided or braid –on-braid. It is stronger than three-stranded twisted nylon and it will not kink. It also has enough elasticity to cushion shock loads. It does not snap back as much as three stranded nylon. Since it does not float, however, care must be taken to avoid entanglement with the propellers. Nylon line is better suited for towing astern than manila line. Nylon stretches too much for an along-side tow. Kevlar is also a good material for towlines. Three-stranded nylon has excessive stretch and, when taken under load, has a dangerous snap-back action. It should not be used as a towline.
Polypropylene has the advantage of floating but does not have the needed elasticity. Shock loads are transferred to the fittings on both the towing vessel and vessel being towed. It also has less strength than other lines of similar diameter. Its use should be limited to protected waters and light tows.
Remember that right laid line should be coiled clockwise. It should always be inspected for wear. Manila line should be opened to inspect the inner fibers (rots from inside out). Laying out a line in successive circles on your deck is flemishing, while faking is laying line in a back and forth pattern.
Chafing gear should be used to prevent wear on towlines that bear on hard surfaces. Prior to towing, towlines should be inspected for chafing where the towline passes over the stern of the towing vessel, where it passes through the chocks, and where it is attached to the disabled vessel. When towing astern, chafing gear should not be used on a hawser which is attached near an automatic towing engine (ATE) to prevent jamming.
Seizing is a method used to make an eye in a bight of wire line where it cannot be spliced.
When cutting wire rope, seizings are put on each side of the wire rope to prevent the wire from unlaying and to maintain the original balance of the tension in the wires and strands. The strongest method of making an eye in wire rope is using a wire rope socket with zinc. Remember that wire rope is classed by wires and strands. A common class of wire is 6 x 37 (more flexible), where the 37 represents the number of wires in each strand. The 6 x 19 class of wire rope is more resistant to abrasion (stiffer). When inspecting wire rope one must look for fishhooks, kinks and corrosion.
When being towed, a fairlead (chock) can be used to change the direction of the tow hookup. Back-up wires on a towed vessel provide safety, strength, and distribution of the towing load.
Handling the Towing Boat
As mentioned earlier, undertake a towing situation with extreme caution. Make sure that you have the proper power and equipment to do the job. The deck hardware for both vessels must be strong enough to handle the load. Bollard Pull is the measurement of the amount of force a towing vessel is capable of applying to a motionless tow.
Bollard Pull
The towline needs to be secured so that it can be cast loose if need be. Cutting tools, such as an axe or cutting torch, need to be ready for use near the towline. Preventers can be used to overcome the whip of towlines when released (canvas, fire hose). An anchor should be readied on the towed vessel in case the towline breaks or the tow is set free. Bridles can be used to reduce the strain on the lines. The lead of a tow bridle is redirected by a chock. The legs of a tow bridle are joined together with a fishplate.
The fishplate prevents the bridle from twisting during a tow. When being towed by one tug, the towing bridle should be connected to towing bitts with a round turn and figure eights. The least amount of tension will be on each bridle leg when the two legs form a small angle with each other.
The hawser, or towline, needs to be attached to a secure fitting near the bow of the towed vessel. The worst possible place to make the towline fast is to the stern of the towing vessel.
This causes the pull of the tow to prevent the stern from swinging properly in response to rudder action. This limits the vessel’s maneuverability. The towline should instead be made fast as far forward as possible. The most important point to remember is to start your tow gently. Keep a steady pull at a reasonable speed to reduce strain. A tug in irons is unable to maneuver. Stern towing pins may prevent a tug from tripping or capsizing when towing a large vessel. A towing vessel is tripped when it is pulled sideways by the tow. The danger of a towing vessel tripping is increased the closer the towline is secured amidships.
Stern Pins/Norman Pins
A tow that veers to the side on the end of the towline is said to yaw. When towing astern, one way to reduce yawing is to trim the tow by the stern. Yawing can occur when a larger vessel is towing a smaller vessel too fast. A towed vessel can lengthen the bridle legs to reduce yawing. An overriding tow is dangerous as collision between the tow and the stern of the towing vessel can occur. A loose tow may cause loss of maneuverability, lines to part, and damage to the towing vessel and tow. Always factor in wind and sea conditions when towing.
Overriding Tow
To reduce stress on the towing hawser when towing astern, the hawser should be underwater. The tug and the tow should ride the wave crests and wave troughs simultaneously to reduce the shock load on the tow line. This is called towing in step. The towline should be adjusted so that in step towing occurs. The dip in the towing line is called catenary. The catenary should be kept in the water while towing. As the tow gets into calmer waters, shorten up on the hawser to allow better handling in close quarters. Swing as wide as possible around buoys and channel markers so that the tow has room to follow.
If a smaller vessel is towing a larger vessel, considerable resistance will occur by waves hitting the larger vessel. This can slow or even stop your progress. One way to avoid these problems to tie alongside the towed vessel. This will make towing more efficient. On the lee of the towed vessel you will be protected from the towline. Towing alongside is also a good idea when the water becomes smooth. Both boats will respond as one unit to the towing boat’s rudder action. Fenders are used between the boats at the points of contact, and springs are used to connect the vessels. In this type of tow, even a dingy can tow a larger vessel at a slow speed. When towing alongside, your vessel should be positioned with its stern extending aft of the tow to obtain better steering control. When maneuvering from a pull tow to an alongside (breasted) tow, a twin screw vessel is more likely to foul a towline than a single screw vessel. Alongside towing is better in crowded areas where maneuvering is more critical.
Hip Tow
If your tow begins to sink in shallow water, the first thing you need to do is to pay out the towline until the sunken tow reaches the bottom. You can then buoy off the vessel. You do not want your tow pulling your vessel under.
Towing using two tugs approximately side by side each using one hawser is referred to as a breasted tug tow. A Christmas tree tow is designed to keep the catenary of the tow hawser to a minimum. For tandem towing (straight line) the more powerful tug should be placed in the back.
Christmas Tree Tow
