These towing concepts are from US Sailing’s Safety, Rescue & Support Boat Handling.
Observer: There should be a person on the safety-rescue boat who watches the tow and alerts the operator if any problems develop. This person will tend the towline and transmit information to the operator while picking up or releasing a tow.
Speed and Length of Tow
These factors will be affected by whether the boat is being towed in rough or flat open waters, a channel or an anchorage. The towing speed should not put any boats in danger, including other boats operating nearby. A longer towline enhances the ability of a line to absorb sudden loadings. In open waters, towing speeds may be higher with a longer tow length, but if the towed boat takes excessive water over its sides, or slams into waves, or surfs down waves dangerously, or the towline is excessively taut, these are signs of excessive speeds.
Towing at too slow a speed may cause the towed vessel to accelerate on each wave or swell, causing the line to go slack, then taut. In this case, increasing the speed may even out the strain on the towline. Typical towing speeds maybe at the maximum wake-producing range of a towboat, so while operating in anchorages, no-wake zones, and close to the shore or a dock, speeds should be slowed to minimum wake speeds. Transverse waves generated behind a towboat may affect the positioning of a boat being towed, and if a towboat increases its speed these waves will move further aft and the towline may have to be adjusted to reposition the tow. Often at higher speeds, a planing type boat is towed hear the top of the backside of the second or third wave to avoid having it surf down the face of the wave and possibly broach out of control, or ram the towboat.
With heavier displacement type boats, it may be beneficial to position the boat on the forward side of the wave to take some of the strain off the towline and towboat. If towing in a following sea, the towline should be adjusted so the boat being towed is positioned on the wave to coincide with the position of the towboat so that each boat slows together as they climb a wave and accelerate together while coming down a wave.
Towing a Powerboat
If a boat has an eye on its stem for attached a trailer’s winch cable or a mooring, this is usually the strongest place to attach a towline. A kicker skiff hook on a pole can make it easier to attach a line to this eye. When towing, it is desirable to tow the boat with its outboard motor raised out of the water to reduce drag. However, if a boat yaws or swings from side to side, it may be necessary to lower the motor to reduce yawing, and in some cases to steer it.
Towing a Sailboat
If a towline cannot be fastened to the sailboat’s bow or led through a bow chock or fairlead, a person should steer the sailboat. If a sailboat has a centerboard or daggerboard, it should be raised 1/2 or 2/3 to improve tacking; if there is no one on the boat, it should be fully raised. Shifting crew and equipment weight aft to raise the bow also may increase tracking performance. Sails are usually lowered on centerboard-type boats to reduce the possibility of capsizing or adversely affecting their control on a tow. If towing short distances into the wind, the sails can stay up and flap in the wind. Another alternative for small boats is to detach the mainsail from the boom, allowing the sail to flap without the danger of a swinging boom hitting someone. On some boats with no standing rigging to support the mast, the mainsail may be detached from the boom and wrapped around the mast and secured.
Towing a String of Boats
If towing more than one boat, measured changes in towing speed become very important as well as the ability of the people in the boats to steer them. If a towboat suddenly decreases its speed, the boats under tow may collide and become entangled, which could be difficult to sort out and in a worst scenario the tow may need to be broken up and started over again. If the speed is increased too rapidly, people on the boats may be caught off balance and sudden loading on the boats and towlines could result in damage. When picking up boats onto a tow, the speed of the tow is critical. Too slow could lead to boats on a tow losing steering control or colliding with each other. Too fast could make it difficult to tie a new boat onto the tow.