Towing the Tender

May 18th 10
By Tim Hull

You get a call at 5:30 in the morning, almost two and a half hours before you’re to take over bridge watch. The mate hasn’t called you at this hour in months. Walking up to the wheelhouse, you adjust your eyes to the surroundings and realize that the tender’s navigation lights are no longer lit. The mate fears the tender is no longer with the vessel.

Slowly, you come about to find that the 33-foot Intrepid, the boss’s favorite toy, is no longer in sight. All hands are called and you reverse your heading to hopefully find your lost tender. Your mind races, “What went wrong? How did I lose this boat?”

This is a story I’ve heard numerous times in the eight years I’ve worked in the yachting industry. The 12 years prior I worked in operations on commercial large line haul ocean-towing vessels.

The principles are the same for both commands. The goal is the safe completion of another journey with no safety issues and that the towed vessel remains with you for the entire ride and arrives at the dock undamaged. The procedure for towing and the correct response plan are the same in both the yachting and commercial industries. Proper planning, administration and training are key. Without these, there will certainly be an issue with the tow at some point. I personally have watched as vessels have towed too fast, beating up the tow, lost a tow, beat the vessel alongside as they re-rig, or frighteningly, placed a man in the water to get the tow and drive it.

Planning

Planning begins well before you even think about towing your tender. Many yachts tow tenders, but many are not properly built for the stresses incurred by a towed vessel. Inspect the towing bits or quarter cleats. Ensure that they are fully backed. I even would recommend tying the backing to a structural component on the yacht, S/S straps or a turnbuckle brought down through the compartment from the backing plate to a structural longitudinal or bulkhead within the yacht. The stress on the fitting can be immense. I cannot emphasize this enough, especially if you’re contemplating towing across vast expanses of water where the potential of a local weather disturbance or a low can catch you off guard. The hole ripped through the deck where the bit gave way would be a greater loss than a missing tender.

Determine a thorough speed curve for both the yacht and the tender. Be aware of the point at which each vessel leaves displacement-mode sailing and begins to move toward semi-displacement mode. Pick a speed in displacement mode for towing. Take a look behind the yacht in calm and moderate sea conditions. Count back at least two full quarter wakes behind the yacht. (On a 100-foot vessel, this might be more than 250 feet back.) The bow of your tow should ride on the back of that wake. It may seem quite far, but that is a safe distance. Distances should be adjusted to fit sea conditions.

Another thing to consider when towing is that bilge pumps are unreliable in the long run. The tender you tow should have good freeing ports in the stern and an innate ability to free water. Navigation lights should be rigged to a separate battery source, even a solar charger, if you will be towing for several days. The tow point must be thoroughly backed and attached to a large surface area low on the bow, but above the waterline. At best, two tow points should be rigged on the nose of the vessel; the primary tow point and the backup point, which an emergency towline can be rigged to.

The tow package should be built to handle the stress and weight of the towed vessel by a minimum factor of five. That is an operating strength of 50,000 pounds for a 10,000-pound tender. The towline should be made of a few separate items: the ship’s bridle, if the tow point is not a center tow bit, and the tow hawser – typically made of advanced aramid fibers. There also is the tow surge gear and connection point to the towed vessel. The surge gear and final connection point are probably the most important and least understood part of the towline. They are used to provide a catenary to the line and a stretch point to reduce shock loading to the tow gear. Without this, you ask for failure of any of the tow equipment at one point or another.

Administration

Administration of this towing package is the second item within a towing response plan. Ensure that all personnel know the procedures of the towing evolution. All equipment must be inspected, cleaned and prepared for use. Many of the tow package items will degrade under UV light, so keep them out of the sun when not in use. Be sure you have plans in place for standard towing operations and emergencies.

Training

The third step is the training of the personnel operating the tender. No one should ever swim for a lost tender. If the tender is properly outfitted, you can retrieve it without endangering a crewmember or the yacht itself. Training the crew in conducting tender retrieval is almost as important as training them to take and release the tow. Take a page out of the commercial handbook and go to the tender, not the other way around – if you have power with the yacht, why pull in a towline to the stern where it cannot be seen and can catch in the running gear?

Towing a tender takes practice, but training will keep everyone on top of their game.

 

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Rating  Average 5 out of 5

2 Comments
  • Thanks for the professional view but please give us more information on the "surge gear" this is the most difficult piece of gear to quantify. Secondly towing at displacement speed is going to make for long passage times, a 25' waterline dinghy will need to be towed at less than 7 knots, a 36' waterline less than 8 knots.
    Posted by yachtone 20/05/2010 22:37:24

  • I use a "Tender Teather" alarm for my 20' tow behind. For the Intrepid, I installed AIS, pretty cheap investment for a $300,000 tender.
    Posted by aeronautic1 19/05/2010 15:12:55

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