Ask The Expert: Towing Tenders

Published: Monday, July 30, 2018
By: Cary R. Wiener, President of Pantaenius America Ltd.

Cary R. Wiener is President of Pantaenius America Ltd. and a maritime lawyer who has worked on many famous cases, including the Exxon Valdez. He is licensed in all fifty states and is passionate about safety on the water.

Question:

We recently purchased a tender for our yacht. It’s too heavy to hoist aboard, so we’ll be towing it. What should we know before we tow?

Answer:

Many yacht owners tow a tender so they’ll have a smaller boat to jet around in or to go ashore, but towing tenders can be dangerous and risky because so much can go wrong. The tender you’re towing could get swamped - or worse, break loose and get lost at sea. It could smash into the stern of your yacht, causing extensive damage. The stresses incurred by a towed vehicle could rip out the cleats on the towing vessel and/or the tender or the mother ship could run over the towing line and chew up the yacht’s running gear.

Here’s how to avoid these risks:

Get Your Insurance Company’s Consent

You never want to tow a tender without proper coverage, and most yacht insurance companies have conditions you must meet when doing so. At Pantaenius, for example, we require that tenders be constantly watched — either by a crew member or a camera. Get these stipulations in writing, and follow them to the letter. Otherwise, if something goes wrong, any loss or damage will not be covered.

Make Sure You Have the Right Equipment

You’ll need at least 100 to 150 feet of towline so you can adjust it for varying conditions. Double braided (braid-on-braid) nylon is your best choice because of its superior combination of strength, stretch, and chafe resistance. Don’t make the mistake of using three-strand twisted nylon instead, assuming it will be stronger. While it does boast excessive stretch, it also has dangerous snap-back action — imagine a huge rubber band — when it breaks. Double braided nylon is stronger and will not kink.

Some yacht owners prefer using polypropylene because it floats. However, it’s not as strong, has little elasticity, and isn’t as efficient as double braided nylon at absorbing heavy shock loads that are transferred to fittings on both the towed and the towing craft. Polypropylene is also super stiff, making it difficult to tie knots that will hold fast.

Having the right hardware is also critical. You’ll need sturdy cleats, or bitts, that are through-bolted to the deck. And, make sure these have strong backing plates (which you can add) to handle the substantial weight from the tow. Otherwise, the tender could yank the cleats right out of your yacht’s deck.

At the other end — the bow of the tender — hardware is equally important. Make sure it has a reinforced towing eye or a bow cleat where you can safely secure the line. Most tenders that are lost while towing are lost because this attachment failed.

Rig It Up Right

The best way to tow a tender is to use a bridle arrangement. A bridle is a separate piece of double braided nylon line that’s attached to both rear cleats of the towing vessel. Leave enough slack so that the bridle becomes a “V” shape when the towline is attached to its center. Also, make sure you attach the bridle to D-rings versus tying it to a single line without a bridle. This will help distribute the strain over as wide an area as possible, plus enable the line to shift as the tender changes heading.

When towing hard-shell tenders, rig a similar bridle around the hull or superstructure of the vessel you’re pulling.

Since double braided nylon doesn’t float, the towing bridle needs to be buoyed with two or more floats. This will keep the towline from sinking and getting swept under the cruising yacht, then potentially becoming entangled with the rudder or propeller. It will also help make the towline more visible to other boaters.

Lighten Your Load

When possible, remove the motor from the tender before towing, and store it safely aboard the mothership. The same goes for oars, cushions, bailers, and other items that are apt to come loose and go flying if the tender bounces about.

Be Prepared to Let Go

Sometimes emergencies arise that call for ditching the tender to protect your yacht. Some skippers keep a knife handy to cut the bridle, but since there’s a lot of energy stored in that nylon when it’s under load, your best bet is to use a snap shackle at the end of the towline.

Watch Your Speed

Start off gently to produce a steady pull until you get up to speed. The goal here is to minimize stress on the towline, boats, and hardware. Your cruising speed should not exceed seven or eight knots. Otherwise, the tender will start to zigzag, and it’s easy to flip over a lighter tender when going too fast. In rough seas, when in high-traffic areas, or when mooring or docking, slow down to two-three knots.

Get in Sync

As a rule of thumb, lighter tenders should ride just ahead of the stern wave — or rooster tail — inside the first wave of wake. For hard-shell tenders, or if swells increase to above four-six feet, you will need to let the tender out, back to the second wave astern.

Regardless of tender size or weight, adjust the towline at the stern cleats so that both boats are in the crests and troughs of waves simultaneously. This may be impossible if seas are rough, but at least try to avoid a situation where the tender is struggling up the back of one wave while the mother ship is running down the front of another wave. This, or the reverse, creates tremendous loading, which causes dangerous surging and thus shock loading by the tender.

Lights On!

Whenever you tow a tender, your yacht becomes a towboat and the tender a towed vessel under the Rules of the Road navigation regulations. This means proper navigation lights are required for both vessels. Using lights at night or in poor visibility is a smart move anyway to avoid having another vessel run over your towline.

Choose Mooring over Docking

In busy harbors, high-traffic areas or while anchoring, you’ll want to draw the tender closer to allow for better handling in close quarters. Keep in mind that docking with a tender in tow can be tricky and challenging, even for seasoned skippers. So, to avoid potential hazards, it’s a better, and far safer, idea to moor.