Hazardous Cross Currents, Abrupt Direction Changes, and Rapid Tidal Currents

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March 10, 2019

Photo: Michael Carr

By Michael Carr – “Memorial Bridge, this is the Thomas Leighton, underway in 10 minutes, request opening please,” he called on Channel 13.

He then paused, took a sip of coffee and keyed the VHF mic again:

“Security Call, Security Call, Security Call, this is M/V Thomas Leighton underway from Freeman’s Point Portsmouth Harbor bound for Isles of Shoals, standing by for any concerned traffic…” He then repeated the call on Channel 16.

Memorial Bridge was only ¼ away to his south, but the fog was so thick he could barely see 100 ft. There was a light southerly wind, and he could hear, but not see, bell and gong buoys in the river.

As he waited for his Mate to tell him all the passengers were onboard and cargo loaded, he fiddled with the radar. He needed to get it just so, showing the bridges, the shore, the buoys, but not much more.

He walked to the starboard rail and looked over the side. The Piscataqua River was in full ebb mode, roaring out to sea at 4.0+ knots. Eddies and turbulent up welling’s were everywhere. He thought about the Coast Pilot words: an irregular bottom & constricted channel produces rapid tidal currents, abrupt current direction changes, and hazardous crosscurrents. “No kidding,” he thought.


He knew what to do, the exact steps he needed to make to move the 90-foot twin-screw vessel away from the dock, turned around and headed down river under the bridge. Memorial Bridge is a lift bridge, which must be raised for the Thomas Leighton to pass under and through the narrow opening.

What makes their departure truly challenging is not just the 4 knot current and fog, but the ebb current back eddies along the dock, so an ebb tide actually produces a current flowing north, not south, along the dock. As you pull in all lines and back into the River your stern is caught in a southerly current while your bow is being pushed north.

On days when there is no fog you can use visual references for monitoring your turn rate and movement down river, but on foggy days, like today you only have your radar and compass, and senses.

He rehearsed in his mind the steps; take in all lines except aft spring line, left rudder come ahead and spring the stern out away from the dock. Sound HORN! Give the crew a few seconds to take in the spring line as you come to neutral. Then rudder amidships and back on both engines, get out into the river and stem the ebb current. Stay parallel to the current. Line up with the bridge, and head to the middle span. Come ahead full on both engines, move faster than the current and maintain steerage. Clear the bridge, then breath.

This evolution would take maybe 5 minutes.

“Captain, we are good to go, we have 120 passengers, cargo is loaded, and gangway if off,” said the mate.

“Ok, standby to take in all lines except the aft spring line, and when you hear our horn, take that line is as fast as you can.”

One more call to Memorial Bridge, “Memorial Bridge, this is the Leighton, I am getting underway now, I can’t see you, and I will coming through on a full ebb tide, can you open now so I don’t freak out?”

“You got it Captain, coming up now.”

A few seconds passed and then he could hear through the fog the siren on the bridge sound, and the gates coming down.

“Let’s do this,” he said out loud.

Carr: Going 50 Knots with Your Hair on Fire

Rudders full left. Starboard engine ahead slow. Thomas Leighton began to turn, her stern coming off the dock. Now they were nearly perpendicular to the dock.

Engines all stop. Rudder amidships. Sounding the horn…a prolonged blast. Backing full on both engines. They were committed. He glanced at the radar to ensure he was keeping station in the middle of the river, stemming the 4-knot outgoing current.

“OK, we are in the river, lined up on the bridge, coming ahead” he repeated to himself. Now he stared at the radar, Memorial Bridge was right there in front of him, this is where the term “shooting the gap” came from.

As they shot through the opening he could see the shadows of steel beams to his left and right. They were through, and he took a moment to gulp some coffee.

“Memorial Bridge, Leighton, thank you for the opening. See you this afternoon,” he tried to say causally over the VHF. “You’re welcome Captain, have a safe trip to the Shoals”, came back from the bridge tender.

Now he needed to focus on the next 4 miles down river, turning left and right as they slalomed down the Piscataqua River headed towards the Isles of Shoals, 10 miles off the New Hampshire Coast.

Soon the mate came to the bridge. “All secure Captain, made an engine room check, heads are clean and smell good. Lots of supplies to offload once we arrive.”

And then he added, “The ducklings are started to accumulate astern.”

Carr: Sable Island Landing

They both laughed. “Ducklings” were all the pleasure boats that followed them to and from the harbor when the fog was thick like today. Most of these small boats had no radar, and some had no compasses, and so they followed the Leighton to and from the Isles of Shoals when the fog was thick.

They joked about steaming in circles or doing figure eights, and watching the many small boats do the same, “We could lead them anywhere!” they joked.

He sounded the fog signal, executed more security calls, stared at the radar and compass while keeping up speed to reduce set and drift.

Soon they were approaching Gosport Harbor on the north side of Star Island. This was an easy landing. No current, solid granite dock, where you can just slide right up. Only issue on foggy days were all the small boats which anchor off the dock face.

He eased the throttles back to slow ahead. Soon the fog started to lift near the Island, morning sun heats the granite island and burns off the fog. And then they were moored. He shut down the engines, and stepped out to the starboard rail. Sipping his coffee he yelled down “hello” to the “Pelicans”, the nickname for those who work on Star Island during the summer. Sounds of happy and joyful voices filled the air, commotion of unloading supplies, smell of seaweed, salt air, birds, and wildlife. He just stood there, leaning on the rail and absorbing the moment.

Read Next: Aground on the Silver Strand


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