King tides: window into future sea levels

Posted 11/6/19

At least once a year, in the midst of a winter gale, a boat will crash onto the Boat Haven breakwater.

Last year, it was on Christmas Eve.

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King tides: window into future sea levels


At least once a year, in the midst of a winter gale, a boat will crash onto the Boat Haven breakwater.

Last year, it was on Christmas Eve.

“I ran out there real quick, and me and the guys grabbed it and hauled it out,” said Terry Khile, the hoist and yard manager at the Port of Port Townsend.

Khile is hoping that there won’t be another Christmas Eve call again this year. But winter brings storms and king tides, leading to large waves and high winds that batter boats around in Port Townsend Bay.

“King tide” is a colloquial term for an extremely high tide. These high tides occur when there are astronomical events that amplify the gravitational pull between the Earth and the moon.

“It’s a natural phenomenon that happens in our little corner of the world caused by the placement of the moon, the earth, the sun and where we are in our orbit,” said Coastal Policy Specialist Bridget Trosin of Washington Sea Grant.

While the moon generally has a bigger influence on Earth’s tides, the sun also has gravitational effects. When the moon and sun are aligned, their gravitational effects compound, and the high tides become a little higher. Winter king tides happen when the Earth is closest to the sun – a position called perihelion. The planet reaches this position in early January each year.

This year, there are several days at the end of November, the end of December and the beginning of January when forecasters have predicted up to 9.7 foot tides in Port Townsend.

On a calm day, a king tide is not an extraordinary event. But it can be a window into the future, Trosin said.

“It provides an opportunity for coastal communities to understand how high water levels affect their lives,” she said.

While a 9 to 10 foot tide now only happens a couple times a year during a king tide, sea level rise projections say that in 50 years or less, those high tides could be the new normal.

“In the year 2050, there is a 17% likelihood that the sea level will rise by 1 foot or more,” Trosin said. “Things that flood right now in a king tide are only going to get worse as sea level rise continues.”

Last year, a king tide coincided with a wind storm, leading to the flooding of businesses downtown and some damage to the Boat Haven breakwater.

Boats anchored out in the bay can break loose of their anchor in a king tide storm and wash up on shore, or wreck on the side of the rocky breakwater. Last year, the Ninaa Otakii, a 40-foot sailboat on the Department of Natural Resource’s Vessels of Concern list, washed up on Beckett Point and stayed there for six months. Meanwhile, another boat crashed on the breakwater, causing Khile and his team members to have to haul it out on Christmas Eve.

When Khile, who manages the haul out operations and boatyard at the port, looks out into Port Townsend Bay, he can already see some boats of concern.

“You get southerly winds blowing a boat that isn’t anchored well, and it will either end up on the beach or on the breakwater,” he said.

Boats anchored in the bay need to have the proper anchor gear, Khile said, and sailors who know the proper way to anchor a boat. Boats’ anchor lines should have the proper scope, meaning the ratio of anchor line to water depth should be 5 to 1.

“At high tides, the water level rises, meaning that angle changes,” he said. “Boaters should also have the proper ground tackle that will hold it. It’s all sand out here in the bay. Dragging anchor ruins eelgrass beds.”

Having a boat out at anchor during a high tide and a storm event is risky, Khile said. He works closely with the Department of Natural Resource’s Derelict Vessel program to report any vessels that look like they’ve been abandoned and may be at risk of washing ashore or onto the breakwater.

Boats moored at the marina with responsible owners are much more safe from the dangerous weather. However, that doesn’t mean that boat owners shouldn’t prepare for stormy weather well before the storms actually come.

“Check your mooring lines, make sure they are not frayed and there are enough of them, make sure your roller furler is secured properly otherwise the wind could shred the sail,” he said. “Make sure cockpit drains and deck drains aren’t clogged for when rain or snow comes. Snow and ice can pile up.”

Khile hopes that boat owners will secure all their lines before storm season comes. During a storm event, he and his crew will be out in the marina checking to make sure everything is secure, but he doesn’t want boat owners risking their own safety walking the docks during 50 mile per hour winds.

The same goes for boats moored at the Point Hudson Marina, although with a 130-year-old jetty that has been slowly deteriorating for years, these boats, and the entire marina, are at a higher risk.

But a storm event is unlikely to destroy the jetty in one go, says Eric Toews, deputy director of the port. It needs to be replaced, but isn’t about to collapse at the next 50 mile per hour gust.

“We do have informal contingency plans for repositioning vessels,” Toews said. “We keep an eye on the weather and have talked with moorage about a protocol.”

The outer south leg of the jetty is in the worst shape, he said. If something were to happen, the port would immediately take emergency action.

Jefferson County Emergency Management is one way citizens can be aware of upcoming storms with NIXLE alerts, sent by text messages to your mobile phone or by email.

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