Days 77-79 (4-6 September) Five Islands, Nova Scotia
We arrived at Five Islands about 1:15 pm after a 5 hour drive from St Martins. Five Islands is located on the Minas Basin Arm of the Bay of Fundy. Our site in the Five Islands RV Park was on the front line near the bank and we could watch the changing of the tides—which we’ve illustrated in the photographs.
Saturday (September 5th) we drove along the coast to Advocate Harbor and Cape d’Or. On our way back to Five Islands we spent some time locating St. Brigid Church in Parrsboro so we could find it Sunday.
Sunday we went to Mass and then went to the Fundy Ocean Research Center. We ate at a restaurant in Parrsboro and had local scallops and clams. They were both excellent.
One of the reasons for visiting this area in New Brunswick and Nova Scotia around the Bay of Fundy is the tidal action: the highest tides in the world. The tide is so high that it literally causes rivers to reverse.
Recall that we saw the reversing of the St. John River on the way to St Martins. We were there at high tide when the tide from the bay literally overpowers the water coming from the river, forcing it to change direction impacting the flow of the river all the way to Fredericton, NB (65 miles by highway).
At St Martins the point of interest was the emptying of the bay and the sandstone sea caves formed in the cliffs. At Five Islands, the horizontal nature of the tides was the main interest. Twice daily, the tide changes from high tide to low tide; at low tide the water recedes beyond the horizon.
The Science of the Tides (from the Fundy National Park literature):
“Tides are the periodic rise and fall of the sea caused by the gravitational pull of the moon and sun on the earth. Fundy’s tides are the highest in the world because of an unusual combination of factors: resonance and the shape of the bay. The water in the Bay of Fundy has a natural resonance or rocking motion called seiche. You could compare this to the movement of water in a bathtub. Although the water in a bathtub sloshes from one end to the other and back again in a few seconds, it takes about 13 hours for the water in the bay to rock from the mouth of the bay to the head of the bay and back again. As the ocean tide rises and floods into the bay every 12 hours and 25 minutes, it reinforces the rocking motion. The bay’s shape and bottom topography are secondary factors contributing to the high tides. The bay becomes narrower and shallower – from 426 feet to 131 feet – toward the upper bay, forcing the water higher up onto the shores.”
There are three interesting ways to observe the tides: the Vertical Effect; the Horizontal Effect, and Tidal Bores and Reversing Rapids.
The Vertical Effect: In the Bay of Fundy tides can cause the ocean’s elevation to rise 50 feet or more. You can see this effect by comparing the amount of water in the bays and beaches at high and low tides. At low tide boats are said to be “on hard“ (sitting on the floor of the ocean). At this time people can walk on the ocean floor and explore interesting rock formations such as sea caves, flowerpots, and windows that are completely or partially covered by water during high tide.
The Horizontal Effect: In some parts of the Bay of Fundy the water retreats as much as 3 miles at low tide, leaving vast areas of the ocean floor exposed. Another low tide activity is digging up clams.
Tidal Bores: In some places when the ocean water begins to return up rivers, a “wall” of water is formed at the leading edge. In the Shubenacadie River, visitors can ride on the Bay’s largest tidal bore when the incoming tide meets the resistance of the river’s exposed sandbars, creating 9 foot waves and rapids.
Reversing Rapids: At St. John, the Bay of Fundy tides rise 28.5 feet. When the Bay of Fundy’s tides are low, the full flow of the 450 mile long St. John River thunders through a narrow gorge between Fallsview Park and the Irving Pulp Mill. An underwater ledge, 36 feet below the surface causes the water in the river to tumble downward into a 175-200 foot deep pool, causing a series of rapids and whirlpools. During this phase the tidal waters are 14.5 feet lower than the river level.
As the Bay’s tides begin to rise, they slow the course of the river and finally stop the river’s flow completely. This short period of complete calm is called slack tide and lasts about 20 minutes. This is the only time boats are able to navigate the Rapids. Shortly after slack tide, the bay’s tides become higher than the river level.
As the Bay’s tides continue to rise, their powerful force gradually reverses the flow of the river and the rapids begin to form again, reaching their peak at high tide. At this point the tidal waters are 14.5 feet higher than the river.
Using Tidal Power for Generating Electricity
One of the interesting places we visited during this stop was the Fundy Ocean Research Center for Energy (FORCE). [www.fundyforce.ca if you are interested.] This research center is investigating ways of harnessing the power of the tides to generate electricity in much the same way that a wind farm harnesses the power of the wind. The turbines being studied range from those using blades similar to a wind farm to more conventional designs - like those used in current hydroelectric power generating facilities. (The following information is taken from FORCE literature)
FORCE is Canada’s lead test center for tidal energy technology. FORCE collaborates with industry, government, and researchers to study the interaction between tidal turbines and the Bay of Fundy environment.
FORCE’s test site is in the Minas Passage area of the Bay of Fundy near Parrsboro, NS. About 160 billion metric tons (2200 lbs) of water flows through the Bay of Fundy each tide, equal to four times the estimated flow of all the freshwater rivers in the world combined. About 14 billion metric tons of that water passes through the Minas passage, helping to create the highest tides in the world.
Research suggests up to 2500 megawatts of clean, renewable energy may be safely extracted from the Minas Passage, enough to power nearly one million homes.
FORCE provides a shared observation facility, submarine cables, grid connection, and environmental monitoring at its pre-approved test site.
Tidal turbines do not need to spin as fast as windmills to generate power because water is roughly 800 times denser than air. Power increases exponentially with speed; every time water speed doubles, power goes up eight times.
Tidal devices operating in the Bay of Fundy may experience tides moving at speeds over 18 kilometers (about 11 miles) per hour, increasing up to 23 kilometers (about 14 miles) per hour over flat ground, and rising up to 16 meters vertically – the height of a five-story building.
Safety comes first at FORCE – our people work in tides that equal the power of a class four hurricane.
FORCE’s environmental monitoring program is designed to better understand the effects turbines have on the environment, and to report those effects to the public. Studies relating to lobster, fish, marine mammals, and other environmental variables are all shared online.
The need for reliable site data has led to the creation of new subsea monitoring platforms - designed to work reliably in the hurricane-like conditions of the Minas Passage. These platforms support new ways of capturing data in high flows, improving both turbine development and environmental monitoring.