Along New Brunswick's Gulf of St. Lawrence Shore

By Reinhard Zollitsch

New Brunswick, one of Canada’s maritime provinces to the northeast of Maine, has two distinctly different coastlines with equally different tidal patterns. There is the steep, jagged rocky shoreline from Quoddy Head, ME down Fundy Bay into Cumberland Bay to the Tantramar River near Sackville, New Brunswick, stretching for about 190 statute miles.

And then there is the much gentler, mostly sandy shoreline along the Gulf of St. Lawrence, 330 miles from Dalhousie at the mouth of the Restigouche River and the border with Quebec, to Port Elgin at the border with Nova Scotia. While the tide waters gush into Fundy Bay at a speed of up to 5 knots, creating the biggest tides in the world of up to 55 feet, the tides on the Gulf of St. Lawrence coastline rise and fall not more than 8 feet (often only 4-5 feet along this New Brunswick shore). But the most stunning difference is the tidal pattern itself.

Diurnal vs semi-diurnal tide cycle

Being a Mainer, I am used to the tide flooding and then ebbing for about 6 hours each, i.e. I count on two high and two low tides during each 24-hour cycle. Technically this is called a semi-diurnal pattern. And it worked fine for me all my life and also last year when I ventured into Fundy Bay to St. John, NB. But I was not prepared for what I found when I paddled the 330 miles from Dalhousie to Port Elgin last August (see attached map and photo 1). The tides in the Gulf of St. Lawrence left me truly baffled and were “totally unpredictable and weird”, like nothing I had ever experienced along our Atlantic Coast or even in European waters.

Researching this phenomenon after the trip, I found the answer in G. Dohler’s charts “Tides in Canadian Waters” in the Sailing Directions, Nova Scotia (Atlantic Coast) and Bay of Fundy. Almost the entire New Brunswick Gulf coast has a diurnal or mainly diurnal tidal pattern, that means, there is only one high and one low tide per day, a rare occurrence.

As a matter of fact, there are only two relatively small areas in all of Canada that have such a pattern: the waters between Prince Edward Island and NB, and around the Magdaleine Islands to the northeast of Prince Edward Island (see attached Dohler’s chart. Other areas around the world include “the northern shore of the Gulf of Mexico, in the Java Sea, the Gulf of Tonkin, and in a few other locations”, according to Bowditch).

How is that possible? The tidewaters in the Gulf of St. Lawrence have two entry points. A relatively restricted northern entry through the Strait of Belle Isle between the northern tip of Newfoundland and Labrador, and the much wider Cabot Strait in the east between Cape Breton Island, NS and Newfoundland. Most of the water of this arm flows in a northeasterly direction towards the mouth of the St. Lawrence River between the Gaspé peninsula and Anticosti Island. But one arm splits off at the North Cape of Cape Breton Island and runs south, towards the Abegweit Narrows between Cape Tormentine and Borden, the site of the new PEI bridge.

I also learned that somehow the tides in the Gulf of St. Lawrence take on a counter-clockwise rotation around a pivot point just W of the Magdaleine Islands, to the northeast of PEI. From this point zero, high water reaches the western entrance of the Northumberland Strait 3 hours earlier than the eastern entrance, at Cape Tormentine.

The Sailing directions for the Gulf of St. Lawrence further point out that a low tide propagates slower in shallow waters than the high tide does, resulting in the high tides catching up to the preceding low tides. The bottom line is this: In a very limited area, from Miramichi Bay to the PEI bridge, the two high and two low tides are more or less compressed to one high and one low tide. Two tidal flows cancel each other out, like two converging wave trains do at certain points.

The tidewaters in those particular areas have traveled different distances. When the “slower” high tide reaches these particular areas, the “quicker” high is already on its way out. You combine all this with a low declination of the moon and you get this rare phenomenon, the DIURNAL tide pattern. It is limited to a relatively small area, as in my wave image. To either side of it, one would observe a transition from truly diurnal to mainly diurnal, to mainly semi-diurnal, to truly semi-diurnal.

18 hours of ebb tide?

I first became aware of this “crazy” tidal pattern in Miramichi Bay, the mouth of the Black River to be exact.  It was low at 6 AM when I got ready to leave Burnt Church, and it was just as low at lunch time at Point aux Carr (see photo 2). I felt the tide was finally beginning to turn at suppertime at 6:00 PM (see photo 3). 18 hours of ebb tide! It seemed totally out of whack and unnerved me. I felt downright discombobulated and irritable. It just couldn’t be! Then I noticed the tide barrel in in a mere 6 hours, crest around midnight only to run out again ever so slowly - - for another 18 hours.

Low tide in the morning
Low tide in the morning

I normally do not buy a tide table because I am so tuned to the regular 6- hour tidal rhythm, am a good observer and feel I do not need to be told that information. You check the tides carefully on your first day on the water, get the cycle in your blood, advance 50 minutes each day since the lunar day is that much longer than our calendar day; voila, what’s the problem?

But I eventually (after the trip, that is) did get the tide tables from the Canadian Department of Fisheries and Oceans, and was stunned by what I found. The area from Miramichi to the PEI bridge (photo 4) was so confusing that the high and low tides were not only given in clock times (as they were for the rest of the Gulf of St. Lawrence shore) but also in two graphs, as visual illustrations (see Escuminac and Shediac area graphs).

For the specific day in August when I was near Escuminac, the high was around midnight, and it showed an 18-hour ebb tide followed by a 6-hour flood (see graph). So far, I was right on, but I noticed that I had missed a small hiccup in the tide curve. In the middle of the long ebb curve, the tide had actually risen in this area by a paltry 10 cm (4”), something you definitely do not notice being on the water or on shore for that matter. If I had noticed it, I would have interpreted it as a “wind tide”, especially paddling in such shallow waters as Miramichi Bay.

Mainly semi-diurnal tides

I had an even more unbelievable experience at the other end of this diurnal tide box. I left Murray Beach just west of the PEI bridge on the incoming tide and made it around Cape Tormentine to Ephraim Island near North Cape in Baie Verte, Green Bay. The major mud flats off this beach (photo 5) should not be a problem leaving tomorrow morning, I figured, since I left this morning on the incoming tide, right?  A quick check of the tides, however, told me something was “wrong”.

It was beginning to flood at 8:00 PM. Would that be high at 2:00 AM and ebbing already for 5 hours at 7:00 AM, my departure time? I hoped not, but since this was going to be my last day to Port Elgin, and I did not have any other options, I did not really worry much. It’s only 10 miles - I could portage that (like fun).

Low tide in the evening
Low tide in the evening

My fears were unfortunately confirmed. When I first stuck my head out of my tent around 6:00 AM, the tide was already too far out for me to float or even drag the boat to open water. I was stuck on shore for an entire tide cycle, which meant I would not be able to get off from here till afternoon or later. I had no idea how long I was going to be held hostage here by the sea.

But since that could not be changed, I enjoyed a leisurely breakfast, did some pre-packing, and was just beginning my reading, when suddenly at 8:30 AM, at its half point, the tide turned and came in again, as if it did that just to pick me up. I am not hallucinating, this was no miracle, no incantation on my part, but just a fact of the truly “weird” diurnal tide pattern in these waters.

But when I rethought this accusatory simplification of my predicament, I realized the tide in Baie Verte must have changed back to a mainly semi-diurnal pattern. It had ebbed for six hours, from 2:00 AM to about 8:30 AM, but only to its half point, and was now coming in again. “Weirdorama”, my kids would say, but whatever the tide was doing, it was time to pack up as fast as possible, in case this tide changed its mind again.

I jumped into my boat when the tide had swept over the muddy part of the tidal flats, to the outer edge of the shore rise. I smiled and often shook my head in disbelief all the way to Port Elgin, where I took out at the first bridge across the Gaspereau River at high noon at almost high tide.

Low tide at lunch time too
Low tide at lunch time too

Paddling on diurnal/semi-diurnal tides

How do these strange tide patterns affect your trip? Not much really, if you are a prudent chart reader and plan your take-outs carefully so you will not be stranded a mile or more from the water when you want to leave the next morning. Till you figure out this strange tidal pattern (and you might not!), only pull out where the deep water comes relatively close to shore, within portage distance.

I did fine all the way from Dalhousie to Port Elgin, but now that you know about diurnal tides in these waters, it would help to get the official Canadian Tide and Current Tables for the Gulf of St. Lawrence, if only to awe at the intricate pattern of transition from semi-diurnal to diurnal, and back to semi-diurnal.  You will experience it all, along this 330-mile-long sandy, duny coastline with its many thin sandspit and barrier islands and unique coastal wildlife and flora. A veritable vacation paradise, for the most part still totally unspoiled, begging to be explored by sea kayak or sea canoe.

I thoroughly enjoyed observing these unique tidal patterns, maybe even more so since I did not know they existed. It is just one more exciting phenomenon to experience on a coastal journey.

Info sources:
Canadian Charts: 4486, 4906, 4912, 4911, 4905, 4406, 4130
Sailing Directions, Gulf of St. Lawrence, (Fisheries and Oceans, Canada)
Sailing Directions, Nova Scotia and Bay of Fundy (Fisheries and Oceans, Canada)
Canadian Tides and Current Tables, Gulf of St. Lawrence, (Fisheries and Oceans, Canada)
G. Dohler: Tides in Canadian Waters, (Fisheries and Oceans, Canada)
Bowditch: The American Practical Navigator. (Defense Mapping Agency, USA)
Boat and gear info:
Verlen Kruger 17’ 2” Kevlar Sea Wind (sea-canoe with rudder, deck and sprayskirt)
11 ounce carbon fiber bent-shaft Zaveral canoe paddle and deck-mounted wooden bent-shaft Mitchell
VHF marine radio telephone
Iridium satellite phone
Airguide deck mounted compass and stop watch

Distances given in statute miles.

© Reinhard Zollitsch