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Discussion Starter #1
I shared this photo in another thread, it kind of got me thinking about how waves break. The photo was captured kayak sailing in fresh water in winds estimated around 15 knots while bucking about 1/2 knot current in about 120 feet of water.

The photo shows a hole in the water big enough for a mans foot to fit in and quite deep. These seas were only about a meter or so.

What is going on here? If this had been a 5 meter sea, would I be safe to assume the hole in the water would be big enough for a man to stand in?

Does any one have any thoughts on these holes/vortexes or have seen other weird effects in breaking waves that make them scratch their heads?
 

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Barquito
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Looks like there is a little turbulence coming off the kayak hull. Maybe this got the peak of the wave spinning.
 

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I've had an 80-foot motorsailer drop something like 15 feet (a guess, by the time it took) into a hole that developed under her in a stiff northerly on a Gulfstream crossing.
Wind against current can cause beach breaker type waves offshore, inshore, in bays or even in a river and at times just pull the water right out from under the boat, leaving her to drop into the hole. The stronger the wind/current differential the more dangerous and radical the situation becomes. This is the main reason NOBODY in their right mind would cross the Gulfstream in a northerly wind!
There are plenty of videos of boats entering harbors or inlets in these conditions that will show you just how difficult these conditions are to navigate.
 
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Discussion Starter #4 (Edited)
Maybe. This is a nice kayak with a pristine bottom. Not much drag.

But it seems a logical explabation.
 

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I’ve never seen anything like that. In my limited sailing experience I’ve only been in one really bad wind against tide situation. Going out the Big Bra d’ Or in Cape Breton. 20 knots against a 4-6 knot current. It was all I could do to hold onto the wheel, standing there I would go from looking at the sky to looking down into the water. Motoring and doing 7-8 knots over ground. What a mess. Standing waves.

But it didn’t last long but nothing like what you show.
 
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I’ll vote for current, either within the body of water or cause by the disturbance of the vessel.

The two things that break a wave are wind blowing it over, especially if current is standing it up, or when the depth of the water gets to approx the wave height, which are the surfer waves.
 
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From the pic it appears the waves are unusually big for the conditions, which would be an indication that whatever breeze there is was blowing counter to the current and standing up the waves. It can also indicate shallow water which will make the waves bigger than expected.
We see that a lot here when the current is going east against an easterly wind, the waves will stand up and curl like beach waves. When the wind is with the current the waves round off and do not curl, but collapse on themselves. It may not be very radical, but it is noticeable if you travel the same waters often enough to get the different conditions. Then you can see it anytime you encounter this and it becomes one of those indications of conditions that you may use to aid in your real-time route planning.
 
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Any response that I would make is purely speculative, but my best guess is that there is more than one wave train direction at play here. I have seen strangely shaped waves either when a power boat wake crosses a larger breaking wave train, or when there is a remnant of an earlier wave train that was generated by wind from a different direction than the current wind, or where there is a river or passage between two land forms that channels the waves at an angle to the main wave train, or where waves are reflected off a near by shore.

Jeff
 

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Discussion Starter #10 (Edited)
I am seeing an interesting convergence of theories here, which is helping me put together my own.

There were no other rivers in the area and no power boats on the water. I don't think I saw another boat all day.

However the wind was contrary to the current, and I think there were *two wave trains at play. There were the wind driven waves moving up river and the permanent standing waves that are always present on the Ottawa.

So maybe as the wind driven wave was blown over the standing wave, the wind driven wave collapsed, but instead of collapsing from the crest as I am accustomed to seeing, the wave collapsed further back, kind of imploded, and this caused the little vortex.
 

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Buzzards Bay is a good one for sea rollers, tide, wind, all coming from different directions. I crossed it once in sporting conditions and boat owner spent most of the time with head over transom :-o
 

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Discussion Starter #12
Going out the Big Bra d’ Or in Cape Breton. 20 knots against a 4-6 knot current. It was all I could do to hold onto the wheel, standing there I would go from looking at the sky to looking down into the water. Motoring and doing 7-8 knots over ground. What a mess. Standing waves.
Did it look something like this :) I took this photo a few weeks back from the bridge at Grand Narrows, Bra d Or.

What a crazy lake.

I think in this pic the tide was funneled through the narrows resulting in an accelerated current mid channel. Outside of the main channel the waves were reasonably tame, but where the current was strongest, they were just plain gnarly.
 

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One of the more interesting places for tidal standing wave action is Cattle Pass ,San Jaun Island.On a clear day no wind , over 1m high pointy both sides,, moving fast. Ran across what I thought was current direction and toppled onto deck with considerable gusto. I'm pretty used to wave action but this was different. As for holes in water. Whirl pools can do this big time but there are other signs so no mystery . Surprising a large critter ,basking shark Cadburosaurus etc, can leave very disturbed action on the surface with no sign of the actual critter. Read somewhere about big critters near the shores of Gichigoomi(sp?) so maybe you encountered one in your canoe.???
 

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We see all kinds of whirl pools like this on the Mississippi. Often much bigger. Many are so large grab the boat, twist it and throw you off balance as you go through them. They are caused by the 5 mph current along with underwater irregularities. On the Mississippi you will often see them in 100 feet of water.
 

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We see all kinds of whirl pools like this on the Mississippi. Often much bigger. Many are so large grab the boat, twist it and throw you off balance as you go through them. They are caused by the 5 mph current along with underwater irregularities. On the Mississippi you will often see them in 100 feet of water.
Hell Gate in New York City was known for the roaring whirlpool that developed with each current change. It was eventually eliminated by a major government works project. It still can be turbulent at times but, not as bad as it used to be.
 

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ARCB,

I think it must have looked a lot like that. i was further East that it got really bad, a couple of miles East of the bridge. The channel narrows, there is a sand bar hard on the North side of the channel. I’ve read they have special concrete anchors for the bouys.

The thing is, you are going so fast you are really slamming into the waves.
 
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Are you sure it wasn't caused by your paddle? Ive not been kayaking in conditions like those in the PIC but it is not unusual to see a vortex as you dip you paddle and pull back. Especially if you have a strong pull as one might need when paddling in those conditions.
 

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Discussion Starter #18
^^^ Good observation, it does look like a paddle vortex.

You can not see it from the camera angle in the first shot, but I wasn't paddling. My paddle was strapped down on deck. Had the sheets in one hand and my camera in in the other.

Here are a couple more camera angles showing looking forward and looking left. I don't have one looking back.
 

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