Broach

[Peach Canoe]

Simply put, this is when the boat is turned off-course to arrive broadside to wind and waves.

The turning of the boat, however-- the yawing, slewing, or sudden rotation about the vertical axis is where the meat of the story lies. Where do these turning forces come from, and what can we do to minimize their effects?

There is a litany of sub-topics that fall under the heading of 'Broaching', and it's a weighty conversation; sub-topics might include the following: hydrodynamics of wave action and the 'relative' flow between crests, wind strength, wind direction, wave height, wave period, boat size, effective 'sail' distribution (all that sticks up above the water), weight distribution, hull design, how a full-displacement hull (a canoe) turns, effective paddle strokes, and the use of drogues.

There are many more, and I invite conversation on this fascinating aspect of our favourite pastime.

While the dynamics of turning may be the body of the story, the ending isn't always of the Hollywood type-- many of us have seen the turn-broach-capsize triplet that has ended in real-life tragedy.

 

[Will Derness]

Broaching....and the terror of a capsize induced by that was easily the most terrified I've ever been on the water.

A group of us were sea kayaking tripping in the Sea of Cortez. We had already put 20 miles behind us in 4 foot seas when we entered the strait that would carry us to a sheltered harbor 5 miles away. The 20-30 knot tail wind kicked up the water in the strait to 8-10 foot swells. They weren't breaking, but the faces were steep and the stern started traveling a lot faster than the bow. No landings, just sheer cliffs to the sea. For the next hour it was constant struggle to keep the kayak in line. I can't remember all the strokes I used, I just remember that one mistake might be a life changer (no roll).

Fortunately all six of us made it, but I think had anyone spilled it might well have been impossible for anyone to render assistance. Despite trying to stay together we became scattered, every now and then you would see a companion when surged high on the swell. In the bottom of those swells, I can't recall feeling more alone.

Canoeing WW seemed tame in comparison.

 

[memaquay]

I had a similar experience to Will's. I was in a group of four canoes, I was the only solo. We were on the lee shore of a very large lake, and had to make about a 4 kilometre crossing. Conditions looked fine. When we reached the middle of the lake, we realized our mistake. Waves were cresting in the six foot range, and we completely lost site of each other, although occasionally I would catch a glimpse of someone as they crested a wave, only to see them disappear again in the trough. I was in my cedar strip Osprey, and as I recall, I didn't worry much about broaching. The waves were so large that I was practically surfing on the downside. We all made it to the far shore, but as in Will's case, if any of us had gone over, there wouldn't have been anything the others could have done.

I find broaching to be more of a concern in solo canoes without much rocker, and in asymmetrical designs. The stern tends to get sticky and doesn't respond as quickly to correction strokes. The Osprey was prone to this more so than the Raven. The Raven had a fair bit of rocker, both fore and aft, so it didn't stick as much. The Chum I built spins on a dime, it's got real loose ends. I haven't had it out in huge waves, but big enough to know that it will do whatever it is told too, although sometimes it needs a little spanking to track as hard as the asymmetrical designs.

 

[Alan Gage]

I find broaching to be more of a concern in solo canoes without much rocker, and in asymmetrical designs. The stern tends to get sticky and doesn't respond as quickly to correction strokes.

That's interesting. I don't have a lot of experience in highly rockered symmetrical canoes but I would have thought the opposite; that a canoe with a stickier stern would be less prone to getting pushed around by the wind. Although I can see where better paddle response would be appreciated as I have had to fight that on occasion in the wind.

What about shear height? If we're talking about the stern getting pushed around by the wind that must come into play as well.

As far as broaching I thankfully haven't had to deal with that other than when I spent some time paddling C1 racing canoes. 18.5' long and tippy as all get out with vertical stems and no rocker. I never did get comfortable in even small wind or waves in those boats. I'd be paddling along on flatwater feeling just fine when a small (and I mean small) boat wake would come rolling past quartering a little from the rear. It would pick up the stern, the nose would dig in and stick, the stern would get swung around, drop into the trough, and next thing I know I'm swimming without ever knowing what happened.

Alan

 

[yellowcanoe]

Terror. Realizing you have to retreat . That usually means making a u turn and momentarily broaching
Straight keeled boats get stuck sideways it requires lots of pure stern draws and hard bow draws. On the downwind side those bow draws can be frightening as the paddle wants to jam under the canoe
Solo I don't usually have as much trouble as the ends are lighter than the mass in the middle
But a MN II and a u turn and you have problems
This is one case where having this double blade is useful. The paddles are fixed more away from the boat and it's a bit easier to keep them from going under the boat

 

[yellowcanoe]

I had a friend who in a q boat. ( a fast sea kayak) did the same as Alan. He was all of a sudden in the water and asked me "wha hop pen?"
It was the ocean. He was pleased he had not been too lazy to put the drysuit on

 

[Peach Canoe]

Someone may surely be able to express this more clearly and succinctly, but this is how I understand it. I'll be discussing the 'turn' aspect of the subject-- the turn happens first, and the broach is the result.

In waves, the water mostly bobs up and down and moves in trains of local circular motions at the surface-- and, there is a little net forward travel at the surface. Segments of the circular motion impart forces that manifest as a horizontal component at the surface: across the crest there is forward 'flow' (from stern towards bow), and in the trough there is backward 'flow' (from bow towards stern). The 'flow' in the trough is faster due to gravity.

I use single quotation marks for 'flow' as the force cycle is local and short-lived.

A displacement hull like a canoe turns from the bow. In this sense I mean the 'effective' bow-- if you're back-paddling, the effective bow is the stern.

When a canoe rises on the crest of a wave, there is 'flow' from astern. If the canoe is moving slower than the 'flow' and is not perpendicular to the wave, a rotational force is imparted at the stern. When the canoe descends cocked into the trough, the 'flow' now comes from in front-- toward the bow, and because the canoe is not perpendicular to the wave, a rotational force is imparted at the bow. As the canoe turns, more side hull is exposed to the force of this 'flow', and the turn accelerates!

There are a number of elements that impart rotational forces to the canoe, and we usually associate this effect with a wind. Therefore let's add in a brisk quartering tailwind as the constant to get things 'turning'.

An element to consider is the 'distribution of sail' (anything sticking up above the waterline). In a solo canoe the paddler sits aft of centre, and that fact alone creates an imbalance in the distribution of sail leading to rotational forces in a wind-- same for packs sticking up, flapping coats and hoods, no spray skirt, paddles in the air, and boats with tall bows.

Weight distribution affects the below-waterline drag profile, and how a canoe is loaded affects how it turns.

It's been argued that a symmetrical canoe hull is better suited to handle wind and waves than an asymmetrical design, and some of the points mentioned relate to this issue. But when you factor in the experience and skill of the paddler, perhaps all bets are off on the relevance of design.

That said, a comparison is appropriate: rising up onto the crest of the wave, the properly loaded symmetrical hull has the advantage both below and above the waterline-- both stems are light-- and with a more-or-less centrally located load, it can straddle the crest. On the other hand, an asymmetrical canoe will be fuller with less rocker astern, and most weight-for-length will be aft, making it more susceptible to being turned in the from-behind flow at the crest of the wave.

When the cocked asymmetrical hull descends into the trough, it's finer forward sections may sink deeper into the oncoming flow and really bite into the turn.

In a wind, there's a natural turning propensity built into a hull that has a taller (more area) bow than stern, and such is the case with an asymmetrical hull.

Broaching is always preceded by a turn, and like everything else in a universe of cause-and-effect, the turn too has causes.

 

[yellowcanoe]

It's called unsuccessful surfing
Very early on in kayaking broaches are taught and you learn to lean into the wave hard if you are in a trough.
Then at the peak of the next wave try your best to get going doe wave. The direction must be perpendicular to the wave to avoid being back in broach

Visuals to many canoeists are unaware how waves act so thanks for sharing

Kayakers being on the ocean more and in perhaps more play situations get very used to this
Until not paying attention

 

[stripperguy]

I would describe the cause as "stern hook", the tendency for a hull to twist and align with the waves when traveling downwind. That's one of the reasons why I eventually sold my DY Special. Sticky stems, straight keel lines (lack of rocker), solo paddler all contribute. Some hulls, like my DY and Alan's C1's (Olympic?) will twist in rollers as small as 9 inches!! As waves heights approach 1-1/2 to 2 feet, a swim is often the end result.
Once that turn initiates, it can be very difficult to withdraw from it and return to a perpendicular track with respect to the waves.

I guess I never gave this much thought, but why is the effect so pronounced with a tailwind and not so with a headwind?

 

[dave0]

This what happens in a shallow stream broach, ain't pretty and took a long time to get her out if you want to count this as a broach. Knee deep but swift enough.

 

[Alan Gage]

This what happens in a shallow stream broach, ain't pretty and took a long time to get her out if you want to count this as a broach. Knee deep but swift enough.

Got a permit for that dam?

Alan

 

[yellowcanoe]

The Peregrine is straight keeled. Never mind the published specs. In reality no rocker
She needs multiple stern spankings. Stern snap draws to keep her in line. This is in usual Everglades seas of 2 feet and short periods

 

[Peach Canoe]

When wind and waves are coming from in front (as opposed to from behind), the dynamics that create and exacerbate yaw are reversed.

If the wind (headwind or tailwind) is blowing exactly perpendicular to the waves, and your desired course is exactly straight ahead, and your paddling technique is directionally stable-- one could imagine a happy (though tenuous) state of equilibrium. But surely that's never the case; therefore, there will always be forces that seek to rotate (yaw) the boat toward its natural condition of equilibrium-- perpendicular to wind and waves, sitting sideways in the trough.

I think it's appropriate to consider the condition of a quartering wind (whether from front or rear) as standard, because even in perfect conditions as described above, we create the effect of a quartering wind the moment we yaw the bow off-centre with an uncorrected power stroke or sneeze.

In a following sea and tailwind, Stripperguy identifies the sticky stem, which may well be the result of a laden, lightly rockered, full-sectioned stern. Rotation begins when rising over the crest, and a powerful draw forward of centre may be required to straighten out the boat; a stern draw may require twice the power to achieve the same corrective yaw. When the boat descends cocked into the trough, rotation about the vertical axis will accelerate in the on-coming 'flow'. Further, the wind assists the turn by blowing on the 'effective sail' area that is mostly located astern.

'Flow' over the crests move in the direction of the wind, and troughs 'flow' opposite. There is some acceleration in the rising side of the trough, and the slowest 'flow' is at the crest of the wave. The waveform vibrates up and down (like when you shake a rope), but near the surface the waves themselves do make some headway downwind.

I think paddling into a wind feels more natural because the physics are intuitive; we're familiar with forward motion into wind-- walking, running, riding a bicycle etc. When secondary effects emerge as the result of a wind from behind, it feels like there's an extra step that needs unraveling to understand what's happening-- like having to translate everything through your first language when first learning a second.

Notwithstanding the fact that below-waterline profile affects motion, here's a short above-waterline headwind/tailwind algorithm:

Over the crest--
Tailwind: The stern may be pushed to one side by 'flow' from behind; the canoe may begin to surf; the tailwind affects the area of greatest sail which affects rotation.
Headwind: The bow may be pushed to one side by 'flow' from the front; the headwind affects the area of greatest sail which affects rotation.

In the trough--
Tailwind: The bow may be pushed further to one side by 'flow' from the front; if surfing, this effect will accelerate; the tailwind affects the area of greatest sail which affects rotation.
Headwind: The stern may be turned by 'flow' from behind which accelerates as you rise up the far side of the trough; the bow may plunge into the oncoming crest; and the 'flow' from the front over the crest may push the bow aside if it is cocked. The headwind affects the area of greatest sail which affects rotation.

dougd, that canoe looks like a keeper. lol

 

[dave0]

Well Peach, that canoe has seen a lot of lot of miles. That was just one incident on one of the canoe trails we were paddling. Just a minor set back but there is more to the "Rest of the Story". ;-) She's retired now unless there is some serious poling involved.

 

[Uncle_Skwid]

I'm impressed with the physical principles being touched upon. I also feel like I'm slipping back into the world of Anthony Burgess with the language of Clockwork Orange.

--If ye wants to curtail the yawing and slewing toss out the bloody drogue!

Or the time I found myself drinking with my 16 year old daughter in Targovishte with a bunch of Ukrainians asking me rather pointed questions in Russian. She was living in Bulgaria at the time and I was simply passing through. --Drink the Vodka, my daughter kept telling me, looking at my glass and kicking me under the table. Drink the Vodka, the Ukrainians kept telling me. Drink the Vodka long enough and you will be able to speak Russian.

Or the story I heard once about a perplexed piano student who asked her teacher whether she should play in time? or in accordance with her feelings? He replied: Why not try to feel in time?

Or the drunk poet from the Midwestern United States who told me in his typical axiomatic way that I will bring one of two attitudes to the art of canoeing--

--and here he probably pointed his finger to the sky to stable the slewing effects often found in the waves of an altered equilibrium--

either music must conform to truth--and he nodded and looked down at the corner of the room, remembering something that got him suddenly chuckling to himself, because for the life of me I couldn't remember bringing up the canoe--

or truth must conform to music.

And while I knew that he was toying with my life, and while I knew the point of art was to get you to think about something else, I decided from then on that I would know where I was at every age. Because eventually, in the stormy weather of perpetual forces seeking the so-called equilibrium of the trough, eventually you will lose. And the question will become not whether you can right what has been wronged, but whether you can be comfortable enough with the truth of your position to sing along

with the wrecking ball.

Good stuff!

 

[Steve in Idaho]

Since you mentioned surfing, Peach, I have a question. I've never been in wind waves big enough to surf or cause a broach, but I do some surfing in standing waves on moving water. In that surfing, weighting heavily on the high side as the boat turns away from the current is at least as important as any corrective strokes - maybe more so. At any rate, carving back into the current with an aggressive edging of the downstream (high side on the wave) side of the boat is always required and sometimes all it takes to keep from broaching - or side-surfing, if you're lucky. Is the same principle active in fighting a broach in downwind waves?

 

[yellowcanoe]

The water is actually moving up the oncoming wave. So you never lean downwind or down wave. Lean onto the oncoming wave hard
Lean the other way and the error will be evident

 

[Uncle_Skwid]

I'm going to venture out into the turbulent waters...

In my less than adequate understanding of the forces at work here, I like to imagine the boat is leaning one of two ways: upstream or downstream. (In this case, upstream means AGAINST the current. Downstream means WITH the current.) I am probably stating the obvious here (and repeating what Peach has already pointed out), but sometimes most of my trouble comes from that which is obvious.

If you lean your boat upstream you will carve. You are leaning against the current and you will CUT the water and the current will tend to spit you across itself like a watermelon seed from between your lips. If you lean your boat downstream you will plane. You are leaning with the current and a swift current will swiftly pick you up and carry you away. Imagine skis and the effects of activating the edges on a hill. Obviously if you're paddling a boat with a "planning hull," let's say a flatter hull with hard chines (imagine, for the sake of the picture, a john boat), you'll have a better edge with which to "dig in" and carve and a flatter hull with which to plane. (Harder edges also mean the current can get a fast grip and whathunk! Many paddlers do not appreciate the harder chines of a planning hull for that exact reason.) But the physical principles for any object in moving water are the same and I lean my soft chined full displacement asymmetrical hull (6" rocker in the bow 5" in the stern) with nearly every stroke. And yes, the lean of the boat is way more important than any of those millions of strokes I am struggling to imperfectly simulate. I would go so far as to say if you knew where you were at every age in the perfect boat for the perfect river you could dispense of the paddle altogether and lean off into the sunset. That's the goal anyway though I've only seen it fluidly achieved in a tiny kayak.

From these humble and obvious beginnings it only gets more complicated and leaves the limited range of my understanding. But as others have pointed out, big waves or big water in general can make determining the direction of flow tricky. Is that big crash of white moving upstream or downstream? (In really big water upstream and downstream become a sort of six-dimensional concept and if you do not know where you are at every age you will quickly become fodder for your so-called friend's youtube video.) Suffice to say (and to repeat what Peach has so eloquently stated above), water at some point in a downstream wave will succumb to gravity and begin to slide back upstream into the trough. To quickly and effectively crest the wave: carve! Or lean upstream, AGAINST the current, INTO the wave, and you'll activate your chine and the upstream current will spit you like a watermelon seed up to the shoulder of the wave where, with a sporty current and a small bit 'o luck, you'll have a spectacular launch and get that goofy grin and your canoe will go airborne. (You'll also find yourself contemplating that portage around that big rapid a little differently.)




By the by, and not to belabor the point, but the quickest, most effective way to learn to feel in time is to allow the forces at work around you to achieve their equilibrium between the water and gravity and you and your boat. Pick a nice warm day and let the beatings continue until you begin to achieve that natural harmonious balance. I mean, when it comes right down to it we're talking about the raison d' etre, we're talking about unlocking the potential of the finest craft in existence.

 

[Steve in Idaho]

.....any of those millions of strokes I am struggling to imperfectly simulate.

Hah! I resemble that remark.

 

[Steve in Idaho]

Carving, et al.

Maybe my terminology is mixed up. When I think of "carving", I am thinking of using the shape of the hull to describe an arc. This is getting confusing to me. I think I shall go paddle....