Handling/ Differential rocker In waves

I had my C1 out yesterday and noticed the same old rear quartering waves issue I always have. I am scheming on building another C1 and wonder how differential rocker would perform on Lake Norman. Lake Norman has a lot of confusing waves from random directions depending on the powerboats. J-Boats and other good tracking hulls work fine going into , quartering or running parallel in the chop. Rear quartering are treacherous. I suspect the shorter waterline of my old Merlin made it more forgiving. Would differential Rocker added to the mix help or just slow me down on flats and not help in the chop?

You could seek out Jon Winters’
writings. He’s one person who might have gotten into dthe differential rocker issue beyond past practices.

coupla questions…
you use the term “parallel to chop”. Why would you travel parallel to the waves or am I missing something? Also please define "rear quartering. Thanks.


Here is a pnet article

Look under Tailwinds.

Winds coming from the stern port and stern starboard side of the canoe are rear quartering winds.

I go “parallel to chop” all the time,…

– Last Updated: Jul-06-10 5:08 PM EST –

... especially on long crossings in my guide-boat (I use that boat as an example because it is somewhat similar to a canoe). Why would you NOT want to do that if that's the direction you want to go? When doing a crossing in my guide-boat, I'm thrilled when the the wind direction is perpendicular to direction I want to go because I can attain the same speed going crosswise to the wind and "parallel to chop" as I can in glass-smooth water with no wind at all. That's the main reason that going crosswise to the wind is a blast!

Bald Paddler might define "rear-quartering" waves after a while, but as long as I responded to the first half of your question, I'll respond to the second half too. Rear-quartering waves come at you from an angle from behind. In other words, if you are going essentially downwind but substantially to one side or the other of STRAIGHT downwind, your boat will be on an angle while on the sloped forward face of each wave, and the stern of the boat tends to get "pushed downwind" faster than the rest of the boat, so the whole boat gets turned more toward a sideways orientation to the waves than the orientation that you are trying to maintain. The more "grippy" the stern, the worse the problem becomes. The kind of differential rocker that is normally built into canoes makes the stern "more grippy" than the bow (rocker at the stern is less than that at the bow), so you'd expect the average canoe with differential rocker to be more unforgiving when dealing with rear-quartering waves. The kind of differential rocker described by Eric_Nyre above is the opposite of the kind that that general-purpose canoes have.

I am trying to work my way through Winters book. Since I am not comfortable with math used that way it will be a while. I guess the differential rocker that I would be using would not help me on the bigger waters I frequestly paddle.

differential rocker advantage
symmetrical canoes trimmed stern heavy present differential rocker too…

When paddling in waves one must not only look at what the stern does, but also the bow. More rocker in the bow than in the stern may possibly be an advantage in most situations, except when paddling backwards.

A modification to my thoughts:

– Last Updated: Jul-07-10 11:04 AM EST –

What I concluded about the effect of differential rocker in "normal" canoes makes some sense based on what another poster said about the kind of differential rocker in boats that are MADE for surfing, but I might have been too hasty in thinking that way. As I think about it right now, the way that the stern gets "pushed too fast" seems more due to "sliding downhill" on the front edge of the wave than to being pushed by the water itself, so I'm thinking that my initial comment was wrong for this particular situation. The extra "grip" on the water that the stern has in a normal canoe with differential rocker is normally more of a problem where water initially contacts the boat, rather than where it streams off the trailing end, which is the stern in this case (you can really feel this when crossing turbulence in rivers). To go along with that line of thinking, they DO put a skeg on the back end of surfboards. To add more to that line of thinking, when I'm rowing my guide-boat downwind in big waves and start getting turned sideways because the stern wants to "go faster than the rest of the boat", dragging an oar blade right alongside the stern does the trick for getting back on proper heading, so perhaps a "more grippy" stern would help, meaning in this case that "normal" differential rocker would help. I hope you get the chance to give it a try. I have a pretty good boat for testing this idea, but since I have better boats for going out in the waves, it would take some real "scientific curiosity" to motivate me to take "the wrong boat" out to get some answers.

I wonder if that "backwards differential rocker" on surfing boats is there simply to make it easier for the paddler to push the stern to one side or the other by ruddering with a trailing paddle blade.

Rocker and rudders
The best answer to rear quartering wind and waves is a rudder.

Sure, ocean surfing craft such as skis and outrigger canoes have lots of rocker. But they also have that rudder.

The most helpless I have ever been in a canoe was in a highly rockered WW canoe (Millbrook ME) going downwind on a lake. I was completely helpless. Couldn’t control the boat at all. I was blown and pinned sideways the whole time.

The tandem canoe and kayaks that were with me had nowhere near my problems. In fact, because they considered me the strongest paddler, they went way ahead of me and abandoned me. Meanwhile, I was helpless and trying to whistle them back. Boy, was I ticked at them.

This extremal situation tells me that stern rocker would be lousy in rear quartering winds, unless you have a rudder. An un- or mildly-rockered boat may be hard to straighten out if it does get blown sideways, but I think it would be much easier to control to prevent that from happening.

how is the rocker in the ME?
Perhaps that ME has more stern than bow rocker?

Many like that for whitewater.

Rudders are no answer!

– Last Updated: Jul-08-10 4:33 AM EST –

I would disupute that "the best answer to rear quartering wind and waves is a rudder". If rudders had merit in tha situation, the most accomplished sea kayakers would be paddling with rudders... but despite some paddlers periodically returning to / flirting with the idea, the sea kayaking community long ago moved onwards to retractable skegs.

I've never come across retractable skegs for open canoes, presumably because most paddlers accept that they are the sea kayakers way of compensating for the fact that it's tough (for them) to adjust trim afloat.

ps. Bow rocker reduces the likelihood of broaching: I'd say that was essential!

bow rocker is indeed important
I think,

and especially the balance between bow and stern ‘behavior’.

Mad River Independence had a retractable skeg for some time,

if I remember correctly?

Personally I prefer a sliding seat to change the trim.

I don’t know why but it seemed as though the term “Rear Quartering” was referring to technique rather than wind. I am familiar with quartering winds.

I’ve always tacked into the wind to avoid broaching, rather than run parallel to the chop. This is new to me. Do you just try to stay in the trough and thereby avoid waves breaking over your hull?


Hes in a guide boat
its wide.

Kneeling in a small narrow solo you have to watch that the rollers dont throw your head overboard. There is almost no room for error and only loose hips will save you.

Running in the troughs at 90 degrees to the waves in a canoe is a tough challenge and one that I do not wish to do in seas where I am soloing.

Rudders, skegs, same but different
Virtually all seakayaks have something under the stern to prevent lateral stern movement–either a molded-in skeg, a drop-down skeg, or a rudder.

My comment about a “rudder” being the best solution for rear quartering wind and waves was meant to encompass any of these stern pinning devices. Actually, an over-the-stern rudder may be the least effective because it often comes out of the water when a wave lifts the stern. I was actually thinking of my outrigger’s fixed rudder, which is significantly forward of the stern about where a skeg would be.

The point is that stern rocker is exactly the opposite shape of these stern pinning shapes (rudders, skegs), and hence will behave oppositely in the wind. That is, instead of resisting transverse movement, the rockered stern will easily be blown aside. And so will the rockered bow. Hence, the canoe ends up sideways very easily.

The ME has 5" of symmetrical rocker on both ends.

I think there’s more to it that width

– Last Updated: Jul-08-10 7:23 PM EST –

The maximum waterline width of my guide-boat is roughly two feet. Sure, the whole boat is a tad more than three feet wide at the gunwales, but the part that's actually in the water isn't all that wide. The extra width and flare helps a lot when plowing through waves, but I don't think it does much when parallel to them other than allow the boat to tip or to let ride level on a sloped wave face without taking on water. If one gunwale dips to the water's surface on a wave face, the overall waterline width really doesn't increase much. I think that the security of that boat in waves is mostly a combination of the low seating position AND the round hull profile that prevents the waves from being able to cause the boat to tip to match the tilting wave surface. When in that same situation in a canoe, it's really the wind that gives me the most trouble, and I don't mind the waves so much or the feeling of letting the boat move around underneath me. In fact, I know with certainty that two of my canoes can't even come close to taking waves head-on or at an angle while keeping water from pouring over the end even remotely as well as the guide-boat, but when parallel to waves they will float up and over without water coming over the sides at all. However, since the guide-boat is definitely my best choice for strong wind and big waves, I have far less experience doing that sort of thing in a canoe.

Sideways to waves
As I mentioned in my reply to Kim, I don’t do this sort of thing in a canoe nearly as much as in the guide-boat. I have no doubt that a good paddler could be pretty comfortable parallel to the waves though.

It isn’t possible to stay in the trough unless you are actually surfing downwind, so when going parallel to the waves the boat constantly rides up and over each new wave. Usually the boat rides up the face of even steep waves with no problems, but if a wave starts curling as it approaches, I’ll lean the other way so it splashes against the side of the boat instead of coming over the edge.

The whole process of rowing a guide-boat is different than paddling a canoe, but based on the handling of that boat it seems to me that a very round-bottomed canoe would be the best choice for dealing with such waves. I have a round-bottomed canoe, but it’s a real bear to paddle in strong wind, so it may be a while before I might accidentally find out how it works in big lake waves.

I love doing in my Malecite

No fear whatsoever, and I push it close to the break zone. But the Malecite isn’t a skinny little solo either.

actually I think stern hull shape has
a fair influence rather than just rocker.

I have had a number of sea kayaks with and without rudders. My CD Caribou has neither skeg nor rudder. When I used to in younger days surf with it, keeping it straight on the wave face by appropriate paddling and bracing was the key. It was fairly easy to do that.

Rudders were a nono. Not only was it going to be in the air a fair amount of time, getting whacked in the head by a sharp piece of metal was an unpleasant prospect should the boat purl.

Now my sharper v shaped sterned boats require quite a bit of effort to get back on track in quartering waves. Only a sharp draw to the stern seems to work and its key to catch the impending broach early.

My softer shaped less v ed sterned boats are easier to get back on track. The Peregrine is supposed to have as much rocker in the stern as the Nomad yet the latter is easier to correct and stays on course well.

When you have a load of gear it seems any v shape in the rear is accentuated as the stern is buried a couple of inches.

rudderless and skegless boats
Although most manufacutured sea kayaks have either a rudder or a skeg (and some have both), there are a growing number of kayakers who make their own kit boats from fiberglassed plywood that paddle without a rudder or a skeg—when I lived in Maine, two of my paddling buddies had rudderless/skegless boats and did just fine with them–they said the hard chine of the boat eliminated the need for either the rudder or skeg—Me–I prefer a skeg==particularly in a following sea but hey, thats just me.