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PostPosted: May 18th, 2005, 10:06 am 
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Location: Wenatchee, WA
From my understanding the primary role of rocker is to facilitate turning. It would also seem that a rockered boat would climb over large steep waves better than a boat without rocker. How much affect does rocker have on the ability of a boat to climb over instead of plow through waves?


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PostPosted: May 18th, 2005, 10:33 am 
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That seems like a simple question, but it's a complex subject. Rocker in a canoe makes it easier to turn a shape that has design characteristics intended to make it not turn. Think of it in terms of common house hold items, if you were floating a flat bottomed margerine bowl and a flourescent light tube in the water, which'd be more inclined to turn? Answer, the bowl. Traditional canoes are more like the flourescent tube and putting a curve on that shape makes it easier to turn. A lot of modern whitewater boats are starting to have a flat planning surface on them. I have an old Kennebec canoe that has a large dead-flat surface both along the keel line and from chine to chine. The last 1/4 of the bottom in both directions is where you see the rocker. That leaves about half the underwater profile with zero rocker, yet the canoe still turns easily because the large flat area provides bouyancy and little resistance while the ends of the canoe that would cause drag if a rotating force is applied are pulled up out of the water to reduce drag. The advantage to this shape is that you've got a flat surface area that you can use to good effect in "carving" the water. Wish they still made that boat.

Rocker won't affect wave performance much. The entry lines on the canoe will have a greater effect. "Full" ends ( a wide V shape) will rise up when burried in a wave. Canoes geared more towards speed will have a very slight angle to the V entry and those will slice through instead of rising up.


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PostPosted: May 18th, 2005, 11:29 am 
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I'm not absolutely sure about rocker increasing stability in WW, but on lakes when waves are large, rocker can make for a more stable boat, since the ends are higher than the center, and the center of gravity is lower relative to the overall flotation when compared to an unrockered hull. An unstable situation on rough lakes can occur when either end is supported by a wave with the center in the trough and out of the water, or close to it.. Rocker can help to reduce that by allowing the stable center part of the hull to sit lower in the trough.

If this also works in WW, there could be some improvement in stability as the more heavily rockered canoe rides through the waves making things easier and more controllable overall, especially when the bow enters a wave and starts to ride over.

Just a thought, it seems there are also unrockered WW kayaks built for speed and racing - their main function is to get down rapids as quickly as possible, and rocker would slow them down. My guess is they'd be less stable than heavily rockered playboats when going through waves, without taking into account the other design elements.

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PostPosted: May 18th, 2005, 12:23 pm 
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Rolf-
Part of my reason for asking these questions is I dumped last weekend in a We-no-nah Cascade going through a monster wave, while my friends in an OT Appalachian made it through. The Cascade submarined in the wave, hitting me in the bow, with a lot of force and temporarily blinding me. We got through the first wave, but as I could not see, I temporaily paused paddling and we capsized to my off side. My bow partner counterpart in the OT Appalachian did not get hit above chest high, as the Appalachian rose up over the wave. Now there are a lot of factors: Their line may have been better, they may not have been moving forward as fast, and I am heavier than my friend in the bow of the Appalachian. I have noticed that the bow on the Cascade narrows down at the bottom in the first two feet. It has to get under water a ways before there is any buoyancy in the very front. My guess is that was a factor. Could also be that the OT Appalachian is 18 inches shorter. The length and skinny bow at the bottom does make the Cascade fast, for being a big wide tripper. We fly right by the Appalachian when tripping.


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PostPosted: May 18th, 2005, 12:48 pm 
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John, it sounds like you've got most of the answers to your question figured out. All of the things you mention could easily have been contributing factors.

The Appalacian is pretty good about poping back out of waves. The next time you have both the Cascade and the OT in the same place, roll them over and compare entry lines while sighting down the keel. About two feet back from the stem on the OT, you should notice that the V entry is kinda "double jointed". There's a transition point there where the designer has attempted a compromise that still retains some speed and tracking yet provides a lot of additional bouyancy if the end gets buried. I really like this about the OT. From my memory, the Cascade doesn't attempt to put in a little "reserve" bouyancy.


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PostPosted: June 7th, 2005, 12:56 pm 
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John Marshall wrote:
Rolf-
The length and skinny bow at the bottom does make the Cascade fast, for being a big wide tripper. We fly right by the Appalachian when tripping.


Here is some additional information for consideration:

I had occassion to go out on a trip to Algonquin with a couple of friends recently. They needed a canoe, so I loaned them our 16 ft Wenonah Prospector for the trip while we paddled one of our Old Town Appalachians. The couple using our Prospector were fairly fit. Hubby was a strong and experienced paddler, the missus was new to canoeing but it looked like she was contributing her fair share of the effort in paddling. I know from experience that the Wenonah Prospector is a pretty fast boat to paddle, but the other couple couldn't keep up to the Appalachina at our normal speed so we slowed it down.

The way a boat is being paddled can make a big difference to apparent performance. If someone else were along on the Algonquin trip and were thinking the boat that was always easily in the lead was the faster hull, they'd think it was the Appalachian which isn't the case. If you want a better sense of relative performance, ask to swap with the other folks to see if it's them or the boat :)


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PostPosted: June 8th, 2005, 12:11 pm 
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John Marshall wrote:
Now there are a lot of factors: Their line may have been better, they may not have been moving forward as fast, and I am heavier than my friend in the bow of the Appalachian. I have noticed that the bow on the Cascade narrows down at the bottom in the first two feet. It has to get under water a ways before there is any buoyancy in the very front. My guess is that was a factor. Could also be that the OT Appalachian is 18 inches shorter. The length and skinny bow at the bottom does make the Cascade fast, for being a big wide tripper. We fly right by the Appalachian when tripping.


Yep, I think you found your answer as to your compared experiences here. The Cascade has a finer entry, and the Penobscot has a fuller blunter bow. I think this has something to do with geography. Mike Chic has long been the big proponnt of boats for flatwater tripping. That's what they do in Minnesota. This characteristic still is exemplified even in their "whitewater" boats like the Cascade, Rogue and Rendezvous. Old Town by example has built is business paddling down, and poling up the rocky rivers of Maine. Thus you end up meeting somewhere in the middle with boats having different genesis but aimed at a similar market.

PK


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PostPosted: June 8th, 2005, 7:09 pm 
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Paul-
I think you are right on. Mike Cich did design the Cascade, and speed and efficiency seem to be the Wenonah ethos. Unfortunately what I need the moment the bow went into the big wave was buoyancy not efficiency. I am wondering how we would have fared if we went into it back paddling instead of forward paddling. This was about a five footer with a glass surface coming into it and then a very steep hump to plow into. Would we have simply lifted over it nicely, or would we find ourselves side surfing? I have not had a chance to try it again.

Rolf- You are right no test of boats is fare without switching paddlers.
John Marshall


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PostPosted: June 8th, 2005, 8:13 pm 
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John Marshall wrote:
I am wondering how we would have fared if we went into it back paddling instead of forward paddling. This was about a five footer with a glass surface coming into it and then a very steep hump to plow into. Would we have simply lifted over it nicely, or would we find ourselves side surfing? I have not had a chance to try it again.


John, I learned how to paddle at MKC, and they aren't known for putting out timid paddlers. So I'm not one either. I rarely back paddle. But I must admit that backpaddling while not as exciting is often the safe dry way to negotiate rapids so long as you can still punch through the standing waves. Getting rejected off the wave, which is much less common in a tandem, is an ugly situation though!!!

PK


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 Post subject: Role of rocker in ww
PostPosted: June 9th, 2005, 7:13 am 
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As like John,my husband and I dumped in a big wave on the Madawaska R. Saturday.We trip in a 16 ft. ,Royalex Evergreen Prospector. I paddle the bow and my husband,who outweighs me by 100 lbs.is in stern. Almost the same circumstances.Plowing thru large wave ,water hitting me in face in bow and temporarily blinding me.I guess I too stopped paddling.We took on a lot of water and went into a role. We were unable to recover canoe and finally dumped in middle of large wave. Luckily water was calm right after rapid.I worry because we plan on paddling the Dumoine in July and I have read there are lots of big waves. Saturday was ok because of the calm water after the dump but on the Dumoine we may not have that luxury.


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PostPosted: June 9th, 2005, 10:11 am 
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John Marshall wrote:
Paul-
I think you are right on. Mike Cich did design the Cascade, and speed and efficiency seem to be the Wenonah ethos. Unfortunately what I need the moment the bow went into the big wave was buoyancy not efficiency. I am wondering how we would have fared if we went into it back paddling instead of forward paddling. This was about a five footer with a glass surface coming into it and then a very steep hump to plow into. Would we have simply lifted over it nicely, or would we find ourselves side surfing? I have not had a chance to try it again.

FYI - Dave Kruger does most, if not all, the design work at Wenonah these days. Don't know for sure, but I'd suspect he'd be the one responsible for the Cascade.

John, it's hard to offer advice without seeing what you were up against, but I often tackle the kind of wave you've described with a slower than current approach. I can usually keep the canoe pretty dry doing it this way and the approach isn't very dependent on hull design for success, it's all about timing.

There are a few things you need to keep in mind. The reason this kind of wave exists (usually) is because fast water coming down a drop is running up against slow water and the water rises 'cause it's got nowhere else to go. The wave closest to the first drop will be best defined and each sucessive wave downstream will be less well defined with some of the downstream waves rising and falling as the water attempts to abasorb the power from the drop. The first wave is easiest from a timing perspective because it'll be consistent, successive waves are harde to get right as they may change as you reach them.

The downstream portion of the wave will be moving faster with more power than the upstream portion of the wave. That means you'll stall on the uphill side if you set what feels like a comfortable speed as you're going down, it should feel a little fast. Approaching the wave at an angle will help a lot. I use the differential in speed between the uphill and downhill sides to help turn the canoe in the approach to the wave. As the bow connects with the upstream side of the next wave, the stern will still be in the downstream side of the wave behind. If I put a bit of angle to the boat with a well timed stroke, the difference in speed will twist the canoe sideways for me. Depending on the size of the wave, my angle could be anywhere from 45 degrees for small ones to almost 90 degrees to current for larger ones. What you have to be careful of is a crest at the top of the wave. If that happens, it'll drop a lot of water into a canoe with no spray deck, but there's a technique that helps prevent that. As my canoe starts to go broadside at the base of the wave, I'll lean it fairly agressively downstrean into the wave. That sinks the chine (edge) of the canoe into the wave and puts a fair bit of bite into it from my hull. Doing that will help lift the canoe over the wave and also reduces some of the height in the wave, but it will make the wave more likely to crest because you're making an eddy of sorts with your canoe. As my canoe nears the top of wave, I'll do a quick tilt back upstream. That puts the opposite side of canoe back into the rising portion of the wave, again helping to lift me over and reducing the eddy effect of the hull. It also present a large flat surface from the bottom of the canoe to block the cresting, forcing splashing water away from the boat. If I timed all of that right, it should put me at the top of the wave with very little forward speed and I can level the canoe out. As the canoe starts back down the other side, I'll stick my paddle into the "green" water on the down stream side of the wave which will turn the canoe back in line with the current again because the downstream water is speeding up, giving me some power. The ends of canoe will spin easily because they'll get airborne as the boat pivots at the top of the wave. All that's left now is to get ready to repeat steps above in time for the next onslaught.


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PostPosted: June 9th, 2005, 10:26 am 
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pknoerr wrote:
I must admit that backpaddling while not as exciting is often the safe dry way to negotiate rapids so long as you can still punch through the standing waves.


PK, you can make backpaddling pretty exciting if you want to! I used to have a paddlinig partner that I loved to push the envolope with. He was a wiry farmer type who weighed a bit less than me. I prefer to paddle left, he prefered to paddle right. When I had him in the boat, he'd be stern and I'd be bow. We paddled enough together that he got pretty good at understanding what I'd want in any given situation and developed enough confidence in me that he'd do what I expected regardless of how unlikely it might seem to be to succeed. We'd be all over the river moving from one side to the other, often right at the brink of nasty places you don't want to go. Basic game plan would be come down a drop, stop foward momentum with one well timed stroke simultaneously setting the angle for next move, tilt hull to catch current and do slight paddle strokes to maintain angle as boat drifts across to the next drop. I call it this kind of paddling Ginger Rogers syndrome. The agressive forward stuff is llike Fred Astaire, but Ginger did everything he did backwards in high heels :). I found this kind of paddling to be great fun and it felt very rewarding. It gives you the confidence to tackle some stuff on long wilderness trips in complete safety that you might get into trouble with otherwise. Not many people teaching this style anymore.


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PostPosted: June 9th, 2005, 11:56 am 
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Rolf Kraiker wrote:
PK, you can make backpaddling pretty exciting if you want to!


Rolf, I agree... Whitewater is exciting no matter how you run it. But, my point was... running it fast you come up on things fast... so strokes have to work or you are in trouble. That's where the excitement comes in. The elegance of paddling accurately with backpaddling, and back ferrying can be just as exciting... but figureing out how to blend the two is the real ticket!!!

PK


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PostPosted: June 9th, 2005, 12:49 pm 
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"John, it's hard to offer advice without seeing what you were up against" Rolf I wish you would come out west and put on a three day workshop. I live in north central Washington and we have some good rivers here. There is also a lot in BC. What you are describing makes lots of sense, but sounds difficult to do. Your timing would have to be just right.
John


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PostPosted: June 9th, 2005, 12:55 pm 
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This is a little off subject, but while we have been discussing the OT Appalachian and the Wenonah Cascade, here is a useful bit of information. The OT Appalachian will nest in a Wenonah Cascade if you take the seats and thwarts out of the Cascade. Six of us are going to Nunavut next month and it involves a flight in a twin otter. That two of the boats nest is critical to hauling everything. We tried nesting the OT Appalachian into an OT Tripper, the third boat we are taking, but it would not fit.


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