C-Forum

I curious. Why are people making the chimes with groove instead of a smooth ones. I would think it have a negative affect on hull performance, but I'm not an expert.

paddling our shallow SE rivers the "hidden chine" is engaged when you want it to be. The chine is not so readily hitting a rock you were not even paying attention to as you prepare for a class III-IV rapid such as on the Ocoee or creeking. Boats paddled with such chines- L'Edge and Ion. I use to paddle the Ocoee as my number one boat with it's nice sharp chine. While I miss several aspects of the OCoee (boat) I do not miss the quick wear of Royalex or hitting a hidden rock and flipping in shallow pushy water.
My 2 cents

There are so many shapes of chines, it's hard to give a simple answer, but I'll try. The easiest answer is that at normal paddling speeds, it gives the chine more directionality- ie, water wants to flow along the chine. This gives better forward and carving performance. A very hard/sharp/square edge on the chine will do the same thing, but does it so at the expense of secondary stability and rock-bouncing-off-abilty (technical term) (see: Prijon Alien. It's a kayak, but the classic example of this). On a boat like the Ion, the concave chine allows for a sharper edge with a more beveled sidewall. Also, the sharper the edge, the more the boat will release when flat spinning while surfing

basically they break up the flow of water...can enhance surfing by helping release the hull or even to create drag. As Wendy mentioned, they are helpful engaging for eddy turns and basic river maneuvering...make it easier to engage different parts of the hull. It is more complex and maybe Jeremy or Craig will chime in but are a good design features in great boats


and did

My impression is that the break allows some separation as the water flows toward the outside edge. That way, the outside hull radius can be larger - less edgy - while maintaining a flatter bottom. When the water is flowing in the opposite direction, you get more resistance - better catch for more precise eddy-catching.

I've also found that at speed, the tri-hull design stays above the water better than a conventional hull. This may be because of it's basically wider, or it just "catches" more support when it prevents water from flowing to the outside. Both my boats that use this hull shape will climb through small waves better than anything else I've paddled.

the reason a tri hull stays higher is because it is a planning hull, when a planning hull comes to speed it rises in the water and a displacement hull comes to speed it sinks in the water. my understanding of the tri hull is this help the boats tracking while keeping it loose while being perpendicular to the flow and this may be bs

this is a trippy edge variety I keep thinking about for a canoe.

whatcha think on this if the side pushed out more for a canoe

Creeker wrote:this is a trippy edge variety I keep thinking about for a canoe.

whatcha think on this if the side pushed out more for a canoe
... (pic omitted)

The bottom of a Fluid Solo (conversion C1) is the first step in that shape... not the double step.

What I found/determined in the single step (IMHO) was that for comfort and stability my knees had to be as wide as possible, so I had get my knees out past the double edge. Which was really simple by merely shaping the bottom of knee pads. So now my knees reached the edges/chimes/bilge and everything was good to go. However for me this resulted in a lost of feel and edginess; which might be good for some. But for me it meant I was trying to carve out past the edge, as in toward center of my knee. That the edge was no longer on the edge, and the result felt as if no edge. That the boat felt like it sort of plowed into a eddy, and didn't really carve back out. And that it wouldn't hold a line as well, so I had to paddle more upright to mitigate to use of corrective strokes (ie more corrective strokes, less pure power strokes). It was closer to the feel of a rounded (displacement) hull to me.

SO it's just speculation, but this may also be true of the two stepped bottom. Of course thoughts coming from someone wanting/wishing for a hard edge.

Please release me... let me go...

Phil... can you post up a few pics of the bottom of a Sauvage SpanishFly for folks?

Pyranha SpanishFly


Robson CUFly


Esquif L'edge


Skeeter/L'edge/SPFly

Spelling Nazi here. So far I have chimes for chines (ding ding, we have a winner) and planning hull for planing hull.

Plus the old mistake---- ALL kayaks, c-1s, and open canoes are displacement hulls, but some of them, under certain circumstances, will plane when there is water passing fast underneath.

The planing versus displacement hull distinction is meaningless. But some boats plane better than others, and some of those are specifically designed to plane.

A displacement hull >does not< sink deeper in the water as it gains speed. Take a rowing shell, with no planing surfaces, one of the fastest human powered hulls. A rowing shell does not sink deeper in the water under power. During the rowing stroke, the shell actually rises somewhat, presumably due to planing.

I've seen rows of round Perception Dashers planing on fast green waves. Just about all slalom hulls will plane fairly easily because they have some flatness underneath.

Try to practice in the privacy of your home. "Some boats plane pretty well because of flatness and chines. But they are still displacement hulls. Human powered hulls don't get up on a plane because of lack of horsepower, but they may plane while ferrying or while riding a green wave. "

Ezwater, I would guess that a rowing shell is disposed to rise out of the water because the rowers weight is back and the power is being applied forward at the beginning of the stroke. Whether this angle of attack leads to a moment of planing in the middle of the stroke, I wouldn't be confident. This is all thinking about singles and doubles, of course. 8's would be a whole different animal.

*edited for autocorrect silliness*

dang ez you know more than 95% of the boat designers that I have talked to in the last 15 years. Give us a design

2opnboat1 wrote:dang ez you know more than 95% of the boat designers that I have talked to in the last 15 years. Give us a design

which one's?

the person that authored this thread has designed and built a few boats himself... rather nice one's from my perspective.

yes... planing but bad spelling seems to be a rather popular thing these days so cut him a break Gary.

Ray... you figure out how to post pictures on Facebook yet?

Craig I was not bashing ez there but rather amazed that he know the difference between how the words are used in the sport and the real meaning.

The chines issue is a very interesting one to me, partly because just any old sort of obvious chines doesn't tell you how the boat will behave. Very sharp, complex chines probably break up cross flow so as to allow the boat to plane on fast water rather than being caught and shot downstream. But such sharp, complex chines might not be best for a slalom boat that has to carve effectively while keeping as much momentum as possible.

I have boats that are flattish, with slab sides and obvious chines, but the chines are not sharp, much less complex, so while they work well for carving turns in and out of eddies, they are "catchy" on crosscurrents and may provide surprises.

I have a c-1 that needs more bow volume (or to have the cockpit moved back), and I think about adding some Estanguet style edges to the bow. I could increase volume and improve handling. Trouble is, I don't know what I'm doing.