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  Hard chines and tracking
  Posted by: RubricOfRuin on Apr-15-13 9:13 AM (EST)
   Category: Kayaks 

-- Last Updated: Apr-15-13 9:15 AM EST --

I've read several threads here about hard chines, tracking and stability issues, but they never seemed to reach any concensus.

Primary and secondary stability aside, with all things being "equal" do hard chines equal looser boat in flat(ish) water? Or that is boat-dependent? Reason for asking, I've tried several boats over the weekend and all hard-chined ones (I never paddled one) - Arrow Play LV, North Shore Buccaneer and Tahe Greenland LC (Tahe less so due to smaller volume) felt very loose in the bow. The maneuverability felt really good, hard chined boats seem to turn on the dime. But tracking? Are they supposed to be so "loose" without skeg deployed? I liked the feeling of hard chine, but the tracking issue was a bit off-putting. Running skeg in flat water seemed odd.


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Messages in this Topic

 

  "Kickier" Feeling
  Posted by: Celia on Apr-15-13 9:25 AM (EST)
-- Last Updated: Apr-15-13 10:36 AM EST --

I have one hard chined boat, that is my go-to boat for her spritely acceleration, and one soft chined. The effect of the hard chines is that the boat reacts a bit more dramatically at the point it hits the chine. It really doesn't do anything differently, it just kicks over quickly rather than sliding in a way that doesn't so grab my attention.

It was interesting to get used to this behavior at first, but the boat still ends up sitting on its secondary and has been rock solid in haystacks that were decidedly over my head. In situations like those haystacks, it does demand more relaxation on my part than the boat with the softer chine. The sharpness of the way the boat switches side to side creates enough inertia that if I followed it with a stiff upper body I'd be swimming.

The softer-chined boat is by far the looser bow, in fact the hard-chined boat is a tight bow. I don't see the exact shape of the chine having much to do with that, it is the rest of the hull design.

As to using a skeg in flat water, it can be useful for both wind and certain current conditions. I can see an argument that if the wind is high enough to want the skeg down the surface of the water should also be disturbed, but certain topographical situations can disturb that assumption.

 
 
  This hard-chined, tumblehome-flat
  Posted by: ezwater on Apr-15-13 11:12 AM (EST)
sided whitewater boat tracks very well, once it gets moving, but once you lean in or out to change course, those chines may leave you tipped up and over.

http://www.flickr.com/photos/ezwater/5615339420/

Chines needn't be sharp to act "hard". The effect of hard chines depends on the design of the rest of the boat. I have a Necky Looksha Sport that has hard chines, and for me as a whitewater paddler, it seems very willing to track. But it might not impress a serious sea kayaker that way.




 
 
  I'm thinking of the Silhouette
  Posted by: slushpaddler on Apr-15-13 11:16 AM (EST)
-- Last Updated: Apr-15-13 11:17 AM EST --

Significant v hull and hard chines. When I demoed one, it felt like it wanted to rest on one side or the other, instead of exactly plumb. Is this what you're describing?

OTOH tracking was great IMO. Much stronger than the other hard-chine boat I demoed at the time, the Anas Acuta. Due, I'd guess, to the differences in their keels.

 
 
  chines and tracking
  Posted by: suiram on Apr-15-13 11:18 AM (EST)
In my experience, tracking is mostly defined by the rocker. Keep in mind - rocker might change depending on load - same kayak will track differently depending on paddler's weight.

Chines do affect the way boat responds to leans.
If paddling is not clean, that is boat wobbles for side to side during the stroke, course deviations might be induced due to chines and not overly pronounced rocker.

Extremes - loaded Greenlander Pro vs Anas Acuta with a light paddler
 
 
  PS...
  Posted by: Celia on Apr-15-13 11:43 AM (EST)
-- Last Updated: Apr-15-13 11:45 AM EST --

My above-mentioned hard chined boat has a single hard chine and a somewhat rounded bottom, not the diamond chining you see in the Necky boats. We have an old Elaho that has the diamond chines. While the Elaho still wants to go sit on a chine, it does so over a more graduated set of positions.

And it is original drop skeg Elaho - straight tracking and this boat have never met. Great in rocks though as long as no one has to handle the metal skeg.

 
 
  Another view
  Posted by: Kocho on Apr-15-13 12:09 PM (EST)
In moving water and white water, a boat with harder chines and flatter bottom will feel loose on the water compared to a boat with similar displacement and other parameters. And I'm not talking strictly whitewater boats. For instance, the P&H Delphin is flat bottomed and rather hard chined and sharp edges in the front and rear, with hard chine with rounded edge near the seat (kind of opposite to other hard chined sea a kayaks, which seem to have sharp edge near the cockpit and soft edge fore and aft). That boat, as long as you do not edge it, is very unaffected by cross currents, compared to a rounded bottom with a V like the Zephyr. The Delphin will go where you want during eddy out maneuvers where you don't edge it, while the Zephyr will be swept downstream. The current just slides under that flat bottom. But if you want your edge to grab and for you to peel out and turn downriver, edge it and it will do what the Zephyr does.

For white water creek and river runners, the same holds true - keep them flat and they are maneuverable. Give them and edge and they will grab the current or track where you want them, for instance during a cross ferry: you eddy out with little or no edge to keep the boat pointed where you want it while you enter the main current, then give it some edge so that it acts as a keel and the boat tracks. Reverse for eddy out maneuvers - edge it at the eddy ,one so the rails catch and you swing inside the eddy for a tight turn by the current (front half of boat digs into the water in the eddy and the rear digs on tue main current, so the boat turns around by it) as opposed to going over and continuing straight into shore/rock.
 
 
  Opinions about round hulls and hard
  Posted by: dong on Apr-15-13 10:30 PM (EST)
chine hulls will never give a reasonable answer. Other hull design features play a much greater part in tracking and maneuverability. The part of the hull that's under the waterline will tell you a lot. A hard chined hull can make carving turns better and it can also reduce side slip when paddling with a side wind. Besides that there really isn't much difference.
 
 
  All boat design is trade offs
  Posted by: Jaybabina on Apr-16-13 8:07 AM (EST)
-- Last Updated: Apr-16-13 8:11 AM EST --

Generally rocker makes more of an impression on maneuverability than any other aspect. Generally hard chine keeps a boat higher in the water with the same load as an equal soft chine boat. It's popular for boat designers to use hard chine on some very rockered boats because it will help counteract the speed loss by keeping the boat higher - since rockered boats are slower. Hard chine gives more initial stablilty than a soft chine given the same width boat. Hard chine also has more wetted surface than a soft chine boat = slower. (same width boat)

The trend in kayak design seems to be more and more semi-hard chine boats desperately trying to get a little of everything.

I still like soft chine boats but you have to try them and formulate your own opinion because the differences can be very slight since so many other variables get tweeked. If two boats were the same width/length/rocker, the soft chine would be the stronger tracker since it would sink deeper and have more centerline holding direction.

 
 
  One design element called "chines"
  Posted by: LeeG on Apr-16-13 10:26 AM (EST)
doesn't define handling characteristics. Unfortunately a lot of advertising copy lends one to think it's a defining characteristic when it might simply be an artifact of a construction technique.
 
 
  it does define handling characteristics
  Posted by: suiram on Apr-16-13 10:28 AM (EST)
Given two very similar boats the one with hard chines will handle differently
 
 
  I own a North Shore Buccaneer
  Posted by: castoff on Apr-16-13 11:46 AM (EST)
-- Last Updated: Apr-16-13 11:48 AM EST --

It has a good bit of rocker and i feel it turns well for a 17'4" boat. It is 21.5" wide and accelerates well and fairly fast. It tracks fairly well too if i keep my eye on where i want it to go. I rarely use the skeg but then if you do it will track very well.

I also have a Shearwater Merganser it is a S&G 23" wide and 17' long with hard chines. It tracks a bit better than the Buc, and has less rocker. It seems to me it has a bit of skeg built into the keel at the stern by design. I haven't missed the lack of a drop down skeg with this boat. When put on edge it turns well.

Both boats carry lots of gear for longer trips. Of the two I prefer the Buccaneer for playing in the surf a slight bit more, but enjoy tripping in both.

I would have to agree with keel profile, length, rocker, etc. probably have much more to do with tracking than chines.

I should add to me both boats seem very stable, even the narrower Buccaneer.

 
 
  Manufacturers say it better
  Posted by: rjd9999 on Apr-16-13 12:44 PM (EST)
than I do, so take a look at the pygmy site.

http://www.pygmyboats.com/hard-chine-vs-multi-chine.html

The key is that hard chines often lead to a flatter bottom on the hull. So this has a definite effect upon handling and upon the profile of the boat (sides tend to be more vertical). Where chines really come into play is when the boat is leaned and the chine acts like a keel, which should impact tracking and stability. How much of the hard chine makes contact with the water (degree of lean, shape of the side of the hull, etc.) affects how the boat responds, so the further one leans, the greater the contact with the water.

As for tracking, chines matter less than the flatter bottom, which has a larger surface area in contact with the water, and whatever keel is built into the design. According to pygmy, the hard chine produces a slower boat due to the flatter bottom (duh), and tracking may be minimally impacted, if at all. As the pygmy site says when comparing their hard and "soft" chine boats, "The cruising speed and stability for all three are approximately the same."

Rick
 
 
  Any kayak can be fun
  Posted by: Jaybabina on Apr-16-13 4:59 PM (EST)
When I visit my brother I often use his second boat which is a Cape Charles 17 (Chesapeake Light Craft). Basically an unsophisticated 24" wide hard chine wooden tank. I always enjoy myself in it, and have been in all kinds of conditions and mild surf. I think with a lot of kayaks the basic principals far outweigh the differences and allow you to enjoy a lot of variations in crafts. As long as it's not a severe weather cocking boat and the seat is comfortable, I can have a good time. What's amazing is in groups with other kayakers with longer, faster boats, I can easily keep up without killing myself and I don't consider myself excessively strong or fast.
 
 
  Block Co-Efficient
  Posted by: CEWilson on Apr-16-13 2:42 PM (EST)
-- Last Updated: Apr-17-13 9:52 AM EST --

The best predictor of tracking is block co-efficient. The block is WATERLINE length, width and depth. The less of that block the boat fills the better it tracks. See Winter's, "The Shape of the....."

Full or abrupt chines and a flat bottom fill more of the block, so, predictably, those hulls will track more poorly. Conversely, V bottom hulls track more reliably than any others, but the handling characteristics are not desirable. The simple take-away is finer lined hulls track better than fuller ones.

Tracking correlates somewhat with decreased stern rocker, but deeper sterns effect tracking only because some paddlers carry the blade aft of their body into a partial sweep. Skegged sterns compensate for poor technique by resisting the torquing forces in sweeping strokes. A perfect forward stroke tolerates enough stern rocker to make a hull usefully maneuverable.

 

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