There has been a lot of discussion lately about different kayak designs. In Derek Hutchinson's "complete book of Sea Kayaking", he describes different hull designs, and their characteristics. On the subject of hard chined hull shapes, the description has me a bit puzzled, because, it is contrary to what a lot of kayak owners say about their hard chined kayaks. (From Derek Hutchinsons book "Complete book of Sea Kayaking") "The V-shaped or chine hull, the traditional shape of many Eskimo kayaks, gives directional stability as long as the amount of rocker is not excessive. However, with such a hull it is unfortunately almost impossible to maintain fast forward speeds because as the speed increases the boat tends to plane on the flat chines. The kayak thus retards itself on its own bow wave". (End of quote) I have read a number of reviews from the owners of hard chined kayaks that describe them as "Fast" (see paddling.net's reviews on Nigel Dennis's "Greenlander Pro" for instance). I would like to hear peoples thoughts on this, especially any kayak designers/builders, or people that own both hard chined AND rounded (or soft chined) kayaks. Do you agree? disagree? Thanks, Robert Warren *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Robert Warren wrote: > In Derek Hutchinson's "complete book of Sea Kayaking", > he describes different hull designs, and their characteristics. > On the subject of hard chined hull shapes, the description has > me a bit puzzled, because, it is contrary to what a lot of > kayak owners say about their hard chined kayaks. > (From Derek Hutchinsons book "Complete book of Sea Kayaking") > "The V-shaped or chine hull, the traditional shape of many > Eskimo kayaks, gives directional stability as long as the amount > of rocker is not excessive. However, with such a hull it is > unfortunately almost impossible to maintain fast forward speeds > because as the speed increases the boat tends to plane on the > flat chines. The kayak thus retards itself on its own bow wave". > If the hull form is such (and I'm not sure what this exactly is!) that the hull planes it has the effect of : 1. Decreasing the waterline length and max hull speed is a function of waterline length, and 2. Decreasing wetted surface which will lower the amount of energy needed to maintain the same speed. I'm not sure, for the speeds we're talking here, how these two things interrelate. I doubt that the hull gets up on a plane like a speed boat does. And, I expect the angle of the "V" at the centerline will have an impact also. But which way, again I don't know. Designers can probably throw a lot more light on the topic. It's a good question and I sure would like to hear the discussion. John Blackburn *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
At 04:40 PM 1/15/02 -0800, John Blackburn wrote: >Derek Hutchinsons You know if Derek Hutchinsons says so its law according to him Dana *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I'd have to give Derek's comments a big "It depends". I do have some direct experience with just this topic. I paddle a CD Caribou, and my buddy Ken paddles a CLC Patuxent, among many others in his fleet. Both are hard-chine kayaks, and are roughly the same length and beam. We decided to try and see whose boat was fastest one day, and we raced. My boat began to plane off, just as Derek predicts, but it started planing at the very top end of my ability to propel the boat. Ken's boat showed no signs of planing, and he continued to accelerate past me (Well, for about 30 feet, and then he almost collapsed). We switched boats, and repeated the experiment, with the same results (The Patuxent was able to continue to accelerate until the paddler nearly died). However, the planing effect did not manifest itself until I was paddling well above a speed I could hold for any appreciable distance, I guesstimate about 7-8 knots. I really should try this with a GPS, just to see how good a judge of speed I am. For regular paddling, it seems to have no noticeable effect. I have no problems keeping up with most paddlers, even Ken. So, as I said, "It depends". Wayne -------------------------------------------------------------------------- ------ Wayne Smith wsmith16_at_snet.net Check out my sea kayaking & homebrewing page: http://pages.cthome.net/wsmith16/home.html ----- > *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
From: "Wayne Smith" <wsmith16_at_snet.net> > We decided to try and see whose boat was fastest one day, and we raced. My > boat began to plane off, just as Derek predicts, but it started planing at > the very top end of my ability to propel the boat. Ken's boat showed no > signs of planing, and he continued to accelerate past me (Well, for about > 30 feet, and then he almost collapsed). I'm curious how you determined that the kayak was starting to plane. What indicator did you use? Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
From: "Robert Warren" <rdwar_at_earthlink.net> > "The V-shaped or chine hull, the traditional shape of many > Eskimo kayaks, gives directional stability as long as the amount > of rocker is not excessive. However, with such a hull it is > unfortunately almost impossible to maintain fast forward speeds > because as the speed increases the boat tends to plane on the > flat chines. The kayak thus retards itself on its own bow wave". This seems to be more a function of the flatness of the bottom than the existance of hard chines as inferred by the subject line. Note that a chine refers to the the point where the bottom of a hull meets the sides, not the V at the center (though some use the term that way, as Uncle Derek seems to be doing.) It would seem that a V-bottomed, round chine hull should exhibit similar behavior and a flat bottom with any chine shape should, even more so. I wonder about the ability to get significant semi-planing out of such sloped surfaces. Planing usually requires a fairly flat hull. In planing hulls, the transition from V to flat along the length of the hull has to be rather significant with the flatness dominant in the rear of the hull; in kayaks the V continues the length of the craft with the WL beam decreasing greatly in the stern. A more conventional explanation of the reason for a tad more resistance in hard chine hulls is that they have a greater wetted surface than rounded or soft chine hulls with the same displacement. And of course, there are always exceptions to this. Boreal Designs got around the problem somewhat by combining a rounded bottom with hard chines and flared sides in the Ellesmere. This gives hard chines without the extra surface area of a V bottom. The flat sides still contribute more surface area than a fully rounded hull, though. Someone once commented to me that hard chined hulls seem to hit their speed limit rather "solidly" and they are hard to push further. My limited experience is that this seems to be true. Round chine hulls feel like they can always be pushed a little more, but the hard chines seem to stall out. Given the limits of a paddler's perception, this may not be true. My experiences may be coloured by this expectation. Mike PS - an International Sailing Canoe (sailboat) _starts_ to semi-plane at a driving force to displacement ratio (Fr/W) of 0.1 (Marchaj). Using a kayaker (175lb) + kayak (50lb) = 225, that would be 22.5 lb of thrust on the paddle continuously. Given the intermittent nature of paddling, that would put the actual paddle forces well up into the top of Matt's very useful table of paddling force & hp requirements in the Aug '98 edition of SK. I wonder what the appropriate Fr/W ratio for a kayak is? *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> I'm curious how you determined that the kayak was starting to plane. > What indicator did you use? > Feel, and you also can see the bow start to ride up on it's own wake. Being also a sometimes whitewater paddler, I'm very acquainted with the feel of a boat planing. I have also deliberately made her plane off in tidal rapids, so I could surf the waves like I would in my ww boat. The whole thing was totally subjective, but I did notice at about the same time that the boat was much harder to propel. -------------------------------------------------------------------------- ------ Wayne Smith wsmith16_at_snet.net Check out my sea kayaking & homebrewing page: http://pages.cthome.net/wsmith16/home.html *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Because there are some many variations of "hard chined" boats that have a wide variety of different performance characteristics it is impossible to generalize about them other than to say "Hard chined boats have hard chines." Beyond that you can always find an example of a boat that doesn't match the stereotype For planing, it does help if the boat has fairly straight, flat buttocks lines at the stern that end abruptly like the stern of a speed boat. The sharp edge providing a place for the water to be released from the hull. It is easiest to create this shape with the hard edge at the chine. So if you really want a boat to plane well, it makes sense to at least have the stern half hard chined, but it is not required and not all hard chined boats will plane easily. Tracking generally has more to do with the shape of the keel than the chine. The shape of the bow wave has more to do with the overall distribution of volume at the bow than the character of the chine. The kind of chine is a bad predictor of boat performance. It is often used as an easy short cut to describe performance, but is typically inaccurate. The best predictor is getting in the boat and trying it. If it is fast, it is fast regardless of it's chine type. >There has been a lot of discussion lately about different kayak >designs. In Derek Hutchinson's "complete book of Sea Kayaking", >he describes different hull designs, and their characteristics. >On the subject of hard chined hull shapes, the description ha >me a bit puzzled, because, it is contrary to what a lot o >kayak owners say about their hard chined kayaks. > >(From Derek Hutchinsons book "Complete book of Sea Kayaking") >"The V-shaped or chine hull, the traditional shape of many >Eskimo kayaks, gives directional stability as long as the amount >of rocker is not excessive. However, with such a hull it is >unfortunately almost impossible to maintain fast forward speeds >because as the speed increases the boat tends to plane on the >flat chines. The kayak thus retards itself on its own bow wave". >(End of quote) > >I have read a number of reviews from the owners of hard chined >kayaks that describe them as "Fast" (see paddling.net's reviews >on Nigel Dennis's "Greenlander Pro" for instance). > >I would like to hear peoples thoughts on this, especially any >kayak designers/builders, or people that own both hard chined AND rounded >(or soft chined) kayaks. Do you agree? disagree? -- Nick Schade Guillemot Kayaks 824 Thompson St Glastonbury, CT 06033 (860) 659-8847 *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Robert, Derek used to paddle an Anas Acuta and I wouldn't be surprised if much of his opinion of hard-chined hulls is colored by this single design. The Anas Acuta is heavily rockered, and Derek molded a skeg to improve tracking. I have an Anas, and agree that during a full sprint, it hits the wall early (around 4.5 - 5 knots for me) and feels like it tries to rise and then sink, in quick, alternating cycles. It also generates a lot of turbulence at the bow, that is audible at touring speeds under four knots. That said, subjectively one of the fastest kayaks that I have ever paddled was a 17" wide X 18.5' skin-on-frame kayak, with a deep-V, hard-chined hull, built in Greenland for the local races. I have also owned a Recluse, and other hard chined hulls, that did not behave according to Derek's short description. I agree with Nick that you can't surmise too much based soley on knowing that a kayak has hard chines. Greg Stamer _________________________________________________________________ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide.aspx *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
I agree with John Winters and Nick on this one. At one point John wrote: "...so long as all other parameters were kept equal (hard to do)". Not only impossible to do but we will get different results depending on which of the other parameters it is that we choose to give priority to in trying to be equal. For instance, if we keep the dimensions (or more likely) waterline dimensions equal the chine boat will suffer greater wetted surface and possibly a lower Prismatic Coefficient. Both may lower top speed. However, if the factor we choose to keep equal is a more important one to the paddler like "the stability curve" we may find that we can make the hard chined kayak narrower (cutting its wetted surface and volumetric coefficient--another important factor in speed) and end up with a faster kayak that is just as stable as the rounded chine kayak. Since hard chines can also help retard side to side and skidding motions the hard chine kayak may feel even more comfortable to the paddler than the "equal static stability curve" might indicate (allowing a hard chine kayak to be built even narrower and faster--if we hold the "intimidation factor" equal for our comparisons). Hard chines by themselves don't really tell you much about how a kayak will handle because many other factors in the design can overpower (or enhance) the effects due to hard chines or rounded hull. Yes, hard chines will probably reduce sideways skidding but so will a lot of "V" on the keel (or a skeg or a fin keel on a round hull). Things are not so simple that you can say one thing about a boat always has the same final effect. There is a very complicated interaction of many factors that determine the many aspects of a hulls performance. Everybody would like a simple straight forward answer to "once and for all time, what does this do?", unfortunately, things are often much more complicated. The trick in hull design is to understand the environment and what tends to have what effects in that environment and then blend that knowledge in a way that the hull does what you want it to do in the conditions that the hull will be used in. Some designers get lucky with a hull design even though they don't have a clue what they are doing. If they then have enough sense to keep recycling that hull design over and over with different decks and names on it they might even get a good reputation as a designer based totally on their initial good luck. Of course, if their reputation goes to their head, and they design a new hull that sucks and/or start to provide us with the benefits of their knowledge in books and articles then they leave themselves wide open to bashing. My late dad always said something like, "Its okay if some people think you are stupid. Why open your mouth and remove all doubt?" Matt Broze http://www.marinerkayaks.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
At 10:36 PM 1/16/02 -0800, Matt Broze wrote: >I agree with John Winters and Nick on this one. I just had to see that one again. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
In a message dated 1/17/2002 10:26:54 AM Eastern Standard Time, jaf30_at_cornell.edu writes: > At 10:36 PM 1/16/02 -0800, Matt Broze wrote: > >I agree with John Winters and Nick on this one. > > I just had to see that one again. I just saved that to file for printing and framing! Ralph (Hoehn) *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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