From your seat of the pants, Greyak,
which one has more drag: multi-chine (8-panel hull) or hard chine (4-panel hull)?
Please don’t say, “that depends”.
From your seat of the pants, Greyak,
Bad premise - can’t answer
No design is offered in both hull configurations - so no direct comparison can be made. When comparing different designs, you need to compare the total design AND factor in the user/venues.
Performance is not about chines, or rocker, or deadrise, or bow rake, or anything else in isolation. It’s about all those things interacting together - on the water - with you in it (that last one being the biggest variable of all).
You might as well say,
That depends. Try this, same rocker, same length, same beam, same bow rake, same water line, same paddler and same whatever I forgot to mention. The only difference is chine. Which one has less drag?
For the same cross-sectional area, a semicircle will have the least surface area and rectangle the most. So if you’re talking about skin friction, the shape that best approximates a circle(more panels) should have less drag.
Here’s what the Pygmy website has to say:
“My computer studies and research into the differences between hard-chine and multi-chine kayaks show that multi-chines are somewhat more efficient. For example, if the loaded waterline length (LWL), keel profile, and cumulative stability are held the same, a multi-chine boat will have about 3.2% less wetted surface and be about 3.2% faster at cruising speeds. They will have the same top speed, the same upright turning radius, and the same stability. The hard-chine boat will be a little slower at cruising speeds but will have a tighter leaned turn. If you hold the initial stability the same, the difference is more pronounced. The shape of the stability curves differ. The same cumulative stability to 25 degrees of heel will give you less initial stability and more secondary stability in a hard-chine hull compared to a round bottom hull.
A designer can trade the efficiency of a multi-chine hull for more stability instead of more speed. If I hold the wetted surface, LWL, and keel profile constant, the boats will possess the same cruising speed, top speed, and upright turning radius, but the hard-chine boat will have less stability.
A skilled designer can design excellent craft in either category. In general, if the two designs are similar in other respects, multi-chine boats, with more efficient hulls can be either quicker or more stable. Folks looking for speed often pick a multi-chine hull. For paddlers who like the performance and feel of hard-chine boats they are the right choice. Last but not least, between boats of similar performance, paddlers often let aesthetic preferences finalize the decision.”
Refer to Nick Schade’s comments on…
… chines. He’s the only one I know of who has the same basic design in strip and S&G construction. As near a real world test as you’re likely to ever get. He says difference is of course there but below his ability to detect.
You’ve cleaned up the question, but it’s still meaningless unless you’re designing/building your own.
If you were to take any kayak with sharp chine edges and round them over a bit you will reduce wetted surface and lower skin drag. If you only do it slightly not much else will change (if you go farther and make the hull round - everything changes). It would also only buy you a very small speed difference. A few percent at best.
That translates to little real world difference unless you’re racing - at a competitive level. Serious race boats don’t have hard chines now do they? Again, makes it a non-issue.
Most of the time the chines come down to construction techniques and styling preferences. The rest is a bunch of marketing hype and owner sentiment clouding perceptions.
SOF and S&G will naturally have chines. Strip and other composites can, but usually don’t as hard edges and flat panels are a poor use composite techniques and materials, making for weaker/more vulnerable hulls (composites being like egg shells are stronger with curves).
You will NEVER get the answer you want on this from me. Chines are just not on my list of things I evaluate - beyond looks. Alone they mean almost nothing. There are soft chine hulls that feel like hard chined and hard that feel like soft (whatever “feel” people care to attribute to either). Speed difference is irrelevant outside of theory - and Nick’s boats. Even there, to small to matter.
Paddle what you like.
FYI - I have hard chined (SOF and Kevlar), soft chine, and nearly round hulls.
The one with as few hard edges
a possible will have the less drag.
Nick is right on!