# Greg Barton on rocker

Greg Barton recently published a nice article and video clip explaining/examining the difference between kayaks with plumb bows and upswept bows.

Video: http://216.154.196.56/shared/docs/685/epic%20comparison%20mr.wmv

Personally I’m not sure how much I’m convinced by the video as such. Waves are so random. At some wave lengths some designs are better than others.

I’ve often been paddling alongside another kayak and noticed how one kayak apparently was plunging into the waves while the other was riding smoothly. Then 5 minutes later it was the other way around.

More complicated . . .

– Last Updated: Jul-16-06 9:22 AM EST –

The performance of a kayak in waves (are any two waves ever exactly alike?) is much more complicated than the article and video allow. Being an enthusiastic paddler of both plumb bow and extended bow boats, I can only state that it really depends on the shape, height, and period of the waves as well as the speed of the boat, the course of the boat relative to the waves, and the way and degree to which the boat is loaded.

I'm not a boat designer but my intuition also tells me that the shape of the stern is almost as important as the bow in determining performance in waves. (If the stern resists plunging, the bow will not lift as much.)

The Barton video puts two boats side by side (is the extended bow a CD Solstice?) for a supposed comparison between plumb bow and extended bow, but as the article states, the other variable here is the amount of rocker in the hull. For a meaningful comparison of plumb and extended bow hulls, you would need to use two boats that had the same amount of rocker and were also loaded the same. (Maybe a little extra weight in the bow of that Epic in the video?)

There are certainly wave conditions in which a moderately rockered plumb bow boat will lift and pound more than a similarly rockered extended bow boat.

Interesting!
I would like to hear from QCC owners about the comparison. (QCC claims to have the longest waterline among all makers. http://www.qcckayaks.com/resources/howlong.asp)

Seems to me
that he’s attributing an awful lot to just the bow/stern angles.

Wouldn’t a proper side-by-side require equal waterlines and near identical hull shapes?

I’m no designer but this article and video strike me as sweeping generalisations with ‘data’ contrived to prove the theory.

Holmes

Epic vs. QCC
Here is a visual comparion of Epic and QCC:

http://www.epickayaks.com/products/details.aspx?nid=663&cid=752

and

http://www.qcckayaks.com/kayaks/models.asp

They look very similar if not identical.

Surf or surfer?
JackL’s comments need to be put in perspective. He’s saying the QCC sucks in surf because HE dumped it and had to BAIL four times. For him - 100% true. He also posts about how he has NO use for ROLLING. Pretty darn funny if you ask me.

Such days can be good fun and practice - but wrong boat choice AND wrong skill set for that venue beyond checking your limits IMHO. Obviously he found his pretty quickly (not saying I’d fair any better or making better worse judgments either - so let’s not make this personal - I’m just pointing out something obvious that seems to be getting overlooked).

No one has ever claimed either an EPIC or QCC is an ideal choice for surf zone play. No long boat really is, but they’re good for getting you through it as intended - and very good in open water stuff - as rough as the paddler’s capable in.

Yes, it definitely has to do with more than just bow rake - but Barton has to stick with what people can see and address the common misconceptions that persist in the marketplace. He can’t bring everyone up to speed on all the design variables and technical naval engineering details.

The article and video match my experiences in my QCC (which is not identical to an EPIC at all - thought they do share some features/qualities in the name of handling/efficiency). I’ve seen that pitching and energy draining diving paddling alongside may other kayaks. Felt in many too.

The comparison is valid for paddling somewhere though. It is NOT talking about play boating where the shorter LWL boats make sense. Then the overhangs are a way to keep some length/volume/buoyancy while shortening the waterline to increase lower speed play type maneuverability. QCC/EPIC maneuverability is very good but is designed to be used while moving, not parked. Same for their stability/manners in slop - better the more you’re moving. If your speed is low or zero you may feel more at ease in a boat the the volume concentrated more centrally (playboat) than one that has the volume carried more to the ends (open water cruising).

If your used to one type (either) - the other will likely feel.s off/wrong/worse for a while. After a QCC, kayaks I like such as the venerable Explorer feel dull/dead. But hanging out in a tide race that dampening might be a welcome relief. They are all good at something. The EPIC 18 and QCC 700 are a lot more versatile all around kayaks than may assume. Hardly just flat water cruisers, and much more similar than different to similarly spec’d Brit boats.

Oranges and tangerines, not apples.

Side by side photos
http://community.webshots.com/album/203840239qIxqCQ

Waterlines and hull shapes
No, comparing equal waterlines and identical hulls with overhangs slapped on would not be right either. They are trying to show the advantages of longer waterlines and distributed hull volume on kayaks with similar overall dimensions.

You’re right about there being more to it than bow angle - and there IS a lot more to the EPIC or QCC hulls than that.

Only looking at one variable (be it bow angle, chines, whatever) is never really that indicative of anything out of context - but EPIC is attempting to do some myth busting here, not give a comprehensive dissertation on naval engineering as it apples to small human powered watercraft.

One of Barton’s best points it that bow angle and rocker are totally separate things. People seem to confuse this and assume swept bows = more rocker and more plumb = less, which is a completely erroneous assumption. The EPIC has “ample rocker” - and compared to it the QCC is a banana (see side by sides pics link in other post).

My QCC does bob less and give up less energy/speed than other similar length sea kayaks I’ve paddled (Explorer, Caribou, Legend) - but it is of course not immune to pitching and burying given the right waves. Design is different - but not in any radical way. Heading into very short very steep stuff like 2-3 ft very close wind waves I’ve had the bow buried up to the cockpit. Any kayak would, most just some degree more so.

I can still hold speed more easily in chop/slop as it’s volume is distributed evenly and lines are smoother overall. It’s that simple.

Many pointy enders also have the ends pinched side to side (“fine entry” is 3D, not 2D) and their volume more concentrated amidships. Handy for slow speed maneuvering - but also more drag when punching through waves - and this is compounded by the finer ends slicing down/in more.

See comparison drawing here: http://appliedeccentrics.com/kayak/pinch.jpg

Not a drastic comparison, and drawn that way on purpose -but it is enough variation to see the way the top carries the volume more to the ends, and the max beam at or aft of hip, and has a finer catch - while the lower has finer entry and more volume amidships, has wides point forward of paddler, and a wider catch. These things are more important IMO - but it’s all related and all trade-offs as with everything else. Take all this into account WITH all the angle/LWL and rocker stuff and it gives a better picture.

Pinched ends are another feature seen on British (and related) sea kayak designs that is also attributed to Greenland qajaq heritage - and common on designs with longer bow overhangs (but exceptions as always too).

This pinch is not found on all Greenland types - just common on more recent designs including of course the ONE specimen used to generate most of the Brit lineage (and those shown in the popular how to books).

There are also Greenland designs (particularly older ones - for open water use) that do not have the pinch and carry the volume more evenly. My SOF is like this as well. SMOOTH! Aleut Baidarka also have no pinch.

Anyway - the only points I take issue with in Barton’s article is:

1. No mention of paddling style (ex. - A to B vs. one spot play) and the use of better in “all” conditions. Given what his main point is I can over look that.

2. The way he paints the other types as old Inuit inspired designs and as such being outdated. Given that the Inuit created all manner of paddle craft, with features more varied than “modern” kayaks - including full ended open water types - this is clearly not the case. I suspect he knows all this - and is just making a simplified point for marketing sake. Same way he talks about the ends and rocker (what the casual observer sees) rather than getting into some drawn out treatise. Given his main point I can overlook this too.

Interesting observation with the video
Looks to me like the paddler in the epic has a faster cadence than the “pitching boat”

My other thought is that the Epic would be a little harder to turn.

But hey, I’m new at this, and have never seen a plum bow Epic/QCC style yak.

contrary evidence
The other boat in the video does appear to be a Solstice. I have a Solstice GTS and recently did a similar comparison test on a demo Epic 18 in head seas in Mission Bay channel. There was an ebb opposing a moderate incoming swell and the head seas were larger and steeper than those shown in the video, though by no means large, and not breaking. Contrary to Barton’s claim, and appearances in the video, the GTS was far smoother than the Epic, which rose up and pounded down to a much greater extent than the GTS. In fact, I did not buy the Epic just because of this characteristic, though I wanted a faster boat.

Greg Iaccoca wants to sell his car…
like any other car manufacturer. Greg Iaccoca wants to have you bite off from his motoring perspective so you can enjoy his car the way he thinks you should drive. Maybe I want to drive on the wrong side of the road like the Brits do and find all kinds of fantastic features on the road to exploit. Is that so wrong? If I buy Iaccoca’s car will it make miracles for me where I go, or will it only be ideal where its builder, Mr Iaccoca, envisioned it to be?

Augustus Dogmaticus

MMVI

Dang, I wish I did not have an old
Imac …

CD probably 10- 15 pounds heavier already.

Just another thing.

On the Other Hand
With that classic British car you are at the mercy of Darth Lucas, Prince of Darkness and you have to use cognative dissonance to believe a tractor engine with a DOHC head is an advanced sports car engine.

More to the point, why is it that many kayakers are so reluctant to accept something as simple as “Horses for courses”, people differ in what traits they like and enjoy in a kayak, and competent boats do not have to be made from the same mold?

Don’t they all?
“Contrary to Barton’s claim, and appearances in the video, the GTS was far smoother than the Epic, which rose up and pounded down to a much greater extent than the GTS.”

Personally I find “fuller” hulls tend to pound more going upwind into shorter, steep wind waves, chop, but I also find them to have offsetting advantages. I could make the same comment about some other behavior of boats with more traditional hulls. Its all a compromise. I suspect all boats will do this under certain wave conditions.

going up wind into surf
well I paddle with a guy in a greenland style boat and Greenland paddle. His is one he built himself, (over 275 hours of labor) and beautiful and seaworthy. He never uses a rudder either.

My QCC 700 on the other hand I find to be very rudder dependent, but once you get past that issue you find using the rudder just becomes an enormous advantage, for tracking, control over waves, particularly downwind, and also turning in steep seas should you want to do a fast jibe.

We live in Maine and paddle just about all conditions in up to 20 knot winds and 2-4 foot seas. We hardly ever have glass like conditions. There is always some texture, reflex action, long fetches. We are pretty evenly matched speedwise, The QCC has no problem going into the wind and directly over waves and I would say it slices through them more efficiently as the greenland hull will ride up higher and drop down lower from wave to wave. The QCC will pierce them near their tops instead making it faster wave to wave. Of course these are all anecdotal observations. I’m perfectly willing to be persueded by a more scientific argument that greenland boats are superior. I think overall that greenland style boats may offer better performance and handling as they are more manueuverable and better turners particularly if the 18 foot boat doesn’t have a rudder to help turn it’s long waterline.

Fallacies
Lots of good discussion. My problem with the Barton article is that is that in disproving one fallacy (plumb bow boats cannot perform well in rough conditions)it states another one, that extended bow boats pitch and slam and do not perform well in rough conditions. (Quote from the article is included below).

The choice of a Current Designs Solstice (fairly straight rockered boat) for the video confuses the issue because it is not the extended bow but the lack of rocker that is probably making the Solstice pitch so much in those conditions. (The CD Solstice is not my favorite design, but it can provide a very smooth ride in many types of wave conditions).

A quote from the Barton article:

“We’ve found that extended-bows simply poke into the wave in front of the kayak, while providing very little buoyancy. When the wave hits further back in the boat where there is more volume, this causes the kayak to pitch upward. As the wave passes, the kayak then slams down, creating a large splash and a significant loss of performance.

With a plumb bow and full waterline length, the bow gradually lifts as it approaches the wave, and lands more gently. The longer waterline length gives a much more efficient hull and the kayak performs better in all conditions.”

Barton on a rocker
or even a chaise would be still faster than anyone else here.

af

plumb is more efficient
my take is the discussions about plunging vs rising in waves etc are more a matter of prismatic coefficients (relative fineness of ends) than about profiles. plumb ends have proven to be more efficient. overhangs are extra weight and surface that contribute mostly to windage, pitching, and drag. competition (canoes, kayaks, sailboats) is dominated by plumb bows and sterns.

Amen to that Andrew !
Cheers,

jackL

Design rules
The main reason for plumb bows on competition kayaks is the rules give a maximum overall length, so a plumb bow is required to obtain the longest possible waterline. Racing kayaks that don’t need to meet length restrictions eg: multisport kayaks in NZ, tend to have less plumb bows as these shed weed etc more readily.

With regard to sea kayaks, speed usually isn’t the designers first priority. I think one reason for extended bows is related to flair. As the deck is wider than the waterline they extend the bow so they can bring all the lines together neatly.

I do think some designs take the overhang to excessive lengths but It’s difficult to say how much impact this has on performance.

Kelvin