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  twitchiness
  Posted by: gjf12 on Nov-19-13 1:23 PM (EST)
   Category: unassigned 

Some kayaks are twitchy, think Nordkapps. Some are not, think Cetus. Other examples of each abound.

Often, but not always, one can get used to twitchiness. But it seems to me there is no inherent advantage to twitchiness. You can get the same quick response, performance, etc., in a less twitchy boat. Does anyone actually prefer more twitchiness to less?

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  twitchy
  Posted by: ppine on Nov-19-13 1:27 PM (EST)
Twitchiness or tenderness in a boat is not something anyone really likes. It is something to deal with in exchange for a high level of secondary stability.

Some racing type boats have a very narrow beam which also contributes to twitchiness.

Adding equipment acts as ballast and can help settle some of these boats down a lot.
 
 
  No one likes twitchy, many seek it
  Posted by: Kocho on Nov-19-13 2:02 PM (EST)
-- Last Updated: Nov-19-13 2:07 PM EST --

You can't get the same performance and responsiveness in a non-twitchy boat vs. a twitchy one, if both are maximizing their potential. If one is twitchy for the twitchiness sake and stupidly designed otherwise, yes, a less twitchy boat might outperform it in most situations. The idea is that a twitchy boat is optimized for speed and efficiency within certain conditions and skills and a less-twitchy boat will never be as good in these same target conditions (it might be in other, less favorable conditions).

As mentioned, twitchiness is a side effect of low wetted surface. The idea is to minimize resistance in the water by having a rounded hull with minimum wetted surface. If you also build flare, you will get higher secondary stability. If you do not have flare, the boat will be twitchy all the way until you flip.

Cetus and Delphin for instance emphasize solid primary stability and also give added secondary. Nordkapp is much more rounded bottom and thus less primary, so it feels twitchy. It also does not have huge amounts of secondary, so it is more efficient, as long as you can keep it upright comfortably.

If you could have non-twitchy and efficient at the same time, everyone would do it. Can't, so the different designs optimize for different uses (conditions and skills). I might be faster in my twitchy V10 surf ski on flat or moderate swell than I would be in a less twitchy beginner's boat like the V8. but might be faster in the V8 if I paddle in a confused chop and clapotis.

Another aspect is that a good "twitchy" design like the Nordkapp will remain quite agreeable in confused waters, while a boxy and not twitchy design like the Delphin could bounce around a lot more. Up to a point the Nordkapp will be faster and more efficient to paddle and the Delphin will be slower. However, a point comes where the twitchiness of the Nordkapp might be too much for the paddler to handle and they would tire quick in it, slow down, or capsize, where the same person in the Delphin might be just fine and thus be faster and less tired at the end (but those would have to be extreme conditions beyond the comfort zone of the paddler in the Nordkapp, yet within their comfort zone in the Delphin)...

 
 
  That's good..... but this is a case
  Posted by: ezwater on Nov-19-13 4:58 PM (EST)
where just looking at a hull may not predict what it will do. I have an old Phoenix c-1 with a rather elliptical bottom, and you would think it would be twitchy. But it isn't. It is a bit loose around dead center, but firms up very predictably as it tips.

What's interesting in the whitewater world is that paddlers keep looking for flat bottoms and sharpish chines, even in creek boats. Such boats should tend to be upset by turbulence or crosscurrents more that elliptical creek boat hulls, but some paddlers prefer them. Examples where makers are offering what some paddlers want are the new Jackson Karma and the revised Pyranha Burn. The latest river runners continue to offer flattish bottoms and sharp chines.

It appears that "new school" hulls with flat bottoms and sharp chines continue to offer something by way of control potential that ww paddlers want to have, even though inevitably, a new school hull will be more susceptible to upset in turbulence than a conservative, roundish hull.

It's kind of like what drivers have sought in a Porsche, over the decades. The sucker may spin out if pushed too far, but drivers want the control it offers, up to the limit.
 
 
  Hmm...
  Posted by: Kocho on Nov-19-13 6:21 PM (EST)
-- Last Updated: Nov-19-13 6:25 PM EST --

I'm guessing the Phoenix has plenty of flare above water to give it the solid stability on edge. Have not paddled / seen one, just guessing. It is probably also a wide (by kayak standards) hull.

A roundish hull, especially with a lot of rocker usually translates to deeper draft and a craft that gets pushed around by cross currents and waves more. Creek boats are an example. The river runners with flatter bottoms and less rocker tend to slide over currents (with minimal to no edging applied) so they are unaffected, until you edge them to engage the rails/hard chines.

A round bottomed Perception Pirouette or a Dagger RPM I think are more affected by cross currents and eddy lines turbulence than a flatter bottomed Dagger Axiom or a Jackson Zen for instance, as long as you keep the flat bottom boat flat (edge it, and it tracks straight and gets grabbed by the current to assist in turning or getting out of a hole).

Similar for the P&H Delphin vs. the WS Zephyr in moving water: the rounder deeper V on the Zephyr makes it more "twitchy" on center but with good secondary on edge. The Delphin is more solid on center and with also good secondary. But currents affect the Zephyr more than they do the Delphin. The Zephyr is smoother on choppy wind waves... The Delphin can engage the rear and front rails with edging, the Zephyr does not have them...

 
 
  The Phoenix hull has little flare
  Posted by: ezwater on Nov-20-13 1:10 PM (EST)
above the water line, especially with me in it. It always surprised me how stable it feels, more stable than my Hahn, which was roundish but with more rocker. The Phoenix did have that problem with roundness, because it didn't ferry well and raising an edge to confront oncoming current didn't work.

You're right, flatness and edges are a good thing once one knows to edge the boat to help water pass under. After a while, it seems to happen most of the time without thinking about it.
 
 
  comparison
  Posted by: gjf12 on Nov-19-13 6:15 PM (EST)
Kocho wrote: "You can't get the same performance and responsiveness in a non-twitchy boat vs. a twitchy one, if both are maximizing their potential. "

Well compare the Cetus LV at 17'5" by 21.25" to the Nordkapp at 17'6" by 21.0"; very close dimensionally. Yet the Cetus is not twitchy at all, in fact confidence inspiring, while the Nordkapp LV is quite twitchy. I don't see any performance area where the twitchier Nordkapp loses out. Someone might just like the Nordkapp better, but that is another question.
 
 
  Based on reviews ...
  Posted by: Kocho on Nov-19-13 6:28 PM (EST)
-- Last Updated: Nov-19-13 6:35 PM EST --

The Nordkapp LV has higher top speed (important when fighting currents) and lower wetted surface (important for efficient paddling). As long as one is paddling the Nordkapp in conditions where they don't feel the need to brace much, it will be more efficient/speedy than the Cetus, I believe. You might get tired quicker and develop better paddling technique and core strength in it though :)

Both great boats, the Cetus (MV) I think is the one I would pick between he two for most situations if I had a choice and it was a bit lighter. The Nordlow is a more challenging boat that only pays dividends in special cases for experienced paddlers and might be too much to handle in other situations. So yes, I agree with you that a boat like the Cetus line, that is reassuring and not twitchy but still performs well, would be a better choice for most in most situations.

 
 
  speed
  Posted by: gjf12 on Nov-20-13 1:48 AM (EST)
A friend of mine who owns a Nordkapp LV, among other boats, is vaguely thinking of the Cetus LV precisely because he thinks it is faster. (Less rocker on the Cetus?) I have no opinion myself other than that any difference in speed is likely to be minimal and undetectable.
 
 
  Read:
  Posted by: mcimes on Nov-19-13 2:10 PM (EST)
-- Last Updated: Nov-19-13 2:10 PM EST --

This is basically the same question phrased differently. There is a lot of good discussion on the pros and cons of low primary stability.

http://www.paddling.net/message/showThread.html?fid=advice&tid=1672750

But Kocho basically summed up the whole thread.

 
 
  Cargo - ballast - gear
  Posted by: willi_h2o on Nov-19-13 3:58 PM (EST)
Boats are for transporting stuff and far too many
demo a boat completely empty - i.e. high twitch factor
 
 
  good point
  Posted by: slushpaddler on Nov-20-13 8:54 AM (EST)
 
 
  Some Yes. Some No.
  Posted by: Kudzu on Nov-23-13 5:38 AM (EST)
My cohorts and I are primarily road bike people who sometimes kayak. 95% of our kayaking is day trips laden with little more than lunch. We don't use road bikes as vehicles for camping trips and seldom use kayaks that way. Boat makers need to keep us in mind.
 
 
  If speed isn't important . . .
  Posted by: Glenn_MacGrady on Nov-20-13 12:21 AM (EST)
. . . I can't think of any good reasons FOR ME to have a twitchy hull.

Non-twitchy hulls have always been fast enough for all the various types of paddling I have done, including open and decked whitewater, seakayaking, flatwater open canoe, and outrigger canoeing.

Of course, twitchiness is as much a subjective as an objective phenomenon. With experience, hulls become less twitchy. My current stable hull might have been my younger self's twitchy one.

Until with age, everything becomes more tremblesome again.

 
 
  Stiff and twithcy
  Posted by: pgeorg on Nov-20-13 6:55 AM (EST)
As Glenn has pointed out there comes a time when twitchy is no longer tolerable. The supple youngster compensates for twitchy with smooth quick body movements. The old guy can no longer move quickly or smoothly and will be, at best, uncomfortable with twithcy; at worst he'll be wet. Finally, rigor mortis sets in, you lay him out in the bottom of the boat and twitchy does not matter.

Peter
 
 
  not just speed
  Posted by: NateHanson on Nov-20-13 7:00 AM (EST)
Twitchy, to me is just a pejorative way of saying "easy to edge". Flat bottom boats like the Delphin or Cetus take more paddler input to put on edge. The Nordkapp is much easier to edge with your butt. I think "twitchier" boats allow a more intuitive body-boat connection, but every good thing has it's extremes, and at some point that "easy to edge" feel may turn into "too hard to keep upright".
 
 
  Yes easier to edge
  Posted by: nebeginner on Nov-24-13 7:34 AM (EST)
I'm a novice here, don't have all the technical terms down. To me, the Nordlow is easy to edge. The easiest of any kayak I have owned or paddled.

I would see people edging their boats way over, and could never seem to do that comfortably with the Tempest 165 or 175's I owned. I tried several boats, including an Avocet, Cetus, Aquanaut, and some of the Northshore boats, and they were about the same. Then I demo'd the Nordlow. And bought it.

I guess I thought the Nordlow had more secondary because it was so much easier for me to edge. Effortless. But I guess that's not really secondary.

Edging my Tempests, I guess it was the secondary that was pushing back. The Nordlow does not do that. it will go where you put it, effortlessly. The flip side is that it will equally effortlessly go back the other way, even when you're past the point where a boat like the Tempest would not recover.

I have always felt more comfortable in the Nordlow, more so than any other boat, EXCEPT when I let my self think this is SUPPOSED to be a twitchy boat, so there must be something I'm missing here which is going to get me in trouble.


 
 
  Twitchy is not a hull characterisitc....
  Posted by: Celia on Nov-20-13 9:29 AM (EST)
-- Last Updated: Nov-20-13 11:47 PM EST --

Speed (oops - hull resistence) to accelerate, cruising speed and degrees of heel are oft-measured hull characteristics. Twitchy is in the eye - and butt - of the paddler.

Seriously, twitchy only matters if it is so severe that the paddler can't get comfortable in the boat. But making it more important than the total package will stop you from experiencing a lot of very nice boats.

The sweetest ride in our basement is probably the twitchiest, which makes it a poor choice of boat on days when we are not on our game. But on days when everything is clicking, it is a fast, responsive wholly enjoyable boat to paddle.

I have to ask - why the focus on the Cetus? There are a lot of boats out there which are on the more comforting side. I respect the P&H boats, even have one for my main ride, but I have to wonder if this a troll for a kayak company?

 
 
  Very true
  Posted by: mcimes on Nov-20-13 9:52 AM (EST)
at the local races, a guy who paddled an Olympic K1 tried out a friends V12 and sat on it like a rock. I could barely stay in the V12 when I demo'd it.

How many people do we see on here saying "I have a penobscot and think its unstable. recommend a stable canoe for me" I always laugh at those. But just to echo your point, stability is in the butt of the beholder. I know as I have gone towards lower stability boats they keep feeling more stable all the time. My next boat is going to be a V10, so Ill take another step down the stability ladder, until it feels stable...then who knows...
 
 
  synonyms?
  Posted by: slushpaddler on Nov-20-13 9:56 AM (EST)
"Tender"?
"Lively"?

I agree, it's a subjective quality and mays say as much or more about the paddler as it does the boat. As willi mentioned, load or freeboard can make a difference as well.
 
 
  Yes, that's it.
  Posted by: Guideboatguy on Nov-20-13 12:55 PM (EST)
Those words mean the same thing, and they definitely ARE a characteristic of hull shape, and one that could be quantitatively measured if one wanted to. The point has already been made that a "twitchy" hull (or tender, tippy, whatever) has other characteristics that may be desirable for certain purposes.
 
 
  it's a subjective term
  Posted by: slushpaddler on Nov-20-13 3:31 PM (EST)
-- Last Updated: Nov-20-13 3:32 PM EST --

Semantic point but I think you're talking about "stability". "Twitchy" and the sysnonyms I mentioned are all subjective REACTIONS to a boat's stability. I'm thinkinkg twitchiness depends on paddler experience, as well as size and weight distribution.

I'm sure one could quantify stability and the differences in stability between the same kayak loaded or unloaded.

 
 
  That's what I meant
  Posted by: Guideboatguy on Nov-20-13 5:13 PM (EST)
You can definitely measure the torque required to lean a boat "x" degrees and with "y" load on board (load distributed in some defined way of course). A boat that feels more "twitchy" to a particular person than some other boat WILL require less torque to make it lean by some amount. I was ignoring the fact that an the comfort level regarding this attribute will vary from one person to the next, but not ignoring the fact that any individual's tolerance to "tippyness" will invariably be judged in the context of some other desirable attribute of the hull. Fair enough?
 
 
  lively, tender
  Posted by: wilsoj2 on Nov-23-13 9:37 PM (EST)
Thank you. Twitchy strikes me as the term many paddlers use the first time they are in a boat with less primary (and possibly directional) stability than they are used to paddling.

I own 4 sea kayaks. The one (Nordkapp LV) with the lowest primary stability is also the liveliest, most responsive, and the fastest especially in dimensional seas.

The Nordlow, however, requires one is on top of one's game. So, I often paddle my Romany or Aquanaut instead. I find the current fad of boats which are boxes at midships to feel rather dead in the water. I prefer boats that feel as if they are moving with the water.
 
 
  comments
  Posted by: gjf12 on Nov-20-13 11:57 AM (EST)
Celia wrote: "Speed to accelerate, cruising speed and degrees of heel are oft-measured hull characteristics....."

Twitchiness is also a measureable hull characteristic. See the Sea Kayaker stability curves, for example.

Celia wrote: "Seriously, twitchy only matters if it is so severe that the paddler can't get comfortable in the boat....."

This is not true. Even moderate twitchy can be moderately undesirable. Twitchiness may not be the most important aspect, but it might have moderate importance.

Celia wrote: " I have to ask - why the focus on the Cetus? ..."

Sorry, I did not intend to focus on the Cetus, just an example. The Tiderace Xcape or Xcite are very similar examples, and relatively un-twitchy.
 
 
  Sea Kayaker stability curves
  Posted by: Celia on Nov-20-13 11:58 PM (EST)
-- Last Updated: Nov-21-13 1:08 AM EST --

I can pull the last one - it is around here somewhere - but I believe the stability curve labels are more about resistance to heel. Not twitchiness. I have seen reviewers use that term, but I find it fairly meaningless compared to more specific parts of the review where they talk about how the boat behaved in specific maneuvers.

I did not say that what someone perceives as twitchiness is irrelevant, just that it is a matter of individual tolerance and comfort. If moderate twitchiness - whatever that is for someone - can overwhelm or ruin the rest of their paddling experience, it is a boat to be avoided. But there are many who are fine with that, as indicated by some of the replies above. In that case, other factors come to the fore.

I have experienced boats that I would call twitchy myself, and it has not always been about predictable behavior. It at times has been a matter of how the boat responds to waves from odd directions for example, where the same boat shows much smoother behavior to most dimensional water. This is not the kind of thing that I expect to see measured on a stability curve.

For that matter, neither is what jaybabina is calling twitchiness below. A stability curve for a hard chined boat may not capture that tendency of the hull to not sit quietly. The curves may only be reliable on how the resistance develops after the boat has hit its first chine.

 
 
  Twitchyness?
  Posted by: Andy_Szymczak on Nov-20-13 3:38 PM (EST)
First time I paddled my CLC many years ago it was twitchy, for 5 minutes. First time in my Artisan Millenium, it was twitchy, for 2 minutes. My surf ski embodies twitchyness, and becomes twitchy if I tense up. Which I rarely do! My Summersong was never twitchy!
 
 
  tippy vs. twitchy
  Posted by: Jaybabina on Nov-20-13 4:24 PM (EST)
-- Last Updated: Nov-21-13 8:23 AM EST --

When I think of a narrow boat or one with not much initial stability I think of it as tippy. I often find hard chine boats twitchy. For me it's when a kayak doesn't want to sit solidly on the water and wants to teeter from side to side. I usually experience it in hard chine boats because some are designed to carry a certain load and if it doesn't sink deep enough it seems to float too high and never sits solid on the water. I have been in narrow hard chine boats that are tippy and wider ones that are twitchy. I can usually adjust to tippy OK but dislike twitchy boats that teeter from side to side.

 
 
  Silhouette?
  Posted by: slushpaddler on Nov-20-13 5:09 PM (EST)
I really liked demoing one but when stationary it sort of felt like that.
 
 
  Feeling twitchy?
  Posted by: water_walker on Nov-20-13 6:36 PM (EST)
Paddle harder.

(A simple but effective solution. The leverage gained from a vigorous and balanced forward stroke can make up for a lack of initial stability.)
 

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