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Upswept Bows

When LesG mentioned about the upswept bow design slicing through the waves versus the more vertical in the Brit boat thread, it reminded me that I've long wondered about the virtues of the straighter design. Is upswept better, or non-upswept, depends on conditions, or just a design philosophy?

My Night Hawk is designed non-upswept, and it definitely likes to climb the waves and then slaps down afterwards. I thought I had heard that it's less likely that your bow will take a dive on you.

If this is another rudder/skeg question, then I apologize in advance.



  • Yeah -like rudder skeg
    but I just put some NDK QCC comparison comments at the end of the other thread (long message starting out with a Nordkapp comment).

    Don't know if they make sense or will help - but they're there.
  • Volume
    up front, more than anything else will determine whether the boat will slice through or climb up and over a wave...

    Besides it's about all "trade-offs." My low volume SOF slices through waves. It's a wet ride but it's a wet sport. :) The thing is because my boat is low volume and slicing through the waves, I'm less prone to being affected by wind. My Montuak is upswept in the bow but, being higher volume, it climbs up over a wave and slaps down into the troughs. I actually now find this uncomfortable. I don't like that banging/slapping thing after each and every wave.

  • sweep
    -- Last Updated: Jul-20-04 4:04 PM EST --

    One poster has commented -- from experience --that a raked bow makes the consequences of encountering ice a gentle slide instead of an abrupt stop. That's an important design feature if you're in Greenland but probably less important for most of us. As sing said, volume forward, cross-section shape, and flare are probably more important than stem rake for influencing behavior in waves. But rake is one way of controlling the volume distribution of the bow.

  • Options
    My feelings are every design has a type of paddling or water conditions in mind. My preference in ocean conditions an upswept bow for the slicing ability and leaving the boat at a lower angle when breaking the surf or waves in general and getting back into the water on the back side of the wave.

  • Options
    Compare those pointy-ended Brit boats to a Mako surfski, which uses a completely different approach to bow volume. The bow is shaped sort of like a torpedo with flattened sides. The stem is very plumb, but there's lots of bow rocker. The end result is similar to what pointy ends are supposed to do: enough reserve buoyancy (bow volume) that it's very difficult to get the bow to dive very deep or stay down very long.
  • "Bowshear" Verus "Plumbow"
    A boat with an upswept bow has bowshear. A boat with a straight pointed bow has a plum bow.

    A plum bow is more efficient and faster as it increases waterline lenght.

    Bowshear is to deal with waves and swells, but as Sing pointed out, it is just one factor. A good rough water boat will also have some "rocker"
  • Now compare that...
    ...Mako bow to the bow of QCC Q700. Note the similarity.



    Funny how no one questions this type of bow for rough water when talking about the Fenn, but many will deride the same sort of volume and more plumb ends on the QCC, claiming it is inferior to the old school Brit designs for open water.

    I say they're just different approaches - and think only Sing's comment on confident paddlers really has any merit.
  • Options
    Basically agree, but
    -- Last Updated: Jul-20-04 5:24 PM EST --

    it probably depends in part on what you want to do in that rough water. The Mako is fast but very demanding. If you were designing a boat to spend a week paddling rough water all day every day while hauling a gear load, you'd be thinking less about speed in conditions and more about comfort and ease of handling. I don't know how the QCC handles that tradeoff, but there is a real tradeoff there.

    Should add: I basically agree with Sing, too, but only up to a point. The "I'm skeert" factor still starts kicking in sooner in the Mako than it would in the Scupper. That's my fault, not the boats, but I'd guess about 95% of paddlers would feel the same way.

  • Appearances can be deceiving
    I think some look at a more plumb bow and see less rocker. An upswept design can look much more rockered whether it is or not.

    A side photo of my boat makes it look like it has next to none, yet when you put it on a flat surface and there is more rocker than it looks like. Some Brit designs (and traditional hulls)look pretty well rockered, but put them on the floor and some may be quite flat along the keel between the upsweeps.

    As for wave slicing, plumb bows cut waves too. Both cut, both also rise over. Another set of timing/feel issues.

    Multiple factors come into play, and hard to separate their effect to the point where any one element can be said to be creating a particular handling characteristic all on it's own.
  • Needle Nosed Boats
    So, if I understand you correctly, would it be true that the boats that quickly taper to a needle-like bow that is up-swept have a lower volume and tend to piece the waves more readily?

  • Agree on trade-off too, but...
    ... that's where Sing's point kicks in.

    Stuff that had me "skeert" when I first got my Q700 (basically any chop or wakes at all - as I was coming from a 28" beam SOT), I hardly notice now. I could sit and eat lunch in 3-4x what spooked me when I first got it. Of course I have a long way to go to feel confident in "conditions" of any magnitude, but have not found the boat wanting so far. If anything - I'd say it's got to be a good babysitter/teacher if it can take care of a first time SINKer.

    So far short steep beam chop/wind wave is the most noticeable - and now that I have a better feel for the hull I realize I can mostly just ignore it (a revelation after having fought it for months). Bigger wakes/waves are easier and even more fun (not that we get a lot of big waves here). Rear quartering stuff gets more fun every time out. Boat is amazingly well behaved in sloppy stuff - has to be if I'm enjoying it as a SINK paddler of only about a year.

    The boat does like to get up and go though, and I used that steady forward stroke as a stability crutch the first few months (sort of like skis always are -with the paddle completing the balance tripod). At first I was very uncomfortable going slow or just coasting/sitting in chop. Had to keep moving at a fair rate to feel stable. At some point I separated the balance from the blade and most of it went to the body/coat connection and I no longer needed to be moving forward to feel stable. Doubt I'll ever see that on a ski, as it's not made for sitting - it's 100% made to be moving, but the Q700 is really a fairly ordinary design for a fast sea kayak (very good - but not realy radical in any way) and does a range of things well. Most of which I still have to learn...
  • Options
    I'd like to try paddling a QCC
    one of these times. They do look like nice boats and owners seem to love them. Maybe QCC ought to build a few with rock-bashing layups and really dry hatches and sponsor a few expeditions to see how they stack up on the Brit boats' turf.
  • If your're ever...
    in S FL - I'll hook you up (or Hex, or Jim, Brian, or...).

    Phil could do a heavy glass layup - but bet he'd talk you out of it first. Maybe just stratgically reinforce some areas in the standars S-Glass Kevlar layup (their toughest standard layup).

    Hatches are another issue. Looks like the new ones aren't much of an inprovement. I have very little trouble with mine. If I attempt a lot of rolling/rescue practice or have many waves break over the deck I'll get about a cup or so up front (less since I siliconed the compass adn stopped a samll drain/drip in issue), and have less in the rear now that I changed the skeg setup. No big deal. Something tells me that if I vent I'll get even less water (suspect some suction as deck cools pulling in water from recess around seal) but somehow venting leaky hatches seems redundant (mental note - do it anyway...).

    My ideal upgrades? Lower the reardeck 2-3", put on big oval tupperware hatches and maybe a day hatch(w. third angled bulkhead). Oh yeah, move the front bulkhead back about a foot and beef it up too (so I only need one layer of minicell). Sweet!
  • Yes, It Is Very Complex....
    There are so many factors, and combination of factors, that impact the way a boat handles, including the boaters own size and weight, that about the only way to really judge it is to paddle it for yourself for yourself and see....
  • sounds
    -- Last Updated: Jul-20-04 7:23 PM EST --

    like my ideal kayak too if you got rid of the ugly arse plumb ends, added a little rocker, and gave it an upswept bow.

    you wrote:
    "My ideal upgrades? Lower the reardeck 2-3", put on big oval tupperware hatches and maybe a day hatch(w. third angled bulkhead). Oh yeah, move the front bulkhead back about a foot and beef it up too (so I only need one layer of minicell). Sweet!"

  • Options
    Hey Greyak
    After your "ideal upgrades" are you sure you aren't getting a Kirton Inuk?
    Wait...... that's not possible, it's a British boat :-)


  • yep unless well rockered plum
    bows will tend to generate boat slap moving forward through waves.

  • Inuk not actually British - or a Kirton
    The import the Inuk from Nelo.

    Again another interestion offshore racer that looks quite similar to the supposed flat water QCC. Hmm...
  • I Noticed
    The Revenge has a plum bow and not enough rocker for my taste. I took it out on the open ocean before I left for vacation. I had hull slap coming back in thru 3-4' swells...
  • Slapping vs. Slowing
    Slapping with fuller volume vs. Slowing with fine ends. Those are the two extremes. Most designs are closer to the middle and more similar than different. Brits slightly to the right, QCCs slightly to the left.
  • Thanks All
    I'm happy with my Night Hawk even though it slaps the waves, but it's interesting to know why.

  • Options
    the plumb ends!
    The plumb ends are what make the boat so appealing to the eye. Those up-swept bows look down right silly, like elves shoes without the stupid bells at the tips. Every time I see one of those kayaks, I wince. How ugly!
  • The shortest distance is a ...
    -- Last Updated: Jul-21-04 6:09 PM EST --

    straight line. So going through the wave would be faster than going over it. With the waves going over my deck means less energy to dissipate with the hull, and the waves increase my waterline. Ya think??
    ... Caribou Rick

  • If...
    ... you ignore water density, displacement, etc.


    When we last paddled, I saw your boat (and the NDKs and Impexes) doing quite a bit more up and down rocking horse motion than mine. How is all that cork bobbing (from having less LWL) getting you on a straigher/shorter line?
  • ???
    That was flat water.. Wait till the Bacall...
  • 2005 Bacall will be flat too
    That's my official long range forecast.

    Besides, in your 'bou, you'd better be doing the Bogey next year!

    The big question is: What will Frank be paddling? He needs to up his Isthmus training. Iceman will be on his Mako, Hex will be in his EFT - that leaves Frank free and clear in under 18' SOT if he can just "Paddle on!" instead of off!

    Yeah, it was VERY flat that morning, but over the few wakes we crossed, the more Brit the hull, to more it bobbed. Maybe you didn't notice beacuse you were bobbing with them! Maybe everyone feels steady and only sees the OTHER kayaks bobbing?
  • volume and hull section
    Bow volume and cross section have more to do with how the boat handles seas than the sweep of the bow.

    As already noted very similar appearing boats may handle waves etc... quite differently.

    Boats that have as similar appearance as an NDK Explorer and a Valley Aquanaut handle the same seas differently.

    The most well designed sea kayaks can handle most rational seas. It is often a matter of how the paddler feels with the manner with which the boats deals with various conditions that makes the greatest difference.
  • and no one has made any
    referance to paddling any of these designs with 20-30 #'s of gear up there .
  • loaded
    I paddled my Aquanaut pretty fully loaded for camping -- 10 litres of water, tent, Thermarest pad, extra gear and clothing and some food and juices, etc...

    Of that, well over 20lbs of it was in the bow compartment.

    The boat was fine. It is an expedition boat and was quite at ease laden. This was also true of my wife's Explorer LV.

    The Explorer still rode over most all swell and chop, the Aquanaut continued to cut through small swell and chop, riding over the larger.

    Both were, if anything, more confident handling seas.
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