Advantage of shallow arch hull?

Took a trip to the outfitters a few days ago and saw a Riot rec/touring kayak I liked the look of - I think the name was Evasion 15.5. It has a shallow arch hull; I was wondering what the benefits of that kind of hull are.


I’m no expert but

– Last Updated: Feb-07-05 11:42 PM EST –

One advantage of a shallow arch hull is that it often offers more speed and better maneuverability that a shallow v hull. The arch approximates a circle so offers less surface area.

the shallow v offers better tracking. some shallow arch boats seem very easy to lean from chine to chine (like the seaward foster legend) This characteristic depends on draft, type of chine, etc etc. For a newbie the legend can be disconcerting, for an expert (not me) the ability to quickly shift fron chine to chine is very useful.


Hopefull someody who knows a lot more than me about this will give you better information.

Only One Component

– Last Updated: Feb-08-05 5:52 AM EST –

of the hull design. Other factors like rocker, deadrise (angle from keel to chine), flare to the gunwale, beam width, length, etc, all play a role in the boat's performance.

The Evasion has very little rocker and will track. It's pretty flat bottom (minimal deadrise) and have primary stability over secondary. By "shallow arch" most will be referring to the deadrise and how it goes into the rounded chine. The Evasion has rounded chine much not much deadrise. The rounded chine will be forgiving when you do draw strokes and sculling draw because it doesn't have an edge to catch as would a hard chine boat. But the Evasion doesn't have much flare from the chines to to the gunwale (deck line) which means if you put it on edge, it will go over a bit but will quickly pass the secondary stability and go completely over. If it had more flare and/or more deadrise, you could lean/edge way more without going over. Rounded chines will also tend to be a tad more forgiving on wheen getting on edge but the turns tend towards sliding out. A a hard chine will carve more but does not feel as smooth or as progressive going on edge.

The Evasion hull shape is pretty typical of most the "rec touring" class of kayaks.

sing

Individual Trees vs The Forest:


No offense intended but if you are concentrating on this one design feature to pick a boat than you are falling prey to the marketing copy. The shallow arch / shallow v component of the bottom of hulls is but one very small design component of the whole boating experience. Compare the importance of this feature to something as trivial as air-dams on small import cars. Is there a measurable effect? Sure but does that effect define the whole vehicle experience? Absolutely not!



These kinds of questions come up from time to time among people just getting started in the sport. Probably because their experience with small boats is limited and the choices so wide that people try to draw conclusions about performance and design intent from the crap the marketing guys write to con the uninitiated. Please don’t fall prey to this kind of thing.



The best small boat testing device is your body. Jump in the boat and paddle it. If it does what you want and you feel inspired by the boat then the marketing bullsh*t or specific design criteria won’t matter one wit. Find a boat that inspires you to paddle and paddle often. If you think something looks sexy and that makes you paddle more often, then you will enjoy that boat immensely and you’ll get more than your money’s worth out of it. If you think that hard chines are traditional and you are attracted / inspired by such things than get a boat with hard chines. All of the best efforts by the marketing departments of the world will not make a dog of a design paddle like the sweet hulls of the best of the breed.



As you grow and gain experience with various designs, your body and your spirit with tell you when you’ve found the right boat for your particular body, level of athleticism, skill and budget. No one can definitively tell you what the “right boat” will be for you. All anyone else can do is tell you what boats inspired them or inspired other that they know. It’s an onerous challenge to try and research boats before a first purchase. An often used and effective method is to buy a used boat for your first and then put your butt into every boat you can find, to demo as many boats as possible. This way you’ll know in your heart right from the get-go that your first boat is just a short term thing. Soon enough you’ll learn that the search for the perfect boat is a fool’s quest because your needs and desires will change over time as you learn more and more.



Consider the fact that most serious paddlers often own several boats. Even the experienced paddlers can’t find one perfect boat, so how can an inexperienced paddler ever hope to do what millions of more experienced paddlers have not been able to do?



The “best” boat is the boat that inspires you to paddle and to grow as a paddler. Now get out there and paddle!



Cheers,



Jed

Thanks
to all for your input. For Jed, I should have added that I am not a beginning paddler (I’d rate myself as an advanced beginner, or maybe intermediate on a good day). I have five boats now (two SOTs, a ww kayak, a typical rec SINK, and a touring kayak with a shallow V hull) but have never paddled a boat with a shallow arch hull and wondered how that feature affects performance. Probably should have explained that up front.

Thanks again to all of you who answered.

SP




Thanks
Sorry to have assumed otherwise and thanks for being gracious dispite my assumptions.



Cheers,



Jed

Assumptions aside, it was a good post…
… and useful for the silent majority reading these threads.

Actually, shallow arch hulls are common
while a pure V-hull or a completely flat hull cross section are seen less often.



One extreme of a shallow arch hull is a round hull, which minimizes wetted surface, and is fast, but has unacceptable initial and final stability.



The other extreme of a shallow arch hull is seen in my Bluewater Chippewa, or in the Wenonah Spirit II. The arch is SO shallow that the hull bottom is rather flattish.



Current whitewater playboats mostly have a distinctly flat under-surface, prized for its planing and spinning properties. Racing slalom boats, especially c-1s, have near-flat shallow arch bottoms which allow for good speed but also plane well for fast ferrying across currents.