I am new to WW kayaking and I have seen this terminology but I am not sure about the difference between displacement and planing hulls…I guess I can gather a bit from the terminology but I would like more information if anyone can help.
I gather that older boats are generally displacement style and newer ones are generally planing hulls. Is this pretty much the rule?
Are planing hulls just for play boats?
What are the advantages/disadvantages of both?
If my assumption about hull design is correct and the planing hulls are now pretty much the norm for modern boats, then when did this transition occur?
thanks
Matt
Look at this previous discussion
http://www.paddling.net/message/showThread.html?fid=advice&tid=214954
Displacement hulls are more round in shape and planing hulls are flat. They both displace water but in faster water (like a wave) a planing hull will actually plane. Displacement hulls have almost disappeared from the WW boat market. Current designs almost all have a planing hull of some kind but are very different in other ways. There are excellent river running boats available that have a planing hull. G2d will tell you that longer displacement hull boats are better if you want to go that way. I agree. Most of the skilled paddlers I know who still paddle displacement hulls have longer boats.
Planing characteristics have existed on
selected displacement hulls for a long time. Slalom boats, and “old school” boats which work well on slalom courses, usually have a tubular bow which broadens quickly to a flattish area under the paddler, and extends toward the stern. There should be a moderate amount of rocker under the paddler. These boats actually plane on a fast wave, and their partial planing ability, plus their length, make them easy to drive upstream in “attainments.”
To see some relatively late-model displacement hulls in action, watch for the videos “Essential Boat Control” and “Retendo.” You can see slalom World Cup Champion Scott Shipley throwing ends, planing on big waves, and back-surfing in a 13 foot slalom kayak in “Retendo.” Eric Jackson appears briefly in a Kinetic, and there is one “new school” short planing boat in this video covering a transitional period.
The market concentration on short “planing” hulls has virtually stopped development of longer hulls, but this is a temporary market phenomenon. Check out the American Whitewater article about a bunch of guys enjoying themselves on a 5-day (!) Grand Canyon run in 14 foot Prijon Yukon kayaks. Some of the western runs I have done would have been a sorry joke in an 8 foot playboat.
comparisions
– Last Updated: Oct-25-04 11:59 AM EST –
You find planing and semi-planing hulls on boats geared toward people who just want to run rivers, too. Wavesport Diesel, Dagger GT, Liquid Logic Hoss, Jackson Fun, and Pyranha I3 are some that come to mind.
There are very few true displacement hull boats being made these days. Dagger RPM, Liquid Logic Gus, and Prijon Athlete are probably the best matches that come to mind (but all of these have at least some planing hull aspects to them).
What are the advantages/disadvantages of both?
Planing hull pros
- easy to turn
- sharp chines allow the boat to carve quickly into and out of eddies
- lots of primary stability (depending on the boat of course)
- length and shape let you catch small eddies and give you a number of options if you wind up in a hole
Planing hull cons
- slow
- chines can catch and flip you (more or less so, depending on the specific boat)
- not so good at punching holes
- hard landings off vertical drops
- not much room for gear
Displacement pros
- fast
- holds a line well
- less likely to get tripped by rocks or cross currents
Displacement cons
- harder to turn
- less primary stability
- length and shape give fewer options in holes and won't let you catch as small an eddy
The big shift happened in the last 5 to 10 years.
Displacement hulls these days are found mostly on boats designed for slalom racing and steep creeks, both of which are extreme forms of river running. And even those boats incorporate some aspects of the planing hull--sharp chines for carving turns, flat or semi-flat bottoms, etc.
Displacement hulls also are often the choice of safety boaters who work for rafting companies. Their speed makes it easier to reach a customer who gets ejected out of a raft, and their length and volume makes it easier to let a victim hang onto your stern grab loop. Of course, most of these boaters will jump into a playboat when they're not 'on the clock'...
older kayaks
Interesting discussion - I’ve wondered this myself, but haven’t had the opportunity to try different style boats to really experience the difference. I have an RPM (billed as displacement) that I bought (used) to learn to roll and in the hopes of taking a ww class in the next year. So far I have only paddled class I and II rivers in a rec kayak or a canoe. There are sometimes fun playspots where I’d like to have the RPM, but can’t imagine wanting to paddle all the flatwater in the RPM for the occasional playspot, which made me wonder about the old school kayaks which I’m guessing would be longer and faster in the flatwater sections, and perhaps more comfortable to paddle on flatwater (?). I know someone has a Perception Dancer and a Hydra Mustang and Hydra Taurus for sale. I ultimately decided I shouldn’t be looking for any more boats right now, but I’d be interested in anyone’s thoughts about those older boats.
The Hydra Mustang was patterned after
an Idaho composite boat of the same name, but the hull didn’t come out as sharp in plastic. The original was an excellent boat for its time, flattened arch, kind of chiney, fast but capable of skating back and forth across waves better than many boats of the time. The Dancer is often maligned now, but it was shorter, more maneuverable… it was just too tubular to be a real handler. The Dancer XT (one of which I owned) was kind of v-bottomed, and did not handle well. I replaced it with a Corsica, which was a tremendous improvement. About the Hydra Taurus there is nothing worth saying.
Remember that just as there is no anti-gravity drive, there are no true planing kayaks. There are kayaks which plane UNDER CERTAIN CONDITIONS, and otherwise are just flat-bottomed displacement hulls. “Planing” hulls handle well (at least some of them handle well; some have been awful) because they are short, and the sides, ends, and bottom are carefully designed. If designers put as much thought into modern displacement hulls, there could be some real gains. Of course, in a way they do… when they design boats for creeking or big, heavy water.
I had a Redline
which is a tad smaller than your RPM. A great boat to learn to roll ( I could hand roll one in quiet water easily) and far more comfortable for the flat water piece than my current ride, a Phyrana I:3,which is a planing hull.
I would avoid older boats like the Dancer simply because the newer boats, even older “new” boats like the RPM, etc are so much better for playing, river running and learning.
what I have found so far…
I have a Dagger AQII which is an older displacement style hull.
So far I have found this boat to be fast, stable, easy to paddle straight, and great at punching through about anything. I like this as a new WW paddler. I guess it could be easier to catch eddies. The turning is okay, but I don’t know how much easier the planing hulls are but having decent paddling skills from flatwater makes this boat easy enough to turn for me at least. I do catch my edges a bit though, and I really hate that, but I guess it might be worse with a planing hull. I also find this boat super easy to roll.
Matt
thanks for replies…
Especially the one to stick with my RPM since I shouldn’t be buying any other boats anyway! (No more space in the “boat” barn, and not really any money in the budget either). I took one pool session lesson to roll, but haven’t quite gotten it yet, but mostly because I haven’t found/made time to practice enough. I can get it with a slightly inflated paddle float, which has greatly helped me clear up the problems I had during the pool session (mainly loosening my grip and watching the blade instead of the bow). I just need to get back out there and practice some more. The ww class I want to take says they’ll do a bit more with the students if they already can roll, so I’m hoping to have a semi-reliable roll by spring when I want to take the class. I’m really more of a sea kayaker on the lakes around here and a canoer on the rivers, but man, there’s nothing like going through the waves in a yak, so I’ve got to try ww kayaking at least a little bit!