# Kayak Design: Stern



## burnor (May 13, 2010)

So while I feel like I have a good understanding of most aspects and logic behind design of creek/river running boats... there's one question I still have?

What is the current thinking and logic behind stern designs (specifically deck design). I have paddled many a design and have noted some patterns... for instance liquid logic tends to have flat stern decks or even scooped in the remix. Meanwhile dagger's nomad and done of the Jackson's make a peaked back deck. I've made my own subjective conclusions about them...

While I know this may seem a trivial... I'm really curious if those in the industry could clarify the theory, logic, or testing behind stern designs for specific purposes.

-Thanks


----------



## Roy (Oct 30, 2003)

Not trivial at all! Those older, longer, flatter sterns are designed to back ender you into the hole you just cleared. I want my creeker stern to be peaked to shed water with tons of volume. Basically, it should look like a pregnant ant's butt to spit me out of the hole like a watermelon seed!


----------



## glenn (May 13, 2009)

The stomper and jefe shed water through drainage channels rather than off the sides like a peaked stern. Pyrahna does the same thing. The remix is an exception. I'd wager the stomper has comperable volume to The Nomad or Villian in the stern just shaped differently.


----------



## paulk (Apr 24, 2006)

This has more to do with the hull but interesting article on designing the stinger and why they chose to change it through the years Shaneslogic a kayak blog


----------



## KSC (Oct 22, 2003)

It's a good question. I'd love to hear more designer info on their design choices. It seems like there's been a fairly obvious trend over the years to add a lot more volume to the stern to prevent the dreaded back ender and provide some way of shedding water to that same end whether it be channels, a peaked deck, or both.

Even though it's obviously also a bit of propaganda and I wish it were more technical, I liked this EJ video where he went through and highlighted the design considerations that went into the Karma and their respective purpose. Wrt to the stern, he notes adding lots of volume and increasing the width.

Good Karma- Can’t Live Without It! - Jackson Kayak - Whitewater Kayaks, Fishing Kayaks, Recreational Kayaks Jackson Kayak – Whitewater Kayaks, Fishing Kayaks, Recreational Kayaks


----------



## Don (Oct 16, 2003)

*Stern shape*

Good question.

A few things come into play when looking at a stern: volume, length overall, distance from cockpit, shape, surface area, and top deck shape (concave to convex). 

Kayaks basically have two top shapes: symmetrical or swedenform. The symmetrical shape has the cockpit located in the center of the boat, creating a shape that has similar length in the bow and the stern. Swedenform kayaks have their cockpit location more toward the stern, and to balance the volume a shorter wider shape is necessary. Creekers tend to be more swedenform and most river runners are symmetrical for added balance and tracking (except slalom and Wildwater race kayaks –swedenform need for speed)

Volume in the stern will increase or decrease how high the boat sits in regards to the waters surface. High volume boats stay and want to stay on the surface, while a slicy flatter stern can cut right through the water. A creek boat has the higher volume to stay safely on the surface. While a river runner can do fun things with that flatter added stern length (pivot turns, stern squirts, blast surfing, and stalls).

The more peak to the top deck = the quicker water will shed. A boat like the JK Karma rises quick to it’s top surface, other companies like LL uses deck drains to help the paddler predict which direction their boat will release, and my Murky Water Ninja has a top deck that grabs water and pushes me toward the bottom of the river. Shape matters.


----------



## BrianK (Feb 3, 2005)

So how do these differences apply to the remix. That is a fast boat, does the scooped stern help with the speed?


----------



## Talleyho (Oct 24, 2013)

*Remix design, specifically*



BrianK said:


> So how do these differences apply to the remix. That is a fast boat, does the scooped stern help with the speed?


I understand the negative sentiment associated with the Remix. However, the stern is designed to kick you out of holes and use the scoop as a platform for water to push. If you're getting stern squirted, scoot the seat up or lean forward more. In theory, I suppose it would act like the stinger and drop into the water when getting faster, but that's just an addition and not initial goal. It really does help when going fast and I've felt the stern get pushed out quite a bit. 

However, I don't paddle a Remix anymore, and I've noticed my Nomad doesn't react the same way my Remix did (sometimes I wish it did). 

Another thing you can notice is when running rapids in a more 'stern-heavy' volume distribution. It will become much more stable if you were to lean back. Almost a 'this could save you' mentality. 

Remix is fast, and the scoop helps in choppy water. Remember, drive it like you stole it.


----------



## jmack (Jun 3, 2004)

I do not think the scoop on the Remix makes any difference in speed because it is not usually in the water. The Remix is fast because it is relatively long and narrow compared to most creekers.

I have paddled both the Stomper and the Remix quite a bit lately and you can definitely feel the scoop when water loads up on the stern. It really pops the boat forward in moderate sized holes. It can also ender you all the way back into a really big hole. Keep in mind that the Remix was designed as an instructional/beginner boat 10 years ago. It just happens to work well in Class V for certain paddlers.

The trend is definitely toward most volume in the stern in creek boats. It can keep you on top of the water, prevent being backendered into a hole, and really does not have much downside.


----------



## burnor (May 13, 2010)

Thanks for the post Don... helpful.

I started thinking about all this as I have been paddling a Stomper lately and while I think it's a great boat (there is no perfect boat), I do some real shallow creeking with it... I found that if I at all broach rocks the stomper gets stern endered to high heaven. I borrowed a Nomad when I was in the South East and was quite impressed at how predictable and less touchy the stern felt. My old habitat also seemed a little more stable in this sense. The remix has done the same thing for me, however the increased length makes it feel like the stern is easier to get on top of (getting really forward)?

To avoid a bunch of heckling...I am in no way endorsing one boat over another, but I figured there might be reasons I wasn't aware of that LL makes such flat stern decks comparatively

~B


----------



## leif (Jul 11, 2009)

There's a whole other dimension here (literally). In some situations the stern deck can affect how you turn. Even if you're not doing a full on elevated pivot turn like you would in a slalom boat, a higher (non scooped) stern had a larger vertical cross section. When you take that enormous sweep stroke, you have to blast that stern through some water, usually. The scooped stern makes those corrections easier, making the boat feel easier to paddle.


----------



## barry (May 6, 2004)

Even though it was a piece of shit, gave me chronic back problems, and barely held together one season I miss my old New Wave cruise control. Although it didn't do anything particularly well by the standard we enjoy now; the lack of symmetry in the volume of that boat had some benefits. My experience was that it was very well suited for just straight on forward facing big wave surfing. I don't know this as a fact but, it seemed that when Chuck Kern died it had an effect on stern design toward a more bulbous or higher volume shape.


----------



## Don (Oct 16, 2003)

*Hulls*

Speed is more relative to the length of a kayak than the shape of the top deck. A longer boat is faster- Fact. The Stinger is a long boat, and I want to paddle one badly. I want to feel that fast again. I've paddled Wildwater boats and while very fast, I found it to be more challange than reward. 

Josh is right with what he said. The Remix is fast until it gets weighted down and that has more to do with what is hitting it. The bottom hull, the part reacting mostly with the water, is fast. 

Leif was right too. A stern that can slice through the water will turn the boat quicker during certain movements. 

The Remix is fast for its length and width. Long boats are quicker than short boats, but skinny kayaks are fast. They have less down current drag and resistance.


----------



## Don (Oct 16, 2003)

*What?*

"I don't know this as a fact but, it seemed that when Chuck Kern died it had an effect on stern design toward a more bulbous or higher volume shape."

The Cruise Control is a great boat, but I perfer the Sleek. It stern squirts way better. 

The Cruise Control was a river runner and surf kayak. While the Mongoose was New Wave's creek boat of the day. There was a different choice from other companies too. Lot's of really skilled paddlers have historically paddled harder to paddle kayaks down hard whitewater, just to make things more challanging. It was a way of pushing the needle. 

I don't know what Chuck was paddling when he died, but I don't think it has much to do with the topic. Because Chuck died paddling the portage section in the Black Canyon, no where anyone should be paddling a play kayak.


----------



## barry (May 6, 2004)

I don't recall what boat Chuck was in either. May have been a squirt boat. I suffer from loosening of associations when impaired. Most of my posts vary in relevance to the OP...especially the ones made after about 4:22 in the afternoon. It was a long time ago but, I recall talking boat design with Chan Z when I picked up a replacement boat for my destroyed Cruise Control. Remember Chan? 100mph w/ hair on fire talking about reinforced grab loops, displacement hulls, ergonomics, and getting rid of "ram caps"..."fuck the ram caps" he would say.


----------



## Kyle K (Dec 17, 2008)

*Stern volume and draft*

I agree with everything Don says except one small quible (please note that I think Don is very knowledgable about boats and paddling and I almost always defer to his extensive knowledge and skills).

The volume in the stern does not effect how high the boat floats in the water (draft). That is determined by the displacement of the boat, which is the weight of the boat (including paddler and gear) in relation to the surface area and shape that sits in the water. The boat could be 4" tall or 4' tall, and could have 50 or 500 gallons of air in it and, as long as all other things were equal, it will have the same draft. 

Where volume comes into play is when force (water = weight = force) is placed on the deck, thereby increasing the downward pressure. The more volume (trapped air), the more resistance to being pushed under the water. The shape of the deck (peaked, flat, concave) then determines how the downward flowing water sheds off the deck.

To summarize, the deck volume and shape only come into play when there is force placed on them from above their natural water line. This can occur from water falling on the deck (ex: the curtain of a pourover) or a weight shift in the boat (ex: the bow being lifted as the kayak climbs the backwash of the hole, or the paddler going into the dreaded "back seat" position).

As noted by other posters, both designs, bulbous (Nomad) or shallow (Remix), have benefits and drawbacks. Pick the appropriate boat for how you tend to paddle. Hope this was helpful.


----------

