Wednesday, September 26, 2012

Kayak Hull Design – Hard and Soft Chines – VCP vs. NDK


Thought I’d post an email I sent to a kayaking friend who’s looking to buy a new boat. I’ve owned a number of kayaks over the years and had the opportunity to paddle a good many others when working for AKT. These are just my observations – I’m a fan of a lot of kayak styles so this isn’t an argument for any one type over another:

“Good luck in Boston and when you get around to trying the Chatham 17 let me know what you think. I thought it was bigger volume and more straight running (less rocker) than I wanted when I paddled it 4-5 years ago – but I’d recently come from the Pintail aka “Pin-wheel” which is very low volume and low directional stability, so any boat would feel like a big change after that.

You mentioned the Nordkapp, which is actually a great rough water boat, and excellent at paddling straight distances in rough water. But it wouldn’t be my first choice for a “carving, surfing, edging style” of kayak for rough water, if you know what I mean. To elaborate - the Pintail and Nordkapp both have a softer chine and decent rocker (especially the Pintail and Nordkapp LV). Because of this, they have a wonderful feel in rough water – they feel very stable as the water gets chaotic because they have the rounded, soft chine design. Despite their somewhat reduced initial stability or “twitchiness” in flat water (as compared to the NDK-style boats), they become more secure to the paddler in jumbly water in part because they lack the chine.

However, when it comes to surfing in following seas, or catching waves, or putting out an aggressive edge to carve a turn – the NDK-style boats (like Chatham, Romany, Tiderace, Impex Force, etc.) are good at that because of their harder chine and flatter hull in the mid-section. These NDK-style boats have hulls that grab the water with their chine (hence they carve turns when edged) and also get “stiffer”, i.e. more secure, as you edge them. As the chine is depressed into the water when you edge, the portion of the hull’s displacement volume contained in the chine resists (pushes back) as it is submerged, thereby giving more resistance to the paddler (something about righting-moment or center of mass vs. buoyancy – check a kayak book for that). It’s all relative of course and boat width is a huge factor. But with the exception of the super narrow Greenland boats, I find that the chiney boats add support as you edge them.

By contrast, the Pintail is easy to edge and it just keeps getting easier and easier the more you edge with little resistance until it capsizes! In fact, VCP gave the Pintail more width than its sister boat the Anas Acuta specifically because it lacked a chine and needed more width to have adequate stability. So that’s what people mean when they talk about the “tenderness” or “twitchiness” of the Pintail or Nordkapp. They seem not to resist edging as much. With no chine, the act of edging doesn’t submerge much hull volume down into the water because there is no chine to submerge. BUT one can sit incredibly securely in jumbly water (clapotis) in the Pintail, noticeably more so than in the NDK boats in my opinion, because the round, chine-less hull just “gives” easily when buffeted by incoming waves hitting it in various directions. Pintail and Nordkapp feel very stable paddling through rough water or sitting in rough water. In that sense, they are very fun to mess around in rough water – but are not as good at carving and surfing.


Hope that makes sense – seems counter intuitive I know. Sorry for the long diatribe. I enjoyed writing it. Lastly, the Nordkapp LV is really a new boat, different from the classic Nordkapp – it’s somewhere in between a Pintail and Nordkapp. I thought it felt like a faster, looser Avocet. So it’s fun and fast and would be a good play boat that can also go distances if you need it to. (If you can fit under the deck that is – try it if there’s one around – although I absolutely loved the feel of the Nordkapp LV when I first tried it, when they switched to their plastic seat I found it too tight for my legs). In some respects, you might find a boat like the Avocet or Pintail most "forgiving" in rough water simply because these boats have less volume above the waterline and so less boat for wind/waves to affect. (That's my personal bias, I like smaller boats). All that aside, from what you’ve told me about how you like the Explorer, I think the Chatham 17 is probably a better boat for your needs overall than these lower volume VCP boats. Who knows, coming from your non-rockered and long-length Epic 18 you might find the Chatham 17 small!”



JIM

Solo Kayak Loading in High Wind – with the Yakima Boat Loader

When solo-loading my kayaks onto my car,  they've been blown off the roof by intense winds on two (2) occasions, once long ago and once more recently. And I’ve had a few close calls over the years too – usually prevented by soliciting the help of a nearby stranger. Yes, I am capable of learning from past mistakes, but evidently it takes me awhile to change my behavior. When the wind catches the boat, it can be a total nightmare - potential damage to the boat, the car, and my aging joints as I’ve tried desperately to stop the inevitable catastrophe unfolding before my eyes. Thankfully, thus far I’ve had no major damage that some epoxy/gelcoat can’t fix and no damage to other people’s property. So now these days when it’s very windy, I’ve been following a set procedure to prevent the boat from flying off as described below.

I’ve used the Yakima Boat Loader (photo below) for many years now, to help lift the kayak in two steps. It was the first load-assist device offered by Yakima and is simply an extra bar that sticks out from the front rack crossbar. It works fine – I’ve padded the bar with some $2 foam pipe insulation from Home Depot and I usually stick something under the stern (a rag or pfd) when I lift so asphalt doesn’t grind away at my fiberglass boat too much.

But like all other solo lift-assist “tools” (with the exception of Thule’s Hullavator which secures the boat before it’s lifted), using the Yakima Boat Loader leaves the boat in a vulnerable, unsecured position subject to the forces of the wind until you strap it down.

To prevent the boat from flying off the roof on very windy days, I now lift the bow onto the Yakima Boat Loader bar and secure it loosely with the front cradle’s webbing strap (see my sketch). This stops the boat from being blown off the bar during the next step. To be doubly safe that the boat doesn’t slide off forwards through the webbing loop, I also attach a short bungee cord with hooks from a deck line to the roof rack. Next, I lift the stern up into the rear cradle and secure the rear cradle strap while holding the boat against the wind (with my car, I stand on my rear tire and can do this entire step without removing my hands from the boat). Once this is complete, I can then take my time moving the bow over into the front cradle and then synch the front cradle strap tight. This method takes very little extra time and can be a life saver.

This description may seem like a no-brainer. I post it here for others to read in the off-chance it saves someone a real headache. If you have a better method, please comment – thanks.