Friday, 2 March 2012

Fridays from the Vault - If the Boat Fits, Wear It….

Probably the most commented on blog post we've written was Rob's contribution on the importance of boat fit. It continues to be read widely & we get emails from parts far-flung asking advice on paddler weight with relevance to boat design & performance.
The blog is reproduced below from Rob's Balanced Boater blog, where it was first posted in September 2009:

If the Boat Fits, Wear It
Imagine walking into a specialist outdoor store looking for walking boots and finding there are only two sizes. Then imagine asking why there are only size 9 and 13 and being told that these sizes fit "most people"(read large males). Finally imagine the helpful store person explaining to your smaller companion with size 5 feet that the size 9 is is perfect for her as long as she is willing to wear enough socks.
I think kayaks and shoes have a lot in common and no amount of closed cell foam and wishful thinking will make a small paddler feel connected in a medium to large boat any more than a dozen pairs of socks will make big shoes fit smaller feet.
A few years ago there really was no choice in Australia for smaller paddlers but to follow the "wear more socks" principle. With very few imports and a small market it made economic sense to build kayaks that suited the male dominated sport: i.e. expedition ready boats that performed adequately for medium to large men when empty. Unfortunately because everyone smaller than this would fit into these larger craft, it was assumed the boats fitted them.
Trying a boat for size:
  • It is possible to have too much stability. It is tiring to edge, maneuver and brace an oversize boat, particularly if there is so much initial stability that it prevents you from heeling the kayak easily and precisely. A wide boat that responds well for a heavier paddler with a high centre of gravity may simply simply feel like a barge to individuals shorter and lighter in the torso.
  • The Hip Test: When the boat is tilted the coaming and deck should not interfere with elbows or ribs. If you want to edge and roll the kayak you need to wear it so that the coaming is approximately aligned with the top of the hips.
  • Longer isn't always faster: Although a longer waterline equals higher potential speed this potential is only realised if you can produce enough power to overcome the drag generated by the extra wetted area. A scaled down boat may be a little shorter but the reduced waterline beam and wetted area will often more than offset reduced waterline length.
  • Weight: All other factors being equal, the lower volume (LV) boat will be lighter than standard or HV equivalents. Lighter boats accelerate faster on the water and are easier to handle off the water.
  • Beam: A reduced beam and height amidships allows shorter legs to engage the deck without straining into a very wide ''frog position". A narrower foredeck also allows a closer catch without overreaching, making it easier to roll as well as paddle.
  • Bulkheads: A scaled down cockpit area and closer spacing of bulkheads reduces the floodable area in the cockpit, and makes the boat easier to manage if it is swamped and easier to empty if it is capsized.
About 10 years ago with all this in mind and a complete lack of local options my wife, Sharon,
made her own plywood kayak: a ''Baidarka" built from plans that had been scaled down to give her a boat that would provide the same proportional fit as the larger composite craft that I had always found easy to paddle. Her boat control skills improved dramatically and she handled the challenging maiden voyage from Sydney to Jervis Bay in challenging conditions with new found confidence. These days there are options in the low volume market. Her regular kayak is an Impex Force 3 and she has her eye on an Avocet LV to add to the fleet in the future.
As sea kayakers have become more aware of the connection between boat fit and performance the number of LV models has steadily grown and new LV paddlers seem to be vindicating this move by learning faster and paddling better than ever before.
A spin off from the "Low Volume Revolution" has been the number of medium sized paddlers who have found these general purpose LV tourers make excellent play-boats. But, if you usually paddle a standard kayak don't expect any offers for a test paddle from the LV crew. They will be too busy ''getting amongst it" and won't happily sit on the beach watching you have all the fun.

4 comments:

  1. Very good article. I'm constantly amazed at paddlers who are my size or smaller and who are not strong paddlers who move or want to move into bigger boats. I just don't get it. They want an "expedition" boat that can carry all this extra stuff, then they go away and what they like to do when they get there is rock garden. Well the big boats are just not as good at this. They think the bigger boat is going to be faster. Well developing a good paddle technique is going to provide a much greater increase in speed than getting a bigger boat. Often a bigger boat is just going to make them tired sooner, resulting in more down paddle time and a slower pace.

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  2. Very interesting write up..I totally agree with Greg, but i have a question..From what i read narrow beam boats with low deck provide good handling characteristics. Is this a dowwnside regarding paddlers comfort? And also is there a tendancy to the manufacturers to produce more and more smaller dimension kayaks? Τhanx in advance..

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  3. Clever designers have busted many myths about sea kayak design and how certain set of design principles should' perform. The deck is of far less importance to the hull, although a constricting foredeck can restrict some modern concepts of leg drive and rotation. Manufacturers like Rockpool and Zegul are greatly improving cockpit ergonomics to accommodate lower boat volume but better rotation. As an example I can roll the Zegul 520 every bit as well as the Greenland T because it keeps the low volume aspects that make a good rolling boat, but ditches the 'straight legs' Greenland-style ergonomics.
    In short, the sort of generalizations that used to be thrown around as golden rules with regard to sea kayaks have been successfully turned on their heads in recent years.

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  4. This re-posted article popped up the same day i was discussing boat connection with a friend.
    I'm a fat bloke, but of average height and build, so i figure that the boat designers (being way smarter than me) worked on where you should be in the cockpit and build the boat accordingly.
    In the past i related skill/technique shortcomings to the fit of the boat/size of the boat and customised the cockpit with foam backing, low foam seat etc... whilst i had better 'initial' stability, connection to the boat sucked and it was a chore to turn, edge and roll. I'm clearly too low in the boat (hips aren't near the coaming).

    So my weekend was spent ripping stuff out in order to return the boat to almost factory spec.

    Good article and timing for me!

    Thanks!

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