Friday, April 07, 2006

To sit or not to sit - part 2

I'm just a kid and life is a nightmare
I'm just a kid, I know that its not fair
Nobody cares, cause
I'm alone and the world is
Having more fun than me
Lyrics, Simple Plan: I am just a kid - 2002

I started writing this post post yesterday evening. I wanted to write a follow up on the earlier post "to sit or not to sit" about my experiments with the seating position in the Svalbard kayak. But that was before my son Jelle returned from is his first danceparty at school. He had been looking forward to that party, but he was also very nervous about it. The first time dancing with a girl: that's heavy stuff for a 11 year old boy. I hoped he would have a great time, but alas: he came back quit disappointed. He didn't dare to dance. Such a pity! After Jelle went to bed I wasn't in the mood for continuing this post. And as a matter of fact I am still not. We had a family day today and Jelle got a lot of distraction. Today he went to bed happy again. But to me it's getting clear that a new period appears: "adolescence" with the worries of a teenage kid...

A few words to kayaking though. Some time ago I had a little discussion with Wenley about sitting high or low in a sea kayak. Wenley was thinking about replacing a kayak seat because he found it to high. I mentioned that I prefer a somewhat higher seating position. Wenley challenged me to say something about the mechanics of a high kayak seat.
From a mechanical point of view I admit it's simple: a lower seat brings the center of gravity down, which results in more stability and which should also be an advantage in bracing and rolling. That's one reason why many people replace their fiberglass seat for a lower foam seat. In the early 80's this was the way I was learned to paddle a flat water racingkayak (K1). Pupils that made the step from a training-kayak to a racing-kayak first paddled the very tipsy K1 without a seat with a simple pillow on the bottom of the hull.
But the "ergonomics" is another (and far more complicated) aspect of the sitting position in your kayak. Bringing the seat height higher can make it easier to have good contact with your knees and thighs to the deck of your kayak. It can also make it easier to lean backwards on the deck. With my Svalbard I was surprised by the difference only 2 extra cm's of height make. The better boat-contact and greater freedom of movement made rolling and bracing more relaxed. I also got the impression that the higher seating position invites to a more aggressive and effective high-angle forward stroke. Of course this is very personal and depends strongly on the design of your kayak and your corpus dimensions. But I think it's worth an experiment: lower is not always better ;-)


Susanne said...

For Jelle: maak je geen zorgen: er komen nog heel veel feestjes. Zullen we een keer oefenen?


René van der Zwan said...

Hello Hans,

I agree with you it is better not to lower a seat too much and keep the seat at the original higth. Partly because the paddler can get lazy and not forced to learn on improving stability. On the other hand: you are rigth in telling that a lower position is NOT an advantage for your paddling style. Apart from that: it is more difficult to replace the original, higher seat once you are "grown" in mastering the stability of your kayak and don´t need the low seat any more. I also believe that the boatcontact at the hips is better with a polyester seat because it is more solid. When you "work with the hips" in controlling the kayak, a foam seat is easier deformed because of the force you apply and because of that, your "hip-commands" come through a little delayed.

A higher position leads indeed to a better high-angle paddlestroke which can be more effective than a lower one.
The boatcontact will ofcourse also change by lowering the seat , but it depends on the heigth of the foredeck and of the persons physics if a higher seat is an advantage or disadvantage. F.i. a very big person can gain something in boat-contact by lowering the seat. On he other hand you can say that if that is the case the kayak is too small for that person and it could be better if he/she starts looking for a better fitting kajak. Besides that this bigger person is probably that long that he is still high enough above the waterlevel to make an effective paddlestroke possible.

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