Boat Building Forum

Find advice on all aspects of building your own kayak, canoe or any lightweight boats

Re: Other: On measuring rocker
By:Pete Roszyk
Date: 12/6/2003, 11:41 am
In Response To: Other: On measuring rocker (Mike Scarborough)

: It's a slow day here with the snow coming down outside so I thought I'd pose
: this question. Can the BBS community come up with a standardized way to
: measure rocker? A method that is quick and easy and repeatable so that we
: can all talk about rocker and be describing the same attribute of a kayak.

Hi there, Mike.

When this question was posed a couple of years ago, it became clear there is no real quantifiable standard in use.

The best response that I can still remember applies at least to kayaks with more-or-less straight stems:

If one extends the line of each stem to intersect where another straight line coming off the keel line would extend to, then that is the point from which to measure for rocker.

That is, if the bow (for example) were NOT rounded off on the lower corner, where the stem/keel intersection WOULD be, then that is the measuring point.

This came up when I was assembling a CLC boat. The plans indicated that there was a rocker to the keel, but the manual didn't say how much or how to get there. When I e-mailed CLC to ask, the answer was unclear and uncertain, so I ended up making up my own number.

Good luck: this is what I now call a 'fuzzy' number, but it is truly important. The folks at Pygmy built a couple of prototypes for their Coho. One, which I did paddle for a while, had an inch or so more rocker than the eventual production kit. I found it much easier to turn, but the Pygmy folks said that there had been more negative comments on that prototype's handling in the wind. I liked it, though, and usually add just a bit more rocker to the ones I build.

Cheers,

Pete Roszyk,
in Snohomish

Messages In This Thread

Other: On measuring rocker
Mike Scarborough -- 12/6/2003, 10:41 am
Re: Other: On measuring rocker
Jay Doorly -- 12/10/2003, 3:10 am
beautiful mystery
Water Pixie -- 12/10/2003, 4:08 am
Re: Other: On measuring rocker
Jay Doorly -- 12/7/2003, 1:25 am
rocking rockers
mike allen -- 12/7/2003, 2:26 am
Re: Other: On measuring rocker
ChrisO -- 12/6/2003, 2:46 pm
Re: Other: On measuring rocker
Roger Turgeon -- 12/6/2003, 5:21 pm
Re: Other: On measuring rocker
Nick Schade - Guillemot K, ats -- 12/7/2003, 9:07 am
Re: Other: On measuring rocker
mike allen -- 12/8/2003, 3:12 pm
Re: Other: On measuring rocker
Tom Yost -- 12/6/2003, 6:32 pm
Re: Other: On measuring rocker
Pete Roszyk -- 12/6/2003, 11:41 am
Re: Other: On measuring rocker
LeeG -- 12/8/2003, 3:54 pm