I have shipped a couple of old woodworking machines, but not a kayak. If it were me, I would be crating a kayak. They are notorious for damage, some more so than others. So I would want it is a good sturdy wood box. They move everything by forklift so make it fork lift friendly.

I would check with someone like http://www.freightcenter.com/ I can not remember who I used last time but I got a very good rate and service. Of course you can check straight with the Truck lines too. I found it much cheaper to drop it off and pick up the terminal too.

Hope that helps and let us know what you find out.