Anyone still in need of Christmas ideas for their sea kayaking partner, I would definitely recommend Howard Jeffs Sea Kayak Navigation Aid or SKANA. At around £15 plus postage these are available direct from Howard Jeffs at http://www.howardjeffs.com. They are big enough to measure distances and yet being flexible they are able to be kept on the sea kayakers chart table on their spray or fore deck. It comes with a handy lanyard to help prevent its loss.
The plotter can be used on both OS and Marine charts to take a bearing, measure distance and speed, and on OS maps (1:50,000) obtain a grid reference.Here I am using the plotter string to take a bearing from Ganavan sands to the Lismore lighthouse. I've simply aligned the plotter to the map and taken the plotter sting to the Lighthouse. The bearing can then be read off and magnetic variation added as required. The plotter string can also be used to measure straight line distance as well as say an indented coastline. Being flexible it can also be used with some gaffer tape as a repair patch to your boat.
An excellent piece of kit.
To buy one, contact Howard Jeffs through his website.