Picked up one of these off the net 2nd hand for only £100. Unfortunately my boat's chart table is ¼" too narrow to take it but I never could resist a bargain.
They will probably tell you not to do it, but I did and I was told by somebody else, you can check, when you take the puck to the edge, the signal is lost before the centre of the puck, or infact the side is at the edge, get somebody with one wired up to show you. But I know it can be done, mine works fine. Use really good scissors, or go to a place with one of those guillotine jobbies!
That's right, I remember now, its ages since I used one. The signal is lost before the Puck gets anywhere near the edge.
Mind you, shaving some off will mean the Puck is held even further away from the edge due to the fiddle which is around the chart table.
As an ex-Yeomanite I can confirm that you will be able to trim a wee bit off the edges without buggering it up.
However, the wires extend beyond the working limit of the puck thing so only take off what you need.
Before you do that though, is there room to mount it underneath the chart table? The Yeoman will work through up to about 25mm of GRP or wood, and you can recalibrate the thing to cope with being back to front and upside down compared to mounting it on top of the chart table. All you then need to do is come up with a way of holding the charts still once you have referenced them.
We've got a yeoman plotter, actually we've got 2. The one now is sporty but the old one never fitted on our table so we got a pasting table which not only worked as a table but as a carry case for the plotter and charts. Because the pasting table was pretty ugly I then made a yeoman case for it as a warm-up for my GCSE textiles project. The case now has the sporty one in it and looks beautiful on our chart table.