Hi Graham. You know how a conibear sits when it is set? On the bottem, there is about a 1" gap between the jaws (depending on how you set it). So if you put two nails against one set jaw (inside), and another in the middle on the opposite one, the set trap will be strongly anchored in place.......upright.
If done right, the 110 will be submerged by about a third, and set about 16-18" back from the middle board with the apple on it that is ABOVE the water. The set encourages the 'rats to just easily swim into either end of the raft and through the conibear. Just make sure to anchor it so it doesn't drift into the sides.
Although I haven't tried it, but if you set this in a good enough area and use meat instead of fruit, and footholds instead of conibears, there could be a good chance that you would nail a few mink or the odd otter if you're lucky.
There's a ton of tricks for 'rats and they all work good, but this little raft setup always produced for me, and when the season is over, just chuck 'em in the bushes and use 'em again next year. Cheap and easy.
Another goofy little trick I used to do for 'coons was to anchor a #1 1/2 Victor coilspring in about 4" of water at the edge of a creek or pond. Drop a bit of lure and make sure that the pan was covered in shiney aluminum foil. Curoisity gets them quite often.
Good luck guys and keep us updated on your adventures!
Tree