I'd be inclined to try some bleach on it Mark, that stuff is cheap as chips and will eat through the 'er leftovers. But you do need to be very careful with it, particularly if you use a spray applicator, rubber gloves, face protection and overalls. Keep it off your skin, and be sure not to let the bleach drip onto anything other than the bilge plastics as it will leave bleached marks. It should remove any crud from under the bottom edges of any woodwork, but it will mark the sides of woodwork if you aren't very careful indeed. Bleach can be purchased from any supermarket, but do take care with it.