Help to fill small hole in bathroom sink

[Adrianlle]

Greetings from the U.K. On our recent trip my wife dropped something heavy into the bathroom sink of our 2004 yellow trim Cook. It is brittle and she made a small hole about the size of a large screw head. I would like to repair it so that the repair is as discrete as possible. Sikaflex would work but would not give the smooth shiny finish like the rest of the sink. Can anybody please suggest a product that might work to be waterproof and has a finish like the white sink plastic? I wondered if there was anything used on boats to repair the white plastic found there. Thank you. Adrian