If you don't think you can make this use a plastic ship and make your waves out of crusty butter cream on wax paper and let it dry over night and then place it on the cake the next day. Falon this would be a dream for calebs pirate party!
Vanilla White Cake with Ombre Swiss Meringue Buttercream
C-motion - This is a great technique to use as waves on water or for beach scene cakes! For water, use blue colored icing — or try a two-toned wave look using blue and white icing in the dame decorating bag or stripe the decorating bag with icing color.