They make liquid bilge cleaners for just this purpose. Biodegradable liquid. Pour some in the bilige, add some water, drive around a while and then pump it out. They work great. I've also used Simple Green in the same maner with good results. See link http://www.iboats.com/Bilge_Cleaner/...view_id.342304
Well I'll tell ya what worked great for me while I was killing ants(differant thread). Mr Clean (orange) cleaner, while I was killing the ants I was like Hmm hate to waste the bucket full, so I cleaned under all the seat cushions(bow) the PFD storage(cooler) and the bilge compartment and both side compartments on either side of engine and it worked great for me!! I am not saying, thats what works best, Only I was very happy with the results and my boat smelled like oranges for a week, Oh origanly was looking to use something that was pet safe and these guys right here on Iboats recommended orange cleaner, Thats why I used it Boat was sqeaky clean!!