Sometimes it takes acid to clean the hull,it too will have to be stronger to clean.Care should be taken as to not let it drip on concrete,check with your local boat dealer,they will have a acid mix or use H. acid or M.acid.Also tarp the trailer under the boat when useing stronger acids,most boat trailers have a poorer Qkly paint and the acid will fade it a little if not covered.
Nomatter where you wash these boats please do not let your run off spoil my fishing nomatter what kind of chemical you use.