I recently did a wash while the boat was ashore with assistance from various brushes , a mop and microfibre cloths .
I also used some Demon Foam mixed with plenty of water which worked very well at dissolving muck from being ashore near trees . Brushing into the slip resistant surfaces was necessary but the foam had done it work and the dirt lifted easily.
Some folks may worry about the foam in the aquatic environment in which case the cleaning product may be used sparingly.
If you use a jet wash then be prepared to clean the adjacent boats in the marina of all the muck that you may blast onto them.