Guns are too noisy, just an oar and some conch shells is all you need aboard a boat - perhaps a crossbow as well. Once you dispatch your first "anchor rode climbing" zombie, simply tie him off and use him/her as the anchor. The others will walk past the dead zombie that is safely holding you securely. Now if you do drag through coral then you'll need another zombie, maybe a few!
1971 23' Oday Pop Top
You can't steer a boat that isn't moving? Just like a life - P. Lutus