I am relatively sure you don't need one, but I could be wrong.. I have been without one since the rebuild. When you get to a 20' boat hp is unlimited or so I have been told. LOL.. Not a bad idea to stay within rated capacity but we had 10 people and a dog on the V last year coming off the scallop grounds after my buddys boat broke and I took 5 of his crew and his catch on my boat.. I wouldn't want everyone to get up and walk to one side at the same time but otherwise it held the people very well. Might have been more difficult to explain twice the limit in scallops and why not enough PFD's had we been stopped.
