If you don't mind hauling it off the boat to empty
SeaLand SaniPotties are considered the best quality on the market. The 962 is just the smaller version of the 965 without the option to permanently install it. Keep in mind that 2.8 gal isn't much capacity...so if the 965 will fit, I'd go for it instead....'cuz I've never heard anyone complain that their portapotty was too big. But--if you do, get the MSD option, 'cuz a full 5.6 gal tank weighs more than 40 lbs...a bit much to carry up the dock. You don't have to install it...but I've always believed that it's better to have an option that you don't need than need an option you could have had but didn't get.