If you want a quiet toilet....
All raw water electric toilets are noisy, so if quiet is important, your only two choices are manual or an electric toilet designed to use onboard pressurized flush water. Your best choice for a manual is the Raritan PH II...for an electric, the Raritan SeaEra. A toilet that can be either manual or electric is not a good choice...'cuz they're all manual toilets with a motor added that only replaces the pump handle..the pump is still a manual pump. The motor pumps the toilet much faster, and with a much shorter stroke than pumping manually, which causes it to take longer to prime and therefore wears out the rubber o-rings etc much faster--which leads to more frequent need to rebuild the pump...and also causes the toilet to "choke" on flushes that deliberate pumping manually can push through. A lot of people who thought they wanted an electric toilet that can also be a manual toilet have gotten so disgusted with it that they've just disconnected the motor permanently and put the pump handle back on. These toilets also cost as much or more than a electric toilet.Besides, there's no advantage to a toilet that can be converted to manual in the event of a power failure...'cuz if you don't have enough power to flush an electric toilet, you don't have enough to power anythng else either...so whether you can flush a toilet or have to resort to using a bucket is the LEAST of your worries!So if you want a manual toilet, the PH II is the best choice...but if you want an electric toilet, go with one that's designed to BE an electric toilet, not a "hybrid."These folks have the best prices I've found for both the PH II and the SeaEra: http://www.boatfix.com/elec/rartoi.aspBtw...what's wrong with your Newport that makes it inoperable?