First, unless space is an absolute issue if someone were to ask for a Spectra 150 I would easily convince them that an extra 1K for a Cape Horn Extreme is money
Though it is not absolutely necessary to route
your brine discharge to it's own thru hull
fitting, brine discharges are installed above the waterline because, as Cancun
Mike says, to see that your system is running and operating properly. You will get a feel for what is a normal flow and a quick glance over the side can reconfirm this. Most watermakers are installed in areas that can be hard to access and for a quick view while operating a discharge few inches above the waterline makes it easy and well worth the simple work to install it there. Brine discharges below the waterline are a very
bad idea as the weakest link can be an easily broken piece of plastic at the watermaker allowing a water opening in the boat.
AC plunger driven watermakers are a very noisy lot for the most part, you just can't get away from it. Spectras are going to be the quietest watermakers of the bunch. The Ventura 150 is a different beast than the Catalina
300 and the sound made is different from each other. A lousy installation
can make even a Spectra annoying. But a Spectra installed properly is going to be very quiet. I have ways to install a Ventura 150 that even the guys including Michael in Tech Support at Spectra don't even know about that will make it even more quiet than the installation
recommendations in their own manual.
With all due respect to the poster, the post below is all utter nonsense.
Interesting. Do they mention anything about where to mount the pump in relation to the discharge? Would seem to me that you could locate the pump anywhere above or below the bootstripe which, without guidance on how much head
the pump can handle, makes the recommendation nonsense.
You can build a RO unit for a fraction of the cost. Schedule 80 pvc is more than adequate for the pressure vessel. A plumbing
supply house should be able to set you up with higher schedules if it makes you more comfortable. The membranes can be sourced, and all you need is some pvc, a 1.5 hp ac piston pump, and some hydraulic hoses, and a day to assemble and install, and you'll produce fresh water.