Rainman watermakers: No extra holes in the boat!
I first read about Rainman portable watermakers (desalinators) some time ago, and I admit that I was very intrigued by the concept. I don’t typically write about products unless I have first-hand experience using them though, which is why I have, until today, failed to mention this unique concept here on this blog. When I noticed that our boat neighbors, Gary and Marie, had one on board, and seemed to be using it quite regularly, I made up my mind to invite myself over to check out their system. Gary was more than accommodating, welcoming me onboard to give me a complete overview of how the watermaker works. What I learned follows below.
The system that our friends have on their boat is completely portable. They keep both the membranes and motor unit stored in a locker when not in use, but I understand that it is possible to mount the membranes more permanently, and that some people prefer that type of installation.
The entire system can be seen below. This is the self-contained gasoline version. There is also an electric version designed to run off a Honda 2kW generator, or equivalent. Purchasing that model would obviously make sense if you already own a generator.
The system that Gary and Marie own has a very high output. This dual-membrane watermaker is rated to produce 100-140 lph (23-32 gph). When looking through their literature, I also read that Rainman offers a compact version that produces 50-70 lph, apparently good for those who have less storage room on their boats, and also an “economy” single-membrane unit, also designed to produce 50-70 lph.
I noticed that the guts of the motor looked a lot like the Honda 2000 generator that we had on ZTC. I guess that makes sense because the Rainman brochure says that the motor is made by Honda!
When running, the volume of the motor is also equivalent to a Honda 2kW generator, which are known to be relatively quiet.
The image below shows how the hoses are routed. From the membranes, the brine discharge line (green) is dropped overboard, the high pressure hose (black) is connected to the motor, and the product water output is led to wherever you’d like (deck fill, jerry can, etc.). The intake hose, from the motor unit, is also dropped overboard. Gary mentioned that he tries to keep the intake line, and the brine discharge line, somewhat apart from one another. The big advantage of a system like this is that it requires no additional holes in the boat to operate!
Note: I would not rely solely upon taste for testing the product water quality as they show in the above promo video. We use a TDS (total resolved solids) meter to check the salinity of a watermaker’s product water, in addition verifying that it tastes and smells OK. Our friend Gary does the same.
You can see the raw water intake hose is overboard in the image below. The hose has a 1-way valve on the end, and I believe that Gary told me that there is an optional extra filter that can be added to the end of the hose, for use in extra-silty water.
The non-proprietary membranes are stored in their own carry case. There is a pressure adjustment valve mounted to the membranes, and a pressure gauge so that you can dial in the perfect operating pressure.
As a bonus, there is also an optional pressure washer gun that can connect to the unit. Pretty cool, eh?
Gary and Marie sail on a beautiful Lagoon 440. We first crossed paths with them in Barbuda back in 2012 when we were sailing on ZTC. It’s been very nice to re-connect with them here in Grenada. Big thanks for inviting me on board to check out the watermaker!
It’s worth noting that we have nothing to do with the Rainman company. We are not sponsored by them, or affiliates, nor did I contact them before writing this post. I just think this is a pretty cool concept, and were I in the market for a new watermaker, I would definitely consider one of these portable systems.