Friday, January 30, 2009

Water, the Key to Life...and Adult Beverages!

Doug here...

If you have been paying attention to the blog, you may remember Tammy mentioning that we were in Haven Harbour Marina in Rock Hall, Maryland, to have our watermaker installed. Now, many of you may be up to speed on what a watermaker is but I'll bet very few of you know how it makes water. I thought I'd write a short blog entry about the watermaker and the excitement that came along with the installation.

First, we decided to buy a watermaker from a reputable company rather than buying the parts and assembling it ourselves. A lot of cruisers, to save money, do the later, but I didn't think my mechanical skills were quite up to the task. We purchased the Newport 400 by Spectra Watermakers. In a nutshell, this takes salt water from the ocean, filters it three times, runs it through a reverse osmosis process (more on that later) and voila... distilled water. The Newport 400 uses a Clark pump, which is very quiet, and makes 16.5 gallons of nice pure water per hour using only about 26 Amps of DC power.

The first step in the process of making the water is to use a lift pump to pull the water from the ocean through a thru-hull fitting and a strainer. It then pulls the water through a 20 micron filter and then a 5 micron filter to clean it as much as possible.
The cleaner the sea water the longer the filters last. In the Chesapeake Bay, they don't last very long. In the islands they should last for about a month of making about 50 to 60 gallons a day.

After the water is pre-filtered with the 20 micron and the 5 micron filters, it passes into the Clark Pump where it goes through a reverse osmosis process to desalinate the water.
Watermakers don't actually MAKE water, they DESALINATE water. Now how does it work? The underlying technology is pretty cool. If you put non-salty water in a container on one side of a membrane and salty water on the other side of the membrane, the non-salty water will osmose through the membrane until the pressure on each side is equal. With normal osmosis, the water moves to the salty side of the membrane until equilibrium is achieved. If you apply pressure to the salt solution side equal to the osmotic pressure you can create equilibrium without the water moving. If you add additional pressure you can actually force the pure water to flow from the salty side to the non-salty side. This process is called reverse osmosis. So basically, the clark pump puts pressure on the salt water to make the pure water reverse osmose to the other side of the membrane, thereby "making water" and leaving salty brine behind to be flushed overboard. The osmotic pressure of seawater is approximately 460 PSI. The Clark Pump produces pressure between 800 and 1100 PSI, depending on the temperature of the sea water. Colder water requires more pressure.

The folks at Haven Harbour Marina ordered the watermaker for us and we docked at the marina for a couple days to have it installed. Installing it entailed mounting it on the wall in the lazzarette and running power and water hoses through the wall into the engine room. We already had a thru-hull in place in the engine room to get the water from the ocean. They had to cut a small thru-hull just above the waterline in the lazzarette for the salty brine to be flushed from. In addition to setting up the water maker and getting electricity to it, they had to run a very small hose from the watermaker in the lazz, at the stern of the boat, forward to the water tank which is under the sole in the master stateroom about forty feet away. All of this took about two days and they were ready to go. Then Murphy took over the installation. You know... Murphy's Law.

When they tested the unit, the probe that tests the salinity in the water after it has been desalinated was faulty so the unit kept rejecting the water it was making. The manufacturer in California had to over night another one out to the marina. That arrived late in the day the next day and was successfully installed. Once the unit was successfully pressurized, it began to leak. After testing all of the fittings they had put in, the team realized that the leak was coming from inside the watermaker itself. Once it was opened, it was determined that the people at the factory had tightened one of the connections into the manifold too tight and had cracked the plastic manifold. So the team got back on the phone with the manufacturer and had a replacement manifold mailed out for over night delivery. Late the next day, Friday, the manifold was installed and the system was fully operational.

This system is the coolest thing. You push a button, either on the front of the unit in the lazzarette or on the remote panel installed in the pilothouse and the system starts making water. You tell it how long to run and it runs for that long, shuts itself off and back flushes itself with fresh water to keep it fresh until the next time you use it. It is so easy and so far has worked flawlessly.

The team at Haven Harbour were great, as always, and did a fantastic job. Neither of the problems were of their making and they got them fixed within 24 hours... each. They kept their spirits up and did not get too frustrated. The two main guys, Randy and Mike, were on the boat, often curled up like little pretzels, due to space constraints, for the better part of four days.

Now we can make water in the islands to replace the small amount we use each day. Water in the islands is very expensive and often not very good quality. This Spectra watermaker makes water that does not even have the hint of salty taste to it. In fact, the water has absolutely no taste at all. It is essentially distilled water. There is a little release valve and hose on the side and you can direct the water flow to it to taste the water before it gets mixed in the big tank. It is totally tasteless. I know because I tasted it!

No comments:

Post a Comment