Watermaker in a catamaran forepeak

[workmaster2n]

I've recently purchased a Seawater Pro water maker with the 220 volt AC motor and am just about to start the installation. The previous owner said there used to be an engine driven water maker on the boat, and the evidence of that is a high pressure pump in a storage locker, an unused through hole near the starboard engine, and an unused through hole well above the waterline that appears to be a brine discharge line.

For reference, I've got a Roger Simpson designed cat with mid mounted shaft driven engines, just to try to paint the picture.

At the bow of the starboard hull is a forepeak storage area. It's where a forepeak berth would be, but there is no berth, just an empty fiberglass room. There is an 80 liter diesel tank in that area (the belly tanks have probably long since rotted out and are not plumbed in), and fishing rods along the wall.

I had convinced myself to install most of the water maker up in that area. I could mount the pressure vessels opposite the fishing poles and the motor could be mounted on the floor, forward of the diesel tank.

This brings up a few problems.

First, the whole kit weighs in at around 50 kilos. That's a lot of weight forward for a cat and I'm a bit worried about the performance hit. The boat isn't a performance boat and doesn't sail amazingly as is. I'm afraid I might turn her into a motor sailer if I put too much weight forward.

Another issue is movement of the forepeak area. That's the area that is going to get slammed around the most and have the most movement in big seas. I trust adhesives these days, but that's a lot of weight kicking around up front.

The advantage of the forepeak area is that I can see the runs for the diesel lines, so I know that running the water from the feed pumps to the high pressure pump would be trivial, as would be the runs for the electrical. Also, if there was a leak or spraying of salt water, there isn't anything in that storage area that can't get wet.

When I think of other areas to mount the water maker, I can't really come up with a good place. None of the bow lockers are anywhere near water proof, so I don't think I can mount the AC motor in those. The only locker in the cockpit is on the port side. I don't think there are any pipes or wires that run into the transom lockers, so I'd be drilling blind if I went that way.

I think the previous water maker had the pressure vessels mounted under the settee in the saloon. But that is where the house batteries live and I'd rather not test their water proofness.

The starboard side stern berth is an inboard single. The berth is actually over the curved part of the hull, so I don't think there is enough room to mount the motor in there. On the outbound side of the berth is a pantry and behind that a long cabinet. There is probably enough room in the long cabinet to mount everything, but then I'd be giving up a decent amount of storage, as well as that area not being super kind to random sprays of salt water. Also, I haven't noticed any wire or pipe lines leading to that cabinet, so I'm not sure how I'd get power and water there.

Am I being too paranoid about the weight penalty and potential slamming of putting the motor and pressure vessels in the bow? Or should I be willing to put quite a lot of effort into mounting the unit further astern?

[Chotu]

I think you’re fine putting it up there. A diesel tank in that area is what’s a crime. Since that crime has already been committed, no harm putting a watermaker there. It’s a very small weight in comparison to a diesel tank.


Use epoxy or 5200 to mount it and you can forget about your worries with the motion up there.

[tkeithlu]

Is there any chance of moving the fuel back to its original midship location? 80 liters of diesel is 68 kg, and you're talking about adding 50 kg. Just how much that sum hurts your sailing/handling I cannot speak to, but it is a significant weight. Shifting the tank would at least make adding the watermaker to the bow a neutral change from your current situation.

[workmaster2n]

Originally Posted by tkeithlu

Is there any chance of moving the fuel back to its original midship location? 80 liters of diesel is 68 kg, and you're talking about adding 50 kg. Just how much that sum hurts your sailing/handling I cannot speak to, but it is a significant weight. Shifting the tank would at least make adding the watermaker to the bow a neutral change from your current situation.

Unfortunately, I can't access the belly tanks. They are glassed in and there is no access panel. I've been quoted $30,000-$50,000 to get the tanks out, remade, and replaced. Previous owner said the mid ship tanks should be fine to clean out and replumb in. First boat buyer me believed them. That was a quick lesson learned.

[stormalong]

Make sure that your water intake is well below the waterline. Pressure pumps don't like air and membranes are ruined by oil. The bow is far from an ideal place for drawing clean, air free water. The lower the intake the better. Oil floats on the surface and air goes down quite a way, especially if you intend to use the watermaker while moving.

[workmaster2n]

Originally Posted by stormalong

Make sure that your water intake is well below the waterline.

Thanks for the reminder. The intake is actually right next to the intake for the engine, so mid ship and well below the waterline. I've purchased 2 boost pumps to ensure enough water makes it up to the high pressure pump.

[workmaster2n]

Thanks for all the feedback.

While poking around the boat today, I found a cable conduit that runs to an underfloor compartment in the cockpit (similar to where some liferafts are kept), but my compartment is completely glassed in from the underside.

The rough fit looks like everything will fit, so I'll be looking to install the water maker in this cockpit locker instead of the bow.

It's not a perfect location, but I like it a lot more than riding up front in the bow.