How loud is an AC watermaker pump

[sailorboy1]

Since generator manufacturers play pretty loose with their sound ratings, how loud really is a piston pump on an AC powered 20-40 GPH watermaker?

[tkeithlu]

I would not want to sleep in the same cabin with my 160 GPD Spectra watermaker, but it's nothing compared to the mechanical noise (not exhaust) of my 4-53 Detroit Diesel, nor is it objectionable when we are at anchor. It's not a major issue. Nothing like running a genset.

[mikereed100]

The short answer is 'pretty loud'. I think I remember clocking ours at 82 db? Louder than the Honda 2000 at any rate. It lives under the port bunk with the membranes so we keep the lid open when running to avoid heat issues. We have taken to stuffing a cockpit chair in the companionway of that hull, which significantly reduces noise. The bright side is that it only takes an hour to make 33 gallons, so the pain is short-lived and it is tied with the refrigerator for 'favorite toy'.

[a64pilot]

I plan on mine going in the lazarette with the generator, keep the noise in the same place.
Rich assures me that is well within the heat limitations. I think they are essentially very close to being a pressure washer? So noise ought to be similar?
Secondary noise seems to be what is noisy on a generator, that and it's enclosed. I bet bolted to a concrete floor and in an open area they are no louder than claimed, although I have no idea what is claimed for mine, it's exhaust is much louder than I thought it would be, but I also have a very short exhaust run.


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[EvilRabbit]

Originally Posted by sailorboy1

Since generator manufacturers play pretty loose with their sound ratings, how loud really is a piston pump on an AC powered 20-40 GPH watermaker?

Pretty loud on our Sea Recover 900. But she is making 140lt an hour.

[PaulinOz]

We have a 180 lt/hour unit 240 volt AC and it is noisy. The high pressure pump is mounted to a motor bed glassed to hull in bilge area.

The generator is not the issue for noise what so ever. I now only run generator and water maker when sailing or motoring. Being on a bridge deck Condomaran in the words of Sgt Schultz "I here nothing". Just need to put a 2 hour timer on to know when the tank is full. Other advantage I feel the water maker sees fresher/cleaner water on the move than in most anchorages.

[SV THIRD DAY]

A lot of the noise isn't actually from the Hp Pump itself, but the vibration it sends into the mounting base. Cat pumps are significantly louder than General Pumps...why...I can't honestly tell you, but I've heard them side by side and it a pretty noticeable difference. Of the vibration isn't dampened it can transfer and amplify like a snare drum. We run the Honda 2000 up on the bow and the water maker is mounted under the lower salon couch in what we jokingly call our "Media room" and we can watch a video with the water maker running and not need to turn the TV volume up. Do we know it's running, yes absolutely, but the general pump doesn't chase us out of the room. What's funny and illustrates the point about noise transfer, our water maker sounds louder when I'm in the dinghy up next to the hull where the water maker is mounted than when in the same room with it in the locker. When they REALLY get loud is when they are cavitating and gasping for sea water flow. Piston pumps don't like to "suck" and want to have a flooded head pushed into them. It's amazing how loud they can get when cavitating.

[Mikado]

Originally Posted by sailorboy1

Since generator manufacturers play pretty loose with their sound ratings, how loud really is a piston pump on an AC powered 20-40 GPH watermaker?

I have a 600 GPD watermaker with a 4.5 HP AC motor and a belt driven Cat triplex pump.

The unit is mounted on the bench top in my work shop with good anti-vibe rubber feet so with the door shut the sound is not that noticeable.

I've never measured the dB's but if I had to compare it to something I would say it's about as loud as a Kitchen Aide stand mixer running on high.

[a64pilot]

When something like this is mounted to the hull dive the boat, you may be astonished.
I took decent pains on my Generator install to try to prevent secondary vibrations, plate it's mounted on is very stiff, generator is double isolated with two sets of mounts, not loud in the boat at all and you can put your head on a bulkhead and it won't vibrate.
But dive the boat to clean the hull or something and directly under it, it's so loud you can't stand it. Amazing how much noise is transmitted to the water, or maybe how much better or hearing is in the high density water?

[barnakiel]

To avoid noise we placed the pump 'far' from the unit. Still, the hoses transfer plenty of noise and so we ended up with less noise, but less localized in the boat. Bad. It is less noisy now but it is noisy everywhere close to the system.

b.

[Rainman]

I agree with Rich. General Pump HP pumps are quieter than other options on the market. I also agree that it depends on where it's installed.

We performed sound level tests of all Rainman systems:
1. Petrol / gasoline
2. AC Electric
3. 12VDC Electric

We tested them in an open lot at 6 metres (20ft) distance. We also tested a Honda 2kVA generator running at three different speeds as reference points:
1. Maximum load
2. Powering Rainman AC system (~1250 watts)
3. Idling unloaded in eco-throttle mode

The numbers themselves shouldn't mean much to you since you won't be running the pump in an open lot. However, it may help give you a feel for the sound levels compared to a Honda generator. Remember, 1dB is the minimum difference a human ear can detect, and 3dB increase is doubling volume (logarithmic scale).

While this is a Rainman specific test, my expectation is that other AC watermakers running General Pump HP pump will be similar sound levels.

[mikereed100]

I suspect a lot of the noise produced by my motor is due to the fact that I have it bolted directly to a plywood mount that is in turn glassed to a bulkhead and the hull. I wonder what others have done to dampen the attachment? Some methods I have seen are heavy exhaust hose doubled over, rubber feet, rubber gasket, etc. I have not done anything yet as the noise is not unbearable and I don't want to provide the AC motor with an excuse to vibrate off it's mounts.