Air conditioning pump clogging on Chesapeake - strainer issue?

[malbert73]

Hi everyone-
My boat has an installed cruisair AC system which works fine. This year I have had an unusual number of times that the raw water flow stops due to clogging of the intake strainer. This then trips the breaker for the AC. I have been running this unit on my boat for 7 seasons and this is the first season I have had this issue. I think it's because the jellyfish count is up. It usually clogs with sea nettle jellyfish on the Chesapeake (I have found bits of jellyfish in the raw water intake when unclogging, as evidence)
The pump is located below waterline and is a typical centrifugal pump. I replaced the AC water pump">raw water pump 2-3 years ago when the old one failed and it works very well when not clogged. It never clogs underway, only anchored.
When not clogged it pumps very briskly. I have a shop vac on board and usually have to blow air down the through hull to unclog and get it working again. This has happened every 15 minutes at times and once I actually rigged a hose with a strainer basket as a strum box just to keep it pumping on a very hot day.


6 years ago I noticed the through hull intake for AC had no external strainer (but has a high quality bronze strainer basket internally) and I installed an external strainer like the one pictured. Just as what I thought was a good preventive measure.


So my questions are:
1. Has anyone else had their system clog so easily from jellyfish? I seem to have noticed no one else at marinas and anchorages this summer with issues except me.
2. Is the external strainer an issue? Ie should I remove and just let the internal filter basket take care of jellyfish and seaweed (less common on Chesapeake). Maybe this will stop the flow less (until basket fills)
3. Should I consider a rubber impeller driven pump that will be more powerful and able to suck jellyfish through the external strainer? I only consider this because my genset has an identical external strainer and it's located only 18 inches from my AC intake, and it never stops pumping water when the AC clogs.

Thanks for any ideas on how to solve this annoyance!

[redneckrob]

Originally Posted by malbert73

Hi everyone-
My boat has an installed cruisair AC system which works fine. This year I have had an unusual number of times that the raw water flow stops due to clogging of the intake strainer. This then trips the breaker for the AC. I have been running this unit on my boat for 7 seasons and this is the first season I have had this issue. I think it's because the jellyfish count is up. It usually clogs with sea nettle jellyfish on the Chesapeake (I have found bits of jellyfish in the raw water intake when unclogging, as evidence)
The pump is located below waterline and is a typical centrifugal pump. I replaced the AC raw water pump 2-3 years ago when the old one failed and it works very well when not clogged. It never clogs underway, only anchored.
When not clogged it pumps very briskly. I have a shop vac on board and usually have to blow air down the through hull to unclog and get it working again. This has happened every 15 minutes at times and once I actually rigged a hose with a strainer basket as a strum box just to keep it pumping on a very hot day.


6 years ago I noticed the through hull intake for AC had no external strainer (but has a high quality bronze strainer basket internally) and I installed an external strainer like the one pictured. Just as what I thought was a good preventive measure.


So my questions are:
1. Has anyone else had their system clog so easily from jellyfish? I seem to have noticed no one else at marinas and anchorages this summer with issues except me.
2. Is the external strainer an issue? Ie should I remove and just let the internal filter basket take care of jellyfish and seaweed (less common on Chesapeake). Maybe this will stop the flow less (until basket fills)
3. Should I consider a rubber impeller driven pump that will be more powerful and able to suck jellyfish through the external strainer? I only consider this because my genset has an identical external strainer and it's located only 18 inches from my AC intake, and it never stops pumping water when the AC clogs.

Thanks for any ideas on how to solve this annoyance!

For what it's worth I'm running into exactly the same issue on the Chesapeake this summer. I also think it's the jelly fish. Don't have a great solution, but was thinking about a change in pump type like you as well.

[malbert73]

Glad to know I’m not alone. Do you have an external strainer also? Was thinking if I remove maybe jellyfish can get sucked in and caught in strainer basket which won’t clog as quickly

[a64pilot]

External strainers are another argument, many think they are necessary and required, I don’t and think they cause problems and don’t solve any.
Dive your boat and open the strainer up and leave it that way, if that solves the issue, next haul out, remove them.
At least you can open yours, most cannot.

[SSgtPitt]

We installed an inline fitting and a couple of ball valves to the hose after the basket strainer. We hook up a water hose to the inline fitting and by turning a ball valve we can force fresh water either direction to either blow out critters before the basket strainer or the other direction to clean out the heat exchanger in the ac unit. This has been one of my best little tweaks and it works wonderfully.

[ScubaPete]

I'm on the Chesapeake too, and I have a similar AC pump setup with the identical external strainer as you. Jellyfish are heavy at certain times, and the floating sea grass seems to be more plentiful than usual, especially when the winds and tides seem to concentrate it in certain waters. In addition to those two problems, you could have hard growth (barnacles, oysters) inside your intake. With the opening strainer like we have, you can open it up and clean out deep into the intake through hull.

[daviddiscenza]

I've heard from other members of the Catalina fleet on the Chesapeake that this has been a bad year for jellyfish so no, you're not alone. They haven't been a problem up at my end of the Bay (Worton CReek). I have had an eel swim up the intake which reduced the water flow and tripped the alarm. I'm told this is fairly common.

I'm with a64pilot. I would opt not to have an external strainer.

Thanks to SSgtPitt for the idea of an inline fitting for an external water hose. I'll have to add that to my setup.

[KadeyKrogen38]

I have external strainer installed for thirty two years and never one issue. I do get barnacles encrusted in intake, so placed a T fitting on intake. By removing the top plug I can rod barnacles out of intake.

[svfinlandia]

I have had this problem for years in North Carolina. How deep is your intake through hull? Mine is only about 3 inches above the waterline, and since that is where jellyfish swim I pick up a lot of them. The only possible solution I can think of is to put the intake through hull deeper in the water where it would not suck in as many jellyfish since they swim on or close to the surface. Of course that would mean putting another hole in the boat and closing off the original one, so I just keep cleaning the filter.

Al, S/V Finlandia

[thinwater]

Add an external strainer. I did not have one, and then I added one (mid-Chesapeake). You can also clog hoses with fish, which is even worse.


Centrifugal pump is fine.


You will have to dive and chop the barnacles out with a screw driver every month in season. It's easy. I don't think being able to open it helps much. Just use a thin screw driver and wobble it around.

[TBW]

same here; for ssgtpitt
any chance of a picture or your setup?
thanks

[sasirles]

I had the same problem a few weeks ago in the Chesapeake, both in Knapps Narrows and in Solomons. I'd clean out the strainer and it would clog up again in about 30 minutes. I then went to Jackson Creek in Deltaville and had no problems. The water temperature in all three places was in the mid to upper 80s. I observed far fewer jelly fish in Jackson Creek than in the Maryland locations. So, in addition to water temperature, there must be other factors explaining the jelly fish problem. Maybe currents?

[Sailshabby]

Originally Posted by malbert73

Hi everyone-

Thanks for any ideas on how to solve this annoyance!

Might also check the hose where it meets the pump. Might be clogged. Don’t ask me how I know...

[malbert73]

Originally Posted by thinwater

Add an external strainer. I did not have one, and then I added one (mid-Chesapeake). You can also clog hoses with fish, which is even worse.


Centrifugal pump is fine.


You will have to dive and chop the barnacles out with a screw driver every month in season. It's easy. I don't think being able to open it helps much. Just use a thin screw driver and wobble it around.

Good input, thanks! I have an external strainer already and thought it may be making things worse as maybe better to just clean out the strainer basket.

[malbert73]

Originally Posted by svfinlandia

I have had this problem for years in North Carolina. How deep is your intake through hull? Mine is only about 3 inches above the waterline, and since that is where jellyfish swim I pick up a lot of them. The only possible solution I can think of is to put the intake through hull deeper in the water where it would not suck in as many jellyfish since they swim on or close to the surface. Of course that would mean putting another hole in the boat and closing off the original one, so I just keep cleaning the filter.

Al, S/V Finlandia

Thanks! Mine is on bottom of hull midline so really no where else to put it deeper-