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Head Sea Water Intake and Shower / Refrig Pump Out

KZW

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May 17, 2014
698
Catalina 310 #307 Bluewater Bay, FL
I recently acquired a 2005 C-310. Learning about the systems is interesting given the inaccuracies in the Catalina owners manual. I spent the day trying to trace hoses in the Fresh / Gray / Black Water System.

It appears the shower / refrigerator sump pump dump line goes to the seacock for the head seawater intake line. This is the way it is set up on my boat:

The seawater head intake seacock is located behind a small door to the stern of the head. Open the seacock, pump the head and water is drawn in. In the picture the macerator is on the left and the head intake seacock is on the right. Under the head sink is a Y valve. Turn it one way and the refrigerator drains. Turn it the other and the shower sump drains. Both feed a pump, whose output is connected to the head intake seacock.

Questions:

1. Why didn’t Catalina just connect the output of the sump pump to the head sink drain seacock? It is located directly under the sink!!!

2. The head intake seacock is below the water line, meaning there is water pressure as soon as it is opened. Given the sump pump also puts pressure on the line, what prevents the water from forcing its way into the head pump intake?


On another subject: Where is the seacock for the air conditioning inlet water???
 

Attachments

Jan 4, 2006
2,812
Hunter 310 West Vancouver, B.C.
Looking at your second picture only, I'd be a little nervous if the sump pump didn't have an anti-siphon loop on it. I think you'll find most sump pumps, bilge pumps, and any other pump discharges are above the water line. Your boat may be relying on a check valve to keep it afloat :eek:.
 

Attachments

Jan 4, 2006
2,812
Hunter 310 West Vancouver, B.C.
I think we can all sleep a little better seeing the anti-siphon loop in there.

Mind you, they could have saved some tubing and a loop by discharging above the water line.

I guess you'd have to be there to appreciate.
 

KZW

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May 17, 2014
698
Catalina 310 #307 Bluewater Bay, FL
So, why didn't Catalina just connect the sump pump to the sink drain seacock???
 
Nov 16, 2012
897
Catalina 310, 2000, #31 Santa Cruz
I'm sure this is no surprise to anyone, but the plumbing on our 2000 C310, #31, is quite different. Only one thru hull behind the little door in the head; and it only goes to the head intake. The shower sump goes to a three way valve under the galley sink (presumably also connected to the reefer drain, although I haven't seen it yet), then the sump pump, and exits via a thru hull right next to the galley sink thru hull. The macerator thru hull is located next to the engine cooling intake, under the rear berth.
 
Dec 2, 1997
7,602
- - LIttle Rock
The macerator thru hull is located next to the engine cooling intake, under the rear berth.
Oooops...that's not good! If the engine is running while the tank is being dumped--which is not uncommon--the engine intake can pull in sewage...UNLESS--the engine cooling water intake thru-hull is FORWARD of the macerator pump discharge thru-hull AND the boat is also underway while dumping if the engine is running.

Same principle--which a lot of boat builders seem to overlook--applies to the toilet intake thru-hull relative to the toilet and/or macerator pump discharge thru-hull. The toilet intake should always be at least a couple of feet forward of any waste discharge thru-hull...'cuz if the discharge is forward of the intake or even too close to it even though aft of it, flushing the toilet pulls the waste back into the toilet.
 
Nov 16, 2012
897
Catalina 310, 2000, #31 Santa Cruz
Oooops...that's not good! If the engine is running while the tank is being dumped--which is not uncommon--the engine intake can pull in sewage...UNLESS--the engine cooling water intake thru-hull is FORWARD of the macerator pump discharge thru-hull AND the boat is also underway while dumping if the engine is running.

Same principle--which a lot of boat builders seem to overlook--applies to the toilet intake thru-hull relative to the toilet and/or macerator pump discharge thru-hull. The toilet intake should always be at least a couple of feet forward of any waste discharge thru-hull...'cuz if the discharge is forward of the intake or even too close to it even though aft of it, flushing the toilet pulls the waste back into the toilet.
I agree. Seems like a bad co-location. Now that I've freed up the head intake thru hull (plumbed that line into the sink drain) I could probably move the macerator to it. I actually don't think we'll ever use the macerator, but if we ever did....
 
Jan 17, 2013
348
Catalina 310 St. Simons Island, GA
Don't know where to start because I have Catalina 310 Hull #1 which I love so here goes: There are two thru hulls in the head compartment. One for head intake and one for overboard direct discharge. My reefer and shower sump pump discharges through a separate through hull under the sink - but not the sink thru-hull. My macerator discharge thru-hull is next to the engine water intake but it is aft of the engine intake so if you have the engine running and are moving forward I don't see how the engine intake would end up sucking in the macerator discharge. I'm pretty satisfied with the way my Cat 310 is laid out which begs the question: If things were not broken, why did they they try to fix them on subsequent 310's?
bob
 
Dec 2, 1997
7,602
- - LIttle Rock
Just be sure that if your engine is running when you dump the tank or flush the toilet that you're moving forward, not sitting idling...and that your toilet intake line is connected to the thru-hull that's forward of the discharge thru-hull.
 
Nov 16, 2012
897
Catalina 310, 2000, #31 Santa Cruz
I have hull #44 with the same layout as hull #1
Interesting. Hull #31, quite different. Only 1 thruhull aft of head. Macerator empties aft of engine cooling water intake on starboard side of boat. No Y valve between head and holding tank. Shower sump/reefer drain thruhull is next to galley sink drain.
 
Sep 29, 2008
1,783
Catalina 310 #185 Quantico
#185 is similar to #1 and #44. It seems to work just fine. While I was reading this I figured out why there are 2 thru hulls under the sink - otherwise you would need a T fitting to connect them all in and that would not be cool. Overall the design is pretty simple and makes sense. FWIW, I never use the raw water intake to the head as we use the shower/fresh water so we can cycle the water in the tank a little more to avoid it getting funky. I run the macerator once a year to make sure it still runs.
 

KZW

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May 17, 2014
698
Catalina 310 #307 Bluewater Bay, FL
I have # 307 (2005). There is a single through hull under the sink. The Y valve there switches between draining the shower sump and draining the refrigerator.
There is no Y valve in the hatch at the aft of the head compartment. There are two through hulls there. One is the Macerator through hull. The other is the sea water inlet for the head. This same through hull is also the outlet for the shower sump / refrigerator. The head dumps directly into the holding tank. The holding tank dumps through the macerator. No, Catalina didn't update the drawings in the manual. The drawings still show the Y valve at the macerator outlet. It took some time to trace the hoses and sort it all out.
 

JRT

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Feb 14, 2017
1,779
Catalina 310 211 Lake Guntersville, AL
I'm bringing this old thread back up and wondering if anyone has done this change, I really don't understand why I'm using a below waterline thru hull for both intake to head and discharge from shower and fridge sump by Y valve.

So, why didn't Catalina just connect the sump pump to the sink drain seacock???
 

Tom J

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Sep 30, 2008
1,600
Catalina 310 Quincy, MA
I'm bringing this old thread back up and wondering if anyone has done this change, I really don't understand why I'm using a below waterline thru hull for both intake to head and discharge from shower and fridge sump by Y valve.
Maybe to flush out that smelly seawater that accumulates in the head intake hose? Just sayin.
 
Dec 2, 1997
7,602
- - LIttle Rock
Sounds like a PO mod, not something Catalina would have done. Connecting the head intake line to the head sink drain line is a great idea...in fact, I've posted instructions for doing that many times and have also included 'em in my book. However, the discharge from the sumps should be ABOVE waterline...that's the whole point of having sumps instead of just routing all the drains directly overboard.

--Peggie
 

Tom J

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Sep 30, 2008
1,600
Catalina 310 Quincy, MA
Sounds like a PO mod, not something Catalina would have done. Connecting the head intake line to the head sink drain line is a great idea...in fact, I've posted instructions for doing that many times and have also included 'em in my book. However, the discharge from the sumps should be ABOVE waterline...that's the whole point of having sumps instead of just routing all the drains directly overboard.

--Peggie
Mine is plumbed same as the OP's. I assume it is standard to that era of C310's
 

JRT

.
Feb 14, 2017
1,779
Catalina 310 211 Lake Guntersville, AL
Yes this is how the 310 is plumb. I'm not saying connect intake to sink drain, I'm saying connect shower and fridge drain to sink drain.
 
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