shower drain pump

Jul 27, 2015
59
catalina 30 SF bay
I am sure this has been discussed prior but ideas would be helpful. Has anyone found a drain pump box that will work or a method of using a direct inline pump and what would be the best location be to pump the water out. Does a thru-hull drain need to be above the waterline? Thanks, Brad
 
Sep 24, 2018
4,153
Catalina 30 MKIII Chicago
The hose on many C30's is epoxied in. On my 94 it's shot. There's no way I would be able to attach anything to it without it crumbling. I would check the condition of the shower to bilge hose before moving forward. If it's usable, then maybe a box could be installed in the bilge?
 

jssailem

SBO Weather and Forecasting Forum Jim & John
Oct 22, 2014
23,948
CAL 35 Cruiser #21 moored EVERETT WA
Does a thru-hull drain need to be above the waterline?
If it is an open drain through the hull, yes. Otherwise, water will come up the drain and flood the boat. This assumes that the shower floor is below the waterline.

Here is a typical shouwer drain box with a pump. You can plumb a through-hull well above the waterline for the pump to pump the grey water overboard.

1770337267601.png
 
Feb 26, 2004
23,182
Catalina 34 224 Maple Bay, BC, Canada
Brad, you should investigate different kinds of pumps and what they can do. Inline centrifugal pumps cannot raise the level of water if the sump box is below the pump' they won't pump air. Centrifugal pumps will work if they are submerged in the liquid they are meant to move, like in pre-built shower sump boxes or some bilge pumps.

If the sump is located below the pump, the diaphragm pump is the one that can "suck the water up" from the lower sump box through a hose and pump it out.

Discharge from a diaphragm pump can be done via a thru hull below the waterline. A vented loop should be between the pump and the thru hull. There should be a check valve between the remote sump and the pump. [This is how my boat was built.]
 
Jan 11, 2014
13,611
Sabre 362 113 Fair Haven, NY
The centrifugal pumps in most shower sumps can pump to a below waterline through hull, however, it is essential that the discharge hose go above the waterline to a vented loop and a check valve be installed between the pump and the vented loop. On my not-a-Catalina the shower sump pumps up above the waterline and into a T in the sink drain. The drain serves as the vent and the hose must enter the drain hose above the waterline.

The best engineered tank/pump combination I have seen is from Whale. The ones from Attwood and Rule are more affordable as they use bilge pumps. Whale Gusher pumps can be plumbed directly to the shower drain and can pump when dry.

 
Jul 27, 2015
59
catalina 30 SF bay
I saw an article where the pumps was plumbed directly into the shower drain hose and the outlet hose was tapped into the head sink drain. I think that's an idea that I like I am heading to the boat tomorrow. And we'll look at it deeper.Thanks for all your help.I appreciate it everyone
 
Sep 24, 2018
4,153
Catalina 30 MKIII Chicago
The waterline is 18-24" above the cabin sole for everyone's reference.
The best engineered tank/pump combination I have seen is from Whale. The ones from Attwood and Rule are more affordable as they use bilge pumps. Whale Gusher pumps can be plumbed directly to the shower drain and can pump when dry.
Someone posted a comparison of Rule verse Johnson. If what they said was true, those pumps are at the top of my list when my bilge pump dies
I saw an article where the pumps was plumbed directly into the shower drain hose and the outlet hose was tapped into the head sink drain. I think that's an idea that I like I am heading to the boat tomorrow. And we'll look at it deeper.Thanks for all your help.I appreciate it everyone
Both sink drains are below the waterline. However, check the routing of your shower drain to see if it's going through a large block of wood and resin towards the front of the bilge as I mentioned earlier. If it is, your options may be a bit more limited. Before you make any major investments or changes, try using the shower to see how difficult it is.
 
  • Helpful
Likes: jssailem
Jul 27, 2015
59
catalina 30 SF bay
I have taken a look in the past and yes, it goes down through the block of wood directly into the front of the bilge the hose is gone, I'm assuming that I would be able to take an appropriate tool that I don't know what it is and auger the old hose out. And epoxy, a new one in I will know more when I get there this weekend.That's the first thing to do before I invest anything else