Macerator

1987 MK 1 Catalina 34 Macerator Change

By Jon Windt; s/v Della Jean

NOTE - Before doing any projects, I highly recommend that you first go through the “Critical Upgrades” list and verify that your boat has all of the applicable items addressed. There is a link on the Message Board (copied here) entitled “CRITICAL UPGRADES – DO THESE OR ELSE!!!” that will take you to them. It is a good way to both learn your boat and make sure it is safe.

Original Sanitation System Description

I purchased my Catalina 34 in April 2015. She is a 1987 MK1, hull #493.

The sanitation system starts with a ¾” hose connecting a dedicated thru hull under the head sink to the inlet of the Jabsco manual toilet. From there it travels through an anti siphon loop to the toilet bowl inlet. The discharge from the toilet is through a 1 ½” sanitation hose that connects to the upper outboard corner of the holding tank. There are three additional sanitation hoses connected to the holding tank. One is a 1” sanitation hose that connects the top of the holding tank to the vented station on deck. The second is a 1 ½” sanitation hose that connects the holding tank to the pump out fitting on the deck. The third is a 1 ½” sanitation hose that connects the lowest corner of the holding tank to a 90 degree elbow FPT x hose barb threaded onto the macerator pump. The macerator discharge is a 1” sanitation hose that connects to an anti siphon loop and ends at the thru hull.

The macerator pump is a Jabsco 18590-2092 marine run-dry macerator pump.

FYI: Although rated for 1500 GPH, actual flow depends on the rise from the pump to the discharge thru hull. Per the installation guide for RULE bilge pumps, the Rule 1500 with a 5 foot rise will flow ~ 875 GPH with a 1 1/8” hose.

Background

Working on the macerator pump and sanitation system was not something I thought would need to be done for several years. I thought that because when I bought the boat, I was told the previous owner had replaced all of the sanitation hoses and the macerator pump.

The PO may have done that, but I noticed the pump leaking while I was running the 12 volt outlet wires to a dedicated fuse block. Looking closer I noticed the nut was loose that holds the pump housing to the pump/motor. It turns out the nut wasn’t loose, the actual stud had failed. When I looked at the other three, a second stud had also failed. When I took the pump housing off it turned out all 4 were in the process of failing from severe corrosion.

This write up provides a summary of the macerator pump replacement I did with photos. I've numbered the photos to help with connecting the text to the associated photo.

This was not a very complicated project, but a very unpleasant one as you can imagine when dealing with the holding tank and no shut off. All in all, I ran ~ 2 feet of new 1 1/2” ID SHIELDS RUBBER Poly X Sanitation Hose from the holding tank to the macerator pump. I also added ~3’ of new 1” ID SHIELDS RUBBER Poly X Sanitation Hose from the macerator pump discharge to the anti siphon valve. The motor is rated as 16A. I could have stayed with the original 15A circuit breaker on the main distribution panel for the macerator pump/motor, but decided to change it out to a 20A per the owners manual. The wiring is 10 AWG and had already been run as part of my complete electrical upgrade completed in the 1st Qtr of 2016. Details for that are in a separate write-up titled “1987 MK 1 Catalina 34 Electrical System Upgrade” I added to the Tech WIKI.

As a final note, every boat is different. The routing, methods, and hose lengths I used may not work on your boat. Please read this as a summary of what I did, not as a manual of what you must do. This is one way, not the only way. Good luck and I hope you find this write up helpful.