1987 MK 1 Catalina 34 Adding A 2nd Electric Bilge Pump

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. Don’t put it off.

Original Bilge System Description

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

The bilge pump system consisted of one Whale brand manual bilge pump and one Rule 1500 Gallons Per Hour (GPH) electric bilge pump.

The manual bilge pump has a 1.12” corrugated hose led aft from the aft bilge section to a Whale pump mounted in the aft lazarette. The discharge for this pump is located on the centerline of the vessel at the lowest point on the transom.

The Rule 1500 electric bilge pump has a 1 1/18” corrugated hose led aft to the transom where it discharges in the upper starboard corner of the transom near the split back stay chain plate. The hose consisted of several sections of two different types of hose and 3 in-line check valves attached with SST hose clamps. Two sections of hose were press fit together without any hose clamps and as a result had minor leaks. The electric pump is controlled by a 10 amp breaker with an auto/on/off switch arrangement located on the Main Distribution Panel.

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, and the Rule 3700 with a 3 foot rise will flow ~3,000 GPH with 1 ½” hose. Total with both pumps on is ~3875 GPH or ~ 64.5 gpm exiting the boat.

Background

I am refitting my C34 for future short and extended cruising. A priority for me is reducing failure modes. Popular opinion is that after the integrity of the hull, the integrity of the bilge pumping system is most critical. My current set up with one manual pump and one electric bilge pump provides no redundancy so for me is not a robust enough system. Three “common” failure modes are an unexpected failure of the engine water exhaust hose causing the engine to fill the hull with water or, the single electric pump or switch fails, or a sea cock or thru hull fails before you realize the failure has occurred. While a single 1500 Gallons Per Hour (GPH) pump (which doesn’t pump 1500 GPH as noted earlier), may be able to keep up with the ingress and provide you time to stop/slow the flow of water, the safety margin of the system can be improved by increasing the number of pumps.

Adding additional bilge pumps is a choice I’m making. The cost of ~$335 for the Rule 3700 pump, switch, bracket material to mount them, hose, clamps, and vented loops for me , is a small price to pay for the peace of mind, and increased reliability. As an FYI – I may add a 2-way selector valve to the engine raw water inlet before the filter with a hose to reach into the forward berth section. This would give me a high flow mechanical pump for a true emergency for minimal cost with the turn of the valve.

FYI: Regardless of how good the bilge pump system is, it is dependent on an electrical and battery system that can run them for the necessary period of time. I’ve recently completed a major electrical upgrade of the batteries, charging system, and core electrical systems so believe I’ve got the electrical system covered.

This write up provides a summary of the bilge system upgrade I did with photos, plus a parts list. I've numbered the photos to help with connecting the text to the associated photo.

This was not a very complicated project, but like most projects I’ve done on this boat, nothing was straight forward the first time around. It required lots of thought and decisions each step of the way. All in all, I ran ~ 25 feet of new smooth bore 1 1/8” bilge hose, and about 25 feet of new smooth bore 1 ½” bilge hose. I added a second Rule 3700 GPH pump with a separate float switch connected to a dedicated 25A on/off/AUTO breaker on my Main Distribution Panel. The wiring 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 MK1 Electrical System Upgrade – Feedback Requested 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.