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

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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.

Before Photos

The following photos show the boat before adding the bilge pump system upgrade. The text description for each group of photos is above them. They are provided to help give you a picture of the starting point.

Photo (1) is the existing Rule 1500 pump and switch mounted on an ~ 5/16” raised surface glassed into the bottom of the bilge. Notice the severely rusted hose clamp. I was not able to loosen it so used my Dremel tool to cut the metal band to remove it. Photo (2) is the aft most bilge section. The 1 1/8” hose for the Rule 1500 and one of the in line check valves ran along the bottom of the bilge and through a ~2” hole in the port to starboard stringer to attach to the pump located in the center bilge section. Also in this bilge section is the end of 1 ½” manual bilge pump hose. It had a screen tie wrapped over the end to keep debris from being drawn into the hose and eventually the pump. The screen was torn and the hose clamp for the in-line check valve was rusted.

(1)1500 Pump and Switch.jpg

(2)1.12 Hose check valve and manual pump.jpg

Photo (3) is the 1st keel bolt in the aft bilge section with the bilge hoses moved out of the way. Photo (4) is the 2nd keel bolt in the aft bilge section also with the bilge hoses moved out of the way. Both showed quite a bit of corrosion from the standing water that used to sit in this section. One of my first upgrades was to install a SST propeller shaft and change the packing gland material to a Gortex product. Now this section remains dry. Later in this write up are photos after I cleaned all the keel bolts With Davis brand FSR.

FYI – I’ve been told that Gortex can only be used with a SST shaft. Don’t know the reasons behind it, but you can’t use Gortex with a bronze shaft.

(3)1st Aft Keel Bolt Corrosion.jpg

(4)2nd Aft Keel Bolt Corrosion.jpg

Photo (5) is the same bilge section but farther aft under the subfloor showing another rusted hose clamp on the 1 1/8” bilge hose. I point these out because this is the primary bilge pump system that could fail, even with a good pump and switch. I suggest you look at your bilge hoses and clamps, even if not planning to change anything.

(5)Rusted Hose Clamp.jpg

Photo (6) is under the aft cabin on the starboard side. The hose shown is the ½” fresh water supply line from the aft water tank going to the galley sink area where it connects into the main fresh water line with the starboard water tank prior to the fresh water pump. Previously I had run the starter, alternator out, and main negative cables through this opening. I found a way to route those cables more directly to the engine compartment. See photo (7). This routing change is both better electrically, and it gets the hot and cold fresh water hoses to the head sink out of the engine compartment which then frees up this opening up to run the 1 1/8” bilge hose for the Rule 1500.

(6)Aft Water Pass Thru Under Aft Cabin.jpg

(7)Cables With Chafe Protection.JPG

Photo (8) shows the thru hull for the 1 1/8” bilge hose. The thru hull is located high on the starboard side of the transom near the split back stay chain plate.

(8)1.12 transom thru hull.jpg

Photo (9) shows the manual bilge pump hose in the aft lazarette with the propane locker and shelf protecting the radial removed. The manual bilge hose discharge thru hull is very low on the transoms centerline just barely out of the photo. The two light colored hoses are the vent lines from the propane locker moved out of the way to get in this area to work.

(9)Manual Pump Hose Connection to Thru Hull.jpg

The Design Goals

Locate all components to be easily accessible and serviceable with minimal effort. Add a Rule 3700 electric bilge pump to add pump capacity and have redundancy in the bilge pump system. Remove all in-line check valves and use vented loops as an anti-siphon for the 1 ½” bilge hose system, and to minimize run back into the bilge from the 1 1/8” bilge hose system. Remove corrosion from keel bolts. Size all hoses to match the pump exit and to be smooth bore inside for minimal flow resistance, and outside to make clamping more secure.

Rule 3700 Pump & Float Switch Installation