Fresh Water Filters

Technical Articles

Tag: water pump

Questions arise on how to filter the potable water carried by our vessels. Warren Updike, Warr De Mar, #62 writes:

On our boat the Jabsco water pump has a plastic housing on the input side with a small screen inside. This is not a filter, per se, as it is simply intended to protect the pump from particles large enough to damage the impeller. This pump is located under the port settee where one water tank is located in our early version of the C-320.

I installed a separate filter between the pump and the tanks. I used a Pentek 158002 Blue/Black 3/8" Filter Housing with a CBC-5 carbon black water filter. This filter is the same size as the Culligan C-2 very popular in the RV trade. The carbon black filter is the key here, use no other. The result is that the water from the taps is very drinkable with virtually no "tank" taste. Even if you add chlorine to your water tanks this filter will remove the chlorine taste. I bought all this from Be sure to buy the separate mounting bracket and filter wrench too.


Rebuilding Raw Water Pump - Part Numbers

Technical Articles

Tag: water pump

Alan Albrecht, Milagro, #751 has the Euro version Yanmar (3GM30FYEU) and writes: Johnson Pump, USA does not sell a rebuild kit for our pump version F4B-903. Here are the correct impeller numbers (both Johnson and Yanmar) for this model as well as the individual part numbers required for a rebuild of the pump.

1. Impeller = Johnson Number 09810B or Yanmar 128990-42200

2. O-Ring = Included with Johnson Impeller kit above or Yanmar X0506523-01 (The O ring was out of stock but any automotive right size O ring should work)

3. Cam Johnson 01-452888

4. Cam screw Johnson 01-46794-03

5. Shaft Johnson 01-45313

6. Bearing Johnson 01-45207-3 (This is actually a bushing similar to what you have on an automotive water pump. You will need a universal bearing press to change this out.)

7. Yanmar cooling water pipe 128690-49010 (This is the formed hose between pump outlet and the heat exchanger you might as well change it while you are at it)

8. Glycerin, Vaseline or lube to lubricate the inside of the pump until it refills with water.

Other useful numbers:

9. End Cover Johnson 01-42388-2

10. End Cover Screws 0.0141.500

11. Replacement F4B-903 Pump Johnson Number 10-24165-2 (it is around $400 USD)


You may want to consider installing an automotive radiator flush and fill kit on the pump inlet hose to help prime the pump at start up. Items 3 and 4 are optional for a pump rebuild if the originals are at all usable. If you have other problems e-mail Johnson Pump directly they were very responsive and helpful:

Stripped Threads on OEM Jabsco Head Pump

Technical Articles

Tag: head

After reading the May issue of Mainsheet, Australian C-320 owner Mike Cole, Mio Dio, #421 passed on this tip applicable to stripped threads or broken bosses on the OEM Jabsco Head Pump, a common occurrence when getting a bit assertive in reassembly. Mike writes:

Some years ago I also over tightened 2 of the screws holding the pump top and broke off the raised bosses. I didn't replace the body assembly but used a 1/8 inch drill and drilled thru the pump top and body top flange. I then inserted 1/8 inch bolts long enough to assemble with a lock nut on the underside----it works fine. Underneath each of those raised bosses there is a cavity which I think was probably formed when the bosses were pushed upwards during manufacture--the lock nut sits neatly in the cavity. I think they should have been made that way originally not using the self tapping screws originally supplied.

Holding Tank Monitor

Technical Articles
After 3 years sailing Silver Lining, including some extended trips, I finally got around to installing something we’ve always wanted – a holding tank monitor. Normally, I would have not considered an internal, float-style system, but the WEMA kit received high marks on a recent Practical Sailor magazine test. So went it went on sale this summer, I figured the time (and price) was right. 
I purchased the gauge (HTG-WW) and 12” sending unit (SHS-12) online ( for about $83. WEMA recommends that the sensor be sized so that its bottom is no lower than the ¼ full point of your tank. This is to keep it out of the “sludge” and minimize the chance of fouling. Although the sensor can fairly easily be removed for cleaning, I chose to locate it as close to the tank vent fitting as possible. The reason being is that I usually introduce fresh water to the holding tank via the vent line while pumping out. I believe that helps to flush out any solids. Positioning the sensor close to that fresh water spray may help to keep it clean also. 

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Washdown Pump Project

Technical Articles


Several excellent how –to articles have been written in Mainsheet on installing washdown pumps in larger Catalina models and due to time constraints I am going to limit this one to a few notes based on my installation and about four year’s use of our upgrade.


I decided to install PEX tubing instead of hose for the hidden run from the pump to the hose bib. It is much easier to run through the hard to reach areas behind the seats as it is self snaking. It is very freeze resistant and it eliminates the need for clamps by using compression fittings. This has proven to be an excellent, no-maintenance choice. I only needed to drill one hole to run it from under the head sink to the anchor well and that was through the v-berth bulkhead. I installed a few plastic pipe support clamps under the seats to prevent the tubing from sagging and holding water in the low spots when it needs draining.



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Mounting an LCD TV

Technical Articles

Tag: upgrades

I hope this will help you decide on how and where to mount a TV. I bought my bracket and TV at Best Buy in San Diego. I use a small inside TV antenna with a power booster while on the hook or mooring at Catalina. At the dock at Coronado Yacht Club we have cable TV. I have a small inverter that powers it and the DVD player.

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Follow-up to a Hot-Running Engine

Technical Articles

Tag: yanmar engine

Geoff Stevenson, a former C320 owner who now owns a C350, called me after reading the May Mainsheet to point out another possible reason for a hot-running engine. He reminded me of the “recall” on certain Yanmar 3YM engines to correct an inadequately engineered cooling tube array. His experience (on both boats) was an inability to reach max power settings and chronic overheating.

These early (2004/2005) engines have a 38-tube heat exchanger, and some very early engines were reportedly also fitted with a smaller capacity raw water pump than is now used. The fix is to replace the original 38-tube heat exchanger core with a new 63-tube one, and change the water pump if necessary.

If you have a 3YM engine exhibiting similar problems, you may want to check with Yanmar to see if your engine is covered under their (silent) recall, especially if you have an engine serial number under 6,000.


- Karl Mielenhausen, Silver Lining, #690

Connecting An Anchor Washdown

Technical Articles

Tag: pump water upgrades

Prior to our extended Chesapeake cruise last year, I installed an anchor Washdown largely based on the experiences and recommendations of Allan Field, Sea Shadow, #808.
His project can be seen at 
At the time, I removed the hose to the marine head and connected the thruhull to the suction side of the washdown pump, since we avoid using saltwater to flush. Since that time, I have plumbed the washdown into the sink outlet using a “Y” connector. This also allows the ability to easily flush the washdown hose by introducing fresh water through the sink. Winterization is also easily accomplished by using the sink to introduce antifreeze to the system. BTW, I would have liked to double clamp on the “Y” however the length of the fitting did not allow for sufficient area for a second clamp. Fortunately, it was an extremely tight fit for the hose and I doubt it would slip off even without a clamp!

Karl Mielenhausen, Silver Lining, #690

Upgrade to a Larger Holding Tank

Technical Articles

Tag: head upgrades
This spring, we replaced our factory 12 gal.tank with a 22 gal. Ronco B348 tank, the same model now used by the factory on newer C320’s. Why do this? We are cruisers. We like to anchor or moor rather than take a slip. We hate having to pump-out every three days. I use the rule of thumb of 3-4 gal. per day for the two of us. With the new tank, I figure we’ll get at least 6 days between pump-outs.
The original tank was shorter but wider and not nearly as long. It sat on a wood shelf the legs of which were glassed to the hull. The new tank is much longer, taller, but narrower, and needs to sit on the hull so the shelf had to come out. Removing that shelf was the worst part of the job.
The advice received from the C320IA discussion list, including pictures from two owners, was invaluable in giving me the confidence to proceed with the project. Just knowing the job is doable makes it easier to undertake. Having the practical advice makes it worthwhile.  
I bought the tank, hose, and fittings from Catalina in Florida. Ellie Quinn in Parts was a big help. She knows her stuff and got the parts to me quickly. By the way, the prices were as good or better as I could find elsewhere. You can pay $8-$10 a foot for better hose; but, I didn’t bother. The production stuff is good enough for my needs.

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Bilge Backflow Preventer

Technical Articles

Tag: bilge
Frustrated by the bilge partially refilling after the pump stops? Adding a check valve on the pressure side of the pump can help reduce the “backwash”. See the photo. (Many boaters believe that check valves are not favored in bilge pump systems. They reduce flow, are notorious for failing and the added obstruction increases the chance of a stoppage. If you install one, inspect it frequently. – Ed. Note) Another alternative is to replace the OEM pump with an 'automatic' pump (Rule has one) that has no float switch and mounts directly in the bilge (minimizing backwash by eliminating the bilge to pump hose run). They work by performing 'check runs' every few minutes; if the impeller senses resistance (water) the pump continues to run and pump out the bilge. No impeller resistance means no water, so the pump shuts off within a couple seconds. The Rule pump I bought and refer to is rated at 500 gph, draws 1.9 Amps, and is much quieter than the OEM pump.

Warren Updike, Warr De Mar, #62 and Bob Seastream, Intuition, # 906

Accidental Jibe Preventer - Rigging a Boom Preventer

Technical Articles

Tag: rigging sails upgrades

According to Wikipedia, “A preventer, or jibe-guard, is a mechanical device on a sailing vessel which limits the boom's ability to swing dangerously across the boat during an accidental jibe. The uncontrolled jibe (or gybe) is feared by all sensible yachtsmen. The heavy boom can potentially inflict severe head injuries or dispatch crew members over board; even the mainsheet or traveler can also inflict serious injury. Uncontrolled jibes may also damage the boat itself.”

On Sea Shadow, a Catalina 320 (#808), we take the threat of the uncontrolled jibe very seriously. While I have always secured the boom to a forward deck cleat when sailing any lower than 120 degrees apparent off the wind, it was not until I had the opportunity to sail with Orlando Duran on his Catalina Morgan 44 that I learned a better way to rig a boom preventer.

The main sheet on the C320’s runs thru two blocks. On the aft most block, I hung a 3-inch shackle from the bail that the block attaches to. Picture number one shows this arrangement.

From each of the forward deck cleats, I hung 3-inch shackles and then a single block off each of them. The reason for the long shackles here is to leave room for mooring lines. Picture number two shows this arrangement. Note that the preventer lines are in the stowed versus deployed position in this picture.

Moving aft, I hung a single block on the base of each stanchion port and starboard sides for a total of 8 blocks, 4 on each side. Picture three shows this arrangement for one of the stanchions. This picture also shows a Garhauer E-Z glide genoa fairlead car, a wonderful addition for keeping one in the cockpit when the cars need to be moved.

At the base of the forward part of each side of the aft wraparound-stanchion, I attached a single block with cam cleat. Picture number 4 is a close-up of this block but it also shows in picture number 3.

Sea Shadow has two 66-foot preventer lines, one for port and one for starboard (red line for port, green for starboard). West Marine's professional rigger spliced onto the end of each preventer line Quick Release Shackles, both visible in picture number one above. These two shackles are then attached to the shackle on the aft most mast bail, again visible in picture number one above. The preventer lines then run forward to the blocks on the forward cleats (see picture number two) then back through the blocks at the base of the stanchions and through the blocks with cam cleats (pictures three and four). Once these lines are deployed, I can control the boom 100% from the cockpit.

I was hesitant to use the anchor roller for any of this. Worst case scenario on Sea Shadow in a particularly violent accidental jibe probably is that the boom breaks or bends mid-boom or a deck cleat pulls out. Worst case scenario by using any part of the anchor roller is the anchor roller plate gives way, the forestay breaks and the mast comes down. (NOTE: I did hang a block off the anchor bail and run the asymmetrical spinnaker tack line through this block and up to the ATN Tacker. A rigger saw this and cautioned me that this puts loads on the anchor roller and there is a danger of it pulling out. But the maximum apparent wind I will fly the spinnaker is 12 knots; gets any higher, the spinnaker comes down.)

Our spinnaker pole is mounted to the mast on a track so is fairly easy to handle, much easier than when deck and/or stanchion mounted, as one end of the pole is always attached to the boat. Between the preventer rigging and mast-mounted pole, we have no hesitation going DDW (dead downwind) wing-on-wing under virtually any conditions. Note that although we carry and use an A-Sym spinnaker, the A-Sym is not a DDW sail.

Allan S. Field, Sea Shadow, #808

Overheating Engine

Technical Articles

Tag: engine

An overheating diesel is usually the result of one of three conditions: either the engine is working harder than normal (possibly due to a clogged or defective injector), the supply of cooling water has been reduced, or the thermostat is failing to open. The actual temperature of the cooling water will also affect your engine’s operating temperature but this is a change that usually occurs gradually as the season progresses.

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Improved Boarding Ladder

Technical Articles

 Tag: upgrades

The MkII design features a redesigned boarding ladder which can be deployed from the water. On my pre-MkII boat, ladder deployment, if in the water and not having a mate onboard, was a concern of mine. I attached lines to the latches and to the ladder and they can easily be reached while in the water. The lines release the ladder and pull it down to the water. Safety is a good thing.
- Wayne Strickland, Wayne's World, #594

Reducing Icebox Volume

Technical Articles

Tag: upgrades galley

One of the many modifications we have made to Tradewind, hull number 626, is to reduce the interior volume of the icebox using removable pieces of foam. On previous boats we were accustomed to using an ice chest and rowing ashore every couple of days to get ice, so having refrigeration was a true luxury. But the cavernous volume of the icebox required more engine hours, and beyond milk for cereal, a couple of cold beers, produce, and a few other items needing to stay cold, the rest was wasted space. So I set about making it into an ice-chest sized volume.

dumpsters around the harbor I collected several discarded Boogie Boards for their foam. It can be measured and marked with a Sharpie pen, and accurately cut with several passes from a filet knife. Just cutting a rectangle to sit on the “ledge” about twelve inches down reduces the volume by about a third, and means no more blindly groping for items in the well at the bottom. Then I cut a vertical piece which fits snugly under the gasketed plastic insert in the middle to reduce the volume by another fifty percent, and the result is about the size of an ice-chest. After returning from a cruise I remove all pieces and swab out accumulated moisture from the well at the bottom, as I have plugged the drain, (I keep a dry bilge.) So now our solar panel mounted on the bimini, along with minimal motoring, keeps up with the electrical demands of our refrigeration system.

- Dave White, Tradewind, #626

Repairing the Aqualift Muffler

Technical Articles

Tag: engine upgrades

The Aqualift muffler on Silver Lining recently developed a leak due to a crack in the underside of the base. Unfortunately, this appears to be a problem that has affected a large percentage of our owners, so there was an abundance of information on our discussion list to review. A C36 owner also assisted me as he had been through the same problem, although his cracks were in a different location (the exposed portion of the base as well as inside the mounting holes). I have also heard of cracks to the hose tube. After hearing bad reports about the quality of the Catalina factory repair, and not wanting to be without the use of the boat for 2-3 weeks, I decided to make the repairs myself.


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Head Maintenance

Technical Articles

Tag: head maintenance

There has been a lot of discussion recently about replacing the marine toilet. Several members have taken the advice of others (including testing recently conducted by Practical Sailor magazine) and are replacing the Jabsco Compact unit with the higher rated, and more expensive, Raritan PHII. It appears to be a fairly easy conversion, although new bolt holes for the base must be drilled.

Here are a few tips for getting the most life out of whichever marine toilet you use:

Some marine writers advocate pouring a cup of vegetable oil or mineral oil down the toilet to keep those valves supple, and to lubricate the seals of the manual pump plunger if the unit has one. However, the nation’s foremost expert on marine heads, Peggy Hall, directly contradicts this advice. If you have a manual head, she suggests that you dismantle the pump occasionally, check the plunger stem and its O-rings and coat both with a PTFE lubricant (such as Synco’s Super-Lube Teflon Grease).

At the end of each weekend, or any time the boat will sit, after you've closed the seacock, run a quart of clean fresh water through the toilet, followed by a cupful of undiluted white vinegar. The clean fresh water will go a long way toward preventing odor from permeating the head discharge hose. The vinegar dissolves sea water minerals so they don't build up in the hose. Be sure to push the vinegar all the way through the discharge. Don't leave it sitting in the bowl more than a few minutes. It won't do any good sitting in the bowl, but it will cause the joker valve to swell up and distort if it soaks in vinegar for days.

Cleaning Interior Wood

Technical Articles

Tag: interior maintenance

What is important to remember is that you are actually cleaning and polishing the finish, not the underlying wood. For us, that means the cured Target Coatings Oxford II water based acrylic lacquer or, more recently, the 7000 series HybriVar WB, which offers more clarity and chemical resistance. So put away the oil soap or lemon oil and use plain old window cleaner. High pH cleaners (ex. 409) can dull the finish over time. If you’re trying to remove fine scratches, Target Coatings recommends 3M Finesse. I’ve had some good luck using a paste polishing compound designed for automobile clearcoat finishes. It has given the sole on Silver Lining some additional luster and richness – just don’t overdo it and make it too slippery. Also, never use any wax or silicone-based products.


LED Lighting Addition

Technical Articles

Tag: upgrades interior

We’d arrive at the boat at night, we’d find ourselves stumbling around looking for a flashlight and trying to find the light switches. My solution was to install two red LED fixtures (ABI - 471124). One is located behind the companionway stairs and the other is located over the circuit breaker panel, shining down to illuminate the switches. I used a spare position on the panel and installed a 5A breaker in order to have a way to easily switch the fixtures on and off. The fixture behind the stairs was easily recessed into the bulkhead; the one above the panel needed to be surface mounted, requiring the fabrication of a mounting block. An unexpected benefit has been in using these lights while anchoring out. They make a great “nightlite”, drawing little current (60mA total), yet providing enough light to move about the cabin. Putting one more fixture in the head compartment (the usual late night destination) will make this installation complete.

Trash Can Alternatives

Technical Articles

Tag: upgrades interior

Several of our owners have come to the conclusion that the factory-supplied trash can location (under the galley sink) is woefully inadequate for anything more than daysailing or for storing your cleaning supplies. Three alternatives have been suggested, each of which offers a larger container with improved access. Several owners have an under the nav table arrangement. Orlando Duran (Cuba Libre 2 #112) suggests placing the trash can (13L size) under the nav table, installing a couple of hooks and running some shock cord around the can...out of site, out of mind. Joe Barrett (Island Time #689) suggests using a couple of suction cups instead of the hooks. Pat Moriarty (Sexual Heeling #130) made a beautiful, slide out cabinet for under the nav table (see photo).

Also suggested is the behind the stairs alternative. Jon Vez (Solstice #582 ) found that a larger Rubbermaid trash can that fits the 'large size' trash bags fits perfectly between the forward engine cowling and the companionway steps. It is just snug enough to keep it in place while heeled and exposed enough to toss things in from the cockpit. Adam Weiner (Kele #218) has a variation on this approach and has a can on top of the stored hatch boards. To hold the can in place he cut and sanded a piece of teak into a nice shape, screwed the teak piece into the teak bar above the ladder and pivots this piece over the lip of the trash can. The big advantage of this set up is that it is accessible to the cockpit AND the galley.

Lastly, Bruce Stanley (and others) have attached a small trash bin to the inside of the galley, undersink, door (very handy for scraping plates) and then they move the trash into a larger bin located in the port lazarette (at the stern) where they also separate out and store recyclables.

Anti Siphon Valve Maintenance

Technical Articles

Tag: maintenance water

There are 3 anti siphon valves on our boats and they each have a critically important function and, as such, it is vitally important that the valves operate properly. I believe that the majority, if not all, of our C320’s use the vented loop with “duckbill” valve as opposed to the check ball type valve. The good news is that these valves are easy to access and easy to maintain.

The anti siphon valve in the port lazarette is used to prevent water from siphoning through the cooling water seacock, through the engine cooling system, into the mixing elbow, and into the Aqualift muffler when the engine is not running.

The other two vented loops are located in the “medicine” cabinet over the marine toilet. One is used to prevent water from being siphoned through the seacock and into the shower sump and the other prevents water from siphoning from the seacock into the toilet.

On the top of each of the vented loop assembly, there is a threaded plastic cap with a small hole in it and in which is a small buna rubber one way valve that resembles a duck’s bill. The valve is normally closed, but if a vacuum is drawn within the loop, the duckbill valve (which is pointing down, away from the cap) opens, allowing air to enter.

Maintenance is simple:

1/ Remove the cap and insure that the hole is clear. Never plug the hole and don’t replace with a solid cap. If water leaks from the cap, it means the “duckbill” is missing or defective.

2/ Remove the duckbill valve, being careful not to tear it. Clean with nothing stronger than white vinegar. Do not lubricate and especially avoid contact with solvents and solvent-based lubricants, such as WD-40. (Ref: Art Bandy, Forespar)


Shake, Rattle, and Roll

Technical Articles

Tag: diagnostics engine prop

Here’s an interesting story but not a good example of the usually good troubleshooting skills I pride myself on having...

The last couple of times I've been out, I noticed a sort of rattling under power but only at one specific rpm. The usually trusty, Yanmar 3GM was a little rougher at idle (in gear) also.

It sounded like I had caught a fishing line and the lure was whacking against the hull as the prop turned. The noise was louder in the cockpit, but barely noticeable in the aft cabin. Since it only occurred at 2000 (+/- 50) rpm, I was ignoring it.

Finally had a friend listen and he offered to dive the boat. No fishing line found. All zincs still tight to shaft. Shaft turned easily. No cutlass wear. No prop or shaft fouling (which was good since I pay a diver to clean every other month). No obvious prop damage.

So I decided to avail myself of the excellent alignment procedure and calculation spreadsheet that we have on our website ( Opened up the engine to shaft coupling and it proceeded to open up to the tune of a .071" deflection at the top position!!! Side to side was fine.

So I said WOW!!! The front of the engine really needs to be raised (perhaps in combination with dropping the rear). Only then, was when I discovered that the jack nut on the portside front mount had come loose and was actually down to the base of the mount. So, that mount was doing nothing except constraining the engine foot from going any higher. What I couldn't believe was that the engine did not appear to be shaking wildly at the offending rpm, but apparently the shaft was whipping to some harmonic.

Anyway, I got the up/down alignment very close (.002) and gave up trying to horse the engine left/right once I achieved a .003 misalignment laterally. Runs smooth as silk now.

Funny thing, I was relating this story to a friend who had previously owned a C320, and he said that the exact same thing had happened to him.

So, checking the locknut and jack nut tightness, as well as the screws into the engine bed, are now on my annual maintenance checklist. Consider adding it to yours or to your pre-launch checklist. The alignment itself is non-trivial, but, checking mount bolts, checking cutlass play, checking thrust play, checking coupling bolts and wires, and changing the transmission fluid are simple things to do and should be done.

Winterization Tips

Technical Articles


Whether you winterize your Catalina 320 yourself or have your boatyard do it, the following can serve as a guideline for the work that should be accomplished.


Remember that the primary objective is to prepare your boat for the possibility (or inevitability) of freezing conditions. Fluids must be removed or protected and nothing should be aboard that might be damaged by low temperatures. As always, manufacturers’ instructions have priority. We’ll start with the engine, since that is best winterized prior to haul out, and then assume the other systems are winterized “on the hard”.

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