Catalina 320 stemhead fitting sudden failure. Check your rig!

Technical Articles
Catalina 320 stemhead fitting sudden failure. Check your rig!
The design of the original stemhead fitting (the part that is bolted to the bow, to which the forestay attaches) lends itself to the initiation of crevice corrosion type cracks that progress through fatigue until the entire fitting gives way with a possible loss of your mast! This file shows where the crack originates, and some examples so you can better check your own rig.


This first picture shows side by side the original design (and a replacement without the side 'gusset plates'). The left end is the part that projects upwards towards the mast and to which the forestay, or bottom of your furler) attaches...
Continue Reading 0 Comments

Adding a Backstay Adjuster

Technical Articles

Tag: upgrades rigging

Submitted by Jon Vez


Following is the procedure I used to install a backstay adjuster on my 1999 320. This method requires no drilling and will work fine if you use a bimini.

The 320 has a substantial masthead type mast with no real ability to bend, so the purpose of the adjuster is not to induce mast bend, but to tighten the forestay when sailing upwind. Tightening the forestay allows you to point higher, reduce heel, and lessens the tendency to round up in strong breezes.

This configuration also allows you to back off the tension on your backstay for improved sail trim when off the wind. Many sailors see a backstay adjuster as an upgrade just for racers, but I believe that this upgrade is equally compelling for cruisers as well. Having a well trimmed boat with less healing and better upwind performance simply adds to the pleasure of sailing!

To create the attachment points for the adjuster, you will simply replace the clevis pins at each backstay tang with a D shackle. The pin that comes with the D shackle replaces the original clevis and the ‘D’ portion becomes your attachment points for the adjuster’s blocks and tackle.


I chose to create an adjustment on each side of the backstay. I originally took this approach to increase purchase, but there is the added benefit of creating less clutter in the cockpit. The starboard side is my ‘course’ adjustment and the leeward the ‘fine’ adjustment.

The actual installation time was about 3 hours for two people including tuning the rig.

Continue Reading

Lubricating the Head Pump

Technical Articles

Tag: head pump


On, Isle of Wight, we would often have a problem with the Jabsco plunger screeching and being difficult to pump. It just so happens that when the boat was delivered, we found a crack in the pump housing and Catalina sent us a new pump to us for replacement of the defective one.


The maintenance instructions in the manual with the new pump, noted that the proper lubrication for the pump plunger was petroleum jelly (Vaseline). Some owners never get around to reading the manuals that come with the boat, but with a replacement part its difficult not to. So every time the pump leather got dry and difficult to pump, we dutifully removed the pump plunger to lubricate it. To do this remove the 6 screws that hold the top of the assembly to the pump body. Carefully remove it to save the gasket and the rubber flapper valves that switch from “”Flush” to “Dry”. When removing the top assembly note the position of the rubber flapper valves so they will be correctly positioned when the top assembly is replaced.


We have lubricated that pump several times. We removed the plunger. Smeared the inside of the pump body with Vaseline above and below the plunger, and replaced the pump top tightening the screws. And the pump always worked so smoothly we wondered why we always waited too long to relube the plunger.

However the last time we did the miracle cure we over tightened one of the screws. These screws fit into raised bosses on the pump body. In over tightening the screw, one of the bosses broke off of the pump body and it was impossible to get the seal necessary for the pump to work.


So the moral of the story is, if you want an easy operating Jabsco head pump, lubricate it with petroleum jelly. Note: be careful not to over tighten the gasket screws for fear of popping the screw bosses from the pump body because it will require a new body assembly. The cost was approximately $115 when we replaced it and it is kind of messy and stinky. This might also be a good time to replace the JOKER valve if you have to replace the pump assembly. Sometimes you can catch one of these heads on sale for about the same price.


Webmaster Note: West Marine sells a liquid product called “Head Lube”. A splash of this in the bowl with  one pump when leaving the boat works well also.  When winterizing, RV antifreeze does a nice job of keeping the plunger flexible and the system pumping smoothly.

Refrigerator Top Insulation Tip

Technical Articles

Tag: galley refrigerator

One easy way to keep items in the refrigerator colder is to cut and install a Reflectix blanket at the top of the refrigerator opening.  This material is a double layer foil covered bubble wrap insulation.  It easily stays in place by just pressure fitting.



The tops close without disturbing it and it’s easy to access the food inside by just lifting up the edges.  Makes a surprisingly big difference in how cold things stay inside.


Cabin Top Clam Cleats for the Mainsheet

Technical Articles


Tag: rigging

There have been several discussions over the years on our discussion forum about using the Mainsheet Clam Cleats that are mounted on the cabin top.  There has been some confusion from time to time about the purpose of the Red Spring Gate.  One might think that the purpose of this is to guide the line into the teeth of the cleat.  In fact, its purpose is precisely the opposite.  Its purpose is to Prevent the line from jamming in the cleat when you don't want it to.  When the gate is down, a line can be jammed in the cleat.  When the gate is up, it prevents a line from jamming in the cleat.




Proper use of the mainsheet Clam Cleats


C320 Snap Davit Installation

Technical Articles

Tag: upgrades exterior

Snap Davits for Sailboat

About the Author: David Swanson and family currently sail their 2007 Catalina C320 MK II sailboat, Emily Ann, out of Shilshole Bay Marina on Puget Sound. They originally kept their boat in San Diego and sailed it for two years there exploring the SoCal coast and Catalina Island before moving their boat to their home waters of Puget Sound.


Cruising Southern California and the Puget Sound on our 2007 Catalina 320 MK II Sailboat requires that we carry an inflatable dinghy. To make the process of carrying the inflatable easier, I mounted a tilt-up davit system that is traditionally used for power boats to our Catalina 320 sailboat. The tilt-up davit system was manufactured by Weaver Snap Davits ( and adapted to our C320 MK II. Our inflatable dinghy is an Achilles LSI 2.90 ( The length of the Achilles inflatable is 9’-6” which is well within the 11’-9” beam of our Catalina 320.

About 10 years ago, when our children were much smaller, I installed a similar set of snap davits on our Hunter 30 sailboat. The system is very easy to use, helps in boarding the dinghy, and keeps the inflatable secure and out of the way when sailing or motoring. It is an elegant way to carry our inflatable dinghy when sailing, cruising, and island hopping.

This new set of Weaver Davits that I installed on our C320 MK II are slightly different with a “snap up” feature. We had Weaver industries build a custom set of Snap Ups to match the angle of our C320 transom and also install an “intermediate” snap up hole to allow us to vary the height at which we carry our inflatable dinghy. I created a sketch of the dimensions and rake angle of our stern from our C320 and provided them to Weaver Industries for the fabrication of our davits, so if anyone would like them, just send me an email and I can forward a PDF copy of the dimensions that we used for our 2007 C320 MK II sailboat.


2007 Catalina 320 MK II, Emily Ann, with Inflatable Dinghy Stowed on Davits

We have had many people comment on how elegant this system works to stow our inflatable, so I thought that I would share our installation with fellow C320 owners. 

The rest of this article explains how these were installed.


Continue Reading

Antifouling for Prop

Technical Articles

Tag: maintenance prop

From the C380 List and Warren Elliott:

When liberal amounts of grease fail....

I have been using Pettit's #1792 Zinc Coat Barnacle Coat" [$20 Defender, grey] for several years with excellent results. This is a pressure can of spray pint..2 or 3 light coats are used. Dries very quickly so easy to overcoat.

However last season quite a lot of unusual tiny barnacles accumulated on prop & shaft. Apparently some new organism came from who knows where.

I spoke with two different Pettit reps. One suggested trying same paint again...perhaps the growth was result of unusual weather, etc.

The other rep suggested I switch to their "Alumispray" [#1863, $30 Defender, black], which is basically the same formula but made to ablate.

Taming An Erratic Tachometer

Technical Articles

Tag: engine diagnostics

Courtesy of the C380 List and Tom Soko, Juniper, C400 #307:

It might not be as bad as you think. When I bought my 400 in 2009, I noticed the same symptoms with the tach. Sometimes accurate, but mostly very high readings (I knew the engine wasn't idling at 4k!), and the tach varied quite a bit while the engine was stable at one RPM. I first checked all electrical connections, and they were all tight. I talked with Dennis at Seaward Products. They build all the engine and electrical panels for CY, and have done so for many years. Dennis is the panel guru, and most likely assembled your panel (yes, him personally!). He suggested using a small screwdriver and moving the selector screw back and forth a bunch of times (the A-B-C-D screw in the back of the tach). He said that the internal contacts sometimes get corroded, and that by moving the screw, the contacts are somewhat cleaned. Sort of like old-fashioned TV sets with manual tuners. The contacts get dirty and need to be cleaned. My selector screw was fixed in place by a small drop of ?lacquer?, but Dennis said not to worry about it, it's OK to break the "seal". He told me he put the drop there to keep "happy hands" away. After you move the selector switch, you can put a drop of nail polish on it if you want to, but it's not necessary. BTW, my tach has been working well for the past 1.5 yrs after I cleaned the contacts. Hope this helps.

Filtering Potable Water

Technical Articles

Tag: water

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 the cooling water pump on the EURO version Yanmar

Technical Articles

Tag: yanmar 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 the Jabsco Head Pump

Technical Articles

Tag: head pump

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.

Routing Ducting for a Reverse Cycle AC Upgrade

Technical Articles

Tag: upgrades interior

There are no pre-engineered duct paths built into the C-320 contrary to some widely held beliefs. Some HVAC upgrades are very simple and minimize ducting and attendant carpentry associated with concealing the ducting. Others like the ones pictured here are more complex and involve a great deal of carpentry.



Continue Reading

Adding a Dedicated Starting Battery to the C-320

Technical Articles

My dedicated starting battery is sitting on a shelf that I added in the space just forward of the forward 4D in the starboard side settee. As a slight port list is typical for many C-320 owners and the space is ample for the purpose, this is a favorite location for many later model C-320 owners where the batteries are located under the middle of the starboard settee. This location is also desirable in keeping the new jumper wires short which reduces resistance and voltage losses.


Continue Reading

Flushing the Holding Tank

Technical Articles

Tag: head

For what it's worth, here is the recipe we've been using for flushing the holding tank for winter lay-up. We think it is very effective as the last flush is quite clear.

Holding Tank Recipe Ingredients: 
  2 c. Calgon Water Softener (liquid) 
  1 c. liquid laundry detergent 

Add two cups water softener in 1 gal. hot water. Pour/pump mixture into tank. Add one cup detergent to 1 gal. hot water. Pour/pump mixture into tank. Let sit for several hours then top off tank with fresh (hot if possible,) water and let sit for a few more hours. Even better is to sail with the tank full to thoroughly agitate the mixture in the tank. Pump out and rinse/pump with fresh water. 

Tip: Many RV stores carry a wand that attaches to a hose to provide a high pressure spray. Use this in the inspection port of the tank (if you have one) then rinse/pump again with fresh water. You may also be able to go in by removing the vent fitting on the top of the tank.

- Warren & Pattie Updike, Warr De Mar, #62

Continue Reading

Clogged Exhaust Elbow on Perkins M30

Technical Articles

If you happen to have a Perkins M30 diesel in your 320 and you idle the engine to charge your batteries, you risk building up carbon deposits in the cast iron exhaust elbow at the rear of the engine where the raw water mixes with the engine exhaust on its way to the water lift muffler. When this occurs, the symptoms typically include loss of engine rpm coupled with excessive amounts of thick black smoke caused by incomplete combustion of fuel since the engine can’t “breathe”. Removal of the elbow is pretty straight forward although the four nuts that secure it to the exhaust manifold can be a bit of a challenge. 

You could opt to clean and reinstall the elbow if it’s in otherwise good shape, however if it looks like the one pictured here you’ll have to spend the $350 or so for a new one. Either way after tackling this job you will probably find fewer reasons to idle your engine in the future.  

John Dean, Midnight Run, #227  


Yanmar Shifting Problems

Technical Articles

Tag: yanmar diagnostics transmission

Several C-320 IA members have been experiencing shifting difficulties with the KM2 transmission on the Yanmar 3GM engine. A marina neighbor experienced the same problem with the same engine in his Hunter 34, so we did some research on the problem. It didn’t take long to find numerous references on the internet including, sadly, some real horror stories about low time failures and expensive, non-warranty, repair bills.  This article steps through diagnosing and correcting these problems.


Continue Reading

What Color Is Your Exhaust?

Technical Articles


The color and quantity of exhaust smoke tells a great deal about the condition of a marine diesel engine. All marine engines create smoke to some extent, but if the diesel engine is in good condition, the quantity will almost be invisible. Defects that affect the fuel, breathing or compression will prevent correct combustion and lead to excessive exhaust smoke.

The following analysis comes from U.S. Master Marine Surveyor Rob Scanlan and is presented courtesy of RCR Yachts.

Continue Reading

Steering Cable Failure

A failure of the steering cable was reported by Ken Danko on hull 802 on 12 October 2008. Conditions at the time were choppy seas and 25 kt winds. Ken's assessment and photos are captured below, along with responses by Gerry Douglas (Catalina Yachts) and Ed Siess (Edson).

At the end is additional thoughts and learnings from Ken and a reaction to the information provided by Edson.

My suggestion would be immediate inspection of your steering cable and rudder stops, looking especially for wear in the same area as Ken's failure (recognize that cable wear has also been reported at the chain link end inside the pedestal). Follow up with annual cable and stop inspections.

Continue Reading