Offshore Log:
A Major Overhaul For A Faithful Perkins

Of all the work done on Calypso during its six-month hiatus in New Zealand, none was more important—and expensive—than rebuilding the diesel engine.


The auxiliary engine of the average cruising sailboat takes a lot of abuse, and our Perkins 4-108 has been no exception. In just over three years of operation, the engine accumulated almost 2,000 hours. Unfortunately, a large percentage of those hours—well over half—was spent with the engine functioning as a lightly loaded generating plant.

Offshore Log: <BR>A Major Overhaul For A Faithful Perkins

In addition, the engine sat quietly in the hull for a decade while a boat was built around it. Despite periodic turning over by hand, the years of inactivity did the engine no favors. It was tired before its time.

By the time we reached New Zealand, the engine was in dire need of help. Oil was pouring from the rear seal. Every gasket on the block was weeping. Actual oil consumption was impossible to monitor, as so much oil was oozing from the engine. The deep engine pan was packed with absorbing mats to make sure oil couldn’t find its way into the bilge.

At the same time, the engine never failed to start and run. But it certainly was a mess. It was clearly time for major attention.

Seaquip is the engineering firm (Kiwi for “mechanics”) at Gulf Harbour, Whangaparaoa, where we hauled. John and Jan Lucas of Seaquip are conscientious and capable, if sometimes stretched a bit thin by the amount of mechanical work facing them this year, with so many overseas boats adding to their normal workload.

Rather than undertake the rebuild themselves, they removed the engine, tore it down to its components, and sent the pieces out to a variety of specialist firms for overhaul. The block and head went to an engine remanufacturer, where it was taken apart to its smallest bits. The engine was totally rebuilt to factory specifications down to the crank bearings.

The fuel injection system went to another firm.

The heat exchanger was cleaned and re-soldered, the manifolds cleaned thoroughly. During the process we found bits of rubber in the heat exchanger from our impeller failure in the Caribbean two years ago.

The aluminum water injection elbow was still serviceable, but was showing signs of deterioration, so it, too, was replaced. All rubber components—boots, hoses—were renewed.

The instructions were simple: If it showed signs of wear or corrosion, replace it or rebuild it. The engine was to be returned to zero-hours condition.

I took the starter, the alternator, and spare starter in for checkout and overhaul as necessary. Almost on a whim, I brought along the spare alternator, which supposedly had been rebuilt in Trinidad. What we found was depressing.

In Trinidad, I had paid $400 to Dockyard Electrics—about the same price as the same alternator new in the US—for an alternator overhaul. Most of that went for a new rotor. Unfortunately, it appears that nothing else got much attention. When we opened the alternator in New Zealand (it had been in a box, unused since the “overhaul”) several diodes showed heat damage in the form of melted solder, and the pulley nut threads were stripped. The “overhaul” had left me with an alternator dangerously unfit for use.

The moral of this is pretty simple. Be explicit about what you want when you ask for repairs, and ask for a detailed description of what has actually been done. This, of course, requires a fair bit of knowledge on your part, or else complete faith in the person doing the work for you.

Exhaust System
When building Calypso, I had placed the exhaust outlet just above the designed waterline. This was a mistake. In her fully loaded cruising condition, the boat floats about 4″ below the original waterline (since raised) and the exhaust outlet is immersed. Not only was it impossible to monitor cooling water flow, but there was a considerable amount of back pressure on the engine.

It was time for a re-design.

We raised the exhaust outlet more than a foot above the actual waterline. This required replacing and re-routing the exhaust hose as well as making a substantial fiberglass patch in the hull, fortunately all below the waterline. The exhaust is now well clear of the water, even with the boat heeled on starboard tack.

Offshore Log: <BR>A Major Overhaul For A Faithful Perkins

At the same time, the plastic Vetus LP-50 waterlift was replaced with a larger-capacity, semi-custom waterlift of high-temperature fiberglass. The new muffler was built on a footprint similar to that of the Vetus (we have a severe space constraint), but with a substantially larger capacity to reflect an exhaust hose run of almost 7′.

The fiberglass inlet and outlet pipes for the new waterlift were glassed into the muffler after refitting the engine, so exhaust hose runs could be as undistorted as possible.

At about $200, this fiberglass muffler was substantially more expensive than a plastic waterlift, but we consider it money well spent. Unfortunately, C.T. Burling, the manufacturer, is a small New Zealand company with no desire to expand into the overseas market.

By changing the heat exchanger boots, we were able to simplify an awkward cooling water run between the exhaust manifold and the water injection elbow, eliminating several right-angle bends.

Prop and Shaft
As reported in a previous article (PS, March, 2000), we had already removed, cleaned, and inspected the prop shaft, polished and serviced the Max-Prop, and replaced the stern bearing.

Chasing Leaks
No major overhaul goes smoothly, and the engine was no exception. After test-running the engine, we began to chase problems. A drop of dirty engine oil at the bottom of the bell housing suggested that the new rear seal was leaking.

Off came the gearbox, and we found a minute crack in the seal housing, possibly the result of an over-torqued fastening. Fortunately, we could get to everything without pulling the engine again, but it wasn’t easy, and the engine overhauler spent a few uncomfortable hours hanging upside down to replace the damaged housing and seal.

The newly rebuilt raw water pump leaked, as did the backup “rebuilt” pump we carry as a spare. In chasing a new pump, we discovered that the old one was now obsolete, and had to be replaced with a new design which required slight modification to fit our particular installation. At $400 US, the new Jabsco water pump was an expensive replacement.

By choosing the best components from our obsolete water pumps, we ended up with one good spare, so we’re still in business in case of a pump failure. Miraculously, the old pumps and the new design both use the same impeller, and the same quick-change Speedseal cover fits both models.

Then we started on the fuel leaks, which fortunately were concentrated at the connections to the engine-mounted fuel filter.

With a clean and dry engine for the first time, minute leaks stuck out like a sore thumb. The shift lever shaft on the gearbox decided to leak, too. Fortunately, that proved to be a simple face seal that was replaced without disconnecting anything more complicated than the shift cables.

Fine Tuning
Although I had spent a lot of time lining up the alternator and refrigeration compressor when I built the boat, we discovered minor belt alignment issues when the engine was reassembled. It took a disproportionate amount of time and effort to correct these, but it is a critical effort if you want to minimize belt wear.

We also emptied out and cleaned the fuel tank, since we had purchased a bad lot of fuel somewhere, and were clogging fuel filters at an alarming rate. We took advantage of the empty fuel tank to replace the deteriorating sight gauge, fitting a shutoff valve to the bottom of the new gauge.

Offshore Log: <BR>A Major Overhaul For A Faithful Perkins

The corroded metal-jacketed fuel lines were replaced with simpler rubber fuel hose, eliminating several potential leaks at connections.

We are now 99.9% there, but are determined to get everything perfect, or at least as perfect as they ever are in the imperfect world of boats.

A New Regime
We have learned valuable lessons from our engine overhaul. We will now load up the engine more when using it as a generating plant. On passages, the engine will be run in gear when charging, even if there is plenty of wind to move us along. If we have to run the engine for charging purposes when the boat is alongside a dock, it will also be run in gear. Our new step-down transformer should reduce engine running time when we are dockside in 220-volt countries.

At anchor, this is more problematic. You obviously cannot run the engine ahead when anchored, so it must be run astern, loading up your ground tackle, which is not necessarily bad.

We will also run the engine harder when it is used for propulsion. To conserve fuel, we have been running the engine far too slowly. While it may be less fuel efficient to run the engine harder, the engine likes it better. A diesel really likes to be run at about 70% of its continuous rating. In our case, that means we should turn the engine at around 2,100 rpm, rather than the 1,700 or so we have actually been using as a baseline.

We may have to back out about a degree of pitch from the prop to run the engine at this speed, but that’s the beauty of the externally adjustable pitch on our Max-Prop VP. It’s a 30-second job underwater to adjust the prop pitch.

Cruising sailors have to look very differently at the way they operate their engines, compared to the average weekend sailor. Engine hours add up very quickly when the main engine is your primary source of power generation, and this type of hours is not good for it. With a cruising boat of over 40 feet, an auxiliary diesel generator is a serious option to be considered. You can probably get 10 years out of a small diesel generator before an overhaul is necessary. Overhaul or replacement of a generator is far simpler and cheaper than the same job on the typical main engine.

A large percentage of the boats we have encountered are equipped with solar panels, wind generators, or both. Properly engineered solar and wind generator installations are less common than bad ones, and should really be done as part of a complete electrical package before you go cruising, rather than as pieced-together bits along the way. If we were starting from scratch, we would probably redesign the generating systems to take advantage of wind and solar power. As it is, we will almost surely install one solar panel to maintain the batteries when we are off the boat.

Our re-designed engine installation, newly overhauled engine, and new operating regime should go a long way toward improving the efficiency of our cruising lifestyle.

This was a major expenditure in both time and money, involving 107 hours of hired labor from Seaquip. Add to this the outside labor involved in the basic engine rebuild, the fuel injection overhaul, and the electrical rebuilds. The entire bill was about $6,500 U.S, which is about 60% of the cost for the same job at a good yard in the U.S. My own labor added another 80 hours to the project.

Unless you are keen to take the other extreme—no engine, no electrical system—it’s all part of the cost of cruising, but it’s one we’re willing to pay. In the next six months, we expect to use the engine a lot as we traverse the light-air regions of southeast Asia. We will also need a strong, reliable engine working our way up the Red Sea less than a year from now.

Don’t worry, we also got new sails to go with our renewed engine. We’ll talk about those next month, after a 1,400-mile shakedown to Australia.

Darrell Nicholson
Practical Sailor has been independently testing and reporting on sailboats and sailing gear for more than 50 years. Supported entirely by subscribers, Practical Sailor accepts no advertising. Its independent tests are carried out by experienced sailors and marine industry professionals dedicated to providing objective evaluation and reporting about boats, gear, and the skills required to cross oceans. Practical Sailor is edited by Darrell Nicholson, a long-time liveaboard sailor and trans-Pacific cruiser who has been director of Belvoir Media Group's marine division since 2005. He holds a U.S. Coast Guard 100-ton Master license, has logged tens of thousands of miles in three oceans, and has skippered everything from pilot boats to day charter cats. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him by email at