14. May 2023

The finite story of the engine 1

We are struggling with persistent engine problems. In retrospect, it has to be said, actually ever since we set out with Mabul in September 2022. Only we hadn’t really noticed it yet and I kept fighting symptoms but never found the causes. In this and the following blog, the failures, misfortunes and breakdowns of the engine will take us through our journey from St. Maarten to the BVIs to the south of the Dominican Republic.

After three exhausting weeks at anchor in Marigot Bay of St. Martin, we finally lift anchor and move on. Next stop: The British Virgin Islands, or BVIs for short. Here our friend Florian is already waiting for us, who unplanned had to book himself into a hotel for a few days, because we were waiting for a delayed delivery in St. Martin.

We set course for the British Virgin Islands

After leaving the bay under motor, we set sail and set course. The forecast promises moderate wind, but at least it is supposed to come from the northeast, perfect! For the passage we plan about 18 hours, it should be about 90 nautical miles. In the end it takes a few hours longer because the wind is getting less and less. In the early morning hours Mabul makes only 3.5 knots under full sail, but the engine stays off, after all we are still sailing!

After almost 21 hours and 94 nautical miles, we drop anchor off Spanish Town, Virgin Gorda. So far everything seems to be fine with the engine, but since Grenada it hardly runs for more than 20 minutes at a time. We only use it for anchoring, otherwise we sail, and the wind has never left us completely. The only thing that makes me wonder is that we can’t get the RPM above 1800, no matter how much throttle you give it. According to the manufacturer, the engine should be able to do 3000…

The first meal with Florian on board

While I do the entry formalities, Florian comes with Barbara and Ralf on their catamaran SV Lille Verne to our anchorage. The two sailor friends from Switzerland have taken him along without further ado, because they also wanted to go from the capital Road Town, where Florian was in the hotel, to Virgin Gorda. When I come back, Florian is already on Mabul and has already received a welcome drink and the first briefings.

Unfortunately, the further forecast doesn’t let a good mood arise. Doldrums! And that for days! Even when the forecast ends after seven days, there is no sign of improvement. A big vortex in the North Atlantic sucks all air away, so that partly even west wind with 2-3 knots is announced. Well, that could be something! Actually, I was looking forward to sailing here in the BVIs, because there are many small islands and you have to constantly maneuver to get through everywhere. And all that without any wave to speak of, as we have heard from many sailors who have sailed here.

Sundowner on SV Lille Verne

But what can you do… We have a motor and the distances between the anchorages here are so short that you can get around without having to burn a lot of diesel. So we motor the next days crisscrossing the BVIs to offer our visit some variety. If you’ve never been on a boat before, you’ll find that driving under motor is great. After about three days I notice that the engine temperature is a bit above the normal 80 degrees. I don’t think much of it yet, but check the coolant flow and clean the filter that keeps the coarsest dirt from the sea away from the engine.

Then Jan, Florian’s husband, finally arrives from Berlin. He had an involuntary stopover in Guadeloupe, because the pilot decided to fly through on approach to St. Maarten. Now we are complete and can explore the rest of the BVIs together.

On the way to the legendary White Bay on Jost van Dyke Island, where the Painkiller drink was apparently invented, I watch the engine temperature and hope that cleaning the filter was enough. It wasn’t! Now the temperature rises to 95 degrees and my only option for the moment is to get off the throttle. So we chug along at 3 knots to the nearest anchorage, Sopers Hole on the main island of Tortola.

The new impeller in the housing of the sea water pump

I disappear into the engine room and suspect the seawater pump (I already checked the cooling water pump and the thermostat weeks ago in Dominica and found them to be good, and yes, the engine did get too warm there). The impeller already has some operating hours on the clock and is a classic wearing part. I open the sea water pump and pull the rubber part from the shaft. Unfortunately, the used impeller still looks pretty good, but since I already have it in hand, I replace it anyway. While the crew tries to buy some provisions ashore, I have another idea. Maybe the inlet strainer on the underwater hull is so clogged with mussels and growth that too little water can be sucked in by the pump. So armed with a wire brush I dive under Mabul and scrape away all the dirt.

The marina of Sopers Hole

Hoping now to have solved the overheating problems, we continue our trip to White Bay, where we are looking forward to a painkiller on the beach. Already after 20 minutes we see: Nothing, everything is the same, so we continue at a snail’s pace. Finally arrived, the next disillusionment. The entire bay is packed with day-trip boats and charter catamarans. Unbelievable how many of these gigantic plastic piles fit behind the reef in the small bay. Idyllic is different.

We have no choice but to drive into the next bay, hoping to find a free place there. Again, bad luck, here everything is so tightly packed with buoys that you have no chance to anchor in between. On top of that, all the buoys are booked out weeks and months in advance by the mostly American charter tourists. So one more bay, engine temperature still critical…

Shortly before nightfall the anchor falls in the almost empty Garner Bay. On the way I continued to ponder the cause of the overheating. Our engine has a water – water heat exchanger, which means cold seawater is drawn in from the outside, which cools down the actual engine coolant. Both circuits flow around each other in the heat exchanger separated by what is called a heat exchanger element to dissipate the heat from the coolant to the cold seawater. However, when this bundle of copper tubes becomes clogged with dirt, salt deposits and fouling, it can no longer dissipate enough heat from the engine.

While the crew leaves Mabul for an extended dinner ashore, I put in a night shift. Of course, the heat exchanger is not easy to reach and the first thing I have to do is dismantle the alternator to get to the end caps. The first cap comes off easily, which can’t be said for the second. But that one has to go too, otherwise I can’t pull the heat exchanger element out of the housing. After even the biggest hammer and the longest lever do not lead to success, but rather to greater damage, I scratch away only a little superficial salt deposits. The element doesn’t look very clean, but if you compare it to elements shown in YouTube videos, it doesn’t seem particularly bad.

The heat exchanger element in the housing

Frustrated, I put everything back together and install the alternator. Meanwhile it is 11 o’clock in the evening and I am done. A short test run to see if everything is working as before shows: Nothing works anymore. The engine does not start, the starter motor only clicks. This is a sign of an empty starter battery, but it should be fully charged. After all, we have been driving all day under engine. I give up and fall into bed, dead tired, without dinner.

The next morning Jan and Florian decide to visit White Bay by land. Should I bring Mabul back to life in the meantime, we will meet there. As soon as they are off the boat, I dismantle the alternator again. Maybe I messed up the wiring last night and that’s why the starter doesn’t get enough power anymore. Unfortunately, everything is fine and I’m getting to the brink of despair. Battery full, wiring ok, starter relay too….


I don’t know why, but I connect the engine to our house batteries and try to start the engine again. Lo and behold, the starter turns and the engine starts! Hooray! But why? Our starter battery is just three months young and fully charged. No matter, the engine runs, it is still early and in the White Bay hopefully still an anchorage to get. I leave with Karin and we don’t dare to turn off the engine. After half an hour, of course with increased engine temperature, we are there. The bay is still relatively empty and we anchor behind the reef.

We see Jan and Florian in a beach bar and immediately jet over with the dinghy to spend a nice day together here. The drinks are good, the weather is nice and so is life.

Taking a break in White Bay

The next day we slowly head towards Beef Island, here is the airport of the BVIs. Unfortunately Florian has to leave Mabul the day after tomorrow. As a last stop we picked a lonely island, Guana Island, only three nautical miles from the airport. Now the decisive moment, I turn the ignition key and expect the worst (the engine is now back on its starter battery). But the engine starts without any problems, we lift the anchor. Today even a little wind blows, so we set sail and sail to Guana Island. Also there the engine starts when we enter the bay. We enjoy another great day without tools, but there is a nice beach, few charter boats and good company!

The last anchorage before Florian leaves

Today we start early, Florian should be at the airport at 11 o’clock, so that he has no stress. When leaving the bay, the engine starts willingly, I give a little throttle, check the coolant. What I see there, I do not like at all! Instead of clear water, I see deep black water and a lot of smoke. Not good at all! I take off the throttle, the water changes its color to gray, still with some smoke. Again a little more throttle and immediately it turns black again. Shit! What now again?

To avoid further damage, we immediately roll out the genoa and I stop the engine. Karin takes over the helm and tacks up and down off Guana Island while I try to find the fault. No leaks in the engine compartment, oil level good, oil color also, cooling water good, nothing obvious. The channel to Beef Island is very narrow, and the wind would be right on the nose. I don’t want to beat the wind, especially without the engine as a rescue in case of emergency.

So I try to start the engine again. Nothing. The starter clicks. So I clamp on the house batteries again. New try, same game, clicking starter. Fuck! Meanwhile we are losing time and it’s getting tight for Florian to catch his flight in time. Karin then has the decisive idea: Tony and Mel, sailor friends, are only a few bays away from us, maybe they can pick up Florian from Mabul and bring him to the airport? We call them and experience, as so often, real sailor solidarity again. Not five minutes later we see on the AIS how they are sailing in our direction. Fantastic!

The somewhat different departure with the help of our sailor friends Mel and Tony

We sail as close as possible to the channel they will be coming out of. When we see them, we heave to and Tony comes with the dinghy to Mabul, Florian jumps over together with the luggage. We are infinitely grateful to the two for their quick help, not knowing that they will save us again today. Tony rides with Florian directly to the airport, half an hour later Florian gives the all-clear. Everything went well and he even had time for a coffee.

We decide to sail around to Road Town, the capital. There are marinas, mechanics and all the necessary stores to bring the engine back to life. But it is a relatively long distance and the wind moderate to little. While Jan enjoys his first day of sailing, my thoughts continue to circle around the engine. Do we now have to deal with a fatal engine failure? That would be the super gau and would mean that we would have to sail back to tax-free St. Maarten, since an engine is expensive, especially in the BVIs.

When we finally get around Great Camanoe and Beef Island, we are beating the wind toward Road Town. However, the wind is getting less and less and dusk is already approaching. Anchoring under sail is a first for us and now probably also in the dark! When then four nautical miles before Road Town the wind breaks down almost completely and we still make somehow scarcely two knots of speed, we realize, we need help. This is not going to work.

Again Karin contacts Tony and Mel, who are already in Road Town. Without even asking a question, the two immediately say: “You won’t make it! We’ve been watching you on the AIS for hours and now we’re going to come with the dinghy and tow you!”. Wow, we are speechless and relieved. Shortly after that we see them coming and they take us in tow. With her 25 hp engine, Mabul makes a solid 3.5 knots of speed and we glide off into the night and into Road Town.

Mabul in tow of Tony and Mel’s dinghy

After what feels like an eternity we reach the bay and drop the anchor right next to Tony and Mel’s catamaran SV Utopia III. Then we pull Mabul backwards with both dinghies, there is a jerk, the anchor sits. We have a last nightcap with Jan, who starts his journey home tomorrow. Instead of Mabul, however, he has to take a cab to the airport. But that is the least of the problems.

After a comatose night I ask our sailor friends Thomas, Martin and Tony for advice about our engine. Independently of each other, they all have the same suspicion: hydro lock, there is water in the cylinders which cannot be compressed and thus the engine can no longer turn. The most common causes are a defective cylinder head gasket (cooling water in the cylinder) or a problem with the exhaust (seawater in the cylinder).

A few Google searches later, I get to work. First, I decompress the cylinders by removing all the glow plugs. As a result, each cylinder now has a hole and the engine should turn easily unless it already suffered connecting rod or piston damage. Relieved, I find that I can turn the engine by hand at the crankshaft! Hooray, no fatal damage, no new engine needed! Next I try to get the engine to turn without plugs from the starter, if I can do it by hand it should be a cinch. But what can I say, all I hear again is the now familiar clicking sound. That can’t be it!

Some kind of electrical problem. I check the starter relay again, the wiring, the entire electrical system of the engine. No error detectable. Again, I don’t remember how I came up with it, but I try to short-circuit the engine. So just like in old movies when cars are stolen. And bang, the starter turns the engine as if nothing had happened. I still don’t understand why, but for now it helps me to check the hydro lock. I let the starter turn the engine again and meanwhile look at the openings of the missing glow plugs. No splashing coolant or seawater, but fine diesel mist. That’s how it should be.

Now the cross-check, glow plugs in, V-belt on, short-circuit. Engine starts and runs smoothly. What a relief. Not three hours passed since I was almost sure Mabul needed a new engine.

The motor panel from behind, where does the short circuit come from?

To clarify the question, why the engine does not start with the ignition key, much more time passes. After three days of hair-raising workarounds, sweat and curses, I get to the root of the problem. The alternator!

The charge controller of the alternator is defective and shorts the engine panel as soon as you turn the ignition key. This causes the voltage to drop immediately and the starter motor can no longer build up torque. Unbelievable… Fortunately, a brand new alternator is on board, I replace it and now the engine runs as desired again.

A test drive reveals that the engine also works under load, the alternator charges the batteries and for some inexplicable reason the overheating problems have also come to an end. The latter, however, makes little sense, since I did not change anything in the cooling system. In the meantime, I could also rule out a faulty temperature sensor.

The problem is finally found and replaced: the alternator.

Absolutely happy about the new engine conditions we leave Road Town and drive to Peter Island. There we spend three days and nights without touching any tools. We enjoy the loneliness, the clear water, do a great dive and prepare for the coming long passage to the Dominican Republic.

How it goes on there with the engine – and it doesn’t go well! -, you will find out in the next blog…


Distance covered: 242 sm
Time: 2 days 3 hours
Average speed: 4.5 kt
Engine hours: 23 hours
Damages: see above 🙂

More photos from the BVIs can be found here.

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