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Article by Derek Dunn
for the 40 plus fishing boat association

My battle with an unknown foe!

I first met John Tapner in the spring of 2000 when I was down at the harbour at Charlestown, (this harbour lies on the upper section of the river Forth, mid-way between the Forth and Kincardine bridges.
Charlestown is where the Bruce's is berthed, (Use your search engine to find “Lifeinnavyblue” ) this boat is registered with the 40+ FBA. I was tending to the needs of her Kelvin engine, model K3 which I rebuilt for her owner, Fred Rowe, when John appeared on the aft deck.
“Could you help me with my engine on my new boat?” he asked. Well, I wanted the time for the next couple of years to rebuild my two Kelvin model E4’s and my first impression was to send John packing.
Being a curious, engineering type of person, curiosity got the better of me;
I am not the type of person to pour over the latest type of GPS, fish finder or auto –pilot, – I tend to vanish down to the bowels of the boat to see what is there.

John’s boat is called “Amazing Grace” and she had recently arrived in the harbour and promptly changed ownership to John.
I should now explain that John has turned 70 years young but is boat-daft! He has owned sailing yachts all has adult days but as his years have advanced he has found the comfort afforded by sailing boats to be a bit lacking. He therefore part exchanged his last sailing yacht for, “Big Gracie.”
Amazing Grace is a 1942 Danish seine netter, previously called Camilla, of some 52 feet in length and 15 feet beam and 8 feet draft, aft and I believe she is around 50 tons deadweight. (She is registered with the 40+FBA).

I was indeed curious to find out what made her tick!
As we walked along the pier, I asked John what kind of engine she had; he didn’t seem to know. Very curious!
“Was it a Gardener?” I asked……………… No.
“Perhaps a Cat?”……………………………No.
Maybe it was one of these Calensens I thought…………………..No, not that either.
I looked at the boat and mentally tried to calculate the horsepower required to drive her, at least 150 SHP.
What could the beast be?????
I have visited and worked on boats and I knew that in order to work comfortably, I had to have room, headroom and breadth, in which to work and looking at the boat, she appeared to have all of that. The wheelhouse stood very high, which is in keeping with the Danish tradition.
”Well,” I said, “let’s have a look.”
My biggest mistake!!!!
On entering the engine room I was met by the monster, 8 feet from top to bottom, 2 cylinders, BIG pistons. I looked all around it and found a plate, Hundested, Denmark.
This meant nothing at the time but I now know more about the company.
[Through the mysteries of email and the internet, I have been communicating with a Mr. Per Romer who works for Hundested and there are still spare parts available!]
Model number, engine number and year, 1975. Not old either.
Horsepower, 200 at 345 revs per minute.
I looked further and the penny dropped, it was a 2 stroke diesel and after some later research, realised it did not work on the diesel cycle but was in fact a semi-diesel or surface ignition, or hot – bulb engine, which works on a lower compression ratio than a true diesel.
[Note, the sump of the engine is dry and the lubrication is done via a pump driven from the governor shaft. Oil is then dripped from small bore pipes connected to the pump into the three crankshaft roller bearings, (yes, roller bearings, the middle one is huge!) three lubricator quills on each cylinder barrel for piston ring lubrication and other various other moving parts on the engine].

After a good look around I discovered that the beast was in a very poor state, the pistons seemed to be seized and the crankshaft looked like it was also stuck, the inside of the crankcase was very dirty.
The boat should have been called the Amazing Disgrace!!!!!!!!!
The more I worked on her the more it would appear she had not been cared for properly.
I have two colleagues, David and Richard, who work for the same employer and both were prepared to help in the battle, all three of us are ex-merchant navy chief engineers, no fishing boat ever in history has had so many qualified engineers onboard at the same time!!

The first job was to arrange some kind of lifting device because the whole thing had to be dismantled. John went to his local scrap dealer and found a length of steel “I” beam and we cut a hole at the top of the forward bulkhead and poked the beam through into the deckhouse and secured it with a coach screw. The big engine sucks large amounts of air when it is running and the builders have fitted a ventilator from the top of the wheelhouse down into the top of the engine room. The aft end of the beam was therefore rested in the opening of the air vent. We then procured a running trolley and a 1 Ton chain block.
The cylinder heads were removed and stowed away into the aft end of the engine room and large amounts of diesel poured into the cylinders.

The boat was built to go to sea for long periods of time and she has six fuel tanks, three on each side. These tanks must be around the 200 gallons capacity each and I persuaded John that she will never need this capacity again and if we cut out two tanks we would have more stowage space for bits of engine.
I found it difficult and expensive, to acquire burning gear so we set about the tanks with an angle grinder – a long and dirty job!
The summer was fast approaching and John has other sailing interests on fresh water so I decided that we call a halt to the proceedings until September. The diesel in the cylinders would hopefully do its job.
No luck there!

The diesel did not seem to be soaking down passed the rings – ah well, another plan failed. I should explain that being a 2 stroke, there are two exhaust ports in the cylinders about half way down and the corrosion to the piston was clearly visible. There is a water-cooled exhaust expansion chamber bolted to the cylinders and the exhaust proceeds vertically upwards out passed the wheelhouse to atmosphere. The exhaust must have been left uncovered for some time allowing rain to come in and work its worst on the aluminium pistons and cast iron rings and cylinders.

We started cutting out the 2 fuel tanks, which were to be sacrificed and this proved to be a long job. It took almost a month of much swearing and cutting and stalling of the Yamaha generator. Eventually the tanks were out and this gave us more stowage space. I should state that we work on Sunday mornings from around 10 am until about 2 in the afternoon.

The exhaust expansion chamber was removed and stowed aft beside the cylinder heads. This showed very clearly the damage to the pistons at the ports.
Now for the pistons!!
On this type of engine the big ends are in three parts: the bottom half of the bearing, the top half which has a flat top and mates with the flat bottom of the con-rod. The three components are clamped together with the two big-end bolts. Both of the big ends were removed and it was noted that the top half white metal was like crazy paving. New white metal bearings were required. It is of note here that the bottom halves are brass with no white metal. Being a 2 stoke, there is no downward pull on the bottom end as with the four stroke during induction. Therefore no running metal is required. There are however, two deep grooves in the bottom halves and I assumed this acts as an oil reservoir during starting.
I started with the forward piston and managed to procure three feet of railway line. This was suitably drilled through the vertical web and positioned over two cylinder head studs. I borrowed a 50 ton hydraulic ram and this was set beneath the railway line and on top of the piston. All was set.
The cylinder head studs are 28mm in diameter and I calculated that we could safely exert the full 50 tons on the two studs without failure.
Slowly the hand pump was worked and the pressure increased to 30 Tons ----- nothing!
We left it for a cup of coffee but nothing happened, at this point the yellow streaks up our backs was clearly visible.
More pressure. This time we approached 45 Tons and there was an almighty bang, the whole boat seemed to shudder. The piston had jumped down about 10mm, more pumping to 45 Tons, another 10mm of movement and so on.

The jack only had a stroke of some 6 inches so we had to back off and add packing pieces in order to continue. The piston was being forced down into the crankcase and we had to watch carefully so as not to contact the crankshaft. When we were within ¼ inch we had to stop and lift the cylinder barrel. This was done and the cylinder blocked on wood, pumping was then re-commenced and the piston forced out some more. More lifting of the cylinder and more pumping until eventually the piston was released. (I think that the full travel of the piston during this operation was some 28 inches). We had just enough room to lift the cylinder over the piston with a little rocking. The cylinder was then swung aft leaving the piston sitting inside the crankcase top half.

The aft piston was next --- a different story!!!!!!
The 50 Ton jack was no use, when the full 50 Tons was exerted and the relief valve in the pump was lifting, there was no movement of the piston.
Plan “B”.

I was working in a factory in Perth and they were working on the fabrication of new flood prevention gates for the city. After welding the various fitments to the gates, they had to be made perfectly square so as to be watertight. In the area of the factory used for this purpose I spied a large hydraulic ram set. I ascertained that they had hired this 90 Ton ram from “Lloyds Equipment Hire”, the very tool I needed.
The next step --- two lengths of railway line across four studs and the 90 Ton ram.
All the preparation work was done and the next week I hired the ram set. The ram was positioned and the pump pressure increased. This time we didn’t stand beside the engine, we had a 3 metre hydraulic hose and took the pump into the main accommodation and closed the door to the engine room.
We exerted some 40 Tons and checked all the bits and pieces for the correct position – all OK.
Back to the pump and it was shit or bust time!

The pump was slowly worked up to about 75 Tons when there was the now familiar bang and shudder, only much louder. Success! The piston had moved, or had it, had we smashed it all into a large jigsaw? With hearts in mouths we entered the engine room. Yes, the piston had moved. More pumping, more banging and the piston moved down around 4 inches. This jack had a shorter stroke than the previous one so we had to reposition and pack more often. The total time to extract this piston was some 6 hours. When it was finally out I was knackered, (a good engineering word). With barrels off the pistons could be swung ashore and loaded into the back of my car for the next stage. More of this later.

The shaft was stuck but not seized solid. I inserted a steel bar into the flywheel which has some holes drilled into the circumference. These holes are used to turn the engine to top dead centre before starting. With the aid of our trusty chain pull, anchored to the frames of the boat and the other end over the bar, the flywheel was turned. Copious amounts of diesel was poured over the shaft bearings and within an hour the crankshaft could be turned by hand using the bar in the flywheel. The flywheel is 4 feet diameter so I suppose we had a fair leverage.
Next job flywheel removal. The nut on the front of the flywheel is 5 ¼ inches across the flat ------ that is not a common size in any toolbox! We have a 4 foot stilson wrench which was fitted over the nut, again our trusty chain pull was employed.

Once the chain pull had been tensioned I hit the stilson with the big hammer – first go it moved.
Puller? The railway line again and the 50 Ton hydraulic jack!
Two long studs were fitted through the ‘wheel and the railway line fitted over the jack. We were up to 40 Tons before we broke the grip of the taper on the shaft. The flywheel was removed from the shaft but because of the weight, it was only lowered a smidgeon on to blocks laid in the bilge then leaned forward to be propped and lashed to a beam positioned across the opening of the engine-room door.

Next the crankcase top was removed in order to expose the crankshaft and bearings.

This engine has a large mechanical clutch between the engine and propeller control housing. After the clutch there is the propeller control housing which is in effect a large gear for winding the blades of the controllable pitch prop.
The clutch was dismantled quite easily ready to lift the shaft up in order to clean out the sump and all the parts on the shaft.
John, as you can imagine, is not flush with spare cash and I was always aware of this fact. I warned John that the crankshaft bearings would need to be replaced and that they would be expensive. We were all pleasantly surprised when the bearings were cleaned and oiled and they ran very sweetly indeed. I then dismantled the shaft coupling and checked the control gear for the prop. This too, seems to be in good order.

During the course of my work I met one of the managers of a medium sized engineering company and he very kindly offered to repair the corroded pistons. The pistons are cast aluminium and should be easily repairable with TIG welding.

Next week we will be engaged in cleaning the big end journals on the shaft making ready for the return of the newly metalled big ends. The big ends will have to be scrapped–in and fitted properly, this is a long job, that we are all aware of.
If all goes according to plan the beast will be ready to run around May. I will write again to keep you all informed, meanwhile all donations should be sent to:- only joking.

Derek Dunn.
20-02-2002.

Re-Metalling Of Big Ends - LISA MARIA

Hundested Semi-Diesel Hot Bulb Engine -  LISA MARIA

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