Repowering a boat, step by step

Repowering, step by step

1 – We start with this 4JH -TE Yanmar 55 hp installed in 1986. The tachometer marks about 6,000 hours, which is longer than usual for a sailing boat. That is because the boat was used for charter in its early years. A very erratic operation of the gearbox, the recalcitrant white smoke in the exhaust, cooling casing in its last stages of operation and a crack in the bell foundry were the most conspicuous problems of this engine.

We decided to repower when the Yanmar stopped working at the entrance port after a piercing noise in her womb. We had no intention to invest one hour or one euro on repairing (the mechanic confirmed that it was dead). Fixing it was more expensive than repowering.

motor marino Yanmar averiado

2 – After considering different options, we choosed a Solé Diesel Mini 62 of 59 hp. We took on consideration that the Mini 62 is a marine engine with a low spin rate, 3,000 rpm. Most of the marine engines (that come from automotive) get it’s best performance on power and consumption too high on the curve, even making use of the turbo .

Wen sailing on a motor boat, there is no problem on maintaining the engine at high rpm. It has been designed for it and only at those high revolutions the engine gets its best performance. But wen sailing with very little wind, cruising, it is common to combine sail and engine at 1,200 / 1,500 rpm . Since we are using a helix Brunton ‘s self-adjusting step , this type of navigation allows very high average, the propeller is supported and pushed by the sails.  This is an engine that delivered much of its power under a regime of t when closing it. This is a marine engine that provides the most of it’s power at a low revs. And perfect for this kind of navigation.

Instalaciones fábrica motores marinos solé diesel

3 – We went to pick up the engine with a motorcycle trailer, to the Solé Diesel’s factory in Martorell. About 40 km from Barcelona’s port. This transport system is used by many marine mechanics since it makes it all easier at the docks. The trailer can be easily set under the crane and move it around the esplanade.

motor marino sobre remolque de moto

4- The Jeanneau Sun Kiss has a detachable floor with direct access to the marine engine. This is a “must” for certain reparations and specially on engine repowering.
We had previously uncoupled all the cables, screws… from the old Yanmar. About half a working day.

desmontando con la grua el motor marino averiado Yanmar

5- With the Yanmar’s engine block at the floor, the mechanical starts to set the Mini 62 to carry it on board. It is good to use the same crane time to dismount and mount both engines, but it does not allow you to invest any time on improving the engine’s room space (painting, soundproofing…). You have to make a decision there.


6- The new marine engine is being settled to the bed a few minutes later the old one has been removed. If you are going to replace the shaft, you have to do it without the engine. Forgetting it will mean to lift the engine again.

In this specific case, the old shaft had many electrolysis bites. This did not allow the installation of a rubber stuffing box.

We had designed for us personalized supports for the Solé Diesel marine engine, which fitted perfectly to the Yanmar’s bed. This made much easier and cheaper the repowering.


7- With the marine engine still loose on the bed, you have to align it very carefully, adjusting hight and inclination of the engine block to the shaft. The silent-blocks have thin screws with double side that allow very fine adjustment of each one of them individually.

To fix the shaft and keep it centered, the mechanical has turned and divided in half a teflon cilinder, and has setled as a temporary rubber stuffing box.


8- The centered finishes with the perfect adjustment of the shaft and the gearbox. The mechanical turns both plates to confirm the correct aligned, both horizontal and vertical of the marine engine and the shaft. It is important to not to fix yet the plates with screws, otherwise might provide incorrect information.


9- Once the engine is aligned, it is the moment to fix the silent-bloks to the bed.


10 – Once the silent-blocks are firmly screwed, we must review the alignment with the precision gauge. If it is required, it is the moment  to readjust the silent-blocks.

alineado del motor marino

11- The engine is already align. Now is time to move backwards the shaft to be able to instal the rubber stuffing box. We have choose a Cal Seche PSS.


12 – Once the rubber stuffing box is adjusted, it is the moment to screw the shaft to it’s terminal, and then to the engine’s plate. The new Solé Diesel Mini 62 is already installed on the bed. Now it is time to settle the peripherals.


13 – We find a new location for the cooling water filter and the fuel filter at the stern, screwed to a support made of aluminum bent. Both filters stay accessible for future visual inspections and maintenance.


14- Since we are repowering, we renew all the fuel circuit with reinforced hose specific for fuel. We also instal a stopcock.


15- The cooling water circuit keeps the recently renewed bypass valve. But we install and adjust new water cooling inlet hose.


16- The exhaust vent changes its side, following the location of the cooling circuits of the new engine. This purger must avoid salt water coming inside the engine.


17 – The exhaust is now installed with the main waterlock. We have also renewed the exhaust hose, they were old and of different diameter. To maintain the exhaust outlet, we settle a diameter reducer at the ending of the hose.


18 – Another renewal is the old remote, and old Teleflex with many miles and misfunctions. We replace it for a newer one also from Teflex which perfectly adapts to the old anchorage.


19 – Before setting the cover, we apply Sikaflex. The picture is from before going over with a moist finger on soapy water.


20 – Once the engine is installed and verify by the Solé Diesel official dealer Talleres Antonio Ochavo, we instal the electric box. It just requires fixing it and guide the cable that goes from the engine to the box and connecting it all with a plug.

A good tip for repowerings is to take a picture of the connections. That way with just one print, it will be easier to remember later on.


21 – Since the Solé Diesel instruments panel is smaller that the hole, we design a white methacrylate base.


At last, we run the hourmeter with 12 v. voltage. So the starting point of our new marine engine is not zero, but 6000 hours.

Hopefully our new marine engine has a long and peaceful life.


Author: Enric Roselló – Marabierto
Originally published at RANC magazine


Recommended links

– When to repower a sailboat?

– Choosing the new marine engine for our boat


This post is also available in: Spanish

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