The realisation came gradually. The iron co-sailor, who had been on board the Michalk family's Sigma 38 for more than 30 years, broke down more and more often. "Reliability declined," says Daniel Michalk matter-of-factly. For one season, more or less intensive repairs were still part of the on-board routine, but in preparation for a longer summer trip, the engine went on strike once again, the family council decided to pull the ripcord.
"One alternative would have been to have the engine completely overhauled," says Michalk, but this would not have been possible without the yacht being out of use for a longer period of time. In addition, the spare parts situation is so bad that the operation would have been difficult and the continued operation of the engine did not seem sensible anyway. The decision on the make and size of the new engine was not an easy one. "We would have liked to have taken the opportunity to install an engine with a larger power reserve. And we were also dreaming of cruising at a lower speed than before, not least to get by with less fuel," says Michalk.
The available space on the Sigma 38 would also have accommodated a larger engine than the old three-cylinder with around 30 hp. However, the installation position must be taken into account, as it must be possible to reach all maintenance-relevant parts later on. And these are positioned very differently in the various makes. Anyone planning to install a new engine must take this into account if they want to be able to reach the water pump, filter and V-belt later on and, if necessary, provide appropriate inspection hatches before the new installation.
The same attention must be paid to the subsequent routing of supply lines and connections. After installation, it must be possible to lay them without tight radii. Finally, it is important to measure whether the drive fits, for example whether the cut-out for the saildrive is correctly positioned or the height of the shaft for connection to the gearbox of the new motor is correct.
Are the requirements for installation met?
With the Michalk family on board, the space and installation position would even allow the desired change to a larger engine. But then, according to the owner, he started to think about what conditions would have to be created for this. He checked whether the existing drive train and his propeller were sufficiently dimensioned and quickly came back down to earth: with its 25 millimetre diameter, the installed shaft is ultimately the limiting factor. Taking its length into account, more power than before is not at all advisable, Michalk finds out.
Changing to a stronger shaft, however, would be a more complex undertaking and more likely something for winter storage. It would require a new stern tube, new bearings and, in the case of the Sigma 38, a new shaft bracket under the hull and, of course, a new propeller. Owners who are interested in a more powerful engine should ask the manufacturer of the unit in question about the required dimensions of the propeller, shaft and gearbox and, if in doubt, seek the advice of a shipyard that has experience in installing engines.
Price-performance ratio should be right
Once it has been decided which features the new engine should have, the difficult choice of make follows. When making their decision, the Michalks attached great importance to the price/performance ratio, which they measured in terms of quality and up-to-dateness. Equally important to them is the spare parts situation. "The Craftsman has a fuselage engine from Mitsubishi. And it is used as an industrial engine all over the world. The spare parts situation is very good," says Michalk.
Removing the old machine is no problem. Michalk documents all the connections and installations with the camera on his mobile phone so that he can see what it looked like later. He then treats all the screw connections that need to be loosened with rust remover over several days. Later, heat is still required in some places, which he obtains from the heat gun after shielding the surrounding area with aluminium foil. The engine can then be easily lifted out of the ship using the mast crane.
Now the owner prepares to install the new drive. To do this, Michalk makes a template from simple wood, on which the four flexible engine mounts are positioned with millimetre precision as they will later be on the engine block. The installation template also contains the exact point at which the shaft will later be connected to the gearbox and the angle at which this will be done. All the dimensions required to build the template are provided in the manufacturer's manual. The template is now used to create the required motor foundation. In the case of the Sigma 38, there are two laminated steel beams on which the engine mounts can be attached, slightly offset, in the same way as the old ones. Only a small amount of height levelling will be required after installation, which can be adjusted on the mounts themselves.
Does the engine fit? Consult a boat builder in some cases
In some cases, it is possible to attach the engine mounts to the old foundation, but the different dimensions of the new engine block make it necessary to work with spacers, which may have to be custom-made. Or even major modifications to the foundation may be necessary. In such cases, it is advisable to consult a boat builder. Before the engine finally takes its new place on the prepared foundation, it is advisable to lay the new electrics, as it is easy to access everything while the engine compartment is empty. Once the switch panel has been installed and the wiring harness laid, all that remains, apart from plus and minus from the starter battery, is a plug contact for connecting the panel to the engine.
If a conventional shaft system is available, it is essential to check whether the shaft and clamping flange fit together before installing the new drive. In the case described here, the shaft was slightly oversized and the flange had to be turned slightly from the inside by the fitter. Such things should be avoided during the installation phase.
Align the motor exactly to the shaft system
When the big moment arrives and the new engine block floats into the ship on the mast crane, the essential work has already been done if the preparations are good. Great care is required to align the engine precisely with the shaft system. This is best done by a specialist. The connections of the Bowden cables for the throttle and gearbox, the electrics and power supply as well as the lines for cooling water, exhaust gas and fuel supply and return should not cause any major difficulties if the preparation is done well, and it is recommended that all the old hoses are replaced as part of this.
If the new motor has a different direction of rotation or power than the old one, the propeller must be replaced. Or, as with the Michalks, a folding propeller is installed. The manufacturer supplied two new blades for this, which could be fitted without much effort. To summarise, it can be said that the costs of installation can be saved completely in the best case, or at least reduced to the help of specialists for individual installation sections.
However, the time required is considerable. Daniel Michalk only needed around six hours net to remove the old machine. However, this was spread over several days, as was the preparation for the installation of the new drive, which took at least the same amount of time. The actual installation and connection of the new motor can be completed in a weekend with good preparation and the appropriate skills.
The calculation in the example
Time
- Removal (6 hours): Removal of the engine mounting on the foundation, the Bowden cables for the gearbox and throttle as well as the hoses for cooling water and fuel supply and exhaust gas discharge, the battery and switch panel connections, uncrating the engine block
- Preparation for installation (8 hours): Possibly making the installation template, adapting the motor foundation, replacing the old hose lines
- Installation (6 hours): Craning in the new motor, attaching the block and the connections listed above
- Logistics (4 hours): Purchase of parts, internet research, organisation of work, contingencies
Costs
- Engine with reversing gear: 6,550 euros. Craftsman Marine 3.27
- Propeller: 600 euros In this case, two propeller blades had to be replaced because the direction of rotation of the new motor is different to that of the old one
- Installation parts: approx. 200 euros. For example, hose lines, fastening material
- Have it installed: approx. 5,000 euros. Alternatively, consider having the new engine installed by a specialised company. The costs are calculated on a time and material basis and vary considerably. A cost estimate provides information
- Overhaul of the old engine: approx. 5,000 euros. These costs do not include removal and installation
