Hints and Tips



Heating a SO42DS

A step by step guide to installing a Webasto diesel heater in a SO42DS


This may help Jeanneau owners who would like to install a Webasto heater. Many thanks to Mistroma, RHB and J who assisted greatly along the way. The original project was detailed on the Jeanneau Owners Forum - you can read more on the background at: https://bit.ly/11QDlJw


It starts with the delivery of the Webasto marine heater unit. I also ordered 8 metres of 80mm hose, 2 metres of 90 mm hose, 10 meters of 60mm hose, 2 white 60mm outlets, 3 black 60mm outlets, an 80mm outlet for the saloon, 90-80mm reducer, 80-80mm connector, 2x 60/60/60 Y pieces, 1x 60/80/60 Y piece, 1x 80/80/80 Y piece, 1x 90/60/90 Y piece and 1.25 metres of exhaust insulation.


The photo below shows the entire contents of the Webasto kit. The kit contents were very comprehensive, nothing was missing and having all of the correct bits made the job relatively easy.


I decided to install the starboard side from the forward end to the aft end in sequence.


The first hole drilled is the toughest (much checking prior to drilling). The forward cabin lines up with the head vanity unit. The 80/60/60 Y piece is located under the vanity to split the air to forward cabin and heads outlets.



The photos below show the 80/60/60 Y section under the Fwd vanity and the outlet in the fwd head.


The 80mm hose runs behind the saloon seats between a factory installed section behind the galley and the 80/60/60 Y section under the fwd vanity.


The 80/80/80 Y section directs air to the saloon outlet and the forward cabin and head. It is a bit tight to get the factory installed hose section onto the Y section and do up the stainless hose clips.


The hole for the saloon outlet is drilled in the corner of the seat end. The 80mm hose for it is run on top of the hot water system in the corner where a factory cutout is provided.

The other end of the factory installed 80mm hose behind the galley is behind the aft cabin hanging locker. Four screws are removed to remove the backing timber revealing the hose which runs just past the hanging locker opening. The second photo here shows the hose end located behind the aft cabin cloths cupboard.

The top of the side cupboard is removed and the hose can be run in from the aft section of the boat. Two screws either end and two in the middle allows the top of the trim to be removed. A couple of cable ties may need to be cut to allow the hose to go through the available holes in the bulkheads.


A cable pipe is available for the control cable to pushed from the aft section through to the front of the galley. This is to allow the controller to be located above the power outlet in the galley. The only cables already in the pipe in our yacht were the transducer cables so it was quite empty and hence quite simple to push the control wires through from the aft section to just forward of the galley.


Next the holes were drilled for the Aft cabin. The location must be quite low and close to the corner or they could snag on the opening cupboard lid. It is concerning drilling these as it is difficult to know exactly where the hole will appear behind the bulkhead and if not careful, wires or pipes can be damaged.


The 60mm pipe is led across below the rudder quadrant and through to the port side. The access is gained on the port side similar to the starboard side for allowing the pipe to appear in front of the bulkhead between the aft head and the aft cabin. A factory installed hole of the correct size is located below the cable access way and appearing just below the holding tank so the hose is pushed through this opening.


The hole is drilled in the aft head at a location similar to that shown below. The hose can be seen behind the hole. The outlet is installed and the hose connected.


Once the hose and outlet are connected the port side of the boat can be reassembled.


The 60/60/60 Y is located to feed the port aft cabin outlet. Don’t make the radius too small or the hose will collapse reducing air flow.


The 60mm hose is tidied behind the bulkhead and I used a cable securing attachment to ensure the hose was held tight against the bulkhead so it would not rub against the rudder shaft. The heater hose is the lower hose shown in this photo.


The 60/60/60 Y section is now positioned for the starboard side aft cabin outlet. This Y section is reversed to reduce the air flow on the starboard side compared to the port side. This is to try to even out the flow from the starboard side (close to the blower) to the port side which is further away from the blower.


The diesel overflow and cabling had to be moved slightly to allow for the positioning of the starboard side outlet. The cable tie anchor on the bulkhead was moved to achieve this.

The Webasto heater was located on the mounting bracket provided by Webasto on the fiberglass stringer on the inside of the hull. It was secured with 4 large gauge screws. I was concerned it may have become too hot but subsequent trials have not given me any reason for concern.


The Hoses were hooked up. In the factory installation the 90/60/90 Y section reverses the 60mm outlet to reduce flow to the aft cabin. I did not want flow reduced as my wife suffers from the cold and so I really wanted to maximize flow to the aft cabin. in the photo below the exhaust pipe can be seen covered with the heat shielding and going to the outlet installed on the side of the hull.


The next task was to provide the fuel pickup from the diesel tank. I cut back the length of the Webasto provided pickup so it was about 10mm from the bottom of the tank. I then had to grind off the tabs that go under the top side of the tank as the tank opening is only 22mm in diameter. The pickup could then be installed.


You can see in the photo the flange is too big for the hole in the tank, hence it had to be ground back ti fit. The other fuel pickup was leaking so I cleaned the surfaces with acetone and used a gasket sealant prior to reassembly.


The fuel pump was mounted as shown in the photo under the bunk and the plastic fuel line was installed with rubber joiners and stainless hose clips provided.


The power was connected to an existing fuse holder mounted behind the battery switches. After shortening the wiring loom, the brown earth wire was connected to the load side of the Xantrex shunt so that any power used by the system would be “seen” by the battery monitoring system. The main power was fed through a 20amp fuse and the power for the control panel was fed through a 1 amp fuse. All fuses were supplied in the kit and fitted into the original fuse holder on the boat. This fuseholder was fed from the load side of the house battery switch as a factory fitout. The fuses can be seen on the right hand side of the fuseholder shown.


The remote monitoring wire was not required so it was covered in heatshrink and tie in with the loom.


The control panel had to be mounted above the 240 volt outlet in the galley. I was very concerned about removing this panel abut it was so simple. One screw from the cupboard adjacent and it fell out. The cutout for the control panel was made and the panel mounted. The wires were plugged in and the thermostat sensor mounted in the cupboard next door and also connected using the plugs supplied.

The most difficult part of the installation was deciding exactly where to drill the 40mm hole in the hull of the boat for the exhaust. It does not come easily for me to drill holes in a hull. After much deliberating, I decided to make the hole as far back as practical and as high as practical. The outlet has an upward bend in the inboard connection so it cannot be too high. In the end it was positioned about 150mm below the gunnel and just below the back stay anchor point.

The exhaust pipe was cut to length and installed with the Webasto supplied heat proof cover over the pipe.


The 90mm air intake hose was run behind the gas locker and fed downwards in preparation for if I actually get the air intake 90 degree bend and outlet flange. So far, intake air is simply being supplied from within the aft lazarette.

So now we have all outlets in, electrically connected, fuel pickup and pump installed and exhaust installed.


The moment of truth. On first switch on I noticed the fuel pump clicking and I noticed that with each click the fuel would make its way about 50mm up the fuel pipe. Reference to the commissioning part of the manual revealed that when first installed, it may take several switch ons to get the heater to run. When the heater is switched on it has several tries to get fuel to the heater and then stops. With no fuel in the pipe it takes a few cycles of this before the fuel actually reaches the heater. After many cycles of turning on, waiting for the system to time out, turn off and repeat, eventually when the fuel reached the heater it started working.


All outlets were checked and the various modes of operation were checked. The temperature of the exhaust was monitored and closeness to the surroundings noted. It is tied to the diesel filling tube so I may go back and install standoff brackets, however my judgment tells me that it is not a problem as the heat shield cover is quite effective.


The system worked very effectively when I was cleaning up after the job and I now look forward to cold nights on the boat where we very simply heat the environment if we wish.


The bill of materials was very close to what was required as the leftover hose can be seen in this photograph

This project was handled in manageable sections rather than all at once. It required careful planning and a commitment to install the system as closely as I could to the factory standard. I used an EVO3900 (Max 3.9kW) rather than an EVO5500 (Max 5.5kW) as the Australian climate is not as severe as some other parts of the world where Jeanneau yachts are sold.


I hope this may help someone who would like to do the same.