Most large yachts have a blower, a fan that replenishes the air in the engine room. This isn’t a mandatory requirement for a yacht with a donk, the way it is for motor boats with inboard petrol engines, because diesels are unlikely to leak flammable gases and don’t really need to be force-fed clean air.
On yachts with a small engine space, I understand that a blower can help with cooling, but our engine sits in a nice big void and has a nice big raw-water cooling system.
However, any engine, particularly one that – like ours – is over 25 years old, will be a little greasy and smoky, and it also seems sensible to have the facility to pump out any unburned cooking gases that may have dropped from the stove into the bilge.
Vestlandskyss has a bilge blower which we turn on, from habit, whenever we run the engine. We knew that it was situated somewhere under the aft berth, because we could hear it whining when in bed on passage, even over the rumble and roar of the engine.
The fan didn’t seem to be tremendously effective. Sometimes it seemed that the ‘hot engine’ fragrance down below was stronger when the blower was running, than when it was not. Over successive passages, the fan got louder and louder, and finally one day it made such an ear-splitting shriek that I turned it off, and moved ‘find the blower’ higher up the To Do List.
The aft berth is enormous, more like a queen bed, and the mattress is heavy and unwieldy. With nobody else aboard to get in the way, and with the boat tied firmly to the dock, I got the mattress shifted far enough out of the way to open the inspection hatches, and followed my ear to the shrieking blower which was bolted to one of the bulkheads.
Now that I knew which pipe to follow, I traced it forward to an intake nestled in the bilge under the engine. With the fan still shrieking away, and my hand pressed over the open mouth of the tube, I could detect only the faintest susurration of air movement.
Now heading aft, I followed the tube back along the bilge until it disappeared under the steering quadrant. Back on deck, I shifted all the accumulated junk out of the port-side lazarette onto the dock, and climbed back down into the bilge.
Lying on my side, I traced the exhaust section of the pipe as it snaked, neatly and professionally secured to bulkheads and internal struts, until it emerged from under the quadrant and rose through a cluster of unrelated heat-ducting to terminate, suddenly and uselessly, about a foot away from a clamshell vent in the transom.
Even if the blower sucked at full efficiency, it would still only be moving air from one part of the bilge to another.
I dismounted the unit and went pessimistically in search of a drop-in replacement for a 26-year old European fan, discovering to my surprise that the TMC blower is not only still made, but is inexpensively available in Australia.
The new unit slotted easily into place. I fired it up and put my hand over the intake. My palm was instantly sucked hard and tight against the mouth of the tube, and I had a little trouble disengaging it. Quite the difference in power, and at the same time so much quieter, more of a dull whir than a whine.
Back in the lazarette, I manufactured an elbow out of household stormwater connectors, and bonded the whole thing to the inside of the clamshell.
From now on, all of our hot oily smells are going straight overboard.