Fishboat Generator Question

[stevo42]

I've wondered about this for a long time. Allot of fish boats in Alaska run at night with these super bright work lights on, some that shine out head. They say they need to have a load on their generators. Its only annoying out at sea but when you meet one of these guys in a narrow channel its hazardous. I dont need to go into a rant but I was wondering, whats the deal about keeping a load on a generator.

[Quinnf]

The idea is that the diesel engine powering the generator doesn't do well under low-load conditions.  Downtime for repairs means no fish in the hold and no money in the bank, so as a precaution, many/most fishboats run their lights all the time, even in the daytime, to keep the diesel loaded. 

I'm with you on the safety issue.  In confined waters, encountering one of those guys can ruin your night vision in a hurry.  However, when I crewed on offshore races, I always felt uneasy sailing with just the nav lights on.  Even on a moonlit night you can't see squat.  There are lots of things out there that go bump in the night.  Kelp rafts, unlit buoys, drift nets, logs, deadheads, timbers discarded from cargo ships, even partially submerged shipping containers.  Running into the wrong one can be fatal. 

Quinn

[stevo42]

Your right about all the things floating around out there, I'll add half sunk containers to your list of  hazardous. Keeping a sharp eye on the radar and having it adjusted for sea conditions is a good practice but if your a small boat without radar its tough to see whats up there floating just ahead. Theres not near as many dead heads up here in Pacific NW waters as there used to be when there were more log rafts being towed but theres still plenty of hazards to small boats. The thing is theres allot more junk floating around in the "open" ocean these days and allot of the time you really cant pick it up on radar unless the sea is calm, at least in inland waters you might be able to swim ashore.

I see what your saying about the problem being with the diesel engine powering the generator. The engine would not be operating at proper temperature, which is not good,  Yah that makes sense.  Then the generator head doesn't care?

[dieselgman]

The generator heads only care that the humidity is kept under control and with even a light load they will warm slightly and keep this in check.

The engines not only can run cold, but specifically fail to burn most of the fuel and that can result in the slobbering problem. A new machine can fail to break in the rings properly and lead to excessive oil consumption as well.

A loaded machine is a happy machine. If common sense applied, perhaps they could load with resistive heating elements or load banks - this is what is done for many small land-based generating plants.

dieselgman

[stevo42]

What in the world is a 'slobbering' problem, as it would relate to an engine?

[Tom]

"Slobber" is unburned fuel out the exhaust of a diesel engine not working hard enough to maintain proper temp to fully combust it's fuel. This can eventually lead to a "stack fire".

[ronmar]

You can also pull more motor oil up past the rings on an unloaded engine which can contribute to the slobber and carbon buildup.  Unburn't fuel also passes past the poorly sealed rings and into the crankcase.  This dilutes the lube oil, and when you do load up and heat up the engine, the diesel in the hot engine oil can vaporize and cause a crankcase explosion...

Unloaded diesel = Bad:(

[stevo42]

Good to know, thanks guys. I think a stack fire or explosion in the engine room could spoil an otherwise nice day at sea.