Single Prop with Optional Tandem/Paired Diesel using Wing Engine

[Marco1]

On the topic of fuel cleaning, the system we had in place for a large generator was like this.
Two 5000 litre tank and one 1000 litre day tank.
The fuel tanker would dump the bunker fuel into the first 5000 litre tank and we would run an Alfa Laval centrifuge from the bottom of the tank to the top for a few hours and eliminate most of the rubbish, (water, tar and general dirt). When we were satisfied the fuel was ok, we woul let it stay for a day and the next day pump it to the second tank with the same centrifuge.
THe first tank was free to take another load of fuel any time.
The second tank would get the same treatment and from there it was pumped to the day tank.
The 'day' tank had a slow filtering system that would run continuously of the sort called toilet paper by pass filtration, but a bigger version of it.

We were able to run an Ingersoll Rand 7 cylinder generator on bunker fuel that was designed for normal light diesel only because of the centrifuge eliminating all the particles mainly tar that those injectors were not designed to take. Never had a brake down due to fuel.

[FAST FRED]

"You just don´t manage to bunker clean fuel in every port on a passage. And there is no way to get the water, biogrowth, rustflakes and mud out of your tanks by just running a additional filter".

This is correct , but my recommendation was not simply for a 2 element switchable filter , it was for a proper built tank and USING the tank to clean the fuel as part of the normal PM of the boat.

The fuel going into the tank would normally be pre filtered.

IF its a modest boat (under 400 or 500G)the extra time of running a few hundred gallons thru a "Baha filter" doesn't take much longer.

For a larger boat we use a seperiate filter (Fram) that has a hose that clamps over the delivery nozzle and then empties into the fuel tank.

This gets everything that wont go thru a really fine screen OUT of the tank.

The tank it self is not just a box of fuel.

The fill system is a removable tube (tubing with 1/4 --1/2 inch holes) that has a secondary tube of screening that can be pulled to clean it (as needed)from the outside tube.

Below the fill tube is a well that the fill tube sits in ,and the fill tube had at its bottom a cup that fits tight in the well and is below the bottom of the tank when installed.

With the usual 2 or 3 fill pipe inch setup the cup only holds a cup or so , but even a cup at a time the water can be removed with ease.

The complete tubing and inner tubing is used to "bail" the water out of the tank.

On most boats condensation is mild so a regime can be established that pulls the cup regularly when its half full.

No water in the tank? no bugs either.

This is system found on many US Navy Utility boats .

Big hassle if you have a 10,000 gal tank, the centrifugal is the choice , but for use 100 to 1000 gal boats it does work.

Sparkman and Stephens has a fine drawing shown in Skeens "Eliments of Yacht Design " , at your local library.

The big pain is when the best position to install the fill is inside the boats woodwork. Proper clean fuel servicing HAS to be part of the initial design.

FF

[FAST FRED]

So going beyond 62.5 HP is costing me extra fuel because I'm no longer at optimum.

Higher HP rating may work IF the boat has other gear that cont power.

An engine driven generator (fig 2hp per 1 KW), or a large hys system to operate stabelizers .

Engines vary tremendously in where the efficiency actually IS , in terma of load and RPM.

No rule of thumb is perfect for each engine.

What is perfect is a "Fuel Map' but there are harder to get from most engine folks than plans for a Suitcase Nuke weapon.

ASK and see what you get ,
usually just a HP curve and computer generated prop graph ,
which is totally useless for figuring efficiency.

FF

[Bubblehead]

I really like this thread, being a newbie. I've been thinking about 2 questions:
1. How to get rid of the genset and still have nice AC/refrigeration in port. Thinking is to have big (2-3kAh) battery for energy storage, run PTO via clutch to compressor and BLDC motor/alternator. So when engine runs, it powers compressor and charges battery. When engine off, battery runs compressor via same motor/alternator.
2. How to get the dink in the game for emergency propulsion. With a small (Lister AC1) aircooled diesel as the dink engine, perhaps it could be pulled in an emergency and relo'd to a designed mount in the ER to turn a sprocket on the shaft?
Thoughts?

[FAST FRED]

The simplest in port setup is to put two freon circuits in a eutetic plate.

One set has 5/8 or whatever the plate can handle from a big belted engine drive compressor.Usually a cast iron York.

A smaller tubing in the plate allows a std refrigeration "can" condenser 1/8 to 1/4 hp to pull the box down , with hours of running.

As most boxes are well insulated the dockside unit will not run much, after the box is cooled.

Works very well!! For a live aboard.

One contemplation is to Only hook the dockside unit to the freezer section , and "steal" cold to keep the fridge side cool in port.

Offshore both fridge eutetic plate and freezer eutetic plate are on the engine circuit, so the entire system becomes one big freezer.

Since there are no stores offshore, after a week its either frozen or its gone.

WE chose this setup and use a small cooler box . Offshore the frozen stuff is pulled the night before , and stuck in the small box with the next days drinks .

The beer gets cold free , from the steaks defrosting.

Biggest hassle is along shore , where the fridge contents must be placed in the small box ,(to operate the engine compressor) or frozen vegis and containers of milk will result.

FF