Dead Engine

[smbdck]

Just bought a 40 ft. Carver, first big boat I have owned. Got a question about an engine failure before it ever happens and I hope it doesn't.

----twin Crusader FWC gas engines
----Hurth Transmissions


Suppose I'm out cruising and for whatever reason i.e (loss of oil pres./high water temp./mechanical failure/etc.) I have to shut down one of the engines.

1. What should be the max. speed I can operate the good engine.
2. Do I place the transmission lever of the dead engine in neutral or leave it in gear.

Thanks, ****

 

[QC]

Re: Dead Engine

Welcome to iboats smbdck!

The answer to #1 should be as fast as she will go, but there is a problem in that the engine is propped assuming that both are running. Running alone it is effectively over propped (too much pitch). I believe you should run her at displacement speeds (around 9 knots max I am guessing) to keep from severely lugging the engine. How fast is she now with both engines running wide open?

#2 is neutral.

 

[oops!]

Re: Dead Engine

welcome.....

there you go.....

lets hope it never happens!

cheers
oops

 

[smbdck]

Re: Dead Engine

>>How fast is she now with both engines running wide open?<<

28kts.

I'm worried about the transmission overheating on the dead windmilling engine, should I be??

 

[QC]

Re: Dead Engine

28kts.

Wow, nice! I don't think you could get her on plane with a single, and while trying and at all planing speeds she would be seriously lugging I'm afraid. Try it for a couple of minutes, see what happens . . .

I'm worried about the transmission overheating on the dead windmilling engine, should I be??

No. It will circulate fluid, and there is no load, so there is no heat. I found a Hurth manual online and it said that leaving it in gear was an issue . . .

 

[jay_merrill]

Re: Dead Engine

I came up with a hull speed of about 8 knots just because I took off a few feet to account for waterline length v. overall length @ 40 feet.

You might want to practice single engine operations a bit before you have to pilot the boat that way for real. It will handle a bit differently due to asymmetric thrust and you won't be able to use differentilal thrust to maneuver into a slip. The first thing that you will notice is that it will want to turn away from the good engine until you gain enough speed through the water for the rudders to become effective. Because of this, it may be useful to start out with a low power setting and gradually increase it as you gain steerage.

The remaining engine may be able to push the boat somewhat beyond hull speed but you will burn a disproportionately high amount of fuel for the extra knot or two. This is because the amount of power required for any given speed is nonlinear - the higher the speed, the higher the multiple in terms of power. If you have a flowmeter in the boat, fool with it a bit in single engine mode to figure out your consumption rates at various speeds. This might come in handy to determine your ability to get home on remaining fuel for each desired power setting.

New boats are always great so have fun with it!