Single Engine Operation
Single Engine Operation
I know our boats can run on one engine, but if you do it, which engine is better to run and what precautions should be taken with the other motor? For example, should the non-running engine be left in neutral? The shaft will spin. Any issues with that vis a vis seals?
Nick & Barb
Catsaway
2005 PDQ34 #66
Catsaway
2005 PDQ34 #66
Re: Single Engine Operation
Nick,
This has been debated much over the years. The tranny can run fine in neutral according to the manufacturer. Since it is hydraulic, it will not lock regardless of putting it in forward or reverse. You would have to use a mechanical lock on the shaft for that, but no need.
With the engine not running, there will be no water pumped to the dripless seal on the shaft, which could be a problem in certain cases, but with only one engine you will be running at low speed and the shaft will not spin rapidly. Others (and I) report no problems running on just one engine for extended periods.
If you happened to be in a seaway with waves hitting the side of the inoperative engine, one would hope the water could not push past the loop in the exhaust and enter the engine. I don't know how bad conditions would have to be for that to happen. I assume you would not choose to run on just one engine in bad conditions, but it could be your only choice with an engine failure.
As for which engine to use, it matters little IMHO. If the wind/waves/current were coming from starboard, maybe run the port engine to counteract those forces, and vice versa.
I came to the conclusion that since it takes a certain amount of power to push the boat at a given speed, the single engine will work a lot harder. The rudders will be at an angle to maintain a straight course, so there will be extra drag. Fuel savings might be small. If you did it enough, you would extend running time between services, but maybe not enough to be worth it.
BTW, I have had to run our boat 3 times with only one engine available (always a starter/solenoid issue). Getting into and out of locks, loitering at bridges for an opening, and especially getting into a slip can be a real challenge. Hope you never have to do it.
This has been debated much over the years. The tranny can run fine in neutral according to the manufacturer. Since it is hydraulic, it will not lock regardless of putting it in forward or reverse. You would have to use a mechanical lock on the shaft for that, but no need.
With the engine not running, there will be no water pumped to the dripless seal on the shaft, which could be a problem in certain cases, but with only one engine you will be running at low speed and the shaft will not spin rapidly. Others (and I) report no problems running on just one engine for extended periods.
If you happened to be in a seaway with waves hitting the side of the inoperative engine, one would hope the water could not push past the loop in the exhaust and enter the engine. I don't know how bad conditions would have to be for that to happen. I assume you would not choose to run on just one engine in bad conditions, but it could be your only choice with an engine failure.
As for which engine to use, it matters little IMHO. If the wind/waves/current were coming from starboard, maybe run the port engine to counteract those forces, and vice versa.
I came to the conclusion that since it takes a certain amount of power to push the boat at a given speed, the single engine will work a lot harder. The rudders will be at an angle to maintain a straight course, so there will be extra drag. Fuel savings might be small. If you did it enough, you would extend running time between services, but maybe not enough to be worth it.
BTW, I have had to run our boat 3 times with only one engine available (always a starter/solenoid issue). Getting into and out of locks, loitering at bridges for an opening, and especially getting into a slip can be a real challenge. Hope you never have to do it.
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade
Re: Single Engine Operation
Nick,
If your engine raw water intake "scoops" are facing forward, I know from experience the seacock needs to be closed or the engine will hydrolock from the water being forced past the impeller. I think you may have 100 hp engines and the "scoops" may face aft. Check first before taking my word for it. Otherwise the only other issue I have had is when first getting underway, the boat turns away from the powered side until there is some water flow over the rudders. Maneuvering in close quarters can get exciting. I don't have any fuel burn data for single engine.
Hope this helps.
Rafe
If your engine raw water intake "scoops" are facing forward, I know from experience the seacock needs to be closed or the engine will hydrolock from the water being forced past the impeller. I think you may have 100 hp engines and the "scoops" may face aft. Check first before taking my word for it. Otherwise the only other issue I have had is when first getting underway, the boat turns away from the powered side until there is some water flow over the rudders. Maneuvering in close quarters can get exciting. I don't have any fuel burn data for single engine.
Hope this helps.
Rafe
Rafe Williams
"Cat Daddy"
MV34 #32
"Cat Daddy"
MV34 #32
Re: Single Engine Operation
VERY good point, Rafe. I forgot that was a problem for some of our boats.
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade