directional control problem twin Lehman diesels

[DavidAlan]

1979 46' Marine trader trawler with twin Lehman diesels.
"Directional control problem, boat immediately pulls to port each time power is applied. Unable normal maneuvering. Each attempt to power forward, boat pulls to port. The only remedy is to (quickly) put both engines in reverse and apply moderate power in order to stop the pull to port. Warner transmissions. Rudder steering functional. Wonder whether anyone has experiance to similar issue. Any advice would be greatly... appreciated!!! Thank you in advance.

 

[rslifkin]

This sounds to me like the steering is not working properly. At least one rudder may be stuck off to one side. Even with the worst prop walk imaginable (which shouldn't be the case with both engines in forward, as they should be counter rotating props), the rudders should easily overcome it.

 

[psneeld]

Sounds like one engine isn't responding as fast...are the RPMs coming up together?

Any tranny issues? Sounds? Can someone see if the prop shafts accelerate about the same?

Could be trash/growth on one prop more than the other..... any way to check?

 

[ksanders]

Is your port side power train producing propulsion?

Check this at the dock by putting one engine at a time in foreward.

 

[hmason]

Has any work been done on the boat recently? Have you checked the transmission linkages? Sounds like the port engine is going into reverse instead of forward. Just a thought.

 

[C lectric]

Is this a new problem showing only recently or has this been going on for a while?

Have you checked that the control cables are actually doing what they are supposed to do? ie. moving the correct direction? Have you watched the control cables at the gear?

Does this also occur when you first only go to reverse but not trying to correct the initial port pull.

Without more info it almost sounds like the control cable or what it operates at the gear has slipped causing it to operate in reverse.
If the cable is moving incorrectly it could also be caused by a fault at the controls head with a slipped cable clamp.

I think I would first determine if the cables are firmly attached to the levers that operate them OR that they operate.

The following checks should be done only at engine IDLE.

You could disconnect the cable at the gears and run the engines. THen manually operate the on the gear levers to see which direction produces Fwd and Rvs on each gearbox.

Then reconnect and see what each control head lever movement produces, FWD. or RVS. Something may have slipped.

You will also need to KNOW which way the shafts/props turn to produce FWD and RVS.


Hopefully someone can tell you what is going on. I can only ask questions

 

[DavidAlan]

Dear rslifkin,
both rudders were positioned full port. after rotating helm full starboard, went outside stern and observed both rudders remained positioned full port. now I intend to research just how to "fix" the steering issue. very much relieved to know that the transmission(s) were not the issue, and equally grateful for your time and knowledge Sir.
kindest regards,
David

 

[SteveK]

sounds like you have hydraulic steering. The helm turns but the rudders do not move. Check fluid level and look for leaks