Bennett Trim Tabs

[Reelin in the Years]

My Trim Tabs are slow to retract after engine are turned off. Anyone know approx time elapse for typical retraction?

 

[Doc Stressor]

It takes a long time. I've never timed it, but the pump runs for at least 30 sec after I shut down.

 

[seasick]

It takes a long time. I've never timed it, but the pump runs for at least 30 sec after I shut down.

The time also varies depending on how far the tabs were extended of course.
If you want to see if something is amiss, with the motors idling in neutral ,extend the tabs all the way down and then time how long it takes for them to raise all the way. That time should be about the same as the time to autoretract in the worst case. If your auto retract times is significantly longer, I would suspect excessive voltage drop. The voltage at the battery is higher when the motors are running and the tab pump probably runs a bit faster.

 

[DennisG01]

Are you physically looking at the tabs as they retract, or just listening to the sound of the motor? I believe the motor continues for a bit, even after the tabs are actually retracted. The retraction time is simply a "timed event" - there is no way for it to know if/when the tabs are physically retracted.

 

[Doc Stressor]

The retraction time is simply a "timed event"

That is my understanding as well. On mine, it doesn't make any difference how far the tabs were trimmed down or if only one is down.

 

[journeyman]

The retraction time is simply a "timed event"

That is my understanding as well. On mine, it doesn't make any difference how far the tabs were trimmed down or if only one is down.

X2
This has been my experience/understanding also.

 

[seasick]

X2
This has been my experience/understanding also.

I am an idiot at times. Yes it is a timed, worst case , operation.

 

[Fishtales]

I'm sure the tabman will set the record.

 

[Tabman]

It is indeed a "timed event". No mater if the Tabs are all the way down, or all the way up the system will run will run about that long to insure they are fully retracted.

Tom McGow
Bennett Marine

 

[journeyman]

It is indeed a "timed event". No mater if the Tabs are all the way down, or all the way up the system will run will run about that long to insure they are fully retracted.

Tom McGow
Bennett Marine

Thank you Tom! As always, great to have you around!

 

[Reelin in the Years]

24 seconds, of pump in helm takes longer... from Bennett

 

[DennisG01]

24 seconds, of pump in helm takes longer... from Bennett

Huh?

 

[Reelin in the Years]

You are right, spoke to Bennett today . The pump location has a lot to do with retraction time . In 307 pump is located behing helm , creating longer distance for hydraulics to travel .

 

[glacierbaze]

I'm not that smart, but I think those hydraulic lines stay full in both directions, all the time, like a brake line. So the fluid doesn't travel from the helm to the tab, every time you move the control. The pump moves X amount of fluid into one end of the line, and the tab moves a corresponding distance at the other end.

 

[DennisG01]

I agree that if the lines stay full, there shouldn't be much, if any, delay. The only delay should be from whatever/how much the fluid compresses over the length of the line... which would be extremely little. HOWEVER, I have physically noticed that the lines will, indeed, get an air gap in them once the pump runs after fully contracting the rams. Not gonna try and explain the "why" - just noting the "what". Maybe some type of bypass valve?