Trolling Valve.

[chamac]

Hi Folks
I noticed on my "new to me" 2006 MF805, a warning me not to use the trolling valve over 1100 rpm.
I never heard of a trolling valve so did some googlin'
Looks like maybe I have one. See attached.
Didn't follow the cable back yet but it may be going to the morse control on the transom.
Can anyone say if I do in fact have one?
If so, is it worth the risk keeping it. I idle at around 3.5 knots. (Maybe a bit fast)
I do a bit of fishing from her so might be useful for trolling.
BTW, I do intend repainting the bracket and gearbox ;-) I only just got her.

 

[Chris H]

I’ve got trolling valves, I should really find out how to use them as I idle @ 7.5knots

 

[scottie]

Might well be worth trying it and sharing the results

 

[chamac]

Scottie.
After reading about them, I'm afraid to..
Don't want to fry my clutch plates.
Charlie

 

[Portofino]

In the Med the sport fish swim fast .
My boat @ tick-over does 7knots .
I spoke to a sport fisherman years ago about tuna .
He told me 6 miles out , 6 knots for 6 hrs .
I USED to let the Mrs Porto Helm while I sit at the back tied to the Passerelle with 25 cm long lure + 100 kg breaking strain out .It’s looks like strimmer cord .Emphasis on “used to “

I bought this kit many years ago on one of those milestone birthdays.

How ever I don’t use it any more.Something went horribly wrong .

we buy fresh fish instead nowadays.

And yes ^^^ was a haply ending .

kinda put off nowadays.

 

[Alicatt]

The keeping RPM low is to do with the oil more so than the clutch, the way the trolling valve works is that it puts a thin layer of oil between the clutch plates and uses the friction between the clutch plates and the oil to transfer the drive from the engine to the gearbox, usually with a gearbox with a trolling valve they have an oil cooler to make sure the gearbox oil does not get burned
There was a good video on youtube showing how it worked, can't find it at the moment though.

Tesla, Nikola not Musk, used the same principle with his design for a turbine

 

[chamac]

Wow, Portofino
That must have been traumatic ok.
I hooked a tuna between Greece and Sicily once.
It was chased by two dolphins until we got it on board.
Looked like the dolphins were playing with the lure before the tuna took it.
We would have been close to 6 hours out @ 6 knots so 36 miles out.

 

[MapisM]

I’ve got trolling valves

Wow. On which gearboxes?
IIRC, you've got the same MAN V8/800 engines as mine, which are usually mated to the ZF350 gearbox.
And the trolling valve was indeed available (as an option) for it, but even if I've seen several boats with the same powerplant, I never came across any with trolling valves...

 

[Chris H]

Wow. On which gearboxes?
IIRC, you've got the same MAN V8/800 engines as mine, which are usually mated to the ZF350 gearbox.
And the trolling valve was indeed available (as an option) for it, but even if I've seen several boats with the same powerplant, I never came across any with trolling valves...

My gearboxes are twin disc.

 

[Alicatt]

What is a Marine Transmission Trolling Valve? - Seaboard Marine (sbmar.com)
The difference in the system above and the system that is used by MAN with the ZF gearbox is that the engine speed is fixed to a maximum of 900 - 930RPM and the throttle leavers control the amount of slippage from 100% slippage to 0% slippage
This is what I found while looking for information about the engines on a boat I was interested in.
Edit: that boat did 10knts at 900RPM, my old boat did 6.5knts at tick over and way above the 3knts speed limit in our harbour, and at 6.5knts the wash off the little boat was huge and I used to get stick from the harbour master for coming in too fast.

 

[Portofino]

What is a Marine Transmission Trolling Valve? - Seaboard Marine (sbmar.com)
The difference in the system above and the system that is used by MAN with the ZF gearbox is that the engine speed is fixed to a maximum of 900 - 930RPM and the throttle leavers control the amount of slippage from 100% slippage to 0% slippage
This is what I found while looking for information about the engines on a boat I was interested in.
Edit: that boat did 10knts at 900RPM, my old boat did 6.5knts at tick over and way above the 3knts speed limit in our harbour, and at 6.5knts the wash off the little boat was huge and I used to get stick from the harbour master for coming in too fast.

View attachment 124833
View attachment 124834

You just nudge up first click for a few secs let the boat move a bit get rolling then flick it back into N as it moves within the speed limits.
Odd little burst now and again while mostly passing by in N .let momentum carry it .
No need what so ever for a trolling valve in the marina .

They are for fishing , not game big fish ?

Same with turning , rudders ahead and click one side up into F and the other back into R for 1-3 secs then both to N .

Manoeuvring with big pitched props is a delight / doddle , click up 1 sec later click back to N .