Trolling valves and clutch packs

[AKBM]

Hi.
I installed the ZF trolling valve 7 months ago.
I know it makes the clutch slip to slow the boat down and I heard it damages the clutch pack.
One day I went out fishing and used the trolling valve but the trolling speed decreased dramatically. It was doing 1 knot instead of 2.5 knots.
I asked those guys that installed it and they replied the clutch pack might have worn down.
Paid heaps for it and been out only 15 times... Can they actually wrack your clutch packs this quickly?
How come other people use trolling valves and they are perfectly fine?

Many thanks

 

[gordmac]

No idea but worth a bump.

 

[Latestarter1]

I have only been involved with trolling valves on ZF IRM 220A's

PROVIDED properly interlocked clutch wear no issue.

Take a look.

Myths and legends of trolling valves

Frequently Asked Questions


Do I need a trolling valve?

Trolling valves are used to reduce the minimum speed of a vessel. To accomplish this the shaft speed of the vessel must be reduced. This may be required for fishing purposes or while the vessel is operating in confined spaces, and minimum wake is required.

What is a trolling valve?

A trolling valve is merely a variable pressure regulator, which works with the existing pressure regulator to provide for a low range of pressure control. This pressure range of operation is between 7 PSI (.5 bar) and 95 PSI (6.5 bar). This lower pressure will cause the clutch pack to slip allowing the propeller shaft to operate slower than the normal "in gear" speed.

What's the valve's range of operation?

For practical purposes there is no minimum shaft speed that can be obtained. Under certain circumstances the shaft may stop turning. The maximum shaft speed is expressed as 70% of the normal "in gear" shaft speed. Operation of the trolling valve to obtain greater than 70% of the normal shaft speed will lead to clutch "chatter" and will damage the gear box. The engine speed may be increased if a greater shaft speed is desired. Engine speeds must be at or near idle during trolling operation.

For example: If the normal engine idle speed is 600 RPM and the gear ratio is 2:1, then the maximum shaft speed during trolling should be limited to (70% of 300 SRPM) 210 SRPM. If a greater shaft speed is required, the engine idle could be increased. In this case the engine RPM should not be raised above 857 RPM since this RPM is equivalent to 600 RPM in gear (no trolling) normally.

The engine speed should never exceed 1000 RPM during trolling. Some applications have a lower limit.

Can I use my trolling valve to dock my boat?

The clutch pressure is reduced during trolling. This means the response from ahead to astern or vice versa is very slow. This reduced or lack of control could lead to damage or injury should the vessel contact fixed objects. For this reason, it is not recommended to use trolling valves for docking purposes.

How do I control my trolling valve?

ZF offers both electrical and mechanical trolling valves. For mechanical valves, any means of moving the control lever can be used to operate the valve. If mechanical systems are used, you must ensure that the control lever can be moved in small increments to ensure repeatability of operation. Electric valves have proved to be the more easily controlled type. Many marine control systems are available to properly control the valve. Electronic control systems allow for easy adjustments of the valves' range of operation to suit different applications.

Regardless of the type of valve or control system, there must be provisions made to prevent the operation of the vessel in a situation so as to damage the clutch plates in the gearbox.



Courtesy ZF Marine transmissions

 

[omega2]

What are trolling for? and where.

 

[piratos]

rolling

What are trolling for? and where.

Would have thought somebody else would have replied....

""
Trolling is a method of fishing where one or more fishing lines, baited with lures or bait fish, are drawn through the water. This may be behind a moving boat, or by slowly winding the line in when fishing from a static position, or even sweeping the line from side-to-side, e.g. when fishing from a jetty. Trolling is used to catch pelagic fish such as salmon, mackerel and kingfish.

Trolling can be phonetically confused with trawling, a different method of fishing where a net (trawl) is drawn through the water instead of lines. Trolling is used both for recreational and commercial fishing whereas trawling is used mainly for commercial fishing.

Trolling from a moving boat involves moving quite slowly through the water. This can be accomplished with the use of a special trolling motor. Multiple lines are often used, and outriggers can be used to spread the lines more widely and reduce their chances of tangling. Downriggers can also be used to keep the lures or baits trailing at a desired depth.

""

Trolling is a the usual way fishing for Salmon from a boat.

 

[Bandit]

Trolling Valves are fitted to generally motor boats with large engines which with the limitations of propellers pitched for performance can on the other hand be quite heavy handed for manoeuvring. Some motor boats have a tick over speed of 5 or 6 knots with both engines in slow ahead which is quite a handful.

You will often find motor boats have trolling valves fitted for manoeuvring alone so that this 5 or 6 knots can be reduced to 2 to 3 knots for close quarter operation.

Yes they can also be used for fishing.

 

[JSYmartini]

I've just had trolling valves fitted to my ZF 220's by MIT Engineering for the purpose of escorting long distance/open water swimmers.

I haven't fitted the boxes back in yet so can't comment on their operation yet.

I was doing 5.5 knots idling, 3.5 if on one engine. Ideally I need to get down to a knot or even less.