DIY electronic rudder indicator?

NUTMEG

NUTMEG

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www.theblindsailor.co.uk
All right this might be a dumb idea but please bear with me.

Wheelhouse motor sailor with cable wheel steering. I am used to a tiller. At slow speeds, berthing etc I have no idea where my rudder is pointing.

Elec rudder indicators cost lots!

Here is a cunning plan. A bog standard fuel gauge sender, float type, fixed to the stump (no quadrant) of the rudder shaft in such a way that amidships is in the 'half full'. Stbd = full and port = empty. The gauge could be mounted in the wheelhouse and marked appropriately with the 1/2 full position representing amidships.

Seemples!

What have I missed?

Any views before visiting a scrapyard with spanner in hand!

Cheers
 
Sophie19 said:
All right this might be a dumb idea but please bear with me.

Wheelhouse motor sailor with cable wheel steering. I am used to a tiller. At slow speeds, berthing etc I have no idea where my rudder is pointing.

Elec rudder indicators cost lots!

Here is a cunning plan. A bog standard fuel gauge sender, float type, fixed to the stump (no quadrant) of the rudder shaft in such a way that amidships is in the 'half full'. Stbd = full and port = empty. The gauge could be mounted in the wheelhouse and marked appropriately with the 1/2 full position representing amidships.

Seemples!

What have I missed?

Any views before visiting a scrapyard with spanner in hand!

Cheers
Click to expand...

Turk's Head on the wheel works for me.

But I also have an old rudder reference arm from an Autohelm auto pilot you could have. Talks NMEA0183.
 
You would be fitting exactly the same as a rudder indicator so of course it will work, the sender on most rudder indicators is a 10 to 180Ω VR the same as a tank gauge and the instrument is again the same workings, only issue I see is most rudder indicator dials (if analogue) are quite a bit bigger than a tank gauge.
 
lpdsn said:
Turk's Head on the wheel works for me.

But I also have an old rudder reference arm from an Autohelm auto pilot you could have. Talks NMEA0183.
Click to expand...
Showing my ignorance now but,what is a rudder reference arm? NMEA I sort of understand but how would I use the data? Wouldn't I need some sort of display?

Old sender units and gauges I understand!
 
Sophie19 said:
Showing my ignorance now but,what is a rudder reference arm? NMEA I sort of understand but how would I use the data? Wouldn't I need some sort of display?

Old sender units and gauges I understand!
Click to expand...

It's part of an auto pilot. You mount it near the rudder and connect it to the quadrant (or alternatively an arm connected to that). As the rudder moves the arm of the reference moves and alters the signal it gives out.

Here's an example of a modern one. Probably very similar to mine. Raymarine took over Autohelm (although there were many intermediate stages).

http://www.mesltd.co.uk/raymarine-rotary-rudder-reference-transducer-p-168.html

Actually, I should withdraw the NMEA0183 statement. I believed it did (the wiring looks like NMEA wiring) but I can't say for certain as it talked privately to the autopilot controller.

As David 2452 says, it's probably very similar to a fuel tank gauge internally. I haven't taken it apart.
 
As David 2452 says, it's probably very similar to a fuel tank gauge internally. I haven't taken it apart.[/QUOTE]

Sounds interesting and may be more robust than a fuel sender. Do you happen to know the resistance + and - ?

Did you have a figure in mind? Perhaps PM me?
 
You could make up a simple system using a centre zero moving coil milliamp meter. You need 2 linear potentiometers around 1000 ohms total resistance. One potentiometer is mounted on the rudder post so that it is at the centre of its range. Another similar potentiometer (or just 2x 500ohm resistors) are wired in a bridge circuit. ie one end of each of the potentiometers goes to +ve supply the other end of both potentiometers goes to -ve. Now the voltage between the 2 potentiometer centres is zero if the 2 potentiometers are at same (mid) position. A voltage appears between the 2 potentiometer centres if there is an imballance. This voltage is either +ve or -ve depending on the error (rudder deflection). The second pot in lieu of the resistors can be used to set the meter for zero deflection.
Another ressitor (variable potentiometer again if you want) will calibrate to give the desired mter deflection for a given rudder angle.
Now you could use a digital volt meter module to measure this voltage and rely on the -ve polarity indication or no polarity indication for showing right or left rudder. Or even use an existing digital volt meter with a transfer switch.
Just a thought for those who like to fiddle. good luck olewill
 
A passing thought. Fuel tank senders of the type proposed, work and are lubricated by the fuel IMHO. I think the working life in air might cause premature failure.
Two ganged rheostats are available from various sources also centre driven voltmeters, a better option in the long run.
 
lpdsn said:
Turk's Head on the wheel works for me.
Click to expand...

+1 for a Turk's Head on the spoke that is "up" when the rudder is centred. Surely if you're more than one revolution of the wheel from centred it will be pretty obvious, unless the wheel is far too low-geared?

I steer by tiller, though. I keep meaning to do a decorative Turk's Head on the tiller, and forgetting to do it!
 
I have 6 full 360* turns lock to lock. Is that normal?

Reason for all this is that last trip out I had the wheel and rudder centered (I thought) and attempted reversing out of her berth. In fact the rudder was to stbd by a turn and the boat slewed her stern that way, the tide caught her and finished the job by pushing her against the stern of a 50' ex admiralty harbour launch. No harm done to either boat but embarrassing to say the least. Hence the desire to KNOW where the rudder is at very slow speeds or astern.

Hope the cheapy Chinese gizmo will do the trick. Anyway, I can't tie a Turks head! Barley manage a reliable bowlin:)

Steve
 
Sophie19 said:
I have 6 full 360* turns lock to lock. Is that normal?
Click to expand...

Not really, on a sailing boat. We have a bit less than two full turns, and our wheel is not massive.

If it's a heavy motor-sailer with a tiny indoor wheel then your six turns might be necessary though. How heavy is the wheel to turn? If you can turn it easily, you could maybe change to a bigger drum to have fewer turns and still an acceptable load.

A wheel with lots of turns like yours definitely needs a rudder indicator though - very sensible of you to be fitting one.

Pete
 
I did build a DIY indicator as I have twin hydraulic steering.

I used a sealed pot connected by a sutiable arm to the rudder shaft and the indicator is a strip LED indicator based on strip LED voltmeter chip (can't remember the IC number at the mo.

For a multi turn single steering or twin mechanical wheels one of there may do the job.

http://www.davisnet.com/marine/products/marine_product.asp?pnum=00385
 
prv said:
Not really, on a sailing boat. We have a bit less than two full turns, and our wheel is not massive.

If it's a heavy motor-sailer with a tiny indoor wheel then your six turns might be necessary though. How heavy is the wheel to turn? If you can turn it easily, you could maybe change to a bigger drum to have fewer turns and still an

A wheel with lots of turns like yours definitely needs a rudder indicator though - very sensible of you to be fitting one.

Pete
Click to expand...

Thanks Pete. The wheel on Rose is fairly large, certainly much larger than a car. There is some resistance turning it but easily turned with one hand. I can not change the drum as she has a single cable steering system. A sort of rack and pinion at the wheel end and a big clamping arrangement at the rudder.
 
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