Some of our members feel this is the killer feature. While underway, to find optimum VMG, we can adjust the distance that the boom is away from the centreline in the neutral position using infinitely variable adjustments on a dial. On a variable day we can adjust the neutral position without coming ashore. We can even do it mid-race….
This feature is extremely good when implemented alongside either the 2D Joystick, or the 4 position Pinch and Puff implementations.
We are going to use dial (R Knob) that sits on the right hand top surface of your Spektrum. It’s the only dial we have on a DX8 and the software knows it as a switch labelled “RKn”. Unlike the other switches which basically have two or three positions (0/100 or 100/0/-100 ) the Rotary Dial transmits a variable number each side of centre between 0 and 100 according to where the dial is sitting – just like turning up the sound volume on your car radio. The dial very usefully beeps at “zero” so you can tell if it is centred.
When the dial is centred (easy to feel a click under your fingers – try it), we are neutral. Dial clockwise to tighten the mainsheet, dial left to ease it out.
We shall aim to have the dial centred at the Neutral position 2 in the Pinch and puff model.
To set up the VMG Fine Tune, we shall use another Mixer. Scroll to the Mixer on the Main menu
Select “Mixing” and you should get the Mixer List
We are going to take P-Mix 2 for the VMG Fine Tune – as you see above it is on inhibit at first.
Click to open mixer 2
Now click on Normal to see the data fields
We need again to assign a master and a slave. Our Master will be RKn the Radio Knob. Our slave will be the THR which is where our mainsheet winch is plugged.
Change the two INH fields to indicate this.
Now we have to set some values (and correct direction) for our VMG fine tune.
On the boat in the workshop we get around 10mm when we turn the dial away from zero. To the left we need to see around 10mm of easing the mainsheet from the neutral position, and when we turn the dial clockwise we want to see the maximum seeing the mainsheet coming in 10mm.
Probably because we had too invert this channel it needed minus numbers to get the direction correct. By coincidence, a 10% setting each side gave us around 10-12mm of sheet out and in.
As all the mixers are now “ON”, they can work in conjunction with each other without problem. You can use it to fine tune the distance from the boom to the mainsheet post. If you need more than 10mm, simply adjust those Rate numbers.
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Datchet Radio Sailing Transmitter Manuals - Spektrum 