I posted this on SotP a little while ago and it is worth posting here. Basically how I set up my underblanket
Here we go. First you need to add a couple of things to your underblanket and also to your hammock.
Preparation
Get all four bungee cords from the end of the underblanket through a cord lock. Do this at but ends. It is footery but you can manage. Next add a piece of cord about 1m long to one of the tabs at each end of the underblanket. Lastly add a small loop of string to the carabiner, ring or hook at end of your hammock.
Setting up
Set up your hammock as normal. Put the underblanket IN the hammock and spread it out. Take one of the cord locks with the bungees through it and pass this through the loop of string on the hammock ring.
Do this at both ends. You can now tip the underblanket out of the hammock and it will hang under the hammock.
Take the string you attached to the underblanket and pass it over your ridge line (either the hammock ridge line or your tarp ridge line) and tie it to the opposite loop
Do this at both ends.
That is you set. To adjust the tension of the underblanket simply press the cord lock and either pull the bungees tighter or loosen them as required. Remember you want the underblanket resting gently against the underside of the hammock but not squeezed against it.
The string over the ridge line helps to take the weight of the underblanket and also spreads it. Like the bungees these may need adjusted but are easy to set.
Now you can lie back and enjoy the warmth.
Used mine this weekend as did Warthog 1981 and Stuart_Blink and we were all toasty warm. Just used our sleeping bags as blankets as the underblanket keeps you warm enough underneath on its own.