Part of your comment is one reason I don't like Helicopter set-ups, especially with a "naked" line section of light breaking strain mainline. You should be using a line strength of at least 15lb to my mind.
Have a read of these, some good pics and ideas here:
http://www.carp.com/carp-forum/viewtopic.php?t=51296
http://www.carp.com/carp-forum/viewtopic.php?t=36456
http://www.carp.com/carp-forum/viewtopic.php?p=519408#519408
http://www.carp.com/carp-forum/viewtopic.php?t=37603
Thanks for your patience. That last thread had a brilliant picture in it and would be my preferred set up. The only thing is, if the beads can release then how do you prevent them sliding down the line on the cast or when playing a fish? This is probably obvious but not to me I currently use Daiwa sensor brown 15lb. I don't want to use a leader so should I go for a higher breaking strain line? The new lake I am fishing has some nice twenties and probably thirties too by now. What size beads should I use and which of the two sizes of sinker?
The beads I used on that set-up were 8mm Rubber beads. A small PVA string loop or foam nugget will stop the beads sliding down on the cast, but it honestly doesn't matter that much, as you want them to slide up the line on impact with the water, so that the rig itself settles on the silt.
As for playing fish, it doesn't matter if they slide down to the lead attachment, in fact it is more likely to help avoid the trailing lead getting snagged or stuck in anything.
I've landed a fair number of fish to over 30lb on 15lb Daiwa Sensor, its a pretty good line, and years ago I did use it with Helicopter set-ups.
i still only use 12lb line.
in my mind if i need to use heavier i shouldn't be fishing there