It became obvious recently that the halyards in our mast were having a party inside the mast tube and were twisted. The fact that my ordinarily very tolerant crew was reduced to cursing at the effort needed to hoist and drop the kite suggested  all was far from well in the halyard department. 

Obtain some long lengths of stretchy net curtain wire confiscated from your grandmother's house or bought legitimately from ebay. (30m is on offer and does it). http://www.ebay.co.uk/itm/30M-WHITE-WINDOW-NET-CURTAIN-WIRE-30p-Per-Metre-100FT-Long-Hanging-Cord-Cable-/310409196478?pt=UK_Home_Garden_Curtains_Blinds_CurtainFixtures_Accessories_EH&var=&hash=item4845d473be

These, you will find, pass down the mast a treat and are very easy to see and retrieve from within the mast tube.  Use one length each for the main, jib, kite and pole height concurrently. It is fairly easy then to ensure that the trace wires and thus the halyards are not twisted. (Take the heel off and have a look, to be uber sure). You can thread the halyards with the mast lying flat in a fraction of the time of other methods. 

This top tip comes to you courtesy of A J Squire who tells me he learned it from Howard Steavenson and handed down to him no doubt, from his father, Robin. Whatever, I commend it.  Once done, you may then re-hang your net curtains.

Middle-aged man, solvent and not bad looking, wishes to meet elderly grandmother with a view to helping launder her net curtains.  Please reply only if your net curtains are at least 22ft 6ins wide.

Yep; this is a good tactic Derik. She won't realise the game until too late and she has the whole street peering into her living room while she takes in the latest Eastenders. Meantime, back at the dinghy park...

If however you wish to save the ladies blushes, a suitable length of 1X19 1/8" diameter rigging wire is excellent and to my certain knowledge over 40+ years never fails up to 40' which is the longest I have used it for, if you want to be super cool (Like Harry Spencer's boys at Cowes do.) you can fit a smooth swaged terminal with an eye on one end but tape does almost as well. The wire coils, but uncoils straight bends but is not floppy and can live in the bits box on the trailer or in the boot of your car.

Fair play David, this is indeed perhaps an even better top tip with an added X cool factor. Though net curtain wire might edge it on cost, if not elegance; providing one's name does appear later in the local court pages before a bemused readership. 

Either is preferable to hanging from a building window and cajoling a chain link weighted trace line down the mast tube which has been my method up to now. And which is hopeless, especially for a Merlin with so much scope for twisted lines.

Absolutely contraindicated in my case as a vertigo sufferer too! An electricians mouse would be as good but 1x19 seems a nautical solution to a nautical problem, though I have used 1x19 as a mouse in electrical conduits too.