Well, we are in the opposite camp, like whips with LONG lashes. We feel that if you can’t REACH the horse to TOUCH him with the lash, your whip is pretty useless. If you don’t actually plan to use it, why even have it? Whip cracking does make noise, but our horses at least, figure out the noise means nothing and will ignore the noise later. Whip crack is often “overdone” with noise, when instead, the lash should be out there touching him LIGHTLY to show you are NOT to be ignored. Word command is given, whip touch means he MUST do as asked, NOW.
Like any other horse tool, bit, crop, spurs, the long lash whip is controlled by the person, helps horse with those light touches, to bend, go forward as asked. Horse is NOT afraid of whip or jumping around if whip is used near him or touching him. Really important, since whip in the carriage is a huge aid in your driving, helping you develop his bending, from the vehicle. You have no legs driving, whip replaces them for the horse.
I think 30ft lines will be a useful size, while keeping in mind that handler is ALWAYS moving in an interior circle to the horse out on the lines. So handler may be doing a 10-12-15ft circle, with horse out at the end of his long lines. Lines going around his rump, will shorten length a bit, yet doing LARGE circles helps keep horse from being sharply bent ALL the time, like short lines cause.
You may need to do some extra homework, with a long lash whip, because you NEED to hit what you aim at. You need to hit “target” LIGHTLY, like a stroke with a finger, if possible. Whip use is NOT punishment, but an aid in forward when asked, bending if needed, on his side.
I will agree that purchased long-lining whips are badly weighted, top heavy and never have a long enough lash to be actually useful. Hard to use, wears your wrist out, totally ineffective to the horse as an aid because you can’t reach him.
We buy light, inexpensive Driving whips, usually with a LONG stick of 5 to 6ft. We have found it easier to have a longer stick to direct the lash accurately, than going with short stick and even longer lash length. Whips can lead a hard life here, so I tend to buy less expensive ones, $20 range or less if possible. Doesn’t hurt as bad if they have an accident, ending their usefulness!! We got some real nice, inexpensive whips from Country Carriages USA, which had long sticks. Nice enough to even use showing! I usually get several whips at a time, when I find them like this. They are nice and light, have held up well to some hard use. I keep a new one back for shows, so it looks nice.
http://www.countrycarriagesusa.com/
I remove the short black whip lash end, then add length on to the whip lash loop with parachute cord. I make loop ends on the parachute cord so one end loops onto whip stick loop, then black lash end is looped onto parachute cord extension. You end up with whip and long enough lash to use for long lining. I can make it as long as needed, reach that horse out on the lines, front Leader in the Tandem or Four if needed. Cheap fix, keeps weight of whip top much lighter than what we have been able to find or afford, from other whip sellers. Husband likes the lighter whips, says they don’t pull on his wrists with heavier kinds of lash cords. That gets very tiring to your hands, wrist, arms, on long drives or in working horses on the long lines.
So you might give the longer whip stick, add-on lash idea a try. Take time to practice before getting the horse out in front of you. Maybe some long-lining lessons with a SKILLED Dressage trainer who long lines. Many trainers long line, not all are skilled with lines on the horse. We have not had great luck with “gadgets” like side reins to gain headsets. Seems easier to achieve with JUST the long lines alone, and we are in no hurry with our horses. It takes TIME for horse to gain skill in self-carriage, develop the MUSCLE to carry himself like that. Adding on the gadget to force nose in, made things harder, take much longer to have horse understand how to carry himself correctly. I am NOT going to be holding up his BIG head with the reins, he needs to do that himself while learning to be collected, putting hind end under his body. Side reins just have our horses hanging on the bit, no real collection or lightness. Our method, works for us, so it could be useful to you in your long-term training thoughts and plans.
Oh yeah, a dirty whip lash might be MORE useful long lining, than a clean lash. The dirt adds a little weight, might be helpful in better control to direct the lash where you want it. Husband drags his long lash thru a muddy puddle a few times, when he has a new whip to use. Says dirt gives a better “feel” to the lash in using it. Try lash clean first, then dirty the lash and see if it is more useful. If you like a lash clean better, take off the extension cord length and wash it, put it back on the whip stick.