I wouldn't jump with one, there is a danger the horse would not be able to stretch over the jump if it is set anything other than very long (and thereby completely useless)..but then I wouldn't use one ever, apart from polo
I personally wouldn't jump a horse in a standing martingale. If you have it loose enough to jump, then it's probably too loose to be of much use anyway
Just my thoughts though and you do see people doing it
three of the horses i used to compete at Foxhunter and above level wore a standing martingale , two of them with a running martingale as well the other with a hackamore.
Never had any problems with any of them , just make sure they are adjusted correctly.
Actually a useful tool on certain horses.
at the event yard i used to ride at there was one horse (not actually an eventer - an SJ horse) that was always jumped in one...
I always thought it was wrong too - but it never really seemed to hinder the horse and apparently I would have been eating his ears if he hadn't had it on
considering the high standard of event horses they produced I trusted their opinion over mine - - but I don't think I would personally use one when jumping...
as ive just bought a martingale for mine today to see if it will stop him throwing his head up when were cantering on hacks when it comes to slowing down and thought you shouldnt jump in a standing martingale, so i better get a running one.... so went to look in horsey book, it didnt say anything about you shoulnt jump and had a picture of a hunt master in one?
I quite often use a standing martingale for jumping much prefer it as it doesn't interfere with the reins and only comes into play when they really put their heads up. I do have it adjusted correctly and have watched carefully videos of the horses jumping and it does not restrict them.
I remember going to a lecture demo with Blyth Tate who swore by them and would have used them BE had it been allowed.
Have a look in H & H, at the jumping & hunting reports. You'll see loads of horses jumping huge fences in standing martingales & not being hindered at all, (although you are not allowed them for 'Trec', as they are considered too 'restrictive!!!).
Has BSJA changed it rules then??? As I know Micheal Whitaker designed his standing martingale with elastic in it & was the best one of his horses jumped in at home but he couldn't use it for competions???
Over here it seems pretty normal to jump in a standing martingale, and I do as the romans do, but only to a point. If the horse jumps correctly, I don't think they are overly restrictive if fitted correctly, however, a horse that is unbalanced, stumbles, or pecks will use their head and neck to rebalance themselves - in a standing they can't do that, so that's the danger factor for me - and I won't personally jump a horse in one once you hit anything over a 'pop over' height for the horse