Previously, two posts considered cross-training in other budo. The first set out the benefits as a means to deepen understanding of your primary art. The subsequent post looked at another side of the issue - that some martial arts teachers might forbid their students to seek training at another dojo. That post also suggested that students caught up in such an arrangement may have picked the wrong person to train with in the first place, and speculates on such teachers' selfish motivations.
So - here we have two solid arguments in favor of "cross-training." It seems like a good idea, right? Find a different (though maybe related) art form, and go for it, right? Not so fast. There's a right way, and a wrong way, to train at a different dojo. If done right, you can obtain benefit for yourself and do credit to your home dojo. If not, well - read on.
Let's first assume that you are a student in good standing, who is also not a raw beginner. A very-beginning student who seeks training in another art form gives a teacher the impression that you are not serious in your practice in the first place. The term for this (at least in English) is "dojo-hopper." The sense is that the student is in some sort of martial arts shopping mall, with various things on offer. Come in, poke around, try a couple things on, and go on to the next store. This is definitely how to shop for a prom dress, but most budo teachers take their practice seriously, and expect students to do likewise.
Next, let's consider motivations. I am not talking about jumping ship and looking for a new teacher - that's a different subject altogether (see above). And I seriously doubt you would look around and think to yourself, "I'll bet I could deepen my understanding of the principles of [fill in name of current practice] by trying out [something else]." More likely you saw something on YouTube or even (shockingly, but it does happen) at a live demo and you thought it looked cool and would be fun to try. NYC is a veritable feast of martial traditions, both Asian and Western, old and new (and even theatrical and cinematic!). It's easy to feel like a kid in a candy store. There is nothing wrong with this motivation. But there is a proper way to go about it. So I am offering a list - from smartest to dumbest - ways to go about cross training in a different budo form.
1. Talk to your teacher and ask for permission to try something else, and ask for her suggestions as to where to find another dojo. For example, you could say, "I was thinking about trying a jujutsu class. I wanted to run the idea past you first. Do you have any suggestions as to who I could study with?" Believe it or not, even in a place as huge as the Big City, many budo teachers at least know each other by reputation, if not personally. Moreover, we know who the crank teachers are; or, at least, we have the means to find them out. Asking for permission, along with asking for advice, accomplishes several goals - it shows the teacher you respect her, and that you respect her opinion. It also puts you in line for a good recommendation with one of her colleagues. Having been recommended and accepted for cross-training in another dojo also shows respect with regard to the other teacher, who then has a clear idea of who you are and may have a sense of what you might be able to accomplish by training with him.
2. Ask your teacher for permission only. This is not as smart as suggestion number 1, but it at least shows enough respect to your teacher that she won't throw you through the nearest wall. Most teachers will say yes (and if she doesn't agree, there is probably a reason, as in she doesn't think you are ready to branch out. If you respect the teacher, you will respect her opinion and ask again later). Some may volunteer advice if they think you might be interested in hearing it; others may just say it's fine, and you are then free to roam.
3. (Moving to less-smart ways). Go somewhere else and don't tell either the primary teacher or the new teacher what you are doing. I don't recommend this, but it can actually work, as long as you exercise some discretion. Don't do what one of my students once did: blow off a request to perform at a demo by explaining that you have a tournament with another teacher that weekend. Just say you're sorry and you can't make it; and you hope to be able to perform with the group at another time. Being so up front about your conflicted schedule may send a teacher the message that you are so enamored with the new style that you are not as interested in what she has to teach (even if that isn't strictly true). Moreover, not supporting the dojo when it asks for your help also makes you look less serious about your practice, unless it involves work or family issues. Your perceived lack of interest may result in the teacher's attention being directed a little bit more to other students instead. Tangentially, if the second teacher learns about your primary art form by other means than your telling him about it, you may find yourself getting the same treatment. I'm jus' sayin'. We like to think that our teachers have better tempers and more wisdom than lowly students (and they might), but they are also human beings (with a lot more experience than you) and they have feelings, too. And those feelings should be respected if you are serious about your art form.
4. Declare that you are going "budo shopping" for other stuff to do - you say you may come back to the home dojo someday, but then again you may not. Believe it or not, this has actually happened. At the risk of stating the obvious, the student has given the impression that the teacher (and her art form) are interchangeable; with one practice being not any better or worse than another. The now-former student in question was fortunate to have done this via email and not in person. Needless to say, this person is no longer welcome (except, just *possibly* as a guest, and paying the guest mat fee). Unless you really intend not to come back at all, I don't recommend this method.
5. Just show up at a new place and disparage your primary teacher to gain favor with the new one. As I said, we all know each other, by reputation if not personally. Remember the six degrees of separation? In the budo world, it's more like one or two. You won't be accepted once the truth comes out.
As my colleague the Budo Bum has said, there are many benefits to cross-training, and most of them won't be revealed until you have spent months (or even years) training in another form. In my budo career, though my primary art is iaido, I have also done some training in naginata, kyudo, kendo, some empty-hand, and I am currently studying jodo as a rank beginner. I also train in Japanese classical dance; an art form that developed in the Edo period that shares many principles of movement with koryu budo forms. Many of my colleagues and teachers both in the U.S. and Japan also cross-train. For the most part, all of their teachers know and respect each other, and are cross-trainers themselves. My teacher, Otani Sensei, when I spoke to him specifically about working with another teacher, interrupted my carefully-rehearsed permission-asking speech by saying, "That's okay, that's okay. Once you know the principle, the technique doesn't matter." I still can't say, all of these years later, that I fully understand his point, but I knew then I had the freedom to figure it out.