Let’s say I have a sweet B5 in Navigation. My Sword skill is rubbish, though, so I get a nasty midi wound (-2D) while fighting off some pirates.
If I want to help my first mate with his Navigation so that we can continue on our way, does he still get +2D for my help (since I have 5 ranks in Navigation), or does my help only count for +1D now because I’m impaired?
1D. You can’t help as well when you’re impaired.
I don’t disagree, but is this actually backed up by anything in the book?
p. 488: “Wound penalty dice are subtracted from stats, skills”
p. 36 talks about how to calculate how many under Helping Dice
Follow-up:
Say I have Agility B5 and a B2 Sword skill. I take a midi wound, which is worth -2D.
By the rules, I can’t use my Sword skill, since it’s now 0.
Can I make an “untrained” check instead, despite having the skill trained? Or am I just totally unable to use a sword at all?
I believe you’re SOL.
I’d say it could go either way, and I’d actually probably go the direction of saying you can roll unskilled if you really want to try. Though, at -2D you’re looking at an unskilled B3 Agility roll, which is basically the worst position to be in considering you’re going to be hosed on damage even if you do manage to connect. That said, I wouldn’t allow for any tests because of the aforementioned skilled vs. unskilled breakdown.
You have the skill, so can’t do it untrained. But you can’t roll the skill because it is exponent 0.
An Inverse Hana Montana!
P.S. It is the danger, and I find interesting aspect, of starting out a character with raft of B1 and B2 Skills. Get hurt early and you are forced to play very much counter to initial build.
Thanks. That’s going into my list of amusingly named… ahem, “amorous” techniques. 
No, no, no. You are thinking of the Reverse Hannah Montana: Beast of Both Worlds.
I’m talking about the Worst of Both Worlds.
I think that the wounded dices for untrained are doubled. So a Sword B2 and an Agility B4 are both 0D with a -2D injury.
No, the injury dice are not doubled for stats.
Since wounds are subtracted from stats and skills and helping dice are based on the skill exponent, I would assume that you base helping dice on the current exponent. For example, if you had a B5 the -2D would make it a B3 and worth 1D of help. If you had a B7, -2D would give you a B5 and still worth 2D of help.
You are correct! Nice crystal-clear restatement of the consensus.