Pullups during swim..

Minimal at best. If you can't do a regular pullup it might help, kind of like the pullup machines with those platform lifts at the gym.

You want some real fun, do inandouts. Swim something like a 600+, and every 50 hop out and do one of three things - 20 pushups, 20 situps, or 20 frog leaps. Whee!

John 

Nope. I'm a pretty solid boy, and I usually have all my stuff in a martial arts bag. Not too many people come near me, actually. :D (Of course, that could be the lack of deodorant, but hey, whatever works.)

John 

That's why I do 'em! lol  I have no illusions that it helps with anything....it's just fun to do while I'm resting and it's probably the closest to a real pullup I'll ever get!

This reminds me of the 'Chinese fire drill'.  At the stop light everyone jumps out and runs around the car and jumps back in once the light turns green... 

Ace

Yeah, we tried that on the swim team as well. But, one guy skidded in a corner and we ended up with a 9 swimmer pileup on the deck. Elbows everywhere, it was NOT pretty...

John 

I have a great double catch drill. I call it butterfly.

John 

Pullups in the pool are like doing biceps curls with coke cans. Eventually you might see some benefit...

John 

Not true. If someone cant do a lat pull down with 100lbs should they not try it with 50lbs?

Same thing with someone who may not be able to do an unassisted pull-up. To them ( maybe not to you or I) it is beneficial because their muscles are doing something that taxes them. Eventually of course they would reach the point where the benefits fade.

Since I am guessing TKD stands for Tae Kwon Do would you recommend a new student who cant kick head high to just not bother with performing knee high kicks if that all they can manage?

That's a non sequiter. (But no, I wouldn't). The reason I say that it's like doing biceps curls with coke cans is that the resistance is so low that you really aren't stressing the muscles enough to produce growth, and the range of motion is extremely limited so you aren't doing the exercise properly, either.  

 John

Heh.  That reminds me of a recent experience at my swimming pool.  I lift weights, in addition to tri training, and I am pretty muscular.  5'11", 215 lbs, 12% BF.  I'm a decent swimmer, but not super fast or anything. 

So here I am, probably about 2500 yards or so into my 4000 yard swim, and these two teenage girls get into the lane next to me.  Good looking, but I'm not a pervert so I don't pay much attention, until they start screwing around, and splashing, and just basically screwing off.  About 5 minutes of that, and just as I am about to say something, they start swimming laps in their lane.  They fly by me like I am standing still, and I think, fine, they can do that for one lap, anyone can swim one lap really fast, besides, I am tired from my previous 2500 yards, so I must be slowing down by now, right?!?!

Well, no, they keep on going, lap after lap, lapping me like I was treading water.  When I finish my 4000, they are still going, and still going just as fast.  It's funny, I could probably bicep curl each of them and throw them across the length of the pool, but their swimming technique more than made up for their lack of upper body strength.  Probably high school swim team (I say that to make myself feel better)

Anyways, it goes to show that the swim is all about technique and has little to do with strength.  As to the original question of pullups helping, well, I can do about 30 dead hang pullups(on a regular bar, not off a starting block), but that doesn't make me a good swimmer.  So, keep on doing pullup off the starting block, but don't expect it to help you much, if any.