Here's how much drafting helps.

[SURFnTURF]

So Until I got a real race board, one that is fairly tippy, I had trouble getting my heart rate over 140 BPM.   My 3rd paddle on this board was a race, my HR hit 180 off the gun.  I can only take away that it was because I was using so much more of my lower body to keep stable.   
    Anyways....   When I picked up a good draft (as I was getting passed), my heart rate dropped to a low of 163, but averaged about 170 ish trying to stay in the draft.   It was sooo much easier, I felt like I could hang there all day.   
     Yeah, getting into the lead draft is crucial to be a contender for the W.

[NoSaltSuper]

How close were you drafting to his tail?
Just wondering if there's an optimum distance.

I recall from road biking, it was amazing how you could literally stop pedaling on the flats when you held a good draft.

[Kaihoe]

SURFnTurF 

Your comments in heart rate have stopped me worrying. I think you and someone else mentioned their heart rate doesn't get over 140.... I can't get that low (at least when I'm training with a monitor) if I'm paddling hard I sit in the  mid 180's, dip to a static 178 when I'm in a fast 'race cruise'

I'm guessing the difference for you that your race board is allowing you to apply more power to the system..  The board is moving faster, your paddle cadence will be higher and you will be able to pull harder because the board accelerates better..... Just a theory

NoSalt

There are usually four good spots.
- Right on the tail,
- about a board length back their is a rooster tail (often the best ride but hard to bounce up to the tail and if you loose it your off).  At start time (or when you've got 3 guys in front going hard in a line) this can turn into a rideable wave
- Either side in the bow wave
This all depends on the shape of the tail, the rider's weight and how smooth they are

Just remember what goes up must come down.  For ever good spot in the wake there's also patches that can stop you dead, some time your better off stopping and waiting rather than trying to paddle.

[sup_surf_giant]

You must be a little guy.

My max HR is like 160!

[Kaihoe]

Sounds like you've got a great big pump there.  My Max HR for paddling 194

AS for being a small guy I wish  I'd be soo much more competitive   The reality is I'm dropping 15-25kg against the little guys. That before I have the problems of balance and leverage on the paddle cause everything is up higher... Maybe I should get a waka (OC1)