What's needed gear/conditions to break 40 ?

my goal is to break 40 knots...but I haven't even broken 40mph (34.7knots) . Wind and water conditions is what's mainly keeping back. I have a custom speed/slalom board at 55/56cm wide @ 80L ish. and a 6.2 severe mach4. Fins I go b/w a weed and upright..my upright fin is 29cm. anyway... I know the gear is more than capable ...but what wind conditions? and can speeds be achieved in 'not so smooth' water? say chops 12inches or 30cm ? I can always get up to the mid 30's mph (39mph my fastest)....but it always seems like I hit a wall.

also...how many of you constantly change your mast position on the board ? do you change it with water conditions ....sail size ...wind speed ? I kind of set it ...and forget it...and usually feels right...but maybe I should try moving it around. mine is more towards the back....an I seem to have no real control issues.

Flat water is your friend to break 40. I've gone faster than 34 knots in 32 sessions, but every session over 36 knots was on perfectly flat water in Oz (Lake George, Peel Inlet,Albany). My top speed in mild chop (maybe 10-15 cm at Grassy Pt, Corpus Christi) is only 35.3. In comparison, 38-41 knots on flat water was easy. My wife, who is usually a knot or two slower than I am, beat my speed in Corpus by a knot because she found some flatter water.

The one thing that really helped me go from 37 to 41 was advice from guys who had done mid-40s to 50+ knots, and sailing with a bunch of them at the same spot. Some of those guys would have no problem doing 40 knots in 30 cm chop - but at least two of these guys will often go several knots faster than anyone else, and would do mid-40s on flat water in the same wind. Perhaps a better comparison are PWA slalom speeds, which tend to be in the mid-30s (although often in somewhat larger chop).

I can highly recommend a 3-month trip to Western Australia and Lake George to improve your top speed. I increased mine by 3 knots the first time we did this, and 4 knots the second time. Next best is 3 weeks Lake George. It seems everyone who goes there the first or second time ends up improving their top speeds significantly.

and more than that enjoy the journey as well as the destination, don't think too much about the magic number, but all the things you are learning to get there

thanks.....

I try to bear off the wind...but by how much are we talking ? 135deg(approx) off the wind? and just for comparison.... let's say you are sailing 90 deg beam reach to the wind and doing say 30kts....with all things being equal....when sailing off the wind...how much faster would you get ? is it a 20%..30% increase. just trying to get an idea as to how important downwind is ? (I know it is...just trying get some kind of reference)

oh..btw... I am definitely enjoying the journey ....

Just checked the polar plot from my PB 40kt session.
90 degrees, doing 27kts, 120degrees doing 36knots, 135 to 140 degrees hitting 40knots.

But I'm not good at square. I went straight from wave sailing to speed sailing, so everything is tuned for extreme downwind. So fin is probably too small for going fast across the wind.
I'm struggling to hit 30kts square.
Also across the wind is usually more choppy than the speed run.
So my 50% may be an anomaly, I wouldn't consider my self a "good" sailor.

Never done 40 myself, but this video gives an insight into technique for max speed. Also what he says for better 10 second average by not bearing away as soon as the gust hits.