Looking at 50% of the windsurfing photos in the Seabreeze.com.au image gallery I propose a national "Lift your Boom" day.

Next time you sail set your boom 2 inches above where you would normally have it.

And then LEAVE IT there for the whole session no matter how bad it feels at first and see if you get used to it.

Learn from the master :


Set it closer to the height of your nose than your navel

Get ahead - lift your booms

Next time you sail, set the boom two inches below where you would normally have it.
And then LEAVE IT there the whole season, no matter how bad it feels at first and see if you get used to it.
Learn from the master:



Set it to the height of your navel not your nose
Get ahead - lower your booms

Different heights for different kinds of sailing, always has been, always will be.
Speed sailing and wave sailing have very little in common, boom height being one of many.

And use a waist harness for speed sailing

More downhaul though!

And use a 5.8m in 40 knts of wind

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Sparky said..
Next time you sail, set the boom two inches below where you would normally have it.
And then LEAVE IT there the whole season, no matter how bad it feels at first and see if you get used to it.
Learn from the master:



Set it to the height of your navel not your nose
Get ahead - lower your booms

But ....


2sec. max: 52.71 knots
Average speed: 49.48 knots
fastest 100m run: 52.09 knots
fastest 250m run: 50.29 knots

"It feels great to set the bar this high but I’m sure, the day I’ll break the 100 km/h mark is no far away"

Cheers

Hans
NED-85


See, even your Master realises that if he wants to go faster he needs to set the bar higher.

I couldn't resist the temptation to post a photo of a successful sailor with a very low boom. BUT, I would agree with the original post. I think many free ride sailors would benefit from lifting their boom height. And free ride is what most people do!

Pierre Mortafon sails with a low boom from the pics I've seen of him sailing........and he is the equal best slalom sailor in the world.

A high boom gives a definite edge thru the lulls. It creates board lift for sure. If you want more power---go higher.

For really powered up sailing using oversize sails for the conditions,PWA style--- there is little advantage either way.

What about harness line length??
I cant see how anyone can use anything shorter than 28"??
Its like driving your vehicle sitting super close to the steering wheel, no control. Well unless you are over 80
30" is my minimum.
Sorry if this hijacks the thread, interested what peeps are using with lower booms??

I think you will find the speed demon with the low boom in the photos is on about 24inch lines.

Keep your friends close, keep your sail even closer.

..... thats the thing, tuned components all relate to each other. Boom height, mast base position, harness line poistion and length, downhaul and outhaul and fin. You cant just isolate one setting.

Well I am doing all wrong then ??
I have the boom low and 34" harness lines !

Maybe you are having harness lines on both sides?
Both Hans and A2 don't have them on the pics above.
Maybe worth a try?

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jusavina said...
And use a 5.8m in 40 knts of wind

Always, it's the only way to fly

A subtle point about boom height stems from the fact the the centre of lift in the sail lies on the line passing through the mast foot and the centre of the harness lines. If you raise your booms the harness lines have to be moved back to stay on that line effectively widening the fore/aft space between the mast and crew, tipping the mast more upright, and opening the slot at the foot of the sail. If the boom is low the lines move forward tipping the mast back a bit and closing the slot. That might make a difference to a speed sailor.

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NotWal said...
A subtle point about boom height stems from the fact the the centre of lift in the sail lies on the line passing through the mast foot and the centre of the harness lines. If you raise your booms the harness lines have to be moved back to stay on that line effectively widening the fore/aft space between the mast and crew, tipping the mast more upright, and opening the slot at the foot of the sail. If the boom is low the lines move forward tipping the mast back a bit and closing the slot. That might make a difference to a speed sailor.

That's what I love about windsurfing, you get to learn something new every day.

I've felt the difference out on the water, one day the sail feels very well balanced centered on 4, the next day (when I decided to try a lower boom height) i discover I need my harness lines forward more...

What the?

Then someone much smarterer jumps on seabreeze and explains it all

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NotWal said..
A subtle point about boom height stems from the fact the the centre of lift in the sail lies on the line passing through the mast foot and the centre of the harness lines. If you raise your booms the harness lines have to be moved back to stay on that line effectively widening the fore/aft space between the mast and crew, tipping the mast more upright, and opening the slot at the foot of the sail. If the boom is low the lines move forward tipping the mast back a bit and closing the slot. That might make a difference to a speed sailor.

Yes the centre of lift of the sail lies on that line. But the centre of lift of the sail also lies directly above the centre of hydrodynamic lift. (Turning moments about a vertical axis must be zero.) And on powered up slalomy boards, that are sailed flat, the centre of hydrodynamic lift is pretty well at the centre of the fin lift.

No matter where you put your boom or harness lines you will wiggle and distort your body so that the sail lift is over the fin lift and the board goes in a straight line.

Apart from the boom height altering sail shape by redistributing tension, boom height doesn't matter. If you need to "close the gap" just move the mast base forward.

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ka43 said..
What about harness line length??
I cant see how anyone can use anything shorter than 28"??
Its like driving your vehicle sitting super close to the steering wheel, no control. Well unless you are over 80
30" is my minimum.
Sorry if this hijacks the thread, interested what peeps are using with lower booms??

I am 6 foot use 24's and run my boom in the top 1/3 of the mast slot with a waist harness. I used the same lines when I had Slalom gear and now only sail wave gear with the same lines. My arms are fairly straight when I sail so it depends on technique I suppose. If I use harness lines any longer than that it feels like I'm trying to take a dump when I'm planing.

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qldnacra said..

ka43 said..
What about harness line length??
I cant see how anyone can use anything shorter than 28"??
Its like driving your vehicle sitting super close to the steering wheel, no control. Well unless you are over 80
30" is my minimum.
Sorry if this hijacks the thread, interested what peeps are using with lower booms??

I am 6 foot use 24's and run my boom in the top 1/3 of the mast slot with a waist harness. I used the same lines when I had Slalom gear and now only sail wave gear with the same lines. My arms are fairly straight when I sail so it depends on technique I suppose. If I use harness lines any longer than that it feels like I'm trying to take a dump when I'm planing.

If you wear your waist harness on your hips then you can go longer with lines ....if you have your harness just under your armpits then go the shorter lines....if you wear your pants just under your armpits its easier to get discount at the shops.. :p

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Ian K said..

NotWal said..
A subtle point about boom height stems from the fact the the centre of lift in the sail lies on the line passing through the mast foot and the centre of the harness lines. If you raise your booms the harness lines have to be moved back to stay on that line effectively widening the fore/aft space between the mast and crew, tipping the mast more upright, and opening the slot at the foot of the sail. If the boom is low the lines move forward tipping the mast back a bit and closing the slot. That might make a difference to a speed sailor.

Yes the centre of lift of the sail lies on that line. But the centre of lift of the sail also lies directly above the centre of hydrodynamic lift. (Turning moments about a vertical axis must be zero.) And on powered up slalomy boards, that are sailed flat, the centre of hydrodynamic lift is pretty well at the centre of the fin lift.

No matter where you put your boom or harness lines you will wiggle and distort your body so that the sail lift is over the fin lift and the board goes in a straight line.

Apart from the boom height altering sail shape by redistributing tension, boom height doesn't matter. If you need to "close the gap" just move the mast base forward.

Yes all things must be taken together but understanding all the little ramifications is key to board tuning. For eg its easy to say push your mast foot forward to close the gap but if you do you affect planing trim, and its all very well to say the cl of the sail must line up with the clr of the hull but because we have two steering wheels (foot steering and rig steering) then lift trim is a subjective judgement. It's quite possible to have the sail tipped too far back balanced by overly pointing your toes and that's inefficient too.

This topic is one of the most amusing I have read in recent times..

And full of good practical hints. You now know how to shop for the best deal on a 2016 Magic Ride.

But back to the boom. As I see it, board trim is dependant on the location of the mass on the board and the turning moment of the sail in the forward direction. That's a turning moment which tends to drive the nose down. (Fin drag and all that being relatively constant).

Wherever the mast base is put, I'm going to have to hold the centre of lift of the sail over the centre of lift of the fin/board combination to go in a straight line. That puts my mass in pretty much the same spot.

So why does pushing the mast base forward or back affect trim ?

^ Because mast foot forward moves your mass forward.

2 ways to reduce lift
drop your boom down or use a smaller fin

vice versa

Then its a matter of hanging on a putting as much power to weight ratio through both

Think its called MAXED OUT

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NotWal said..
^ Because mast foot forward moves your mass forward.

(but understanding all the little ramifications is key to board tuning.)

So does the centre of effort of the sail also go forward along with the mast foot and your mass ?

Best way to reduce board lift especially in the gusts......use a harness with a very high hook,have the hook fastened with only one fastener from each side so the hook slides. Use a very narrow hook which increases the slide--very important! Then in the gusts put as much weight as possible thru your harness and most importantly along with the narrow hook--commit to powering up your harness FORWARD to the nose of the board.

Then try and maintain that position till the gusts is over. It helps to hold the nose down big time.

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Ian K said..

NotWal said..
^ Because mast foot forward moves your mass forward.

(but understanding all the little ramifications is key to board tuning.)

So does the centre of effort of the sail also go forward along with the mast foot and your mass ?

No it rotates back as you said.