Hi All

I've only racked up a couple of days sailing now (over 2 months). I've planed a
few times and it feels great. On the weekend (Milang SA), I was in estimated
20knot winds (peak) and that was the highest speed winds I have sailed in.

I was wondering what sort of stacks I can expect when planing ?... how can
I react to stop the bad ones ?

On my last blast, it felt like my board was jumping out of the water (the lake was "sloppy").
it was like I was aeroplaning in the air. I didn't know if that was safe or not, so I
depowered. If I carried on letting this happen and the wind got stronger, what would happen ?

Cheers

Ja

The worst stacks (from just planing) have to be 'hooked in' catapults. Which I think was what jp747 was getting at..

You're in the harness, flying along, and then sometimes for no apparent reason, or so it seems, you find yourself being flung around the front and into the water with tremendous force. You will eventually figure out what causes them, and your stance will improve so that they hardly ever happen.

In the meantime, the big thing to remember is to hold on to the boom as you go, and preferably sheet in. (Even if you're not in the harness, the same is true)

This has several benefits.. If you're holding on, you know where it is (and it's not going to sneak up on you from behind and tap you on the head when you're not looking). You also maintain the same orientation, so that the harness lines can't get twisted up making it hard to free yourself when you're underwater and winded. By sheeting in, you slow your impact with the water, and massively decrease the chances of smashing the nose of your board with the mast.


Re: board jumping out of the water - if you're going fast, and it's bumpy, then getting a bit of air is almost inevitable!

On the other hand, if the nose of the board is coming up, and it feels a bit 'squirrelly' then you need to get more force down on your mast foot by sheeting in, and/or by hanging more of your weight on the boom. The same thing can be caused by having a fin that is too big for the conditions. Taking the power off unloads the mastfoot and will make it worse rather than better!

I have a little mantra that I yell out to the guys I'm teaching - "nose and toes" meaning keep the nose of the board down, and point your toes. It's more relevant to getting planing in the first place, but a flat board is a fast board whatever the conditions.

What gear are you riding?

If you're already in the harness the best tip I can give you is to lean forward in the harness. This keeps the nose of the board down through mast - foot - pressure and keeps you in more control. This was one of the best tips I learnt years ago. And when I mean lean forwards I mean to the side of your hips that are facing the nose of the board so that although leaning back in the harness you're actually twisting towards the nose of the board slightly. This will really help control while planing.

I did get trapped under the sail and freaked out as my harness hook seemed to be stuck. It was a close call.
It's fun sailing over powered and trying to keep the rig under control.
Catapults happen so fast that one second your under control the next your flying throught the air and then Splat!
The fin gives you alot of lift and can make the board rail up when overpowered. Basically you have too much lift and can loose control. Pointing downwind can settle the board and keep the nose down. Pull the sail in (over sheet) and dont sheet out all at once because the mast straightens and pulls you forward.
Be careful leaning too far forward in the harness as this can also induce a catapult.
You can hurt yourself if you smack the boom etc so think about a vest and helmet.

Bayblaster said...

I did get trapped under the sail and freaked out as my harness hook seemed to be stuck. It was a close call.
It's fun sailing over powered and trying to keep the rig under control.
Catapults happen so fast that one second your under control the next your flying throught the air and then Splat!
The fin gives you alot of lift and can make the board rail up when overpowered. Basically you have too much lift and can loose control. Pointing downwind can settle the board and keep the nose down. Pull the sail in (over sheet) and dont sheet out all at once because the mast straightens and pulls you forward.
Be careful leaning too far forward in the harness as this can also induce a catapult.
You can hurt yourself if you smack the boom etc so think about a vest and helmet.

Go for these regardless. Helmet, You noggin will thank you for it by "no sunburn" no ugly welts,bumps or dents, and on cold days keeps the warmth in.
Vest usage makes water starts so much easier, plus if you happen to have a major prang, will keep you afloat until you can get help.

jay8192 said...

Hi All

I'm about 65kg. Have a 148L bic techno2 (75cm wide), a maui switch 5.2m
sail, and a 40R select fin.

That is a VERY big fin for a 5.2m sail.. you have a reasonably wide board, so that will help a bit, but only if you get your feet right out on the rail. A 40cm fin would be a better match for a 7-9m sail!

My biggest trick at the moment is crossing up the sail 10 seconds into a down
wind run (not by choice) like all powers of piss and then getting catapulted
(I bit like a gybe but without turning, but the sail goes off to one side taking you
with it and end up landing on the sail).

Probably related to that monster fin - you're either heading downwind to tame the board, or that big fin is lifting and causing you to carve downwind unintentionally.

555: With sheeting in, I'm getting trouble visualising that. Is that like tacking
the sail (pulling it around as you are getting tipped in ?). Does that
make the wind catch the sail and kind of soften the fall ?

It's all about increasing the angle that the wind meets the sail, so pull in on your back hand. As you get flung forward, the 'apparent wind' (so if you were the sail, the wind you'd feel) will come from in front of the sail. If you sheet in by pulling on your back hand (or pushing away with your front hand) you will cause the apparent wind to hit the sail more from the side, generate some lift, and slow your impact.

555: "mast foot by sheeting in," -- mast foot, that's the mast base isn't it ?.

Generally the mast foot is the bit above the universal joint(usually part of the extension these days, but it used to be separate), and the mast base is the bit screwed to your board. For the purposes of what I was getting at, it doesn't matter. Think of it as pinning the board to the water by using the mast. This is sometimes known as 'mast foot pressure' and more recently as 'downforce' - similar to what keeps a race car on the track.

Sheeting in, that's tacking (going up wind) ?

Nope - tacking is the process of turning the board by passing the nose of the board through the wind (jibing is where the tail of the board goes through the wind).
Sheeting in is about increasing the angle that the wind hits the sail. Do not get confused with bringing the sail closer to the centre of the board, that is the wrong frame of reference. You need to get used to thinking about the angle between the sail and the apparent wind.

If you sheet out, the power goes out of the sail, and it creates less force in any direction. If you sheet in correctly, you get the sail producing it's maximum useful power. If you oversheet, you will stall the airflow over the sail, and it will lose power (which is useful in some cases!). Having a powered up sail that is sheeted in will apply a certain amount of downforce to your board, and that is good.

555: "hanging more of your weight on the boom", is that like pulling it down ? (ie: bending my legs and hanging off like on a monkey bar ?)

That's the general idea, although you can apply the force without looking like a chimp! Just push down through your hands like you're trying to take the weight off your feet.

555: "Taking the power off unloads the mastfoot and will make it worse rather than better!" -- but when I do this, I slow down and stop planing ?

For sure, but unless you were actually planning to slow down and stop rather than taming the beast, it didn't really help right?

555: "meaning keep the nose of the board down, and point your toes" -- what do you mean point your toes. Is that when they are in the foot straps ?

Mostly when in the straps, but the aim is to keep the board flat in the roll axis. If you're planing and hanging off the side, pointing your toes (rather than having your weight on your heels) flattens the board, and lets the fin do it's job. That big fin will tend to be rolling the board away from you anyway, so maybe you need to be heavier on your feet to counter that.

Have a read of Guy Cribbs stuff
www.guycribb.com/windsurfing_technique_holiday_DVD_0076v01.htm - especially
Downforce - Keep Control
The Missing Link - Accelerator.
INsight - Look where you want to go.

The others are all good too, but maybe not relevant to you just yet.

I'd strongly recommend finding a smaller fin (borrow one if you have to!) That board is pretty big for you too, but you should be okay with a smaller fin. Something around 30cm will be much easier for you to keep under control.

Still, it's early days yet, and you will only get better as you go along. Gettiing into the footstraps will be a big help - it'll help you avoid the catapults, and depending on where you have the straps positioned, will get your feet out toward the rail which will improve your leverage over that fin!

555 said...

jay8192 said...

555: "Taking the power off unloads the mastfoot and will make it worse rather than better!" -- but when I do this, I slow down and stop planing ?

For sure, but unless you were actually planning to slow down and stop rather than taming the beast, it didn't really help right?

It straightens the mast, moves the power up the sail and unloads the mast base. In chopppy conditions all this can make the board bounce around and cause you to loose control. I'm really talking about sailing overpowered and what can happen if you sheet out to try and regain some control. Wait till you get into the harness and straps, flying along, just trying to hang on in gail force winds and all this will start to make sense.

jay8192 said...
what's a roll axis ? ... is that when you're blasting along and the board is slightly angled in the water ?

Roll is where the board rolls from side to side, the roll axis is an imaginary line which the rest of the board rolls around. If you were to drill a hole from the back of your board all the way through to the front, and poke a shaft down the hole, that shaft would now be on the roll axis as the board would roll around the shaft. Of course, you wouldn't do that, but it illustrates the principle!

so standing on your tippie-toes is pointing your toes ?

Kind of.. but not when you're standing up straight on the board. It only really applies in the straps, and then only when you're hanging way out off the side.

555: "That board is pretty big for you too," -- really ?.. I thought it was too small for my experience level.

Usually, yes, but then people at your stage aren't usually going out when it's so windy and planing around the place. You are quite light - most of the 'big board' thinking is to make the board float comfortably while you're standing there wobbling around in stuff all wind. Seeing as you don't weigh as much as the average punter, you're going to upset the board less by your wobbling. As you go faster in bigger winds (like you're already doing) you need to offset the lift generated by the board with downforce to hold it on the water so you don't blow over backwards, or end up tailwalking (that's the nose in the air swerving around like a rodeo bull trick). You get some of this downforce from the sail, and most of it from using your weight. You can't change your weight all that easily, so decreasing the lift from the board is your only real option. A narrower board will generate less lift, but will also be less stable while you're wobbling on it. So you can see that there is a compromise, and the point where it works for a given set of conditions (wind, waves etc) will change as you gain experience (or put on weight!).

Did you check out the link to Guy Cribbs' stuff?
www.guycribb.com/windsurfing_technique_holiday_DVD_0076v01.htm

jay8192 said...
I'm trying to work out how the fin lifts the sail. Is it because the fin is angled in the water and it's causing a vertical force ? (ie: a bit like an aeroplane wing)

Ah.. the thinking windsurfer's question! It took me a while to figure that out too. It's a combination of lifting like an aeroplane wing (only sideways instead of up), and torque.

Vertical foils can't generate vertical lift. If they could, then an aeroplane would be squashed between it's wings and never get off the ground.

The fin (a vertical foil) generates horizontal lift - so it resists being pushed sideways through the water, and instead pushes back in the opposite direction. That part is easy to see. The not so easy part is how that translates into lifting you and the board up vertically.

That brings us back to the roll axis again, and an understanding of torque / levers. The fin is generating a sideways force, but that force is being applied quite a way below the roll axis, and generates a torque moment around the roll axis, if left unbalanced, the torque from the fin will cause the board to roll to the downwind side.

In order to balance that torque, you need to somehow apply the same amount of torque in the opposite direction. You'll feel the torque from the fin as an 'upward' force under your feet. Torque is a force applied at a distance from an axis, so in the same way as a light kid can balance a fat kid on a see-saw, you can balance the "lift" from your fin by shifting your weight nearer or further away from the axis.

So, all that weight you're using to hold down the fin, is now effectively being carried by the fin which makes the board much lighter on the water. So, the fin is lifting you, the board, and the sail.