just a few questions
1) if we change our sail size does it make our overall travel speed faster or just bring us up to top speed quicker ?
2) is it possiable to assume in consistant wind that changing to a bigger sail wont benafit overall top speed
Here is an example: if im travelling dead down wind as fast as my sail/kite can go and its blowing 20 knots does that mean ill be travelling down wind at 20 knots at maximum peak speed?
I know increesing the surface area of the sail/kite will allow more force to be applied.
call me a dumb noob but im having trouble understanding some of the principles behind it
Well as I understand it, assuming a steady wind, there is an optimum sail size for the conditions, going bigger or smaller than that will slow you down.
You can only extract the amount of power from a sail that you can counterbalance with your weight.
Once the sail is big enough to give you this maximum power, going bigger only adds more drag, and decreases control.
If you go smaller than this, you aren't getting full power.
Probably a bit over simplified, but that's how I understand it.
Travelling dead down wind is a special case though, as the faster you go the less power you have, so you can't go as fast as the wind unless there's 0 drag.
Not sure about kites, but on a windsurfer this isn't an easy direction to travel. It's much faster and easier to go on a broad reach. The fastest is supposed to be 130 - 140 degrees. And on speed gear you can do about 1.5 X windspeed, ie in 20kt winds 30kts is possible, but I don't think that's linear, nobody's done 60kt in 40kt winds
im with u so with windsurfing .
the sail choice is nominal to mass being moved bodyweight.
so what ur sayn is that there is no advantage having a bigger sail to produce top speed if your body mass cant offset it
is it fair to say that if i cant offset my sail in the wind drop down a sail size
just when i went out a few weeks back there was people using the same sail as me but everytime i sheeted in it would catapult me, i had trouble getting back in i couldnt waterstart or uphaul and when i did ended up gettn slung/catapulted even when i harnessed in
in sayn that i was under the impression that if i drop my sail size to meet my body mass i wouldnt produce the same speed os the others
i continually tried and tried to get up on trim and contunually got catapulted thinking that it was my inexperience in sheeting in
i managed to get back to shore and got up a few times in the wind but got catapulted once a gust came in.
i guess i was under the impression that being catapulted meant that i was tryn to meet fullspeed to quickly.
Hi Buster,
You may need more downhaul. This lowers the centre of effort (where the sail pulls from) which means that you will get catapulted less. The sail also reacts to gusts better.
Get one of the faster guys to check out how your sail is rigged.
Yep, good advice as usual from Nebs.
Also how does your body weight compare to the other guys?
It does take a bit of experience to be able to handle a fully powered up sail, you may just be getting a bit ahead of yourself.
Yes, if you can't fully sheet a sail in, it's easier to change down.
But if the wind is fluky, a bigger sail will get you thru the lulls. You just have to decide whether you'd rather grovel in the lulls, or fight for control in the gusts.
Checked out that link Evil Panda
Have to disagree with
"
Why are eighteen footers always sailing upwind?
In a fast boat, there's no point going straight downwind: you can never go faster than the wind. So you travel at an angle..."
It's a fine point whether you differentiate between going directly downwind and tacking downwind.
If by tacking downwind you beat the parcel of air that started at the same time to the bottom of the course, you have sailed downwind faster than the wind. - you could release a smoke bomb to test this -
Maybe it's not possible in current model boats, but it's not a theoretical impossibilty, we just have to make better boats with lower drag.
Land yachts travel many times faster than the wind by using the apparent generated.
Often sailing at 60-80 km/h in 20km/h winds.
Inertia is the idea that an object keeps moving unless acted upon by an outside force. Much of the initial work written about inertia was done by Isaac Newton in the 17th century and became known as his first law of physics. It is one of the basic principles of physics and has a number of real-life applications, as it helps to explain much of why objects behave the way they do.
The idea of inertia is quite simple. Inertia is the principle that is that an object will tend to keep moving at a certain speed and direction unless something else acts to change it. That external force could be almost anything. Friction is a common external force that can change the speed and direction of a moving object. Many other objects can also affect motion, however, from gravity of the earth's pull to another person. The key idea is that an object will keep moving (or stay still) unless something else influences it otherwise.
thankyou evilpanda 10/10............first seabreese physics lesson
there is a method in the madness......................it involves some higly equated maths transposition.
downwind assumption
So i make the thesis that if u had a big enough driving force(surface area on sail)to over- come the inertia (friction)of your vessel,
you could produce the same speed.
Could this a factor on why yachts have multiple sails to produce more force.
hey today i learnt that when i water start in high wind i turned my rig slightly upwind so i was using less of the sails surface area and i could sheet in and turn board angle to change pick up speed this worked well rather than waterstarting on a full sheetin and gettn catapulted
the
noob is learning !!!!!!!!!
ureeka
well done buster, it works to a certain extent the opposite way as well, when under powered you can point a little downwind to help you get up.
