NOOOO...

If you are directly upwind of the kite, it will not slide all over.
That's the key, be directly upwind.
Let's say the wind is coming a bit from the left, but still onshore: Point your kite to the left until the downwind edge of your kite catches the wind( if too windy, put some sand or a wet towel on THAT part of the kite)
If you are upwind or even more to the left of it, and pull on the LEFT rear line together with your bar(just a bit more tension on your left rear lines), and walk back to get your kite inflated, then walk towards it to make it flip on the edge, then pull the right side...sheet out...and..giddy up.
PS: Works better with more wind, light winds and big kites..not so much

You may find some of the information in this thread useful in setting up a system to launch in your situation. The seaweed may be the biggest problem. Setting up a little anchored floating platform like Wetstuff describes could work in your situation, to allow you to launch off your 5th line. You could consider making a Line Tender out of PVC, as described in the post. This would work better in your situation than a Turbo-style-launcher, for unwinding the kite-lines while walking the kite from the platform back toward shore, in order to properly position the kite.

viewtopic.php?f=1&t=2332235

Here is another launch technique you may want to consider. I developed this method and the necessary “belay” tool in order to launch from some very difficult places in the Gorge. It worked fine, but demanded some hours of practice, and of course the time and effort to construct the final version of the “Tool”. I call the technique the “Driftfly launch”, because the kite drifts a little bit and then flys up. The flying up is necessary to shake off the seaweed. A normal drift launch in a bed of seaweed is risky.


viewtopic.php?f=1&t=2328471&start=0&st=0&sk=t&sd=a&hilit=driftfly

I presented a description of various versions of the “tool” in the following thread, the version I presently use is shown on page 2:

viewtopic.php?f=1&t=2321454&start=0&st=0&sk=t&sd=a&hilit=safely+grab+a+line


If you get really desperate, then, just before you resort to buying a “launch boat”, you might want to consider the possibility of constructing and using the “Pipe launcher” as presented in this thread. This is about as unconventional as you can get:

viewtopic.php?f=1&t=2333222&start=0&st=0&sk=t&sd=a&hilit=pipe+launcher

I think it's too risky to try any launch on shore in that situation - even an assisted launch.
If it was the only place I could kitesurf and the water was shallow enough to far enough out :-

I would get a long waterproof bag and carry out bags of ready-mix concrete and pour it into the bag. I would then put something like a heavy chain into the concrete and let the water in. Repeat about 27 metres across the wind. Each time I launched, I would tie two buoys , one onto each anchor. Attach lines and carry the kite and board out. Attach the kite to one buoy by the pump leash.
Unwind the lines and attach the chickenloop to the other buoy. Attach the board to the same buoy.
Walk to the kite and set it up on it's side.
Walk back to the bar, leash in and launch the kite.
Landing is the reverse

You might be able to screw an anchor into the seabed, but someone might steal them.

you could always walk out as far as possible and do a water launch. Be very careful trying it your way. You could always get a friend to pull you out to sea with a kayak

Ok guys, I like what I have read so far because I have a very similar situation. I have a very small launch area, less than 5m wide and litter with debris and a road not far from the grass line just up from the shore. I too have no room for mistakes. Well maybe, but I'm coming back from a shattered knee and dont have all the muscle back in one leg. My problem is the water level. It gets to neck deep very fast. I had to swim like a mofo to get the distance today and miraculously, got my kite launched, messy as it was. It was difficult and hairy enough to where I dont want to try that again.
I wasnt able to board drag out to a safe distance to water start and unfortunately dumped my kite and couldn't get it flying before drifting back to shore.

I'm considering that the only time I can use this launch, the only one around, when it is a slightly different wind direction.

Other than that I would have to only wait for low tide, and good winds. At that point I would have all the beach in the world.