On Monday, March 4, 2013 8:48:26 PM UTC-5, wrote:
Is there any way technically and legally to add a fifth strap to an ASW 15? No matter how tight I pull the lap belts they ride up when ridge flying allowing the shoulder straps to become loose. My head is pretty close to the canopy and a stiff jolt can lead to head banging if the harness becomes loose. I also know having the lap belts out of position can be very dangerous in the event of a crash and would love to alleviate these problems. mdfaddenatgmaildotcom

I have done several installations of a 5th point in Schleicher gliders, but not an ASW-15.
I'll use '19 as an example.
First, you must use a harness assembly intended for the purpose with a receptacle for the added point. You may have to replace your harness.
Procure the additional belt intended to be used with that harness. No home made stuff.
The belt is secured to the bulkhead that mounts the aft end of the control stick. This means it will be a bit, about 2 inches off to one side, and will be near the aft edge of the stick boot. It comes up through a hole about 2 1/4 by 1/2 in the seat pan. On some gliders the belt can wrap around a convenient feature. On others you will need to put in a fitting.
Care must be taken not to interfere with controls and proper anchoring, but this is not rocket science.
There is no reason that this would be considered anything other than a minor modification as long as the original harness mounting is not affected.
It may pay to ask Schleicher if they have instructions, however I doubt it.
Good luck
UH