Ok, probably nobody cares, but in case someone would benefit from my efforts.
A) Have not given up on ramp, now know it can work (elaborate another time) but focusing on bungee launching foil from water. Some good youtube video out there.
B) Bungee learnings interesting. Using a hand winch to load up the bungee. Standard disclaimer - understand risks of winches, measure your load so you know pounds of tension experienced, match each component (bungee, other lines, connections) safely within limits. Experimenting much with bungee (shock line) on 1 inch, 1/2 inch, 3/8 inch and 1/4 inch. There are charts online indicating pounds of force at 100% and more stretch for each, nice place to start. What is hard to find is anything indicating result when you double, triple, quadruple (etc) each size of bungee. I can say with high confidence that the result is not linear, but you certainly increase stored energy. Several online bungee foil examples use 3 strands of 3/8 in bungee (a little over an inch of total bungee capacity). I am presently using a combination of 30ft of 3 strands of 1/2 inch bungee + 15 ft of 4 strands of 3/8 inch bungee plus 6 ft of 1 inch bungee. Why this combination? See next point... I stopped using 1/4 inch bungee regardless of # of strands, too messy and inefficient.
C) The interesting constraint for me turns out to be the winch. Realize the limitation there is having strong enough rope to account for max load, yet enough capacity to hold enough rope to load bungee. I can fit a little over 65 feet of 1/4 inch nylon rope (well over 200 lbs max load I would experience.). The 51 feet of bungee I use (see above) can be loaded over 100% and I have room to maneuver and set line to be ready to use.
D) So, what have I found Regarding inertia that I needed to launch me? Well initially I was trying to achieve my total weight - or 180 lbs including me, board and foil. Problem is, though I can load the line to that capacity, it is impossible for me to hold without an aid, at least not in a position where I can launch under control. I set up various trigger devices to remedy this, but decided to dial back my launch power to see what happens and was pleasantly surprised that I can launch at a more manageable 100lbs. What is actually more important is how LONG I have enough power. That is a place where more lines help. I find having at least 50lbs for at least 20 feet can do the trick (probably overkill for a more efficient foiler). Also, launching with my 95 L board helps, vs a less buoyant board (except in next version with a ramp....). Also, instead of launching directly toward anchor point, angling slightly across (like aiming outside instead of following boat) helps.
E). A unique challenge for me is the fact that I launch from a 8x16 foot raft I have fitted for the exercise. Getting enough anchor to both hold and keep stable when under high load was a challenge, as is doing this in a way that I can avoid and understand any drift. And, as I am in a shallow (3 ft deep water) channel In front of my boathouse, must use my shortest mast and walk the area to clean up any weeds. The good news is boathouse has radio so I have tunes while playing, and Bonnie enjoys making herself useful and entertained. She is good enough to watch the scale as I measure load under various configurations, and record my disasters. However, this is a wonderful and productive way to get through a no-wind day...
