On Saturday, December 2, 2017 at 3:47:41 PM UTC-5, John Foster wrote:
With the rise in popularity of 18m soaring, what do you guys think will be the future of 15m? Are there enough advantages of 15m over 18m for it to continue to have a strong place in competition? It seems most manufacturers are now making 18m sailplanes, that can be converted to 15m, but they primarily start or come as 18m now. Thoughts?

15 Meter class has lots of competitive gliders at what many see as reasonable cost. Values are pretty stable.
My opinion is that they give a great deal of performance while being convenient to own and fly. Assembling my '29 takes almost twice as long and is a lot more effort than my '27 was. It also cost me 66% more than my '27 and the hull portion of my insurance is proportionately higher.
The 18's built now have 2 piece wings to make the trailers shorter and the weight and bulk of the wings less. The break point can easily be put where it is practical to provide compromise 15M tips. The bigger span has the benefit of keeping span loading reasonable when the engine that 80% of new buyers want is installed.
When asked the question I always suggest 15 vs 18 from a balanced perspective.
That said, I love my '29.
With the large number of good ships available at reasonable(your view may differ) cost, I expect 15M will be around a long time.
FWIW
UH