%0 Journal Article %A Schmidt, Theodor %T J.H. Hagedoorn – inventing the Hapa: A review of a geophysicist's ‘other’ work and how it inspired others %D 2001 %J Geophysical Prospecting, %V 49 %N 6 %P 735-745 %@ 1365-2478 %R https://doi.org/10.1046/j.1365-2478.2001.00296.x %I European Association of Geoscientists & Engineers, %X This paper describes J.G. Hagedoorn's work on ‘ultimate sailing’– the combination of a manned kite and a water kite called a Hapa, constituting a minimal sailing system – and the way others have taken up his challenge to sail while suspended from a kite. Hagedoorn's goal has not been entirely achieved, but ‘near’ and partial solutions have been reached. Kite‐Hapa‐sailing continues to pose a ‘Holy Grail’ type challenge to many kite‐sailors. %U https://www.earthdoc.org/content/journals/10.1046/j.1365-2478.2001.00296.x