Which preposition to use with springboard

at Occurrences 1%

Besides the diving tower, there was a floating dock anchored out in midstream, having a springboard at either end.

in Occurrences 1%

Sahwah, burning with impatience to show her skill, climbed nimbly up to the very top of the tower and went off the highest springboard in a neat back dive that drew applause from the watchers, including Miss Armstrong.

of Occurrences 1%

First, with their double-bitted axes, each drove a deep notch into the sapwood just wide enough to take the end of a two-by-six plank four or five feet long with a single grab-nail in the end,the springboard of the Pacific coast logger, whose daily business lies among the biggest timber on God's footstool.

Which preposition to use with  springboard