We don't have synonyms for turn turtle yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are turns turtle and turned turtle.
(v) :
to turn upside down. Commonly used for boats and ships that capsize and turn through 180? so their hulls are above their superstructure, but it can refer to any vehicle in a similar position; to roll upside-down with one's surfboard (usually a longboard) to allow a wave (usually an already broken wave) to pass over
"1998: a surfer prepares to turn turtle in the righthand shot — Kite Aerial Photography"
(v) :
to turn upside down. Commonly used for boats and ships that capsize and turn through 180? so their hulls are above their superstructure, but it can refer to any vehicle in a similar position; to roll upside-down with one's surfboard (usually a longboard) to allow a wave (usually an already broken wave) to pass over
"1998: a surfer prepares to turn turtle in the righthand shot — Kite Aerial Photography"