Unforttunaetly the answer is uncertain. The highest risk for recurrence is in the first six months after the initial event( a lot depends on findings during the workup particuarly the EEG.
The longer ones go on treatment the risk is reduced but never 0. Sleep deprivation, alcohol, certain meds, illness, fever all lower the threshold and make seizure more likely.
The safest is to never sail alone and use life jacket.