[mfdfran]

Por si os sirve de algo consulte directamente a Yanmar que hacer cuando navegas a vela y esta fue la resuesta:

Yanmar requires that during sailing with the engine off (not running), the transmission
shifter must be in the neutral position or internal damage to the gear or saildrive will result.
In other words, we should not lock the transmission.

If desire the propeller does not turn during sailing, either a folding prop or shaft break or
other suitable devices may be used.

Si alguno precisa traduccion, es que no hay que bloquear el eje con la transmision, porque te la cargaras.