SMF - Just Installed!
The best system I have seen is Bob Beasley's walkover "Rosalie Ann". He mounted a key lock that positively made sure they did not open.Maybe when they get back he will take some pictures for you.
#01- Engine hatches hingedEngine hatches were hinged and provided with twist locks. Hatches can be removed by sliding off hinge.
This shows the hatch opened up and held open by a bungee cord - it doesn't have to be removed and when underway it is easier not to remove it.