Greetings,
It sounds like not realy realistic,i know the seabottom has been created,but if your anchor has reach the bottom on 4500m,than there is something wrong.However very funny!!
Than i wish i could see the anchorchain storage on that vessel,and when that anchor has been heaved in,i think that vessel would be sailing the waters,with his bow deep in the water.Because of the weight of that chain.
Regards
Marc