random bottoming out

[lazlow]

Ok bit of a nooby question here, just crash dived to avoid aircraft,on east coast of england,my watch crew didnt see them untill it was almost too late but got under quickly anyway i request depth under keel and it says 130m so midway through crash dive say about 50 m i order a new depth of 80m ,few seconds later i hear my boat crashing into the bottom..glance at the depth gauge and it says 131 m, so what did i do wrong?

I orderd a new depth and a new speed so its not like we whent crashing into the bottom at top speed, its almost like my order to go to 80m was ignored and the chief decided to keep plowing on untill the rocks stopped us :x

I didnt take any dmg from the planes no bombs just some machine gun fire and no crew injured.:doh: