advice needed on pipping

[kat]

hi all, i have 8 duck eggs they on day 29. i think 3 have internally pipped but not sure. how do you tell and how long should they take before external pipping? any advice would be greatfull

 

[hypnofrogstevie]

if you look closely you can see a / mark which looks like a little crack. Kinda like a hairline crack

 

[kat]

how do you tell with internal piping

 

[hypnofrogstevie]

You can hear them pipping at the shell. What I do is put my ear next to the bator and listen carefully. Also check for rocking