asma

You can get crab nets for $10 or less each if you search around. I suggest to save up. Yabbie nets are designed for yabbies unless you modify/hack them up. Not worth the effort in my opinion. 

Cant wait to get a feed of crabs soon.
Goodluck. 

As in a drop net? I see no issues apart from maybe having a hard time getting the crabs out if they get tangled.