Couple of questions.
 

Salute fellow Mariners!

SH5 gaming just got serious for me yet again and have a few questions I needed answering.

1) What is the mission radius for the Eastern Coastal route? I have sunk a few ships though none have counted to the objective. (Using Open Horizons Mod.)

2) What is the best underwater cruise speed? I know 7knots is great above water though can find nothing for submerged.

3) Any advantage/disadvantage to opening tubes before launching eels or is it just a time save?

4) Is it worth having the AA gun mounted or shall I just dismount it to save drag? (Don't want to drop the Deckgun yet as I still use it on lone merchants.)

Thanks in advance.

Not sure about #1.
#2 I'd say anything but flank speed (rough on electric drive).
#3 I usually flood the tubes just after I make target adjustments. That way you get the shot off right when you need it.
#4 it's better to have it and not need it than need it and not have it.