ORIGINAL: rkr1958
ORIGINAL: paulderynck
If enemy convoys are there, you still have a one in 10 chance to find them next turn if the weather is fine, but I would never leave them out in the zero box.
Generally the only time to leave them out is if they are not disorganized and there's a very good chance enemy units will RTB through their sea zone, especially if they are in the 3-box and even more especially if enemy convoys are also present, since if there's an RTB interception battle, they'll get another chance to search for the convoys if the subs are still around, unless the enemy aborts all his forces which is also a good outcome so close to the production phase.
Otherwise all that leaving them out does is subtract one tenth from their chances to find in the next turn, albeit you'll need to take an action choice that will get them out to sea again. Thus it's a bigger consideration for Germany as opposed to the other powers.
So if I understand correctly, in general you return all subs/u-boats during the RTB unless they're in a high sea box (3 or 4) and are in position to intercept allied RTB's?
It seems that depends on the player.
And the options selected because of spending petrol or not if you are using oil rules.
And the season.
In my case, I many times don't return them because even in a 1 or 2 they can dissuade transports from moving freely or at least unescorted (and depending which expansions you are playing with, the escorts come to shortage sooner or later...
Of course it would be nicer to move them anew from the ports and reach a higher level at sea, but in good weather turns, you usually are too busy fighting in the land or moving your units, so you need land movements or at least combined (only possible exception CW should try to get a naval each turn if possible).
However, even the CW needs land moves, be them for blocking the Burma border, redeploy units in Egypt, or for the BEF in France or expeditionary forces in Greece, Portugal, Morocco or Yugoslavia, for example.
And the Germans can't even dream of Navals most of the time, combined being scarce.
If you leave your units at sea, you can use them with an activation from a combined, but also be activated by your allies or by the pass of enemy units.
Plus, if you are trying to attack convoys in a further area, looking for weaker escorts, you'll most probably reach the 1 box maximum, leaving them at sea at 0 box next turn makes your subs get a 10% (at least) to chase convoys instead of a 20%, but that is for free, you don't need any naval moves. And it's still a 10%. The bad side is the worse position against the escorts but we are speaking of weaker escorts and sometimes escorting only in the 0 box as well.
