Or from Murmansk to Iran in Modern Dip

The way to master this is to convoy from St Petersburg to Syria.

http://www.webdiplomacy.net/intro.php#Moves

Basically, you can convoy one army between two coastal areas with one fleet, but you can also use a string of fleets, there is no maximum, as long as all fleets are adjacent and form a continuous string between the area of origin and destination. All fleets need to specify the same origin and destination, and you have to order the army to move to that destination. The drop down menu’s for the moves on this site are pretty intuitive.

Also note that an attack on any of the convoying fleets does not disrupt the convoy, but if one (or more) of the convoying fleets is dislodged, it disrupts the entire convoy.

Hi
Where can I see the rules/mechanics of a convoy that is farther than just crossing a channel?
Thanks