This is a long one, so I apologise for that.
So I originally came up with this rule for Global War '36-'45 (which I shall refer to as GW36), but I suppose it could be used for other games, please just bear that in mind if this seems incompatible to any one game you may be thinking of.
In GW36 each game round takes place in a 6 month period, Jan '36, Jul '36, Jan '37 and so on, and a lot of rules reflect that, such as build times for larger ships and facilities.
  One thing that is difficult to accommodate for with this in mind, however, is that sometimes ships take a hugely unrealistic time to travel long distances, such as from Britain to Hong Kong, even going around the Horn of Africa at 10 knots, it doesn’t take 6 months to travel that distance. Trust me on this one.
As war gamers, we tend to think that any one combat move represents one engagement; a tank battle in Russia (Kursk), a naval clash in the Pacific (Midway), one strategic bombing raid (Dresden), D-Day.
  But within the scope of GW36, this just isn’t the case. A land combat move is a 6 month campaign to capture a large segment of a country, or 6 months worth of uneventful naval patrols, skirmishes, hit-and-run attacks and straight up slugfests around a group of tiny islands you’ve never heard of. A bombing raid on a factory is a 6 month campaign to destroy one district of a city that happens to have some factories in it. Does this make sense?
I hope so, because I’m about to get to the point…
Naval Non-Combat should - with all that said - essentially be a Strategic Redeployment to anywhere in the world. No range limit, just do it. Even with some units having a 3 SZ movement range and perhaps one more for starting next to a naval base/shipyard, it takes a ridiculously long time to get from, say, San Francisco to Sydney. Some distances do literally take months, don’t get me wrong, but not six.
All nations should be able to do this, and almost all vessels (I haven’t discussed this with my gaming group (Kampfgruppe Dachboden) in detail yet) but I think that Costal Subs and TB Destroyers maybe shouldn’t, but even then I’m not sure.
There are some details though…
A fleet (or single ship, but I shall say fleet from now on), during the non-combat move, must trace a safe route from its starting SZ to its destination SZ. A Naval Redeployment may not be used through a SZ that has seen combat, as both moves are happening within the same 6 month period, so a lane can’t be cleared for the main force. It also may not travel through a SZ if:
A nation that it is at war with has any combat vessels present, including subs, or has a Combat Air Patrol over the SZ.
Transports do not block Naval Redeployment. These vessels can, and indeed must, be ignored by the transiting fleet, but the fleet may transit through a SZ with enemy transports. A fleet may not conduct a Naval Redeployment into a SZ with any enemy vessels.
One limitation I have thought of, is that a fleet must pass by a SZ with an operational friendly naval facility per Naval AO (Area of Operations), I would, for this rule, count 6 different areas as Naval AO’s. The north and south Atlantic, the Med, the Indian Ocean, and the north and south Pacific. So a fleet going from New York to Bombay would need to pass by a naval base in the South Atlantic or the Med (if heading east) or the north or south Pacific, if heading west. A fleet does not need to visit a facility in the Naval AO it ends the move in.
In GW36, Naval Bases and Shipyards can not be used by a player that they do not own or are not aligned with, so a UK player cannot use a US naval facility. Quite honestly, unless I have misunderstood something, I think that is a daft rule, and for Naval Redeployment to work, this has to be disregarded.
I like this limitation because it allows, for example, Germany to Redeploy within the north Atlantic, but not suddenly have their entire navy show up off of Midway after a Japanese invasion, knowing that the Germans will - basically - teleport. The limitation allows essentially for fuel limitations.
That’s as far as I’ve got with regards to rules. I’m not sure on a few points, but I do think that this House Rule will benefit the game, as it demands more strategic thinking, an enemy fleet might pop up unannounced right next to a vulnerable spot because you can no longer predict where they can go, but as it is a non-combat move, it does allow a response before any actual combat. I feel this also adds a degree of realism.
  It also allows for more subs to be built, as at the moment, subs can block Naval Redeployment, and I feel that subs aren’t used as much as they actually were during the war. One sub, loitering in a SZ next to a naval facility, becomes a huge headache for a fleet that needs to get somewhere fast. And a string of subs or destroyers can prevent an Operation Rheinubung type of operation.
I’m sure someone will find a loophole or a blatant mistake, but that’s the way it goes.