Western Approaches

Panzer Eight's excellent "WW2 Coastal Wargame Rules" (http://panzer8.webs.com/) don't quite cover convoy rules, which is what I want to do. So here are some modifications.

Turn Sequence

1. Roll a dice for this turn's visibility
2. Move convoy
3. Move sea cards up to 1 point
4. Roll for initiative, the winner takes actions with one ship, alternate with opponent till all ship have had actions
5. Move torpedoes and resolve any hits.

Measurement
I a square grid for naval games. Each ship is placed on a "point" and faces one of the 8 points surround it Each facing corresponds to a compass headings (i.e. north or south west). Each point can accomodate 3 ships, but they must all face the same or opposite compass headings (i.e. all north east or south west). Each point is considered to be 500 yards away from the eight points surrounding it, therefore each turn is between 1 and 2 minutes long.


Collisions
If a ship enters a point that contains another ship that is facing a different direction therye will be a collision. This was one of the mains ways to sink submarines. The ramming ship gets a damaged result, while the rammed ship is wrecked if larger and sinking if smaller.


 2. Visibility 
Each turn check visibility, this is the range at which spotting can occur. A "sea card" has to be spotted before it is revealed to a surface vessel or a false contact, and ships and surfaced submarines must be spotted before they can be fired apon. There is an "ambient" visibility for the whole game. This ambient visibility varies from a of distance 6 points on moonless nights or dense fog and anywhere up to the entire board for daylight. 

At the start of each turn, roll a die, and subtract the score from the ambient visibility. This is the range at which sea cards, surfaced submarines, Vosper, MAS Elco or Higgins boards can be spotted during this turn. For all other vessels, add their defence value to the spotting range. So on a dark night (6 points visibility) on a turn where visibility was rolled at (-4), a corvette (defence 5) could be spotted 7 squares away. Surfaced vessels are always spotted at a range of one point.

Sea Cards
The side attacking the convoy can place sea cards on at any point at least 6 points away from the convoys table edge table at the start of the game (I use 27 cards, each labled for a letter of the alphabet). All ships and submarines are assigned to a sea card. 

If a sea card is spotted, it is revaealed as a ship, a surfaced submarine or nothing. The sea card is left on the table because it could still be a submerged submarine and is not removed till it has been successfully pinged by ASDIC in which case it is reavealed as a submarine at periscope depth or a false contact. Sea cards can be moved 1 point at the start of each turn.

4. Movement

When activated, one vessel can move, then spot and fire guns; or spot and fire guns, then move. Vessels must move in the drection they face, but can them pivot up to 45° for every square they move into.  

MTB, S-boot, PT and MAS,  can pivot 90° for each square they move into. The whole movement distance must be expended. A ship can make single 90° turn per move if it stays in the same square.

Evading
Any vessel at speed 3 or more can sacrifice 1 movement square if it takes evasive action (show this with a counter).

6. Firing

Roll a D6 for each weapon firing; target is straddled on a result = 4,5,6 if within half range, 5,6 if over half range.

- 1 if target speed is 6” 

+ 1 if target speed is 2” or less 

- 1 if firing vessel speed is 6”

-1 if firing while evading

-1 if target is evading

Long shots
Any shot that would take a roll of 7 or more to straddle and rolls a natural score of "6", straddles if a second dice roll is a further "6".

Line of sight
Line of sight is traced from the point occupied by the firing ship the point occupied by the target. If a straight line between these points crosses the base of any ship, or land or smoke, like of sight is blocked.

 7. Damage
When a ship is straddled by funfire, compare D6+Attack factor of that weapon, less D6 + Defence Factor of the target.


0 or less = minor damage from splinters
 +1 to +3 = target is Damaged
+4 to +5 = target is Wrecked
+6 = target is Sinking


Damaged vessels subtract - 2” to their maximum speed (but never less than 1) and half the Attack Factor of their 30mm or smaller calibre. In addition to this, roll one D6 for each gun 37mm or larger, depth charge throwers and ASDIC: 5,6 = KO.


Wrecked vessels subtract a further – 2” to their maximum speed (slower vessels are immobilized) and the Attack Factor of 30mm or smaller calibre is reduced to 0. In addition to this, roll one D6 for each gun 37mm or larger, depth charge throwers and ASDIC: 4,5,6 = KO.

Sinking vessels cannot move or fire (but are left on the table as an obscuction to movement and fire.


Damaged 2nd time = Wrecked. 
Wrecked 2nd time = Sinking.


 10. Torpedoes 
When firing a Torpedo, place a counter (toothpick points) 1 square away from the firing submarine or ship, in one of the three squares  in the arc into which the torpedo was fired. This is the minimum range. After all vessels have been activated for that turn, move the all torpedoes 7 squares along a straight line. each turn thereafter the torpedoe continues to be moved 7 squares along this line till it leaves the board. If the torpedo meets a ship, roll to see if it hits. 
Measure the distance from the submarine's firing position to the target, this is the base score to equal or exceed on a D6. Modify this base score with: 
+1 if firing at the targets rear or forward arc, 
+1 if firing at periscope depth
+2 if the target is evading. 
A roll of "1" is always a miss, a natural "6" is always a hit Torpedoes are ineffective vs. Small and Larger MTBs. 


Work out damage in the normal way. Torpedoes fired by submarines and destroyers have an attack value of 12, those fired by smaller ships and aircraft, 9.

13. Submarines

1) Submarines are considered Slow Vessels (max speed 3”) with a Defence Factor of 4, armed with  4 Torpedoes on the front arc and 1 in the rear and a 88mm Deck Gun (FPS). 


Submarines are a poor gun platform, so subtract – 1 to their “to hit” d6 when firing with Deck Gun(s).

Submarines cannot reload their torpedo tubes during the course of a game.

The main difference from other Vessels, is that they can Submerge at the end of their movement, unless Damaged or Wrecked. This is considered an evasive manouver. Remove the model from the gaming table and consider it “out” from the game.


Submerging

A submarine can be at three levels; surfaced, or submerged at periscope depth or deep. A submerged submarine cannot move. Periscope level is shown with one submerged marker, deep level with two.  A submarine which has gone deep, can add one furthersubmerged markers as its action each turn. This represents it evading ASDIC search by turning or other countermeasures

Sonar search 

Any corvette within three square, and within FPS arc, can make a sonar search on a sea card or submerged submarine within 3 squares on a 4,5,6. A successful search reveal a submerged submarine under a Sea card, or can remove one submerged marker if there are more than two..

Depth charges 

Naval ships who exit a square containing a submerged submarine can depth charge (if they don't move away they blow their own stern off). For each submerged marker the sub has, the ship rolls one dice. If all the dice are:

 "1"s = Submarine 

 "1"s and "2"s Blow tanks and mmediately surface. All submerged markers are removed 

 "1"s and "2"s, or "3"s crew demoralised, submarine must dive to, and stay deep for the rest of the game (not even if ordered directly by Hitler)

Victory conditions
Each convoy should have 10 points of cargo ships (oil tankers count double).


To win the attacking force must sink one ship per attacker, plus one extra ship for each attacker destroyed.


The defender must get one ship accross the table for each escorting ship.


If both sides win, the convoy action was a draw.