Sunday, 5 October 2014

Turning Circles again--update of old post

One of the most problematic areas for ancient ship games is manoeuvring. Turning is something which has to be cracked.
Simple rules such as Corvus can get away with giving an arbitrary angle for each type of ship beyond which it cannot turn in one move. Another way is have cut-out tracks which actually show allowed paths for ships to follow.

I wanted to try and use the data from Olympias rather than arbitrary values. This made things difficult.

One thing we do not have a lot of is space. It is fine to have turning tracks but I long ago discovered they take up to much space. Beyond a skirmish with a few ships they do not work.

At the same time I want to have models which look like ships and not blobs. I want enough space so I can have marines on deck not just markers dwarfing the ship they are alongside.

My compromise - hopefully my final version (touch wood) - is to assume the following...

The ship model occupies the space a ship would at sea including the safe zone of sea-space it needs to function. Ships did not sit shoulder-to-shoulder on the briney. To give space to face threats and to avoid fouling, triremes must have held 50 to 100m distance from each other. My models at 10 cm by 5cm with a scale of 1mm to the metre give such space. It is just a case of imagining the real ship as a 3 cm core in the paper model. Both ships will have their main mast at the same point, so that is our reference.

Olympias' data is our starting point so we have a maximum turn of 180 degrees in one minute. In such a turn the ship crosses about 62m - the 'tactical diameter' of the circle it follows is 62m.
At the same time it proceeds forwards before it turns back - it advances about half distance.

Larger, less manoeuverable ships will have larger tactical diametres and advance further.

We can change T and A by varying the speed the ships enters the turn and the way the rudder is used, but we will stick with basic stuff or we will go mad.

If we give a good 3 this 180 degree turn capability and have one better class to allow for a fast 3 - a tachynaut - we have already made two classes of ship manoeuveraility.

In the trials data the poorer performances of Olympias dropped the turning rate from 30 seconds per 90 degrees to 45 seconds - 50% worse. This could give us a handle on another turning class for a poorer 3 or a heavier ship in good form.

Avoiding tracks - to save space - I have made angular templates corresponding to these classes.
The ships turn by pivoting on the front corner - not accurate -but essential for ease of use on the table.

CLASS          Turn                            Advance               Template Diameter
      A              150 DEGREES          MINUS 70mm       40mm                      
Fast3, Fast2
      B               120                            MINUS 40mm       70mm                      
3,2, Pentekonter, Fast4
      C               90                              0                             80mm                     
4,Fast5,Slow3, Slow2
      D               60                              40mm                     137.5mm               
5 and Up, Slow4

Maybe wierd that the advances for sharp turns are negative , but this gives us a sharp distinction in models capability on the table. 3s can get out of a tight spot, 5s cannot.

The tactical diameter for B is close to 62 and measured mast-to-mast is 65.
If a game turn is 1 minute then the 120 degrees - 1/3 turn corresponds to a 360 turn of 3 minutes for the class B and 2 minutes for class A. Olympias' best was 128 seconds and worst 154 seconds - not too far out.

The best thing about the angular templates is that they save space and give an instantly visible effect which is sufficiently different between classes.

The side of each template is equal to one ship's length which is the unit of measurement in my rules.

Olympia's tactical diameter is about double her length - so too is it here.

Using the ideas above I have now eliminated templates except for requiring a form of protractor to ensure ships do not exceed their capabilities as they turn. This is due to introducing a way of marking the ship's course....... more to follow.

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