Let me try to give some theoretical underpinning for what vale has discovered.
There are basically two configurations we need to consider in determining the long term hammer output of this city:
a) Work crab, farm and any number of coastal tiles, this gives +6F and 1H
b) Work crab, farm , mine and any number of coastal tiles, giving +4F and 5H (+1H with forge, +1H with OR )
The value of the food surplus is dependent on the size of the city and the size of the whip. We have 4 sizes of whip that make sense in this city, 1, 2, 3, and 4.
The minimum city size for a whip is then 2, 4, 6 and 8 and these should be used for maximum hammers. Except a case can be made for growing to size 3 for a 1 pop whip as that allows the farm to be worked for more food output per turn. Here is a table of whipping efficiency in terms of hammers per food.
Code:
City hammers per food
Size Whip1 Whip2 Whip3 Whip4
1
2 2.73
3 2.50
4 2.31 2.40
5 2.14 2.22
6 2.00 2.07 2.14
7 1.88 1.94 2.00
8 1.76 1.82 1.88 1.94
9 1.67 1.71 1.76 1.82
10 1.58 1.62 1.67 1.71
This shows that for small size whips of size 1 and 2 it is better to not work the plains hill. But it seems that for larger whips the hill becomes competitive as the city needs to grow larger and hence less efficient. The plains hill effectively converts 2F to 4H and that is slightly more efficient than a size 4 whip from size 8 and slightly less efficient than a size 3 whip from size 6.
But as vale has already mentioned the actual size of whip is affected by the number of hammers already invested in a build. For every 30 hammers invested the whip size is reduced by 1. The forge and OR (if applicable) reduce this investment by 25% each. So the size of overflows from previous builds and how close we are to having enough hammers to reduce the size of the whip by 1 is an important consideration. It is slightly more efficient to build something that would normally need a size 4 whip by investing 30 hammers in it and making a size 3 whip. So the plains hill can often be used to speed up building by reducing the need for growth and at the same time make the food
Once we know what the size of our next whip is likely to be (say we want to build a Drydock) we know we need either a size 3 whip, in which case grow the city to size 6 as fast as possible (work a coastal tile instead of the hill) or we can use overflow hammers plus the hill and a size 2 whip from size 4 (or size 5 if already that size). We can see from the above chart that each food is worth 2.14H if that whip is from size 6 and 2.40H if from size 4. So we can improve the value of food (in the granary and stored as population) by using the plains hill at a slightly inefficient rate of 2H per food as this improves the efficiency of the whip and hence the overall efficiency of the city (whip and hammers combined). From this we can see that there is a very complicated interaction between working the plains hill and reducing the size of the whip. The effects of the forge and especially OR (which only applies to buildings) complicate this interaction even further.
Generally speaking this city should be kept at the smallest size possible for the whips required (and not grown to its happiness cap as vale initially said in post #160) if what we are concerned with is maximising hammers per turn. Growing larger significantly reduces the hammer value of food, for instance for every 1 larger a city grows a size 4 whip increases in cost by 4 food. Once some useful infrastructure has been installed this city might be grown larger if it used to give some increased trade income and commerce from the coastal tiles.
I hope those of you that like bean counting can appreciate the efforts of vale and myself to resolve our little dispute. I think it has been informative. The game can get very technical and even a simple city like this one can teach us a lot that would otherwise be obscured by the detail of a more complex situation. I conclude that we can generalise what we’ve found here and a grassland farm is more productive than a plains hill in any small city as long as we have a granary and intend to whip in the future.