Author Topic: Ship Design Rules of Thumb  (Read 962 times)

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Offline Garfunkel

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Re: Ship Design Rules of Thumb
« Reply #15 on: November 25, 2021, 03:13:43 AM »
Fuel-saving engines are valuable because your commercial designs will be flying a lot more than your military designs and thus end up guzzling plenty of Sorium if you have thirsty engines.
 

Offline Jorgen_CAB

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Re: Ship Design Rules of Thumb
« Reply #16 on: November 25, 2021, 07:07:23 AM »
Put the largest, most reduced power engine you can on your cargo and colony ships that your tech allows, and then build the largest ships your shipyards support. It's counter-intuitive, but large, reduced power engines actually are cheaper and less mineral intensive, and also build faster, so you can build more of them and negate the fact that they're (somewhat) slower by moving more cargo at a time.

This isn't really a general truth. For colony ships in particular, but also other commercial ships such as transports which have expensive mission modules, the engines are often a minor part of the total cost, so reducing their cost may not reduce the cost of the class very much. For example, a size-60 commercial ion drive with 0.5x modifier (375 EP) costs 93.75 BP. A 40,000-ton (approx.) colony ship at this tech level can cost roughly 1500 to 2000 BP, with four engines making up only 375 BP of that cost. A significant fraction but firmly the minority.

If we have the same engine with a 0.25x modifier (187.5 EP; 4000 RP for the tech, reasonable for early Ion tech) each engine costs only about 23.44 BP, and four engines cost 93.75 BP. This is indeed a 75% reduction in the cost of engines, but probably only a 15%, maybe 20% reduction in the overall cost of the ships. It's questionable I think whether it is worth building 15%-20% more ships which travel at only half the speed.

A better argument for this strategy would be the savings in gallicite, which can still be significant even though commercial engines are much cheaper than military engines already, and the savings of fuel if your refining or tanker capability is not too impressive. Especially later in the game, large fleets of very large ships can place significant demands on these two resources, along with duranium as always, and in my opinion this is a much better reason to prefer the lower-efficiency engines in the mid to late game.

It is worth noting, though, that the advice to build commercial ships as large as possible is generally very good as large shipyards are more efficient - a single large ship will take longer to build than a single small ship, of course, but it will be built more quickly than the same tonnage in multiple smaller ships.

A few remarks... larger ships is not more efficient to build in terms of population employed as it is more efficient with two slipways of 50kt each than one at 100kt. There are not as many benefit with building really large commercial ships as there are for military ships, even relatively small commercial ships can still use the most fuel efficient and large engines you can build and big engines is not a direct cost for commercial ships as they don't pay maintenance.

The benefit with larger ships is spending less cost for the armour belt. Good captains with logistics ratings that benefit loading/unloading rates. There are some cost benefit from building a larger cargo ship as there are some benefit to fuel storage, cargo holds etc... from my early game I just made two equal ships and the benefit are about 25% in cost. but that gap usually become smaller with increasing technology but will still be important. There are going to be rather small benefit with increasing the size from 125t to 250t cargo transport capacity for example, but more to gain from going from 25kt to 125kt...

One of the greatest benefit of low powered engines is definitely better fuel efficiency as fuel usage for commercial ships is a huge issue.

In general I use the smaller cargo ships for short trips with faster load/unload speeds and larger ships for long hauls and who don't need fast load/unload speeds as they spend most of their time travelling from point to point anyway. So I keep two main cargo classes around, one at 25kt and one at 125kt capacity. I then also have mineral haulers with even smaller cargo capacity.

There also are dubious reasons to upgrade commercial ships as well unless you have fuel problems rather than just building new ships to increase the capacity that way. There are a few things to think about here. When you ship a mine you are loosing mineral production while it is in transit so having a ship with twice the speed will cast you mineral production as well as probably more fuel as the engine is less efficient. So... upgrade your ships with careful consideration and not too often.
 

Offline nakorkren

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Re: Ship Design Rules of Thumb
« Reply #17 on: November 25, 2021, 10:18:05 PM »
As Jorgen said, I should have mentioned the gallicite and sorium benefits of building large, low-boost engines; that is the primary benefit I am chasing in my game ATM. Since minerals are the primarily finite resource (second only to the player's time  ;D), and gallicite in particular can be a pinch point, this is a big deal.

Also, the reduction in engine cost significantly reduces the BP required, which in turn reduces the build time. Even though my Mk4 cargo ship is 250k size with 175k cargo space and 1700km/s, it actually builds FASTER than my Mk3 cargo ship which is 160k size with 100k cargo space and 2700km/s.
 

Offline Jorgen_CAB

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Re: Ship Design Rules of Thumb
« Reply #18 on: Yesterday at 09:56:42 AM »
As Jorgen said, I should have mentioned the gallicite and sorium benefits of building large, low-boost engines; that is the primary benefit I am chasing in my game ATM. Since minerals are the primarily finite resource (second only to the player's time  ;D), and gallicite in particular can be a pinch point, this is a big deal.

Also, the reduction in engine cost significantly reduces the BP required, which in turn reduces the build time. Even though my Mk4 cargo ship is 250k size with 175k cargo space and 1700km/s, it actually builds FASTER than my Mk3 cargo ship which is 160k size with 100k cargo space and 2700km/s.

You also should think about speed, speed equal tonnage moved as well... also more speed means less production shortfall from facilities moved as well. Some fuel efficiency can be sacrificed for more speed. That is why I don't like too fuel efficient engines.