How much math is too much?

Is it about space exploration, made more interesting by a mechanic where the players have to manage resources to move from place to place?

Or is it about doing math?

Maybe figuring out a totally different mechanic that lets players interact would be a better option.

Or treating your current mechanic the way it is ("+2 light years" or whatever), and considering that a VALID card, that adds some strategy to the "take-that" element. Because mindless "take-that" is stupid. But in your game, if you have a "+2 light years" card, you maybe want to WAIT and play it when it has the most impact, and NOT have it have the same impact no matter what the opponent is currently doing.

Like any part of a board game you have to ask does the math add enough fun to your board game to justify its existence?

Like you have eluded to you could simplify things greatly by just using making ships fly a certain number of areas on a map. Then you could have something like engines consume X units of fuel to move up to Y spaces per turn. Then you crew consumes Z food and W oxygen per turn.

Instead of using a percentage based system You could have effects last until the ship reaches the next planet or can otherwise logically be resolved. Like leaky fuel tanks uses one more fuel. Or a broken sprocket in the engine limits movement by a space. Or you find a stow away and they consume an extra food.

I going to suggest that you look how the ships move in the firefly board game. (I'm just talking about the players options for moving their ship and not the navigation cards resolving)

You may also want to consider what you want your game to focus on. Do you want it to be an optimize the travel type game or is it more of a take that type of game? If you can find the answer to that question you can then have the game concentrate on that aspect. Or if your really ambitious make both games.

Good luck with your game

I suppose it depends on your audience, but I think the less mathy the game feels, the more inclusive. There are ways you can design mechanics / cards to simplify math but keep it inside the core.

Essentially I’d say bake the math in to the game play itself. Have hidden math. Deck builders are a good example of this. Most of them are inherently about math — setting up a % increase, improving odds, etc. But you never have to do math operations, the math result is just from choices and decision making. Players who enjoy the math can get that little edge, but it also just inherently works for people who don’t.

For cards or upgrades that improve travel time, you can do similar tricks. Instead of a 10% penalty, you can reduce a “roll”, or add an inefficient piece to the player’s engine. This kind of depends on your design having an engine that optimizes as the game goes on, which should be present in most games anyway.

Quick rough example... assume you have an “engine” deck. Your ship’s speed rating determines how many cards are dealt from your engine deck. Let’s say you have a speed of 4.

If I have 4 cards that give +1 travel, and I am saddled with one (“thrusters malfunction +0 travel”), you’ve just mathed in a 20% chance for a 25% travel penalty. But the nice part about this solution is it feels “gamey”, and the % scales throughout the game without more complex math required.

Similar solutions can be found for dice rolls and the like.

Food for thought.