What fallacy is this?

[OmegaGuy]

In a debate involving The Culture, someone was saying that a Culture ship could just sit in hyperspace and attack the other ships in realspace. Then the other debator pointed out that his side had weapons/sensors that could detect and hit ships in hyperspace. The Culture debator responded by saying that hyperspace in that series was different from hyperspace in the Culture series so that tactic wouldn't work.

Then, later on in the debate, the non - Culture debator stated that his ship could hide in hyperspace to avoid the Culture's detection, but the Culture debator claimed that doing so would create ripples on the skein (part of Culture hyperspace) and easily point out the ship's position to the Culture vessel.

I'm pretty sure this is a logical fallacy, but I can't place it exactly.

[mr friendly guy]

Ah, who exactly is making the alleged fallacy? Is it the culture or non-culture debater?

[OmegaGuy]

The Culture debator, since he first says that Culture hyperspace is different from the other hyperspace, and then he says it's the same

[Boyish-Tigerlilly]

If he says X is different from Y but then says "not really" as you say he said, then that's a case of inconsistency.

[Androsphinx]

Hmm... Well, the Culture has two types of "hyperspace" - infra and ultra. So if you wanted to give the culture debater some serious benefit of the doubt, you could assume that he's treating one (probably ultra) as being equivalent to "normal" hyperspace, and the other (infra) as being different.

He would then be arguing that a Culture ship could hide in "infra", but pick up ships in "ultra", and thus would be able to hide in "hyperspace" while also detecting ships in it.

[The Nomad]

There are no two types of hyperspace, merely two directions of the same hyperspace axis (hyper-up and hyper-down, so to speak, one of them leading to a younger universe and the other to an older one). The skein is, however, their name for realspace. Depending on the technical specifics of the other side's hyperspace, the Culture debater could actually be right, flat out wrong or even dishonestly bullshitting. What universe are they debating?

[OmegaGuy]

I think it was Perry Rhodan or something, I was not familiar with it.

[Darth Wong]

In a debate involving The Culture, someone was saying that a Culture ship could just sit in hyperspace and attack the other ships in realspace. Then the other debator pointed out that his side had weapons/sensors that could detect and hit ships in hyperspace. The Culture debator responded by saying that hyperspace in that series was different from hyperspace in the Culture series so that tactic wouldn't work.

Then, later on in the debate, the non - Culture debator stated that his ship could hide in hyperspace to avoid the Culture's detection, but the Culture debator claimed that doing so would create ripples on the skein (part of Culture hyperspace) and easily point out the ship's position to the Culture vessel.

I'm pretty sure this is a logical fallacy, but I can't place it exactly.

It's not a logic fallacy because they do not indicate the reasoning they used in order to arrive at these conclusions. In order to be a logic fallacy, an argument must presume to employ logic.

This is like asking for the mathematical error in an argument that includes no math.

[The Nomad]

I think it was Perry Rhodan or something, I was not familiar with it.

It's touchy, because they have several FTL modes (all basically faster than the Culture's), and I don't recall how they interact with realspace. Note that all PR combat I know of happens in realspace at ranges of several million km, so the PR debater might be the one who makes the fallacy by inflating their abilities. Though they still have their exotic Paratron shields, which are kind of like a Culture trapdoor shield (well, they can probably overcome those too, though how they do it is unknown).
Note that, as DW pointed out, it's not really a fallacy if the Culture debater doesn't explain his reasoning : even if he turns out to be technically right, he's just being a dishonest bullshitter.

[Lancer]

Just ask the Culture debater to provide evidence for his claims or STFU.

[DaveJB]

It looks vaguely like it's a Stolen Concept fallacy; he starts off by saying that Culture Hyperspace isn't the same as the one in the other series, thus their weapons can't affect the Culture ship, then later swapping around and declaring that they are the same, hence the Culture ship can detect the Skein ripples.