Ships on seas scuttle; ships in space 'splode. Simple.

@gowenfawr -- No, not simple. Scuttling ships at sea doesn't atomize the remaining crew. And for that matter nothing prevents a spaceship from being scuttled (i.e. nothing says scuttle=blow up for spaceships).

How would you scuttle a spaceship? It's got nowhere to sink.

Scuttling ships at sea deny access to the ship. Salvage, while possible, is expensive, dangerous, and may not be possible under conditions of conflict. However, a ship in space merely abandoned is more accessible to salvage - the difference between a ship and a derelict is just the amount of usable propellant that can be applied to it. SO, to get the equivalent "deny to the enemy" capability in space, you need to materially alter it (e.g., BOOM) instead of sinking it... (You could 'sink' it in a gravity hole, of course, but that has other issues)

"Scuttle" it into a gravity well; "Scuttle" it by radiation "leak"; "Scuttle" it by fusing all critical electrical components; "Scuttle" it by giving it extreme rotational momentum at the time of abandonment; etc. -- Excepting in science-fantasy settings, the hard vacuum of boundless space is a great place to scuttle a ship. Especially if you've toasted the critical components then the cost of salvage is of dubitable worth.

en.m.wikipedia.org/wiki/St_Nazaire_Raid Take a look at the St Nazaire raid for one of the few instances of a military advantage being gained by deliberately destroying a ship

They do implement a self-destruct on real spacecraft. If a launch is off of intended trajectory and is a potential danger they will order the rocket to self destruct.

@CBredlow True, but a booster is not a space ship. The Range Safety Officer's duties end when the payload/crew capsule achieves orbit. I don't think they could command the International Space Station to self destruct. Nor would they want to: The international stink caused by turning it into another million pieces of orbiting debris would far outweigh the international stink caused by whatever small fragments of it that might actually reach the ground in an uncontrolled reentry.

@jameslarge I think the stink raised by Kosmos 954 crashing into Canada would be far greater than that satellite blowing up in space.

@james large, I feel the ISS is a poor example in this case as it's purpose is completely peaceful and there are no enemies to keep it from.

@Octopus, Maybe I drifted off-topic, but I wasn't comparing the ISS to military ships. I was comparing it to the rockets that the ISS crew ride up to orbit. Those rockets are equipped with self-destruct. At any major launch, manned or not, it is the job of the Range Safety Officer to command the boosters to self-destruct if that will prevent any part of the rocket or its payload from coming down on a population center.

@gowenfawr I like your lovely little alliteration.

@user23715: All of the suggestions you make for scuttling do not really make the ship inaccessible and could be overcome with sufficient technology. Scuttling a ship during WWII made it inaccessible, and is only reversible at great cost and effort. In a futuristic setting with abundant number of spacecraft, you would also need to ensure that whatever you did to your ship is difficult to reverse. Your suggestions don't appear to be too difficult to reverse for a sufficiently advanced civilization. But, destroying the entire ship is pretty difficult to overcome and simple to enact.

@Ellesedil -- Yes, and a "sufficiently advanced civilization" wouldn't need to board your dreadnought to get your military secrets either. The point with my question is the idea of self-destruct as used in the vast majority of stories is patently absurd. And the "harder" the sci-fi (like we see in show The Expanse) the more absurd it is.

Except it isn't absurd. If your plan to scuttle a ship is to spin it really fast, then all that is needed to undo that act is to slow down the rotational velocity back to 0. All sorts of science fiction universes have tractor beams. Destroying only certain components might render some things inaccessible, but you'll need to ensure you don't accidentally leave something sensitive available or repairable. Plus, leaving a ship hull intact provides someone with a free ship hull, plus whatever other systems survived. The only way to know for sure a ship is inaccessible is to destroy it.

In modern real life, the easiest way to make a ship in accessible is to scuttle it and ensure it sinks because no one around is technologically advanced to quickly, easily, and cheaply reclaim a ship from the bottom of the ocean. What is in this comparison that is being missed?

@Ellesedil -- "tractor beams" are magic. I'm talking sci-fi not sci-fantasy in my question. And I've edited to help people to see what exactly I'm asking.

Tractor beams are a field of scientific discovery in real life. It is "magic" only in terms of application and scale.

@Ellesedil -- Yes, and when you can "tractor" a mega-metric-ton ship moving at relativistic speeds, then your tech = magic. Right?

Well, relativistic speeds is currently magic as well, even more so than tractor beams. I think you're too hung up on "scuttling is more realistic than destroying" and unwilling to see how different ways of scuttling a ship can be countered and ignoring how destroying the whole ship simplifies the whole situation so you don't have to worry about how other sentient space fairing beings might counter your scuttling attempt. Anyway, at this point, I think it's time to agree to disagree.

Spin it? You wanna throw up for a while, pass out and then be dead? Or we could just hit this button... - No navy is currently participating in a conflict in outerspace, so they don't need one; there are plenty of other ways to SD any Earthbound vessel.

You guys aren't even trying to understand my question. Please re-read it. -- Oh, and Relativistic speed isn't what you think it is. For the ships in The Expanse the term applies. In Trek sub-light shuttles are capable of relativistic speeds. Etc.

This question is based on an egregiously false premise ("people ignorant of military science think this is a good plot device for their fantasy novels, so everyone should do it").

The better question is why a scuttling system (which may be as simple as dropping containment on the AM) needs a visible/audible dramatic coundown. But remember Galaxy Quest: "Whoever wrote this episode should die!"

Actually, a better question would be "why don't modern day ships self destruct instead of scuttling with the intent to sink?" Then it doesn't need a science fiction component at all. If that's what is really being asked here, then this question is probably off topic and should be asked somewhere else because it is now a naval engineering question.