Musings about ship Armor....

[Ulsyus]

Excessive pruning of quotes can potentially miss important context (as a matter of general principle).
Here is the more complete context of the quote that @mike wightman was citing.

CT Beltstrike, p2:

ALPHA
The only settlement on Alpha is Gerrison. with its accompanying starport and a scout base. The starport, scout base. and settlement at Alpha are buried into one side of the irregularly shaped planetoid. Alpha is held in a tidal lock by Bowman Prime, with one side always facing the gas giant; the inhabited section of Alpha is on the opposite side from the primary. This gives extensive natural shielding against the dangerous radiation which is found this close to Bowman Prime. (Ships under power are not affected--part of the M-drive generates a low-power screen against radiation and meteorite impact--but a power failure during approach within about a million kilometers of the gas giant would be fatal.)
The basic notion here being that "hull alone is insufficient protection against natural hazards" and that a POWER ON (and operational maneuver drive!) condition is required for a crew (and computers lacking a fiber optic backup?) to survive the harsh/hazardous environmental conditions.

However, it would be foolish to overly interpret this quote.
Don't think that a powered up maneuver drive is "all you need" and that a "tin foil hull" is all you need so long as you've got power for your maneuver drive.

Is there any other writing in cannon that covers this? It doesn't seem unreasonable as an idea to cover the dangers of standard cosmic radiation and smaller debris (to save us running a game of anti-rad medicines and hull patching). Is there anywhere else that might explain this, or has it always been assumed that basic hulls (and fuel tanks) would protect from these hazards?

I think modern tank armor merits the ceramic description and thus higher TL.

As I understand it, modern tank armour is a series of layered materials. Much like you'd find in the hull armour layers of a T5 vessel...

 

[Spinward Flow]

a series of layered materials.

Sounds like Composite Laminates to me!

 

[Condottiere]

One of which could be lead.

 

[G. Kashkanun Anderson]

Best shielding against radiation is "lots of hydrogen atoms" ... which conveniently enough translates into L-H₂ fuel tanks for our starship engineering purposes. So wrapping fuel tanks around habitable spaces on deck plans is a good idea, so long as you can keep a decent "width" of fuel tankage to keep things relatively efficient from a thermal management perspective (liquid hydrogen likes to "boil off" at some pretty low temperatures).

Yes, and no. Hydrogen is very useful for protecting us from rampaging neutrons, but considerably less so helpful at keeping gamma and X rays at bay. For that, you need (at current technologies) much heavier shielding, such as lead, tungsten, uranium and the like. There's also gadolinium, a markedly less dense material, but I do not know enough about its overall makeup (other than that it's pretty toxic) to know how useful it is as a shielding material or helpful alloy.

In the Far Future, we might be able harness magnetically contained plasma fields to block a whole lot of unpleasant outer space things, including gamma and x rays. In fact, that is pretty much how I currently explain (IMTU) why Traveller power plants are so hydrogen hungry; but us TL 7-8 primitives don't have that option yet, so we must hide behind sheets of metal. Or walls of rock, in the case of planetoid ships.

At any rate, though, inert (not plasma) hydrogen is just not that good for most typical starship radiation hazards, like when the local star decides to go berserk in your face, because high energy neutrons are not really a part of that equation, while sickening blasts of gamma and x ray radiation are. It is very much helpful, however, for the kinds of hazards that Travellers tend to stumble in to -- such as when your indifferently maintained fusion reactor burps out something unpleasant, or when you happen to find yourself in a dark, interstellar alley somewhere with someone waving a nuke in your face. That's why (at least IMTU) L-Hyd tankage tends to be packed strategically around most Adventure Class ships as additional ad hoc neutron shielding, both against internal (something gone horribly awry in the engine room) and external (nuclear piracy) threats.

This also means, of course, that there is also a big strategic difference between ships setting out to jump, and those coming in from it. At least for civilian vessels, who either choose not to, or simply can't afford to, invest in more permanent (read: bulky and/or expensive) neutron shielding solutions.

 

[Straybow]

Again I suspect you don't get how much armor even 2 inches of steel or the equivalent is.... I.e. a 3 inch Tank (re, Naval) guns will have issues with penetration in that realm.

The Armor 40 of Striker is over 12 inches thick, think battleship levels of armor. Hint a modern Aircraft-carrier's flight deck is only 4 inches thick...

The M-4 Sherman's short 75mm gun could penetrate 88 mm (3½ in) of steel. That's basic run-of-the-mill steel, with simple face-hardening treatment to make it "armor." Don't know what effect material yield strength has on armor effectiveness.

 

[Condottiere]

Warships are moving targets, and deflection plays some part.

Rule of thumb was that armour on a battleship, at least in the vital areas, should be able to protect from a direct hit from it's own main armament.