How long to apply a hull patch?

[Stainless]

Hull or bulkhead patches have been in Traveller since the Classic days.

They appear in the Central Supply Catalogue (pg 156) but nowhere in the Core Rule Book. No source gives the timings for applying a patch.

You'd expect they should be fairly easy to use and optimised for rapid application. However, does anyone want to hazard a guess (or know of a source that gives) how long it takes to apply a patch? I'd say at least one round at the very least under optimal conditions (e.g., normal G, not applied to vacuum side).

 

[justacaveman]

I always make them take about 30 seconds longer than the PC's air supply. :twisted:

Seriously, since time is of the essence in these situations I would think that they should only take 1 major action to apply. IMTU they are peel-and-stick with a can of rapid dry spray foam to help fill in gaps (another major action). You might need a hammer to pound jagged edges kinda flat.

 

[DFW]

Considering that the hole size, configuration (smooth, no prep needed, jagged- needing smoothing to make a flat surface for patch, etc) isn't known ahead of time, the GM would have to make a case by case adjudication.

 

[DFW]

You might need a hammer to pound jagged edges kinda flat.

That's what I was thinking. How easy is it to pound Bonded super dense hull metal, kinda flat? Ouch! Could take a while. :twisted:

 

[far-trader]

I've kind of always presumed the patch was quite forgiving.

Basically a rolled material, quite thin, light and pliable. It gets laid out over the hole/damage, being self adhering (tacky until activated to allow repositioning) and cut, usually just straight along the rolled up remainder, using a basic repair tool included in the tool set (a laser cut function of the laser welder).

Then you laser weld along the perimeter to keep it from peeling off and the patch is activated creating a permanent adhesion to the remaining hull and both stiffening and bulking up the patch.

Patches are not durable enough to be permanent and will eventually degrade and fail.

Time, standard EVA prep time plus time to get to the damage from the airlock and several minutes for a damage control party of 4 to lay out, seal, and activate. Fewer people means more time. More people means more simultaneous patches.

 

[Fovean]

I haven't read the CSC write-up but...

I've always imagined them to be a dense flexible material which you can shake out like a folded sheet; magnetic for positioning, with a battery-operated switch that starts a chemical reaction along the edges to bond it to the hull.

2 - 4 combat rounds to apply, doubled if atmosphere is escaping through the breech.

 

[rinku]

Keep in mind most patchable hull breaches will be quite small. The main requirement is to form an airtight seal quickly, so a tough adhesive plastic should suffice in most cases. The patch is on the best side of the pressure gradient, at least - you won't need much of an adhesive to keep it firmly in place.

If a breach was large enough to cause the air in the compartment to evacuate before a patch could be applied, it's probably going to have incapacitated the occupants anyway, and would be a matter of going in (or out) in suits with plating and welders to fix it. You could work out what sort of size this would be with some assumptions, but my gut feeling would be that more than a few cm in diameter would evacuate too quickly.

But in simple game terms, you should be able to patch any breach that doesn't knock you out or kill you. To answer the original question, I'd say a minor action to grab (unholster) and another minor action to apply. It should be roughly the equivalent of pulling out a fire blanket and throwing it over a fire. I'd also make it a Vacc Suit or Zero G (either will do) check for success (Easy, Dex) to show the effects of crew training and experience vs groundsuckers and passengers.

 

[far-trader]

Keep in mind most patchable hull breaches will be quite small...

I wasn't thinking this applied to anything that small. A Vacc-Suit patch will do that nicely. A wad of gum will probably even temporarily fix those. Possibly even a piece of duct tape (NOT Duck(tm) tape, though it might slow a leak) for a bit longer. Presuming of course that what made the tiny annoying hole did it somewhere accessible from the interior.

Actually I find it difficult to comprehend such minor damage occurring. Traveller ship hulls are pretty much proof against micro-meteoroid impact damage and small and medium arms fire.

I thought the hull patches were designed for major weapons (vehicle or ship size) damage. Great huge holes, from the outside and possibly right through the other side. Things that will pretty much instantly decompress the section and only be patchable from the outside. Not something a bit of flimsy plastic can cover with the aid of air-pressure from the inside.

 

[rust]

Hmmm ... I wonder what diameter the ray from a pulse laser would have,
and what the damage caused by a hit would be like.

To do maximum damage, the ray would have to be as tightly focused as
possible, so the hole it would burn into a ship's hull would probably not be
that big, even when one considers that the melting of some of the hull ma-
terial would probably contribute to the size of the hole.

Well, I have no idea how to calculate this, but if I had to guess I would es-
timate that the hole would probably have a diameter between 10 cm and
30 cm - much more than this, and the laser would be more a searchlight
than a weapon.

 

[far-trader]

Hmmm ... I wonder what diameter the ray from a pulse laser would have,
and what the damage caused by a hit would be like.

Given the (possible if not certain) extreme velocities and movements involved I'd always thought of it more as a slash than a hole for beam weapons. And big explosions for missiles of course

All generally causing further structural tearing along the edges due to rapid expansion. But yeah, defining the type and scope of the damage inflicted will be a key component to working out the rest.

 

[rinku]

I thought the hull patches were designed for major weapons (vehicle or ship size) damage. Great huge holes, from the outside and possibly right through the other side. Things that will pretty much instantly decompress the section and only be patchable from the outside. Not something a bit of flimsy plastic can cover with the aid of air-pressure from the inside.

Those sort of patches would really fall under the Hull Damage repairs per p.143 of the basic rules. Mechanic check, 1-6 hours one tone of spares.

Hmmm ... I wonder what diameter the ray from a pulse laser would have, and what the damage caused by a hit would be like.

Heh. That way leads madness. When GDW looked at realistic lasers for TNE they discovered that "tightly focussed as possible" at space ranges means you are looking at spots in the square metre range, and they had to invent gravitic laser focussing to make it work. Even then, lasers became large dishes on armatures instead of sexy guns in turrets.

I note that MGT has hauled back the range at which space combat can occur from previous editions; however, the size of laser hits is going to depend on the range at which they were suffered. At close range, small puncture that penetrates; at longer range a wide, shallow crater.

The formula from Fire Fusion & Steel is:

I = (P/[{L/F}^2])/R^2

Where I is delivered energy intensity (watts/cm^2),
P = discharge energy (watts)
L = Wavelength (cm)
F = Focal value (cm)
R = Range (cm)

From the same source, a laser needs about 2 Mj per square cm to penetrate a cm of steel.

In the example to demonstrate the problem, they used a 10 metre diameter focal array, using UV wavelengths. This gave a spot at 30,000km of about 70 metres diameter, meaning a gigajoule laser was delivering only 0.3 Mj per square cm.

 

[justacaveman]

I would think that anything bigger than about 60cm would be too big to use a quick patch on and would require something that takes at least a few minutes to apply. I look at the bulkhead patches a quick fix to prevent air loss while you provide first-aid and such to the compartment's occupants.

The Bulkhead patches in CSC aren't made to last more than 24 hours anyway.

 

[far-trader]

I thought the hull patches were designed for major weapons (vehicle or ship size) damage. Great huge holes, from the outside and possibly right through the other side. Things that will pretty much instantly decompress the section and only be patchable from the outside. Not something a bit of flimsy plastic can cover with the aid of air-pressure from the inside.

Those sort of patches would really fall under the Hull Damage repairs per p.143 of the basic rules. Mechanic check, 1-6 hours one tone of spares.

Well there you go, I was picturing the hull patches as something else entirely. Not having CSC, does that shed any light on the possible size of said patches?

How much do they cost? A couple or several credits and yeah I'd say you're talking peel and slap for small holes on the interior (and again, I don't see that being terribly useful, at all). Closer to Cr100 or more and I think they have to be bigger and of a different intent, like what I was imagining them to be.

Or, how heavy/big are they? If they described that.

Then again, if they only last 24hours (and no mention of surviving reentry into atmo stress) then I'd have to go with them being just peel and slap for small holes on the interior, regardless of the cost. Heck, Vacc-Suit patches lasted longer than that in previous rules. Speaking of which, there's another data comparison item, if they are in CSC or some other supplement (or somewhere in the Core book, I've not been through it all yet). What info is there on that?

Besides, what about the hull option for self-sealing? Surely that obviates the need for silly peel and slap patches on the interior, being that it does that automatically (and indefinitely) and much better (permanent), albeit at greater cost and without restoring the exterior (degraded streamlining imo, think the Columbia shuttle reentry disaster effects, ignoring the grav drive float like a leaf atmo reentry ideas some support). So maybe the peel and slap patches are for the ships built without the self-sealing option (a criminal design oversight imo). Or, and my take barring clear evidence otherwise, they are intended to restore external hull integrity, to eliminate streamlining degradation (so you can land safely) and stop (at least temporarily) fuel leaks so you can refuel and jump somewhere for repairs.

As for the Mech check and hours with a ton of spare parts, I pictured that as something permanent. The hammering out and cutting of damaged areas and welding of or replacement with hull material over it.

But anyway, I'm curious what if any details CSC offers that have been left out of the discussion so far, and if they'll point to a more solid grasp of the issue.

 

[rust]

The bulkhead patches from CSC are a set of variously-sized, flexible pat-
ches that comes with adhesive and sealant, the patches tend to fail after
4d6 hours, and the set costs 150 Credits.

Since "a set of" should include at least three individual items, the cost of
a single bulkhead patch cannot be more than 50 Credits.

 

[DFW]

Actually I find it difficult to comprehend such minor damage occurring. Traveller ship hulls are pretty much proof against micro-meteoroid impact damage and small and medium arms fire.

Quite correct. At top speed from Earth to Saturn (average distance) at 6Gs, a ship will be travelling ~9160 kilometers/sec. Running into a 1 gram micrometeorite at that velocity produces ~41,952 MJ. To put this in perspective, the 120mm main gun of an M1 MBT firing a DU penetrator, produces 9 MJ of kinetic energy at the muzzle. So, Traveller spaceship hulls are all but immune to most kinetic energy only weapons. :!:

BTW - because of this, ships don't have windows, nor screen doors.

 

[rust]

Given the (possible if not certain) extreme velocities and movements involved I'd always thought of it more as a slash than a hole for beam weapons.

I also think that a beam laser or similar beam weapon would create a
slash because of the duration of the beam and the movement of both
ships. This is why I was thinking of a pulse laser, the pulse should work
more like a single "projectile" than like a "blade" and therefore create a
more localized damage - in short, a comparatively small hole.

If this were true, the CSC hull patches would seem to make some sen-
se for the temporary repair of such damage, as well as for micrometeo-
rite damage to non-armoured parts of the ship (e.g. bridge windows).

As for fuel leaks, I would suspect that the Lhyd would create too much
pressure to make it possible to seal such a leak with a simple patch,
and that it would be necessary to close off the part of the ship where
the leak occured.

 

[rinku]

So, Traveller spaceship hulls are all but immune to most kinetic energy only weapons.

This is true in a terrestrial sense, but in space it would be easier to accelerate masses to penetrating energies (i.e. railguns and missiles).

I'd be careful abut giving an example of a 6G constant boost to Saturn - that's not a typical run for a Traveller ship, and most ships *won't* have the armour to survive collisions at those velocities. The rules don't go into it, but in reality there's going to be a "safe" cruising speed (based on ship armour, hull and structure, not G rating). This is only going to come up for long in-system travel; for the purpose of operating to and from the 100D limit you can pretty much ignore it.

 

[justacaveman]

DFW said:

BTW - because of this, ships don't have windows, nor screen doors.

Well, how am I supposed to get a tan without a sunroof? And what'll keep the spacebugs out when I open the hatch to let in the breeze during Jump?

:lol:

 

[DFW]

This is true in a terrestrial sense, but in space it would be easier to accelerate masses to penetrating energies (i.e. railguns and missiles).

No doubt. The weapon I referenced was TL 7. Just a base measurement point. Large space based or very large land based mass drivers will of course be much more powerful. For instance, to generate the same amount of force in joules as my example, a 1000 kg penetrator would have to be accelerated to 9.16 km/sec. Hand held and crew served slug throwers are powerless against a spaceship.

I'd be careful abut giving an example of a 6G constant boost to Saturn - that's not a typical run for a Traveller ship, and most ships *won't* have the armour to survive collisions at those velocities.

Not true. M-6 ships have the EXACT same default amour per the rules as other ships. See ship design rules.

The rules don't go into it, but in reality there's going to be a "safe" cruising speed (based on ship armour, hull and structure,

Nope, the rules do cover intra system travel quite well. Reread them if you like.

 

[DFW]

Well, how am I supposed to get a tan without a sunroof? And what'll keep the spacebugs out when I open the hatch to let in the breeze during Jump?

:lol:

EVA in a clear plastic vacc suit.