When does a ship sink?

[miketr]

I have been giving some thought to how to use the SS report to figure out a damage system.

Lets start with some info from a SS2.1 users guide.

Flotation:   Estimation of the pounds of non-critical shell hits required to sink or otherwise destroy the ship based on the displacement plus the volume of the hull above the waterline up to average freeboard between the forecastle and quarterdeck. This is reduced if the ship has Frigate style broadside mounts or is crowded below the waterline.

Maximum shell hits:  Number of standard non-critical shell hits either of the same calibre as the main battery or 6 inch /152 mm if the ship has no main battery. This is based on the flotation calculation.

Maximum torpedo hits:  Similar to the above except that it is based on a standard 20" torpedo non critical hit and is adjusted to take into account the beam (including bulges), the existence of transverse torpedo bulkheads, the roominess of machinery and magazine spaces and whether there are submerged torpedo tubes in the hull

Next lets note the effect of higher stability ships. (this is from the output ofa BB design I was working on since it was handy I used it)

Survivability (Non-critical penetrating hits needed to sink ship):
Stability 1.0
44,479 lbs / 20,175 Kg = 22.8 x 15.7 " / 400 mm shells or 6.7 torpedoes
Stability 1.1
46,719 lbs / 21,192 Kg = 23.9 x 15.7 " / 400 mm shells or 6.9 torpedoes
Stability 1.2
48,784 lbs / 22,128 Kg = 25.0 x 15.7 " / 400 mm shells or 7.0 torpedoes

difference of 2237 (5%) & 2065 (4.67%)


What this tells me a few things.  If we use the SS2.1 Survivability output we are going to in time get ships with high stability and high freeboard; luckily those two stats counter act one another to a point but I would at least expect people to shove the slidebar on the PERFORMANCE tab as far left as possible.  Especially as the seakeeping output is virtually uneffected by the slidebar unless you shove it VERY far left.  Its even worse when you consider there is little clear reward for a high steadiness ship.  I would like to see a reward in the combat system for high steadiness ships.

I would suggest instead we go with a calculation based on light displacement for hit points with a modifier.  My thought had been one for the differnet techs, maybe a 5% modifier BUT the techs are very uneven.  Currently there are six BB/AC techs, three PC techs and five TB/DD techs.  The other thought is a year based difference; figure 1880 is YEAR zero and ships laid down later get a 1% bonus to hit points per year.  Perhaps some type of flat modifier to Hit Points for ships built with the different techs so for example TB/DD x0.50, PC x0.75 and BB/AC x1.00.  The other thought is a hit point tech but I am not sure how much interest there is in new techs.

I am still thinking about torpedo damage and I hope to have something sooner rather than latter.

Michael

[P3D]

I'd have two separate metrics here.

First is structural integrity.
Second is flotation - which can be reduced without seriously hurting the structural integrity of the ship. The way to kill a ship fast.

[miketr]

I agree...  On the flotation damage thats going to come in three sources...  diving shells that hit below the water line, mines and torpedoes.  The SS2.1 guide says 20" torpedo is the standard weapon is that like a 500lb warhead of Torpex or are we talking about a 200 lb warhead of TNT.  Hexanite/Torpex pack way more punch than TNT.

I am thinking we take the torpedo to sink number from SS and turn that into some type of number.  Which the various underwater hits eat away at.

Michael

[RAM]

In WW, I think stab coefficient is used as a base not to decide when/if the ship sinks, but to calculate when counterflooding will be mandatory to keep a ship upright when uneven flooding happens.

I think the way it goes there (I'm not that sure, as I'm also recently back there and rules seem to have changed somewhat) is that with a ship has a 1.00 stab rating, as soon as there is uneven flooding, counterflooding must happen or the ship might capsize.  anything over 1.00 is extra stability, so the ships will need later/less overflooding to avoid risk of turning turtle.


In my own opinion I think that ignoring stability as a factor in N-verse combats is as bad as ignoring steadiness. There should be an extra incentive to put at least a 1.05 stability rating in a ship design, other than achieving a somewhat better resistance to sinking. Maybe counterflooding rules could help with that. If they don't overcomplicate the whole picture, of course.

[miketr]

I don't want to get into counter flooding rules because that would require compartment plans, etc and make doing the battles all but impossile for one person.

I have been exposed to game design before; Starfire in particular a space combat system.  We have two issues realism vs. playability.  The bottom line is when we are looking at something intended for one or two people to conduct FLEET level battles in a timely manor then realism is going to take a very hard hit.

This said I agree that we shouldn't ignore stability any more than we should ignore steadiness.  The question is how to do so without making War and Peace the board game?  Before we can answer that the answer to the nature of a ships ability to take damage needs to be addressed.

Michael

[miketr]

I have been looking around at torpedo damage to capitalships and there are few examples of ships getting hit multiple times while in combat condition.

So any solution is going to have be winged one by us.  Looking at the number of torpedo hits Spring Sharp things ship can take; like the 14.4 for the Bismarck example design.  Its fairly clear that the system is either over estimating the ability of ships take hits or thinks the warheads are going to be really weak.

If we assume lets say a 200 kg (440lb) war head that would be a total of 2,800 kg (6173 lbs).  So for ww1 with warheads of 200 to 300 kg that would take a massive number of hits to kill Bismarck. 

If we plug in ww2 torpedo like the German G7 with a 300 kg Hexanite warhead that would be equal to a 450 kg /990 lb TNT warhead.  So 6.2 hits to kill.

The USN mark 15 had a 825 lb / 374 kg warhead with Torpex so would be equal to about 1,237 lb / 561 kg TNT warhead.  4.99 hits to kill.

The IJN type 93 long lances with their 490 kg / 1080 lb warheads for the mk I & mk II are fairly impressive but they used TNT of course the mk III with its 780 kg / 1720 lb warhead s very impressive.  5.7 or 3.59 hits to kill.

The latter numbers look like fairly reasonable numbers.  So I suggest we take the SS2.1 report and assume 200 kg warheads.  We multiply the SS2.1 torpedo hits to sink by 200 and that becomes the ships flotation value; its simple and easy to track. 

Using the seekrieg dud chance I suggest we start with a 40% for earlier torpedo's dropping to 30% for our current gen weapons and then going down to 20% for 1930's weapons.  Ditto for Magnettic triggers 40% for 1st generation, 30% for 2nd gen and 20% for 3rd gen (with 1940's).  We also will need a improved warhead tech for Hexanite / Torpex in late 30's that gives a 50% boost to warhead yields.

Michael

[Kaiser Kirk]

If I may offer some thoughts

I believe the primary value in a larger warhead is a greater ability to penetrate defenses.  A Long Lance will rupture weaker TDS systems that may withstand an 18" aerial torpedo.   I doubt the actual size of the hole or subsequent flooding will match the ratio in warhead size. 

When looking at Bismarck you see a non-effective hit on the belt, and a critical hit on the steering, neither of which actually did much flooding I believe.

Further, 6 evenly spaced torpedo hits on one side of a ship are far more damaging than 3 on each side, as the latter effectively counter floods themselves.

[miketr]

If I may offer some thoughts

Feel free...

I believe the primary value in a larger warhead is a greater ability to penetrate defenses.  A Long Lance will rupture weaker TDS systems that may withstand an 18" aerial torpedo.   I doubt the actual size of the hole or subsequent flooding will match the ratio in warhead size. 

We lack the ability to simulate such matters in any type of quick manor.  Navweaps.com has the math that explains it but thats not useful to use because its not something that we could use quickly.

When looking at Bismarck you see a non-effective hit on the belt, and a critical hit on the steering, neither of which actually did much flooding I believe.

Critical hits we can deal with...

Further, 6 evenly spaced torpedo hits on one side of a ship are far more damaging than 3 on each side, as the latter effectively counter floods themselves.

Again thats not something we can deal with in timely manor.  The greater the degree of realism make things more complex and time intensive.

Michael

[Blooded]

Just some mentions.

I'll try to track it down, but a short while back I read something about Speed was the best defense against Torpedos in WW1. That hits dimished greatly if the target was going over 15knts.

I am sure you have seen it, but it is great info.
http://www.navweaps.com/index_tech/tech-047.htm

The major concern I have with SS damage is Merchants. They are very overated. But if the bulk of Trade protection is just simple die rolls, it shouldn't matter. How would a combat of say 2 LC raiders against a convoy of 20 Merchies and 5 escorts play out?

Do we have any 'rules of warfare' against Subs yet? The stopping of ships, etc. ?

[miketr]

Merchants unless armed can't fight back and take damage very poorly compared to a warship.  So their crews will run for it, surrender or abandon ship when faced by a warship.  Then all the warship needs to do is put a few medium cal guns into the ship along the waterline and thats all she wrote.

An AMC is another matter in that it will have trained / motivated crews and of course armed but in the end they aren't a warship and will get blown out of the water.  Still such ships can do useful things see HMS Jervis Bay in WW2 or the German raiders of WW1 and WW2.

As to a convoy battle that could be fought out I would assume and the merchants scatter while the escorts attempt to kill the raiders.  That would come down to the battle details.

Michael

[maddox]

On merchants.

Several factors are critical in the comparisation to torpedo damage.

Size of ship.
Age of ship.
Purpose of the ship.
Maintenance of the ship
Crew moral and quality.

The first 3 are perfectly clear.  An old 2000 tons tramp cannot take the punishment a  new 20 000 tons liner can take.
On the other hand, that same tramp freigther loaded with cork can outdo the liner easely.
These facts can be calculated in a combined factor.

The other 2 are more dificult to quantify, but are more a factor of background.

I'll try to illustrate it by things I know from real life.

My father was a canal barge captain from his 19, as a Dutch ship captain, maintenance was important. His ship, de Jacques Stork ,a 1000 tons canal freighter was impeccible. It ran well, did the job as coal or sand transport. But it took effort to make it so. My mum and dad did do, together with their "sailor" Freddy. The white paint was white, the black hull tar was black, the red and blue striping straith as a razer. The Dutch flag washed every 3 days, by hand.

On the other hand, if I see a 9000 tons Russian coaster loaded with scrap passing by. How a ship can be turned in a rust bucket like that. Flags entangled and worn, rust streaking all over the surfaces, the bad asthmatic rumbling of the smoke belching engines, the listless crew hanging over the railings, obviously smoking a bad sigarette, the nonchalant handling, made obvious by the dents and scrapes on the hull.

What ship does has the best chance of surving a near deadly blow?

But that's just an annecdote.
My musings.

If we elect to make a Seakrieg and SS amalgame, MikeTr's calculations fit the bill. 
With merchant having a survivability of 1/4th of their calculated Springsharp 2.1 value -as that's the pricetag issue on them when being build.
This works too for above water damage, not calculating in the effects of the cargo.

[RAM]

Back to warships as such...

I think SS gives us hints at how good is a ship dealing with flooding with # of torpedo hits. However, that number can lead to confusion sometimes, and it doesn't (by far) give a clear picture of the true ability of a ship to fight floodings


Take two ships, 12000 tons each. one has an internal torpedo bulkhead the other doesn't. The first will have better torpedo hit resistance than the second. But in fact the bulkhead will mean little help in containing floodings coming from underwater shell hits...that only helps with limiting torpedo damage. And I think we'll all agree a 12k ton ship isn't a prospect for using internal bulkheads...

More things. SS gives us a % and a flag about internal spaces and compartimentation. the worse it is, the higher chances some equipment under the waterline will be hit.

But the compartimentation is the key here. currently we can have two ships able to stand the same number of torpedo hits ,one with "cramped spaces and compartimentation", the other "excellent". if we take # of torpedo hits only as a guideline, we won't be taking in account the latter's much better internal layout and ability to contain flooding thanks to a much better arrangement internal watertight compartments.

I think we can still take the number of torpedo hits as a baseline, but that some modifificators taking in account that bulkheads can artificially inflate that number, and that internal compartimentation percentages do matter when flooding happens.

[Korpen]

Back to warships as such...

I think SS gives us hints at how good is a ship dealing with flooding with # of torpedo hits. However, that number can lead to confusion sometimes, and it doesn't (by far) give a clear picture of the true ability of a ship to fight floodings


Take two ships, 12000 tons each. one has an internal torpedo bulkhead the other doesn't. The first will have better torpedo hit resistance than the second. But in fact the bulkhead will mean little help in containing floodings coming from underwater shell hits...that only helps with limiting torpedo damage. And I think we'll all agree a 12k ton ship isn't a prospect for using internal bulkheads...

More things. SS gives us a % and a flag about internal spaces and compartimentation. the worse it is, the higher chances some equipment under the waterline will be hit.

But the compartimentation is the key here. currently we can have two ships able to stand the same number of torpedo hits ,one with "cramped spaces and compartimentation", the other "excellent". if we take # of torpedo hits only as a guideline, we won't be taking in account the latter's much better internal layout and ability to contain flooding thanks to a much better arrangement internal watertight compartments.

I think we can still take the number of torpedo hits as a baseline, but that some modifificators taking in account that bulkheads can artificially inflate that number, and that internal compartimentation percentages do matter when flooding happens.

A problem with the springsharp compartmentation is that it is based on the "normal" length. So if a ship have less then 100% armour coverage, SS overestimate the compartmentation, and if longer then 100% SS underestimate.

[miketr]

I think we can still take the number of torpedo hits as a baseline, but that some modifificators taking in account that bulkheads can artificially inflate that number, and that internal compartimentation percentages do matter when flooding happens.

The problem is thats a subjective rule and open to all sorts of fights over the results.

Michael

[maddox]

Unless we can get a Springsharp Nverse version, I stand on the premisse that the Springsharp numbers are the ones to be used.

With a solid modifer set for everybody, if it can't be avoided, but still with a sturby base of Springsharp.