Cruisers Rules

[Kaiser Kirk]

A couple of comments.
- the 30mm protective deck, while 30mm is adequate for the crown, with no "belt" armor means the slopes of the deck are 30mm also, which is not really very adequate, esp as the slope means a lower angle of deflection for incoming rounds. However, depending on the range you're expecting to fight at, you may be able to thin that deck to 25mm and add a bit to the slopes. Likewise sacrificing the bow and stern decks might be useful.

-3000nm seems a bit short. It gives you the ability to steam to Manilla or Guam and back to the Home Islands, or from Manilla to the Straits of Malacca or Australia, but no loiter/cruise time at that range. I would think a longer range would add a great deal of utility, and allow the possibility of an trip to Guadalcanal area. Japan has a large and sprawling Pacific Empire, it seems a poor choice to field a cruiser with short legs.

-On completion times. Generally I ignore the month thing and go with HY for ease. Often my shakedown time does creep into my operational time. If I think any of that might make a difference, I pay attention. That includes launching to clear slips when needed, or calculating out timelines for dock clearance for mass refits.

-Overall, looking at some of my draft cruisers for comparison, I think a 3500-4000 ton vessel would better suited to your needs. Of course, You are the one to judge your needs :)

[Kaiser Kirk]

I think you'll find the additional range worth it.

I admit to some bafflement at the deck choice.
Pregame, there was discussion on modeling protective decks, and as I recall the agreement was to represent thicker slopes, we would add a 2.44m belt armor. You'll see many of my cruisers modeled like this. Though in some cases you'll see 3.66m, as if the deck is sloped at 45degrees for 1 deck (2.44m) then that's a 3.66m stretch. For example, on my Mercury class, you'll see a 2.44m high, 60mm thick "belt", but really it's the protective deck with 90mm slopes and 30mm flat. Hmm I wonder how clear that is in my encyclopedia...? May have to do some editing. *Sigh*

Anyhow, I've used both BigGun (until I got Win7), and now your Ballistics tool, for modeling weapon penetration. There's also data on NavWeaps for the USN's 6"/50 Mk 6 & 8. Basically deck penetration for 6" or less guns under 10-12,000m doesn't even reach 30mm, but belt pen at 12,000yards for the USN gun was estimated at 69mm. What I have in my Naval Weaponry table is even greater for my 150mm/55kg/890mps gun, though that's against older armor. 

The thing is, 10-12,000m is still likely beyond effective ranges until we have directors, particularly for smaller ships with lower spotting tops moving quickly. I was just reading about continuous aim, and that apparently works very well out to ~8000yards, and up to 9.2" guns (larger can't elevate/depress fast enough).

So, it really depends on the the ranges you expect to fight at and what the opposition is lopping at you to say what you expect that 40mm to be "buying you".  It's more than splinter protection from light guns, it would stop most/all HE rounds, but really isn't enough to stop 4-6" SAP rounds, particularly at the combat ranges extant the time of design.

[Walter]

I thought that was for one of the older startup attempts for Navalism, but a few days ago I was thinking about trying to find that rule to apply to all my future protected cruisers.

... but thinking about it and not really remembering any of the details of the discussions back then, using your example, would the 30mm flat not be for a narrower part of the ship than what SS sims for deck armor? If you have a 40 feet wide ship, would SS not assume that the whole 40 feet width would have 30mm while it actually should be much less than 40 feet? I am too lazy to calculate it but the image below from wiki suggests that the 30mm part of the deck would only be for about 40% of the ship's beam and not 100%.

[Kaiser Kirk]

Interesting.

For simplicity, lets say that a protected deck design crowns just above the waterline and is flat in the middle - then each side descends 1 deck level at 45 degrees to meet the hull edge.
Further, let's use the 2.44m/8ft deck level for simplicity.

So a 40' wide ship with a protective deck the first 8 ft is over the sloped portion, 24ft is flat, and the final 8 ft is also over the sloped. 

The slope of the turtleback makes the hypotenuse of a right triangle, with legs 8ft long. So the Slope is sqrt(8ft^2+8ft^) = 11.3ft long.

That would mean on a 40ft wide ship,  with a protective deck there is 11.3ft of sloped armor, 24ft of flat armor, and 11.3ft of sloped armor, for 46.6ft of armored surface.
So really we only would need 3.3ft or about a 1m high belt on each side to adequately provide that thicker slope.
Hmph. That's worth it. (looks at old designs with a tinge of regret).

So why a protective deck?  Well, it's located lower down, and seals below the waterline, so you can dispense with dedicated belt armor. Also, the water will- on short range flat shots- help protect the slopes. Really great for smaller vessels.

Downside, once you start sinking, or if your ship is overloaded, you wind up with free water on top your armor deck, and pours in through uptakes, and thats really bad. Plus you're protecting a smaller area, so have less reserve flotation protected under armor, and lastly it limits the volume you can fit engines into.

I've made the assertion in the past, and I think it's Walter who disagreed, that the

Space   - Hull below water (magazines/engines, low = better): 154.1 %

means you should either expand your citadel, or raise the armored deck level, because I think it means you have critical systems sticking up above your waterline-level protective deck , because they don't fit below it.  You'll see some of my designs exceed 100% a little, but I then change the breakpoints on freeboard, and expand my citadel fore/aft to allow for the critical systems to be protected.

[Walter]

So a 40' wide ship with a protective deck the first 8 ft is over the sloped portion, 24ft is flat, and the final 8 ft is also over the sloped.

The slope of the turtleback makes the hypotenuse of a right triangle, with legs 8ft long. So the Slope is sqrt(8ft^2+8ft^) = 11.3ft long.

That would mean on a 40ft wide ship,  with a protective deck there is 11.3ft of sloped armor, 24ft of flat armor, and 11.3ft of sloped armor, for 46.6ft of armored surface.
So really we only would need 3.3ft or about a 1m high belt on each side to adequately provide that thicker slope.
Hmph. That's worth it. (looks at old designs with a tinge of regret).

How about just using 11.3 ft for the belt height?

On the other hand, according to the image, the flat part of the deck armor is less that 40% of the beam but let's assume for simplicity that it is 50% of the beam. For a 40 ft beam you get a 20 ft wide flat part. Using 10 ft for the sides of the triangle instead of 8, I get about 14 feet. 14 + 14 + 20 = 48 feet (20% of the beam extra). So is it an idea to do this? Would this work?
- the flat part of the deck is 2x what you enter in the sim. A 15mm deck in the sim becomes 2x15=30mm.
- For the height of the belt that will sim the sloped part: h = ((b*1.2)-(b*0.5))/2. With a beam of 40 ft, you get ((40*1.2)-(40*0.5))/2 = (48-20)/2 = 28/2 = 14 feet.

I've made the assertion in the past, and I think it's Walter who disagreed, that the

Space   - Hull below water (magazines/engines, low = better): 154.1 %

means you should either expand your citadel, or raise the armored deck level, because I think it means you have critical systems sticking up above your waterline-level protective deck , because they don't fit below it.  You'll see some of my designs exceed 100% a little, but I then change the breakpoints on freeboard, and expand my citadel fore/aft to allow for the critical systems to be protected.

Actually at 154% you can't expand the citadel any further because then your main belt becomes longer than the ship and SS no longer works at that point (belt weight becomes 'NaN' when you go over the ship's length). Doing a quick test, a 600 ft long ship with a 600 ft long belt has a coverage of 154% according to SS (153.85% according to my calculator based on the fact that you get 390 ft for default length for the main belt to cover 100% of the normal length.

From what I can vaguely remember is that people (not sure if it was here or Wesworld) in the past argued that when "Hull below water" goes beyond that percentage, the machinery would not fit inside the ship (probably because they ran into the belt issue) and it was actually my belief that the added volume of the machinery would actually be put into the height of the ship (where you'd still have space) rather than the length of the ship (where you do not have any space). Actually due to the shape of the ship, you're going to need to put the machinery into the ship's height a lot sooner than that 154% because I doubt there is any space in the narrowness of the bow or in the shallowness of the stern for either machinery or magazines. Of a 600 ft long ship you can probably only use about 500 feet for those things.

[Kaiser Kirk]

How about just using 11.3 ft for the belt height?

I take it because gave 11.3ft as the distance of the sloped part... Hmm I'd say  because belt armor gets duplicated on both sides of the ship, so it would be 5.65ft, and that trends into your next bit.... technically it seems like belt armor also includes fore/aft bulkheads while upper belt does not - at least in SS2, but that's a minor issue.

On the other hand, according to the image, the flat part of the deck armor is less that 40% of the beam but let's assume for simplicity that it is 50% of the beam. For a 40 ft beam you get a 20 ft wide flat part. Using 10 ft for the sides of the triangle instead of 8, I get about 14 feet. 14 + 14 + 20 = 48 feet (20% of the beam extra). So is it an idea to do this? Would this work?
- the flat part of the deck is 2x what you enter in the sim. A 15mm deck in the sim becomes 2x15=30mm.
- For the height of the belt that will sim the sloped part: h = ((b*1.2)-(b*0.5))/2. With a beam of 40 ft, you get ((40*1.2)-(40*0.5))/2 = (48-20)/2 = 28/2 = 14 feet.

Decks can be of any height, they vary in reality. I use 8ft because of something I read once about room people and for pipes overhead being the reason for 8 feet :)
The problem with using a simple multiplier is that the area of the slopes does not scale with the size of the ship - on the 40ft beam, you may have 20ft of flat...but on a 35ft beam the slopes are the same but there's 15ft flat, while on a 60ft beam, that's a 40ft flat. It doesn't scale properly. 

So I'm inclined to a default for protective decks being the amount given as deck armor + a 1m high belt for the slopes. Fairly simple, no extra dread and dire multiplication involved. 
Of course if you want 10ft decks, it's pretty easy to figure the belt height once and just use that.

Actually at 154% you can't expand the citadel any further because then your main belt becomes longer than the ship and SS no longer works at that point (belt weight becomes 'NaN' when you go over the ship's length). Doing a quick test, a 600 ft long ship with a 600 ft long belt has a coverage of 154% according to SS (153.85% according to my calculator based on the fact that you get 390 ft for default length for the main belt to cover 100% of the normal length.

From what I can vaguely remember is that people (not sure if it was here or Wesworld) in the past argued that when "Hull below water" goes beyond that percentage, the machinery would not fit inside the ship (probably because they ran into the belt issue) and it was actually my belief that the added volume of the machinery would actually be put into the height of the ship (where you'd still have space) rather than the length of the ship (where you do not have any space). Actually due to the shape of the ship, you're going to need to put the machinery into the ship's height a lot sooner than that 154% because I doubt there is any space in the narrowness of the bow or in the shallowness of the stern for either machinery or magazines. Of a 600 ft long ship you can probably only use about 500 feet for those things.

Interesting I hadn't done the length calculation. Pretty sure I was the one asserting the machinery wouldn't fit in the ship, because I've said that here :) But perhaps there was a miscommunication, as I was referring to the hull below water area, when the % exceeds it, I agree it sticks up. For my purposes in recent designs* I've placed 110% as my cap for expanding lengthwise, in part because if you look at top-down drawings of old dreadnaughts with high BCs they pushed turrets far out, so I figure there's a little room for adjustment. But if I can't keep the magazines & machinery below that, I go ahead and swap to an armored deck and raise my belt height- which then needs thickening as there's no protective deck behind it. Which is expensive tonnage wise.

We're doing a very nice thread hijack :)

*by recent I mean the various draft ships I tinker up. Looking at my Mercury protected cruiser, I have 135% spaced used, but extended the citadel to within 5% of bow & stern...in hindsight that's probably a bit more cramped than it should be. My bad. But why discussing what's reasonable is good.

[Tanthalas]

Or *drumroll* we could just not worry about it... (FYI we decided on 4' the last time we discussed this, but it got left out during this restart, hence me not bothering with side belts on my PCs).  Many of the OTL cruisers are simply unsimable under the rules they end up at like a .80 composite (I think this has to do with Machinery weight but I am not sure, and couldn't be without more research).  Personally I have always advocated a .80-.85 composite for light cruisers (this would allow us to sim almost any OTL ship ever built) but no one has ever agreed with me.

All that said we really should split this off, while this discussion is useful (and pertains to several proposed ships including Logis), our current discussion isn't really about his ship but a type of ships in general.

[Kaiser Kirk]

Well if we don't worry about it, then someone using a protective deck- common for the period - has to either bolster his entire deck to get the thickness to stop low deflection shot...which also makes the deck ridiculously thick versus plunging and extremely heavy to boot - or they can make a thinner deck with the thickness to stop the plunging, but until ..15,000+m? you have a higher % belt than deck hits, so the deck isn't very protective.

So, I think some simple mechanism to reflect thicker slopes and make protective decks useful would be a good design guideline. That can be my suggested 1m, your referenced 4ft, or walter's formulaic approach.
Further, that discussion between Walter and I on % hull, is a good one as a limit should be arrived at, to denote when it's advisable to move to an Armored deck.

As for comp hull, in wesworld the group moved to lower comp hull for cruisers. As I recall a 0.75 for one size range and a 0.9 for another.
I think you're correct, machinery weight is part of it.  Another factor is probably that speeds listed seem to be trials speeds, and reflect a forced maximum, sometimes without the ship fully kitted out, and so may overstate the case. Then there's a hidden factor in scantling weight. SS seems to be geared towards interwar battleships, and battleship framing is heavy and strong, taking ...oh can't remember exactly, I recall thinking that main bore size seemed to correlate with the % of weight given to scantlings.  Go to light, and damage your ship when firing. So Cruisers would have half or less the framing weight.

[Kaiser Kirk]

Aww, but we had hijacked that thread fair and square ....
:(

[Tanthalas]

Better in here though as some people Proly weren't paying attention to it in there.

[Kaiser Kirk]

Well, can we summarize what we've talked about? I.e. a reasonable way to model a protective deck that might help make some cruisers easier.

Walter and I crunched the numbers, lets' go with my 1m.
Walter provided 500ft of 600ft as likely usuable which is 83.3% of hull, so let's use 85%.

Protective Decks : Protective decks are a lighter means of ship protection than the armor deck & belt, but cover less reserve bouyancy.

Protective decks are assumed to be slightly above the waterline, with sloped sides descending one deck level at 45degrees to end below the waterline.
A 1m high main belt may be used to represent thicker armor on the sloped sides.
In this case the thickness of the slope is (belt+deck).

A protective deck mounted behind a conventional >1m main belt, is presumed to be a turtleback deck, where the deck provides an additional armored layer behind the belt.

Protective decks have limitations,
If % "Hull below water" exceeds 100%, critical systems will be located above the protective deck.
This can be addressed by expanding the citadel by adjusting forecastle/quarterdeck % on the freeboard tab.
At a minimum the forecastle/quarterdeck % must be at least 15%.
Ships laid down prior to 1905 are grandfathered in.

Lastly, perhaps we can take Tan's idea and add Comp hull% as part of the Cruiser Tech tree?
Either lift the Wesworld rules, or Add to Light Cruiser Architecture. I'm in favor to the latter.
We know armored cruisers and heavy cruisers weren't so light and nimble, and we also know that later on we see some very light cruisers or super destroyers.
So here's my proposal:

Light Cruiser Architecture - Main battery in deck mounts/casemates
1880: guns in single mounts or casemates, on side/centerline
1900: ammunition hoists, deck torpedo armament, superfiring mounts,
1910: twin gun mounts (require hoists); powered gun mounts; unrestricted weapon armor, Cruisers under 6000tons must have cross-sectional hull strength > 0.9
1920:  No restriction (high or low) on caliber of turreted guns, Cruisers under 3000tonsmust have cross-sectional hull strength > 0.75

[Tanthalas]

I would say move the strength thing to 1900 and 1910 instead of 1910 and 1920. but other than that yes I agree with everything there.

[Jefgte]

I agree with Tan comment about dates.
Globaly, Kaiser, new rules are ok for me.

Jef

[Kaiser Kirk]

I'm neutral on the 0.9 at 1900.
I suggested it at 1910 only because we're already at 1905 :)

As for the .75 at 1920, I actually had a reason. In the 1920s, you start seeing the introduction of welding, notably on German ships, to allow for lighter weight construction. Then you also saw these light fast cruisers/destroyer leaders/super destroyers in that period. Which made me suggest that tech period.

However, this is just for folks to chew over and discuss :)

[Tanthalas]

Oh I agree in the 1920s some realy "out there" stuff started showing up.  Armour used as a structural component, Welded hulls, etc.  The interesting thing is You can make almost all the ships built then work more or less in SS, while ships built in our Current era quite often require a lower than acceptable composite (although I must admit I have never attempted to sim the German CLs of WW2 or the French Super Destroyers for that matter).

As to already being in 1905 *shrug* how many Cruisers have actually been layed down since 1900, Possibly allow for a redesign of them or view it as a sort of "Continuing development now allows this" thing, or we all declare it a construction reserve that can be used during their midlife refits.