WesWorld

Originally I was thinking about sticking closer to the historical design, but was not sure what to do with all the hull strength. Adding ~ 1000 tons of additional miscellaneous weight is a bit problematic for the stability.

So instead of 20 knots and a range of 9000nm at 10 knots, it has a speed of 28 knots and a range of 10000nm at 15 knots. Should still be possible to carry 500 mines with the 1200 ton miscellaneous weights.

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Also, apparently Japan plans on mining someone...that's a lot of minelayers.

Japan has a bunch of minelayes and they're getting pretty close to receiving the lable 'antique' and will be replaced by more modern ones.

Japan's interests in the Far East could be well served by effective defensive sea mining - which was adopted in the Pacific War. For such purposes, the Tsugaru design probably has more speed than would be required.

Offensively, I believe that larger IJN minelayers were expected to lay their cargos across the track of oncoming USN task forces as part of the IJN's "Great Decisive Battle" approach to naval war. This did not turn out too well for Japan during the Pacific War.

The Tsugaru spent much time acting as a fast transport in the Southwest Pacific - much like the British Manxman and her sisters serving on the run to Malta. It's not a design I would build myself, but it is an interesting approach to the problem and one which is suggestive.

I'll have to stand up for Walter on this one; I've tried simming something similar to the Shimakaze on a few occasions, and it's just not possible with Springsharp. As it is, his sim is noticably heavier than the historical ship, but still several knots slower.

To beat a dead horse, Springsharp just can't handle high-speed designs. I'm definately not endorsing anyone 'tweaking' a springsharp readout, but I'd forgive* a few bad stats (such as seakeeping) for designs in this area. The Japanese did build the historical design, and by all accounts it didn't break it's back or otherwise prove itself severely deficient that I'm aware of.

*[size=1]The above comment does not represent a Moderator's Ruling, nor the opinion of other Moderators in any official capacity[/size]

Since Springsharp calculates its seakeeping at flank speed, and seakeeping degrades substantially at higher speeds, I generally accept lower numbers for seakeeping at those higher speeds. 0.72 is lower than I'd go myself, but it doesn't strike me as all that unrealistic for a 37-knot DD.

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Originally posted by Brockpaine
Since Springsharp calculates its seakeeping at flank speed, and seakeeping degrades substantially at higher speeds, I generally accept lower numbers for seakeeping at those higher speeds. 0.72 is lower than I'd go myself, but it doesn't strike me as all that unrealistic for a 37-knot DD.

A very good point; and there's nothing in our rules about a minimum level of seakeeping. As you say, it is also lower than I would accept.

My comment was prompted by my recollection of the loss of the IJN torpedo boat Tomozuru and the changes it forced in IJN design practice.

My main target was Shimakaze's 75,000 shp output. A seaboat rating of 0.70 is as low as you want to go (except with subs).

I'm planning for a slightly slower Shimakaze II class with a seaboat rating of just over 1, but I'm not sure yet if I wil stick to the 3x2 layout or go for a 4x2 layout.

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Originally posted by BruceDuncan
A very good point; and there's nothing in our rules about a minimum level of seakeeping. As you say, it is also lower than I would accept.

Right. I generally like to keep my numbers over 1.00 - which isn't too hard, considering that I prefer to put together well-balanced designs and don't really bother to try for speeds higher than 35-36 knots. (I sim all my Chilean ships to 18, 21, 27, or 33 knots, and all French ships to 16, 21, 29, or 34 knots.)

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Originally posted by Brockpaine
Since Springsharp calculates its seakeeping at flank speed, and seakeeping degrades substantially at higher speeds, I generally accept lower numbers for seakeeping at those higher speeds. 0.72 is lower than I'd go myself, but it doesn't strike me as all that unrealistic for a 37-knot DD.

I've come round to the view that "poor seakeeping" basically would translate to the vessel having to slow down due to sea state prior to a vessel with "normal" seakeeping.

I bet if the speed was stepped down to 34-35 knots she'd be 1.0+ with the identical hull. Therefore the 37 knot version should be able to slow down to that speed range in response to conditions.

One of my various unfledged projects is to go figure out at which speeds my various vessels hit which seakeeping marks, but I'll never get to that timesink...

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Originally posted by Kaiser Kirk

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Originally posted by Brockpaine
Since Springsharp calculates its seakeeping at flank speed, and seakeeping degrades substantially at higher speeds, I generally accept lower numbers for seakeeping at those higher speeds. 0.72 is lower than I'd go myself, but it doesn't strike me as all that unrealistic for a 37-knot DD.

I've come round to the view that "poor seakeeping" basically would translate to the vessel having to slow down due to sea state prior to a vessel with "normal" seakeeping.

< ... >

One of my various unfledged projects is to go figure out at which speeds my various vessels hit which seakeeping marks, but I'll never get to that timesink...

I suspect that you are quite correct in your assessment. The next time I try to push the design envelope I will try to keep track of the calculations and the results.

Just playing around a bit with something historical from some other nation...

I used the main belt to sim the cargo. Set the length and height of the belt so that 1 unit [SIZE=1](=1 inch)[/SIZE] is equal to 100 tons.

Fuki Maru, Japan Cargo Ship laid down 1942

Displacement:
11,248 t light; 11,519 t standard; 12,923 t normal; 14,046 t full load
15,380 GRT
Displacement light (empty): 3,098 t

Dimensions: Length overall / water x beam x draught
441.14 ft / 428.00 ft x 57.00 ft x 27.60 ft (normal load)
134.46 m / 130.45 m x 17.37 m x 8.41 m

Armament:
1 - 5.00" / 127 mm guns in single mounts, 55.12lbs / 25.00kg shells, 1942 Model
Dual purpose gun in a deck mount with hoist
on centreline aft
1 - 3.00" / 76.2 mm guns in single mounts, 12.00lbs / 5.44kg shells, 1942 Model
Dual purpose gun in a deck mount with hoist
on centreline forward
2 - 3.00" / 76.2 mm guns in single mounts, 12.00lbs / 5.44kg shells, 1942 Model
Dual purpose guns in deck mounts with hoists
on side, all aft
6 - 0.98" / 25.0 mm guns in single mounts, 0.57lbs / 0.26kg shells, 1942 Model
Anti-aircraft guns in deck mounts
on side, evenly spread, all raised mounts
Weight of broadside 95 lbs / 43 kg
Shells per gun, main battery: 200

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 81.5" / 2,070 mm 80.44 ft / 24.52 m 20.00 ft / 6.10 m
Ends: Unarmoured
Main Belt covers 29% of normal length

Machinery:
Oil fired boilers, complex reciprocating steam engines,
Geared drive, 1 shaft, 2,228 ihp / 1,662 Kw = 11.00 kts
Range 17,000nm at 11.00 kts
Bunker at max displacement = 2,528 tons

Complement:
61 - 79

Cost:
£2.685 million / $10.739 million

Distribution of weights at normal displacement:
Armament: 13 tons, 0.1%
Armour: 8,150 tons, 63.1%
- Belts: 8,150 tons, 63.1%
- Torpedo bulkhead: 0 tons, 0.0%
- Armament: 0 tons, 0.0%
- Armour Deck: 0 tons, 0.0%
- Conning Tower: 0 tons, 0.0%
Machinery: 122 tons, 0.9%
Hull, fittings & equipment: 2,233 tons, 17.3%
Fuel, ammunition & stores: 1,675 tons, 13.0%
Miscellaneous weights: 730 tons, 5.6%

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
8,126 lbs / 3,686 Kg = 130.0 x 5.0 " / 127 mm shells or 1.9 torpedoes
Stability (Unstable if below 1.00): 1.10
Metacentric height 2.6 ft / 0.8 m
Roll period: 14.9 seconds
Steadiness - As gun platform (Average = 50 %): 60 %
- Recoil effect (Restricted arc if above 1.00): 0.01
Seaboat quality (Average = 1.00): 1.33

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.672
Length to Beam Ratio: 7.51 : 1
'Natural speed' for length: 20.69 kts
Power going to wave formation at top speed: 21 %
Trim (Max stability = 0, Max steadiness = 100): 45
Bow angle (Positive = bow angles forward): 18.00 degrees
Stern overhang: 7.00 ft / 2.13 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 18.90 ft / 5.76 m
- Forecastle (20%): 10.60 ft / 3.23 m
- Mid (50%): 10.10 ft / 3.08 m
- Quarterdeck (15%): 10.90 ft / 3.32 m
- Stern: 14.80 ft / 4.51 m
- Average freeboard: 11.49 ft / 3.50 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 11.9%
- Above water (accommodation/working, high = better): 61.9%
Waterplane Area: 18,858 Square feet or 1,752 Square metres
Displacement factor (Displacement / loading): 140%
Structure weight / hull surface area: 77 lbs/sq ft or 375 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.98
- Longitudinal: 1.22
- Overall: 1.00
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped
Good seaboat, rides out heavy weather easily

Hmm, they look like something thats going to be coming off US shipyards next year .

*steals Toyota in response*

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I used the main belt to sim the cargo. Set the length and height of the belt so that 1 unit (=1 inch) is equal to 100 tons.

Fuki Maru, Japan Cargo Ship laid down 1942

Displacement:
11,248 t light; 11,519 t standard; 12,923 t normal; 14,046 t full load
15,380 GRT
Displacement light (empty): 3,098 t

I realize that there are several approaches to simming a merchant vessel in Springsharp, but I am unconvinced that this one is realistic.

The tonnage cost is far too high, and the cited GRT is far above the historical for a Liberty ship, which averaged about 7,100 tons IIRC.

Now that you mention it, I copy/pasted the formula I have for Ocean Liners to another part in the spreadsheet in order to alter it for merchant ships, but I think I may have forgotten to do exactly that. I will check once I get home. Guess that's what you get when you're busy with SS and watching TV at the same time...

Yes, the formula was still set to Ocean Liner. Having corrected the formula, I end up with 6674 GRT.

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*steals Toyota in response*

That won't be happening, but Toyota will be taking over the US anyway (as well as the rest of the world). A Toyota for each American family.

If you use other people's stuff without their approval, don't expect the courtesy to be extended back...

Am I stealing Ford or Peugeot or Lockheed or Vickers or any other non-Japanese firm?

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Originally posted by Rooijen10
Am I stealing Ford or Peugeot or Lockheed or Vickers or any other non-Japanese firm?

Nope. You're just copying a merchant ship that's pretty much as American as they come and trying to use it for your own. Perhaps TC's willing to let you have the Liberty Ship design and he's just razzing you about it in return. But don't automatically presume that.

I've seen at least one website that has all/most/many of the period Japanese merchant ship designs posted, including Japan's version of the Liberty Ship. If I run into the site again I'll send you the link.

Forgot this one...

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The tonnage cost is far too high

Not sure what you mean with the "cost" bit.

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he's just razzing you about it in return.

I know that, but that won't stop me from unleashing the sheer terror onto the States that is the eco hippie wheelie bin. One for each American family.

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Perhaps TC's willing to let you have the Liberty Ship

Even if he does, does Japan need it? There is no major WW2-like event in Wesworld that would require a cheap, mass-production cargo ship like that. Wiki is rubbish when it comes to Japanese merchant ship data. The Liberty ship has more data available, is a nice looking ship and I ran accross a line drawing which allowed me to measure the freeboard of the ship with Paint. The sim is me playing around with the design and to see how it works when I use the weight of armor to represent the weight of the cargo instead of the miscellaneous weight.

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Originally posted by Rooijen10
Wiki is rubbish when it comes to Japanese merchant ship data.

Yes, when there's data for Japanese merchant ships at all. However, I had found a website some time ago which listed quite a number of the classes of Japanese merchant ships during the war, together with some photos and specs. Like I said, if I encounter it again I'll link it to you; not sure if I bookmarked it or now.