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Tuesday, January 15th 2008, 12:50am

In need of help

Here we have a relatively light vessel designed in SS2. Reportedly it has historical freeboard, speed, and other atributes. The vessel's seakeeping is reported as very poor. How should such a vessel be treated within a sim system such as this one and Navalism? Since SS2 has admitted problems with light vessels, most destroyers we design for the early 20th century tend to turn into "pocket cruisers" with high freeboard and more guns and torpedoes than historical (mainly just to get the ship to be "seaworthy").

What opinions does this board have on this matter? How would you alter this design to get it to be "seaworthy" yet histoically accurate? How would you treat the "real" seakeeping on this vessel as is? Would is survive in the waters around the South Atlantic and Indian Ocean (especially near the Cape of Good Hope)?

As a moderator an Navalism, a judgement has been requested on this vessel, however my experiance in this field is limited, and this is the best source I have on this matter that deals with SS2 regularly.

Korvette laid down 1912
(design by P3D)

750 t light; 779 t standard; 926 t normal; 1,044 t full load

Dimensions: Length overall / water x beam x draught
260.00 ft / 260.00 ft x 26.00 ft x 9.50 ft (normal load)
79.25 m / 79.25 m x 7.92 m x 2.90 m

4 - 4.00" / 102 mm guns in single mounts, 32.00lbs / 14.51kg shells, 1912 Model
Quick firing guns in deck mounts
on centreline, evenly spread, 1 raised mount
Aft Main mounts separated by engine room
4 - 0.40" / 10.2 mm guns in single mounts, 0.03lbs / 0.01kg shells, 1912 Model
Machine guns in deck mounts
on centreline, all amidships
Weight of broadside 128 lbs / 58 kg
Shells per gun, main battery: 150
6 - 21.0" / 533.4 mm above water torpedoes

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 0.50" / 13 mm - -

Oil fired boilers, steam turbines,
Direct drive, 2 shafts, 22,283 shp / 16,623 Kw = 30.00 kts
Range 3,000nm at 15.00 kts
Bunker at max displacement = 265 tons

83 - 109

£0.107 million / $0.430 million

Distribution of weights at normal displacement:
Armament: 16 tons, 1.7 %
Armour: 4 tons, 0.5 %
- Belts: 0 tons, 0.0 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 4 tons, 0.5 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 483 tons, 52.2 %
Hull, fittings & equipment: 201 tons, 21.7 %
Fuel, ammunition & stores: 176 tons, 19.0 %
Miscellaneous weights: 45 tons, 4.9 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
186 lbs / 84 Kg = 5.8 x 4.0 " / 102 mm shells or 0.2 torpedoes
Stability (Unstable if below 1.00): 1.28
Metacentric height 1.0 ft / 0.3 m
Roll period: 10.7 seconds
Steadiness - As gun platform (Average = 50 %): 37 %
- Recoil effect (Restricted arc if above 1.00): 0.17
Seaboat quality (Average = 1.00): 0.46

Hull form characteristics:
Hull has rise forward of midbreak
Block coefficient: 0.505
Length to Beam Ratio: 10.00 : 1
'Natural speed' for length: 16.12 kts
Power going to wave formation at top speed: 72 %
Trim (Max stability = 0, Max steadiness = 100): 60
Bow angle (Positive = bow angles forward): 0.00 degrees
Stern overhang: 0.00 ft / 0.00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 22.00 ft / 6.71 m
- Forecastle (20 %): 14.50 ft / 4.42 m
- Mid (35 %): 14.50 ft / 4.42 m (7.50 ft / 2.29 m aft of break)
- Quarterdeck (15 %): 7.50 ft / 2.29 m
- Stern: 7.50 ft / 2.29 m
- Average freeboard: 10.55 ft / 3.22 m

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 186.9 %
- Above water (accommodation/working, high = better): 36.8 %
Waterplane Area: 4,523 Square feet or 420 Square metres
Displacement factor (Displacement / loading): 47 %
Structure weight / hull surface area: 24 lbs/sq ft or 117 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.50
- Longitudinal: 1.31
- Overall: 0.55
Hull space for machinery, storage, compartmentation is cramped
Room for accommodation and workspaces is extremely poor
Caution: Lacks seaworthiness - very limited seakeeping ability


Tuesday, January 15th 2008, 4:21am

I recently had similar problems trying to design a small destroyer for Canada. I tried making a small, high speed ship around 900 tons, but due to seakeeping, I had to bring it up to 1200 tons just to make it seaworthy.

My personal opinion would be something along the lines of ships under 1000 tons should be allowed with seakeeping between .50 and 1.00 with the understanding that they won't be able to maintain high speeds in moderate to severe weather, and god help it if it's caught in a real gale, not because it's generally unseaworthy, but because of it's size.

Kaiser Kirk

Lightbringer and former European Imperialist

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Tuesday, January 15th 2008, 4:34am

I think aiming for 1.0 seakeeping is flawed for destroyers of that era anyhow, just hitting the 0.7 for poor should be enough. Second, the 30knt speed may be the trial speed and not represent the practical maximum sea speed.

It sounds like the pictured freeboard has a one deck rise for the forward 1/3 of the ship. Otherwise I'd advocate extending the forecastle aft.

So, if you don't want to drop speed, then I'd raise the freeboard by 2 feet and increase the BC to 0.515 and call it good.


Keeper of the Sacred Block Coefficient

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Tuesday, January 15th 2008, 11:42am

Have you tried a transome stern? For a small, fast vessel it might help a lot. I don´t think it is impossible to raise seakeeping to 0,8 at least. See the RSAN 1935er light destroyer. Even though that vessel carrys less misc weight and TTs she features more light guns and much better seakeeping on a similar size. So there absolutely is a chance to get the design working using SSv2.

Anyhow, if all this is historical (based on which design?) then there is little you can do if you want to stick to that particular design. Otherwise I´d propose a complete redesign.

[Btw, I´m back from moving, phase 1. Still sitting among boxes but at least internet is at hand. Next weekend will be phase 2 when we empty a second appartment to move the stuff to our new home...]


Tuesday, January 15th 2008, 6:17pm

Ah yes, moving phase one, it involves using boxes as a kitchen table for eating takeout food.


Keeper of the Sacred Block Coefficient

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Tuesday, January 15th 2008, 6:28pm

Oh, indeed.

But Phase 1 included so much more: Painting and cleaning of the new home for several days, packing things in my appartment, moving the stuff, bringing very heavy 2,4m x 0,8m mirrors up a small spiral stair (these are doors of our wardrobe), meanwhile damaging the painting of the walls around so they need to be painted again and finally unpacking everything again.


After spending hours to pack all the =)$§/%(/§"%? books and other things, carrying them down two floors and up two floors I now have to undo all my efforts to get the things into these freaking cardboard boxes. As if I´d never packed them. Grrrrrr.....

And this is only the transition phase to part two of our funny little family project. It also includes painting and cleaning of my old home while my beloved one now packs all HER stuff.

Guess what?

I feel kind of tired....

........and old.


In times like these......


Tuesday, January 15th 2008, 7:12pm

I dread the next moving day. I've purchased quite a few books in my current apartment.

The boxes are going to be VERY heavy......

...wait a minute, what was the orriginal topic of this thread? Carry no attention to me....


Keeper of the Sacred Block Coefficient

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Tuesday, January 15th 2008, 7:34pm

Well, at least my notebooks is still at hand. Allowed me to complete a drawing I never found the time to finish. Now it helped me to calm down after hours of shifting stuff around....



Tuesday, January 15th 2008, 8:19pm

Thank you. hopefully that information will be helpful to the situation.


Wednesday, January 16th 2008, 5:07am

To both the design and your next moving day!


Friday, January 18th 2008, 2:24pm

Seakeeping is going to be very poor on such a small vessel anyway. Moving the bridge back to around 30% wl length would be great as it means the vertical acceleration is far less so the bridge crew isn't as sick. The problem is the competiting need for funnels. More size, especially length would help a lot. A raised forecastle is quite useful in keeping off spray but flare towards the bow is probably a bad choice as it reduces the firing arcs. Lighter calibre guns are easier for the crew to man and point in a seaway but obviously do less damage and space is also a problem in mounting enough of them. Adding extra draught enables the ship to move faster through a seaway before suffering hull damage.

I'm not quite sure how SS actually calculates seakeeping, but it is a function of speed. So reducing the speed gives better seakeeping.