Dutch colonial gunboat

[Korpen]

A gun boat intended for colonial service, so it has very shallow draft to be able to get up shallow beaches and river. Long range so it can be on station for long periods of time, and two tons dedicated to a large radio transmitter. Reciprocating engines allow for easier maintenance and better low-speed fuel economy.
The misc weight not dedicated to radio can be used to either carry mines or a landing party (or prize crew) of marines.
If cargo is to be carried, that can if need full be stored i coal bunker (emptied and washed out) as well as deck cargo (misc weight).

In short a flexible little workhorse of the peacetime colonial navy in the HOI.

CGB-4, Nederländsk Gunboat laid down 1906 (Engine 1905)

Displacement:
   401 t light; 415 t standard; 543 t normal; 645 t full load

Dimensions: Length overall / water x beam x draught
   202,97 ft / 196,85 ft x 32,81 ft x 3,94 ft (normal load)
   61,87 m / 60,00 m x 10,00 m  x 1,20 m

Armament:
      1 - 3,94" / 100 mm guns in single mounts, 37,48lbs / 17,00kg shells, 1906 Model
     Quick firing gun in deck mount
     on centreline aft
      1 - 3,46" / 88,0 mm guns in single mounts, 19,84lbs / 9,00kg shells, 1906 Model
     Quick firing gun in deck mount
     on centreline forward
      4 - 0,31" / 8,0 mm guns in single mounts, 0,02lbs / 0,01kg shells, 1906 Model
     Machine guns in deck mounts
     on side, evenly spread, all raised mounts
   Weight of broadside 57 lbs / 26 kg
   Shells per gun, main battery: 95

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0,59" / 15 mm         -               -
   2nd:   0,59" / 15 mm         -               -

Machinery:
   Coal fired boilers, complex reciprocating steam engines,
   Direct drive, 2 shafts, 1 776 ihp / 1 325 Kw = 16,00 kts
   Range 2 945nm at 12,00 kts
   Bunker at max displacement = 230 tons (100% coal)

Complement:
   56 - 73

Cost:
   £0,053 million / $0,212 million

Distribution of weights at normal displacement:
   Armament: 6 tons, 1,2 %
   Armour: 2 tons, 0,4 %
      - Belts: 0 tons, 0,0 %
      - Torpedo bulkhead: 0 tons, 0,0 %
      - Armament: 2 tons, 0,4 %
      - Armour Deck: 0 tons, 0,0 %
      - Conning Tower: 0 tons, 0,0 %
   Machinery: 240 tons, 44,2 %
   Hull, fittings & equipment: 132 tons, 24,4 %
   Fuel, ammunition & stores: 142 tons, 26,2 %
   Miscellaneous weights: 20 tons, 3,7 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     320 lbs / 145 Kg = 10,5 x 3,9 " / 100 mm shells or 0,3 torpedoes
   Stability (Unstable if below 1.00): 1,99
   Metacentric height 2,8 ft / 0,9 m
   Roll period: 8,2 seconds
   Steadiness   - As gun platform (Average = 50 %): 66 %
         - Recoil effect (Restricted arc if above 1.00): 0,03
   Seaboat quality  (Average = 1.00): 1,31

Hull form characteristics:
   Hull has a flush deck
   Block coefficient: 0,747
   Length to Beam Ratio: 6,00 : 1
   'Natural speed' for length: 14,03 kts
   Power going to wave formation at top speed: 52 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 25,00 degrees
   Stern overhang: 0,00 ft / 0,00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      13,12 ft / 4,00 m
      - Forecastle (20 %):   9,84 ft / 3,00 m
      - Mid (50 %):      9,84 ft / 3,00 m
      - Quarterdeck (15 %):   9,84 ft / 3,00 m
      - Stern:      9,84 ft / 3,00 m
      - Average freeboard:   10,10 ft / 3,08 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 155,7 %
      - Above water (accommodation/working, high = better): 180,7 %
   Waterplane Area: 5 397 Square feet or 501 Square metres
   Displacement factor (Displacement / loading): 92 %
   Structure weight / hull surface area: 19 lbs/sq ft or 93 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,50
      - Longitudinal: 1,03
      - Overall: 0,53
   Caution: Hull subject to strain in open-sea
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is excellent
   Good seaboat, rides out heavy weather easily

[Borys]

Ahoj!
I like her. Really good for the NOI - if I had that territory I'd like to have a dozen of such boats.
Still, a radio on a thing like that in 1906 is quite "futuristic".

Borys

[Korpen]

Ahoj!
I like her. Really good for the NOI - if I had that territory I'd like to have a dozen of such boats.
Still, a radio on a thing like that in 1906 is quite "futuristic".

Borys

Kind of, and it possible that not all the ships will have it.
But one of their main function in conflict would be to early warning ships stationed in strategic positions, and to fulfil that role they would have to carry radio, it is  often a week sailing from were these ships will operate to my closest base.
But like i said, it is not likely all ships will receive it, but i rather build a ship to carry it and not equip it with it then later feel the need to retro-fit it on some vessels.

[The Rock Doctor]

Korpen:

I like the idea of the gunboat, but the hull strength is low for a 16 kt ship. 

Can I recommend increasing the length and beam, and reducing that block co-efficient down to around ~.5 - .55, you'll probably be able to get the same speed with considerably less machinery.  That should up the hull strength somewhat.

[Korpen]

There is already a thread about the gunboat: http://www.navalism.org/index.php?topic=347.0
But untill someone merges them i can answer.
Springshap is starange with all small ships, so i am not worried about the hull strenght

While increasing length & beam is possible, it will make it even harder to navigate the ship up small rivers, something that is an important aspect of the gunboat (therefore the extremely shallow draft).

As for other modifications, the first batch has been in service a few month now, so i should start getting feedback from service ;)

But as soon as i get more advanced engines a upgrade and revision is likely.

[Korpen]

She is more of a mine warfare vessel then a true gunboat.
The low freeboard aft is to simplify loading and unloading of cargo and items in the water.
Of the misc weight, 10tons are for a radio set, the rest is for up to 40 mines, minesweeping gear or other cargo.


Type VIII, Netherlands Colonial gun boat laid down 1908 (Engine 1909)

Displacement:
   400 t light; 416 t standard; 485 t normal; 540 t full load

Dimensions: Length overall / water x beam x draught
   196,85 ft / 196,85 ft x 29,53 ft x 6,56 ft (normal load)
   60,00 m / 60,00 m x 9,00 m  x 2,00 m

Armament:
      2 - 3,94" / 100 mm guns in single mounts, 37,48lbs / 17,00kg shells, 1908 Model
     Breech loading guns in deck mounts
     on centreline ends, evenly spread
      6 - 0,31" / 8,0 mm guns in single mounts, 0,02lbs / 0,01kg shells, 1908 Model
     Machine guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
   Weight of broadside 75 lbs / 34 kg
   Shells per gun, main battery: 150

Machinery:
   Oil fired boilers, steam turbines,
   Direct drive, 3 shafts, 5 000 shp / 3 730 Kw = 22,25 kts
   Range 3 000nm at 12,00 kts
   Bunker at max displacement = 124 tons

Complement:
   51 - 67

Cost:
   £0,049 million / $0,195 million

Distribution of weights at normal displacement:
   Armament: 8 tons, 1,6 %
   Machinery: 202 tons, 41,6 %
   Hull, fittings & equipment: 151 tons, 31,1 %
   Fuel, ammunition & stores: 85 tons, 17,5 %
   Miscellaneous weights: 40 tons, 8,2 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     275 lbs / 125 Kg = 9,0 x 3,9 " / 100 mm shells or 0,3 torpedoes
   Stability (Unstable if below 1.00): 1,42
   Metacentric height 1,5 ft / 0,5 m
   Roll period: 10,2 seconds
   Steadiness   - As gun platform (Average = 50 %): 60 %
         - Recoil effect (Restricted arc if above 1.00): 0,12
   Seaboat quality  (Average = 1.00): 1,19

Hull form characteristics:
   Hull has low quarterdeck
   Block coefficient: 0,445
   Length to Beam Ratio: 6,67 : 1
   'Natural speed' for length: 14,03 kts
   Power going to wave formation at top speed: 66 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   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:      13,12 ft / 4,00 m
      - Forecastle (20 %):   13,12 ft / 4,00 m
      - Mid (50 %):      13,12 ft / 4,00 m
      - Quarterdeck (12 %):   4,92 ft / 1,50 m (13,12 ft / 4,00 m before break)
      - Stern:      4,92 ft / 1,50 m
      - Average freeboard:   12,14 ft / 3,70 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 155,7 %
      - Above water (accommodation/working, high = better): 181,0 %
   Waterplane Area: 3 693 Square feet or 343 Square metres
   Displacement factor (Displacement / loading): 87 %
   Structure weight / hull surface area: 24 lbs/sq ft or 115 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,50
      - Longitudinal: 3,16
      - Overall: 0,60
   Caution: Hull subject to strain in open-sea
   Hull space for machinery, storage, compartmentation is cramped
   Room for accommodation and workspaces is excellent

[P3D]

You'd need at least 25kts speed to use 0.5 hull strength.

[Korpen]

You'd need at least 25kts speed to use 0.5 hull strength.

When was that changed?

[P3D]

The lower strength is allowed for destroyers - small fast combatants. 23kts is not fast enough IMO. We did not quantify the speed though.

[Korpen]

The lower strength is allowed for destroyers - small fast combatants. 23kts is not fast enough IMO. We did not quantify the speed though.

Mainly asking as there are lots of ships that have a HS of as small fast combatants but a speed of less then 25kts (about ¼ of all destroyers in the world), and several of them are built quite recently.

And in the Netherlands navy, 23kts is FAST ;)

[Korpen]

A design on a new small minesweeper and partol boat.
capacity for 30ton of minesweeping equipment, or mines, and has a small radioroom.

And it is built out of Teak and other woods, so it should benefit from the half price rule.


Log, Netherlands Minesweeper laid down 1908 (Engine 1909)

Displacement:
   200 t light; 207 t standard; 255 t normal; 293 t full load

Dimensions: Length overall / water x beam x draught
   149,62 ft / 146,98 ft x 21,00 ft x 4,59 ft (normal load)
   45,60 m / 44,80 m x 6,40 m  x 1,40 m

Armament:
      1 - 3,46" / 88,0 mm guns in single mounts, 19,84lbs / 9,00kg shells, 1908 Model
     Breech loading gun in deck mount
     on centreline forward, 1 raised gun
      2 - 1,97" / 50,0 mm guns in single mounts, 3,81lbs / 1,73kg shells, 1908 Model
     Breech loading guns in deck mounts
     on centreline, all aft, all raised mounts - superfiring
      2 - 0,31" / 8,0 mm guns in single mounts, 0,02lbs / 0,01kg shells, 1908 Model
     Breech loading guns in deck mounts
     on side, all amidships, all raised mounts - superfiring
   Weight of broadside 28 lbs / 12 kg
   Shells per gun, main battery: 120

Armour:
   - Gun armour:   Face (max)   Other gunhouse (avg)   Barbette/hoist (max)
   Main:   0,20" / 5 mm         -               -
   2nd:   0,20" / 5 mm         -               -
   3rd:   0,20" / 5 mm         -               -

Machinery:
   Coal fired boilers, complex reciprocating steam engines,
   Direct drive, 4 shafts, 829 ihp / 618 Kw = 15,00 kts
   Range 2 000nm at 12,00 kts  3200nm@10kts  5700nm@8kts
   Bunker at max displacement = 86 tons (100% coal)

Complement:
   31 - 41

Cost:
   £0,019 million / $0,076 million

Distribution of weights at normal displacement:
   Armament: 4 tons, 1,4 %
   Armour: 1 tons, 0,3 %
      - Belts: 0 tons, 0,0 %
      - Torpedo bulkhead: 0 tons, 0,0 %
      - Armament: 1 tons, 0,3 %
      - Armour Deck: 0 tons, 0,0 %
      - Conning Tower: 0 tons, 0,0 %
   Machinery: 64 tons, 25,0 %
   Hull, fittings & equipment: 92 tons, 36,2 %
   Fuel, ammunition & stores: 55 tons, 21,5 %
   Miscellaneous weights: 40 tons, 15,7 %

Overall survivability and seakeeping ability:
   Survivability (Non-critical penetrating hits needed to sink ship):
     359 lbs / 163 Kg = 17,3 x 3,5 " / 88 mm shells or 0,3 torpedoes
   Stability (Unstable if below 1.00): 1,30
   Metacentric height 0,8 ft / 0,2 m
   Roll period: 10,1 seconds
   Steadiness   - As gun platform (Average = 50 %): 59 %
         - Recoil effect (Restricted arc if above 1.00): 0,12
   Seaboat quality  (Average = 1.00): 1,17

Hull form characteristics:
   Hull has rise forward of midbreak, low quarterdeck
   Block coefficient: 0,630
   Length to Beam Ratio: 7,00 : 1
   'Natural speed' for length: 12,12 kts
   Power going to wave formation at top speed: 57 %
   Trim (Max stability = 0, Max steadiness = 100): 50
   Bow angle (Positive = bow angles forward): 15,00 degrees
   Stern overhang: 0,00 ft / 0,00 m
   Freeboard (% = measuring location as a percentage of overall length):
      - Stem:      9,84 ft / 3,00 m
      - Forecastle (20 %):   8,20 ft / 2,50 m
      - Mid (50 %):      7,55 ft / 2,30 m (7,22 ft / 2,20 m aft of break)
      - Quarterdeck (10 %):   3,28 ft / 1,00 m (7,22 ft / 2,20 m before break)
      - Stern:      3,28 ft / 1,00 m
      - Average freeboard:   7,35 ft / 2,24 m
   Ship tends to be wet forward

Ship space, strength and comments:
   Space   - Hull below water (magazines/engines, low = better): 109,0 %
      - Above water (accommodation/working, high = better): 106,9 %
   Waterplane Area: 2 320 Square feet or 216 Square metres
   Displacement factor (Displacement / loading): 130 %
   Structure weight / hull surface area: 27 lbs/sq ft or 131 Kg/sq metre
   Hull strength (Relative):
      - Cross-sectional: 0,92
      - Longitudinal: 2,13
      - Overall: 1,00
   Hull space for machinery, storage, compartmentation is adequate
   Room for accommodation and workspaces is adequate

[The Rock Doctor]

I'm having some difficulty understanding the freeboard; is it supposed to be something like a tugboat's continuously sloping main deck?

Other than freeboard concern, it looks like a handy little vessel.

[Korpen]

I'm having some difficulty understanding the freeboard; is it supposed to be something like a tugboat's continuously sloping main deck?

Other than freeboard concern, it looks like a handy little vessel.

She got a continuously sloping freeboard, untill the quarterdeck, that has a 1m high (or low) break.
This is to put some equipment and cranes closer to the waterline, usefull if you want to retrive a mine or other objects in the water.

[The Rock Doctor]

Thanks.  I'd express concern that the aft freeboard is too low, but I assume this type will only be working in near-coastal areas and not the open ocean.

[Korpen]

Thanks.  I'd express concern that the aft freeboard is too low, but I assume this type will only be working in near-coastal areas and not the open ocean.

That is the intention, also, it is only 4m that is so low, so the ships is seaworthy even if the quarterdeack is awash (and it is likley to be in any kind of weather).