WesWorld

An officer in the Mexican Navy had the idea of mounting the turret from the AT-27 tank on a River Gunboat Hull. The result was the Assault Boat. Officialy it's role is just another Armored River Gunboat. Unofficialy, it's real role is to provide very close fire support for the Cuban invasion fleet.


The circle foward is the main hatch. The oval aft is space topside for a 5 man squad of soldiers.

AS-1, Mexico Assault Ship laid down 1936

Displacement:
24 t light; 25 t standard; 26 t normal; 27 t full load

Dimensions: Length overall / water x beam x draught
50.00 ft / 50.00 ft x 12.00 ft x 2.70 ft (normal load)
15.24 m / 15.24 m x 3.66 m x 0.82 m

Armament:
1 - 1.85" / 47.0 mm guns in single mounts, 3.17lbs / 1.44kg shells, 1936 Model
Breech loading gun in a deck mount with hoist
on centreline amidships
1 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1936 Model
Machine gun in deck mount
on centreline aft, 1 raised gun
1 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1936 Model
Machine gun in deck mount
on centreline amidships
5 - 0.30" / 7.6 mm guns in single mounts, 0.01lbs / 0.01kg shells, 1936 Model
Breech loading guns in deck mounts
on side, all aft
Weight of broadside 3 lbs / 2 kg
Shells per gun, main battery: 150

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0.50" / 13 mm 50.00 ft / 15.24 m 4.00 ft / 1.22 m
Ends: Unarmoured
Upper: 0.50" / 13 mm 12.00 ft / 3.66 m 4.00 ft / 1.22 m
Main Belt covers 154 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2.00" / 51 mm 1.00" / 25 mm -

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 66 shp / 50 Kw = 10.00 kts
Range 500nm at 10.00 kts
Bunker at max displacement = 2 tons

Complement:
5 - 7

Cost:
£0.008 million / $0.031 million

Distribution of weights at normal displacement:
Armament: 0 tons, 1.6 %
Armour: 7 tons, 26.4 %
- Belts: 5 tons, 20.4 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 2 tons, 6.0 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 2 tons, 7.1 %
Hull, fittings & equipment: 12 tons, 45.8 %
Fuel, ammunition & stores: 2 tons, 7.8 %
Miscellaneous weights: 3 tons, 11.4 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
93 lbs / 42 Kg = 29.3 x 1.9 " / 47 mm shells or 0.4 torpedoes
Stability (Unstable if below 1.00): 1.08
Metacentric height 0.2 ft / 0.1 m
Roll period: 10.3 seconds
Steadiness - As gun platform (Average = 50 %): 44 %
- Recoil effect (Restricted arc if above 1.00): 0.18
Seaboat quality (Average = 1.00): 1.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.570
Length to Beam Ratio: 4.17 : 1
'Natural speed' for length: 7.07 kts
Power going to wave formation at top speed: 68 %
Trim (Max stability = 0, Max steadiness = 100): 39
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: 5.50 ft / 1.68 m
- Forecastle (20 %): 5.00 ft / 1.52 m
- Mid (50 %): 5.00 ft / 1.52 m
- Quarterdeck (15 %): 5.00 ft / 1.52 m
- Stern: 5.00 ft / 1.52 m
- Average freeboard: 5.04 ft / 1.54 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 48.9 %
- Above water (accommodation/working, high = better): 81.3 %
Waterplane Area: 427 Square feet or 40 Square metres
Displacement factor (Displacement / loading): 155 %
Structure weight / hull surface area: 17 lbs/sq ft or 81 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.79
- Longitudinal: 12.04
- Overall: 1.04
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped



Thoughts?

47mm shells don't go bang very much.

The shape of the hull is hardly hydrodynamically efficient...

You might be better served with a 76mm howitzer, or whatever bore size the Atlanteans are using on their support tanks, instead of the 47mm.

That would be the 75mm.

Quoted

Unofficialy, it's real role is to provide very close fire support for the Cuban invasion fleet.

Man, and you were giving Shin a rough time for antagonising the Chinese!

Quoted

Originally posted by thesmilingassassin
That would be the 75mm.

Quoted

Unofficialy, it's real role is to provide very close fire support for the Cuban invasion fleet.

Man, and you were giving Shin a rough time for antagonising the Chinese!

And the tail wags the dog again!

Quoted

47mm shells don't go bang very much.

You might be better served with a 76mm howitzer, or whatever bore size the Atlanteans are using on their support tanks, instead of the 47mm.

Coming up in the next version...

The 47mm should be fine for blowing up machinegun bunkers and for direct fire support. It also allows the boat to be used against other boats. And it provides pretty good protection, since the 75mm version won't be able to have a full turret with 50mm armor.

Quoted

The shape of the hull is hardly hydrodynamically efficient...

It isn't made for racing destroyers. That's up to the MTBs.

Quoted

Man, and you were giving Shin a rough time for antagonising the Chinese!

That was my Australian alter-ego! Note that it says unofficially, which means it's covered in layer and layers of beurocratic BS, and is not available for public consumption.


So any problems putting a tank turret on a boat?

Tankturrets on gunboats was used numerous times incl the BKA series from the USSR

Fairly common in riverine fleets in Continental Europe historically, but a little later than the mid 30's

The BKA was around in 1940, as Wesworld is OTL + 5...

Quoted

Originally posted by Vukovlad
The BKA was around in 1940, as Wesworld is OTL + 5...

Wesworld is +3 and up to +5 for aeronautical elements. The vast majority of technological items are still "about" historical timeline.

Anyhow, armored motorized rafts with a turret (albeit non-tank) date back to 1861 at least.

My only real concern with this vessel is with 0.86 draft, is there the room for the tank turret's basket and the gears to support it. But this is a matter of a couple tenths of a meter.

Strangely, even thought I had seen the BKAs before, I never considered them when designing this ship.

I think the turret in the drawing is too big. Wes do you have any dimensions for the At-27 turret?

But it should fit. The AT-27 is 9ft tall, of which the turret is about 4ft. So the gears and stuff are about 5ft tall. This boat from deck to kell is 7.7ft, so it does have plenty of room to spare.

Quoted

The shape of the hull is hardly hydrodynamically efficient...

Kind of like that magnificent Italian vessel, Faa di Bruno, right?
To be honest, looking at Faa di Bruno, I expect the BC of that mexican RPB/AS to be over 0.75, rather than the 0.57 that was used.

Well the hull was based on that of the British Pamela/Una class of river boats (as seen on Jane's WWII). A BC of 0.57 was what gave me the correct displacement using the stated dimensions.

Quoted

Originally posted by Desertfox
Strangely, even thought I had seen the BKAs before, I never considered them when designing this ship.

I think the turret in the drawing is too big. Wes do you have any dimensions for the At-27 turret?

But it should fit. The AT-27 is 9ft tall, of which the turret is about 4ft. So the gears and stuff are about 5ft tall. This boat from deck to kell is 7.7ft, so it does have plenty of room to spare.

The turret is roughly 1.75 m tall and 2.25 m long, hrolf may know better as he designed the tank with tank builder. I'd say you'd have the room for a turret with a 75mm gun. If you do upgun, the turret currently depicted is the correct size I would think, but it would be too large (and round) to be the AT-27 turret.

The AT-27's turret, as designed, is 1m high and 2.25m long.

I was fairly close on my guesstimation. What would be the size of the turret ring then?

I'd have to look to be sure, but I think it has a 135mm turret ring.

Pic with corrected AT-27 turret dimensions, plus 75mm version. Includes 5 ft stick figures.




And the 75mm SS2 version:

Mexico Gunboat laid down 1936

Displacement:
24 t light; 25 t standard; 26 t normal; 27 t full load

Dimensions: Length overall / water x beam x draught
50.00 ft / 50.00 ft x 12.00 ft x 2.70 ft (normal load)
15.24 m / 15.24 m x 3.66 m x 0.82 m

Armament:
1 - 2.95" / 75.0 mm guns in single mounts, 12.87lbs / 5.84kg shells, 1936 Model
Breech loading gun in deck mount
on centreline amidships
2 - 0.50" / 12.7 mm guns in single mounts, 0.06lbs / 0.03kg shells, 1936 Model
Machine guns in deck mounts
on centreline ends, evenly spread
Weight of broadside 13 lbs / 6 kg
Shells per gun, main battery: 100

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 0.50" / 13 mm 50.00 ft / 15.24 m 4.00 ft / 1.22 m
Ends: Unarmoured
Upper: 0.50" / 13 mm 12.00 ft / 3.66 m 4.00 ft / 1.22 m
Main Belt covers 154 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 1.00" / 25 mm - -
3rd: 0.50" / 13 mm - -

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 66 shp / 50 Kw = 10.00 kts
Range 500nm at 10.00 kts
Bunker at max displacement = 2 tons

Complement:
5 - 7

Cost:
£0.013 million / $0.052 million

Distribution of weights at normal displacement:
Armament: 2 tons, 6.2 %
Armour: 7 tons, 26.4 %
- Belts: 5 tons, 20.4 %
- Torpedo bulkhead: 0 tons, 0.0 %
- Armament: 2 tons, 6.0 %
- Armour Deck: 0 tons, 0.0 %
- Conning Tower: 0 tons, 0.0 %
Machinery: 2 tons, 7.1 %
Hull, fittings & equipment: 11 tons, 43.5 %
Fuel, ammunition & stores: 2 tons, 9.3 %
Miscellaneous weights: 2 tons, 7.6 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
58 lbs / 27 Kg = 4.5 x 3.0 " / 75 mm shells or 0.2 torpedoes
Stability (Unstable if below 1.00): 1.17
Metacentric height 0.3 ft / 0.1 m
Roll period: 9.6 seconds
Steadiness - As gun platform (Average = 50 %): 50 %
- Recoil effect (Restricted arc if above 1.00): 0.32
Seaboat quality (Average = 1.00): 1.00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0.570
Length to Beam Ratio: 4.17 : 1
'Natural speed' for length: 7.07 kts
Power going to wave formation at top speed: 68 %
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: 5.00 ft / 1.52 m
- Forecastle (20 %): 5.00 ft / 1.52 m
- Mid (50 %): 5.00 ft / 1.52 m
- Quarterdeck (15 %): 4.00 ft / 1.22 m
- Stern: 4.00 ft / 1.22 m
- Average freeboard: 4.68 ft / 1.42 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 77.7 %
- Above water (accommodation/working, high = better): 76.9 %
Waterplane Area: 427 Square feet or 40 Square metres
Displacement factor (Displacement / loading): 103 %
Structure weight / hull surface area: 17 lbs/sq ft or 81 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 0.81
- Longitudinal: 9.17
- Overall: 1.04
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is cramped

Quoted

Originally posted by Desertfox
Pic with corrected AT-27 turret dimensions, plus 75mm version. Includes 5 ft stick figures.

1) I have yet to actually manage *any* to scale drawings, but don't mind the broken glass in my greenhouse..

The AT-27 turret is 5' tall? Or maybe 4'6" if the stick figure stands up straight?

The 5' men are 10 pixels tall. Both turrets are 8 pixels tall so that would mean that they are 4 feet tall.