WesWorld

I was looking at the recently posted MTB 408 class specifications and I have some concerns.

While dimensionally they match the USN's Elco 80-ft boats to a tee, I really think that they are over-armed for their size and stated crew.

The USN's Mk3 single 40mm gun normally required a crew of 5 to 6, and weighed in at about 1,500 kg. Even if you reduced the crew to 4, with concomitant reduction in ROF, that takes half the crew (16) to man just those guns.

The single 20mm guns each require a crew of two - one gunner and one ammunition number - that makes 12 of 16 crew committed to just the 40mm and 20mm weapons.

The .50-caliber mounts will each require one gunner - that raises the total to 14 crew, leaving precisely two to man the conn, the engine room, fire the torpedoes, and man the other weapons mounts, not to mention maintain communications, operate the radar, etc.

More crew would require a larger craft; a craft of only 50-odd tons cannot take much more. That starts a whole new design spiral.

The historical PT-658 and the Indian MTB-85 are quite similar. The Indian MTB has 2x37mm while the PT658 has 1x40mm and 1x37mm cannon. Both designs and the MTB-408 are very similar in weight and overall armament. The PT-658 also has a crew of 2 officers and 14 enlisted so most likely there is some double duties involved.

Quoted from "thesmilingassassin"

The historical PT-658 and the Indian MTB-85 are quite similar. The Indian MTB has 2x37mm while the PT658 has 1x40mm and 1x37mm cannon. Both designs and the MTB-408 are very similar in weight and overall armament. The PT-658 also has a crew of 2 officers and 14 enlisted so most likely there is some double duties involved.

Citing Navsource entry for PT-658

Quoted

•Armament: One 40mm mount, two 21" torpedoes, two twin .50 cal. machine guns, one 37mm mount and one 20mm mount

Allowing 4 for the 40mm mount, 2 for the 37mm mount (it is an Army AT gun after all), 2 for the 20mm mount, and 2 in the .50 cal mounts, that makes ten crew accounted for. 2 in the con, 2 in the engine room, and 1 to each torpedo mount just makes it at battle stations. Sixteen would not cover the armament you propose to mount and still man the boat effectively.

I had not noticed it before, but I would extend the same sort of concerns to the Indian MTB-85, though the encyclopedia entry does not cite the number of crew. Even more so would be a concern of where you plan to mount the rocket cells to account for back-blast, something the Bharati design would need to consider.

Quoted from "BruceDuncan"

Even more so would be a concern of where you plan to mount the rocket cells to account for back-blast, something the Bharati design would need to consider.

The US MTBs had the rocket tubes on arms that folded out to hang about 2-3 feet off the side of the hull. They pointed forward and were fired electrically by the officer on the bridge when the boat was lined up with the target, a la a strafing aircraft. I've got a book at home that shows pictures of that.

Quoted from "Brockpaine"

Quoted from "BruceDuncan"

Even more so would be a concern of where you plan to mount the rocket cells to account for back-blast, something the Bharati design would need to consider.

The US MTBs had the rocket tubes on arms that folded out to hang about 2-3 feet off the side of the hull. They pointed forward and were fired electrically by the officer on the bridge when the boat was lined up with the target, a la a strafing aircraft. I've got a book at home that shows pictures of that.

Ah. If that is the arrangement, I could see it working with less danger to the crew. The word "cell" suggests a box somewhere on the deck, which would be a whole different kettle of fish.

Yeah. They were hinged so they could remain inboard during periods of travel, and then when they were ready to be used, a crewman folded them out. The book indicated the rockets were "very inaccurate" and they were used mostly for shore attacks, not for anti-ship work.

Quoted from "Brockpaine"

Yeah. They were hinged so they could remain inboard during periods of travel, and then when they were ready to be used, a crewman folded them out. The book indicated the rockets were "very inaccurate" and they were used mostly for shore attacks, not for anti-ship work.

Hmm. That last point could be an important consideration...

The other important point with these types of vessels is that crew is at a minimum number to save space and provisions so your going to get crew members performing double duties. Just because the craft has two 40mm, two 20mm and four 50 cal weapons it doesn't mean ALL will be manned at once or by the usual crew members. The Atlantean MTB-408 class is slightly longer, wider and has more draft when compared to the American design.

Quoted from "thesmilingassassin"

The other important point with these types of vessels is that crew is at a minimum number to save space and provisions so your going to get crew members performing double duties. Just because the craft has two 40mm, two 20mm and four 50 cal weapons it doesn't mean ALL will be manned at once or by the usual crew members. The Atlantean MTB-408 class is slightly longer, wider and has more draft when compared to the American design.

Why would you mount weapons that cannot be manned in battle?

This was most likely the wartime practice, when making a torpedo run you don't need all the AA guns manned, and you won't fire the torpedoes when under AA attack.
Also, most likely, if being used for shore defence and short-range missions a couple of guys ashore can jump aboard as extra gunners. Its only if your living out at sea on extended patrol than habitability is going to suffer.

Quoted from "BruceDuncan"

Quoted from "thesmilingassassin"

The other important point with these types of vessels is that crew is at a minimum number to save space and provisions so your going to get crew members performing double duties. Just because the craft has two 40mm, two 20mm and four 50 cal weapons it doesn't mean ALL will be manned at once or by the usual crew members. The Atlantean MTB-408 class is slightly longer, wider and has more draft when compared to the American design.

Why would you mount weapons that cannot be manned in battle?

Seems to be common practice with MTB's, to give them the swiss army knife style armament. Given their small size you can only pack on so many weapons AND people to man them.

In my own library of reference books I have a book called "Allied coastal forces of world war 2 - volume 2: Vosper MTB's and U.S. ELCO's". It has all kinds of goodies in it. One of which is a section on armaments. The U.S. PT boats used the 40mm mk 3 gun, basically a naval version of the Army's M1 AA gun which was a manually operated gun. The picture in the book shows a crew of 3. It also states that the 40mm mount was not entirely successful in the bow position due to the motion of the bow while underway making the weapon difficult to train. The layout was used on a small number of vessels anyway in gunboat roles which will likely occur with the Atlantean design as well, so the armament layout as listed will remain the same but not be an accurate representation per say.

Quoted

The other important point with these types of vessels is that crew is at a minimum number to save space and provisions so your going to get crew members performing double duties.

https://en.wikipedia.org/wiki/Motor_Torp…s_and_last_crew
Looking there, you have (excluding Ensign Ross): Commander, Executive Officer, Seaman, Gunner's Mate, 4x Motor Machinist's Mate, 2x Torpedoman's Mate, Radio Man, Quartermaster. A total of 12 men for 4x 21-inch TT, 1x 20 mm cannon aft, 2x2 .50 MG and 1x 37 mm ATG.

It is indicated that MM1 McMahon was the only one in the engine room during the collision and that MM2 Marney was killed while manning a turret (no doubt the 0.50" one) so there is little doubt that the two other Motor Machinist's Mates were also manning weapons or assisting with the weapons. No doubt the same could be said about the Radio Man and the Quartermaster.

Quoted

Just because the craft has two 40mm, two 20mm and four 50 cal weapons it doesn't mean ALL will be manned at once or by the usual crew members.

I don't quite agree with the at last bit. Using PT-109's crew as example, if I have a Motor Machinist's Mate who is trained to operate the 0.50" as well, I want him to man the 0.50" and not the 20mm or 37mm gun. Sure positions could be shuffled if one or more guys are killed in action, but under normal conditions I do not need 10 guys running to the same weapon to operate it and none to the 0.50" turrets or vice versa.

Quoted

This was most likely the wartime practice, when making a torpedo run you don't need all the AA guns manned, and you won't fire the torpedoes when under AA attack.

I don't think that that would be the case. If you make a torpedo run on a ship with everyone aboard focused on the torpedoes and all of a sudden an aircraft attacks your boat, you're probably screwed.
However, when I look at this picture I ran across...

... that would make me think that the ones on the bridge (commander and XO) are the ones launching the torpedoes (as well as the rockets mounted on the PT boat in the photo). To me that means that you do not need to keep some of the AA stations unmanned as only a few guys (for example the two Torpedoman's Mates aboard PT-109) are needed to handle the preparations of the torpedoes.

Another thing to keep in mind with the Atlantean boats is that the preceding MTB-404 class has a crew of 17 and less armament than the MTB-408 class with a crew of 16.

Quoted from "Rooijen10"

I don't quite agree with the at last bit. Using PT-109's crew as example, if I have a Motor Machinist's Mate who is trained to operate the 0.50" as well, I want him to man the 0.50" and not the 20mm or 37mm gun. Sure positions could be shuffled if one or more guys are killed in action, but under normal conditions I do not need 10 guys running to the same weapon to operate it and none to the 0.50" turrets or vice versa.

Crew members would be assigned to standard positions yes, but given their is a ships captain on board I'm sure he will micro manage who go's where when he needs all hands on deck.

Quoted from "Rooijen10"

I don't think that that would be the case. If you make a torpedo run on a ship with everyone aboard focused on the torpedoes and all of a sudden an aircraft attacks your boat, you're probably screwed.
However, when I look at this picture I ran across...

... that would make me think that the ones on the bridge (commander and XO) are the ones launching the torpedoes (as well as the rockets mounted on the PT boat in the photo). To me that means that you do not need to keep some of the AA stations unmanned as only a few guys (for example the two Torpedoman's Mates aboard PT-109) are needed to handle the preparations of the torpedoes.

It makes sence for the Officers to be the ones firing the torpedo's as they are the ones operating the boat during maneuvers.

Quoted from "Rooijen10"

Another thing to keep in mind with the Atlantean boats is that the preceding MTB-404 class has a crew of 17 and less armament than the MTB-408 class with a crew of 16.

Acctually that's a good point because the MTB-404's should have 16 crew members given the lesser armament. That said just because I list a boats armament as such it doesn't mean that every boat will have that armament as standard. Theres little need for depth charges in riverways, unless you lack fishing rods.......

Quoted

Crew members would be assigned to standard positions yes, but given their is a ships captain on board I'm sure he will micro manage who go's where when he needs all hands on deck.

I think that that is what I was trying to say. At least if you mean with the micro manage bit that the boat's commander does that when he gets his crew or gets a new crewmember and not at the moment when he needs all hands on deck.

Quoted

Acctually that's a good point because the MTB-404's should have 16 crew members given the lesser armament. That said just because I list a boats armament as such it doesn't mean that every boat will have that armament as standard. Theres little need for depth charges in riverways, unless you lack fishing rods...

The thing is with the MTB-404 class there is clearly 'or' and 'or' in the armament section. I read the whole MTB-408 class armament section as 'and' and 'and' because of the lack of 'or'.. so you get:

MTB-404 class armament
- 1x40mm
- 1x20mm
- 2x0.50 cal mg (2x2)
- 1x60mm mortar or 4x21"TT or 10 D.C.or 2x21" TT and 8 D.C.

MTB-408 class armament
- Two 40mm
- two 20mm
- four 50 cal mg (2x2)
- one 60mm mortar
- two Mk-1 eight cell 130mm rocket launchers
- two 21" type 12 Torpedo's
- four type 2 Depth charges

Well I still have to get cracking on Atlantean reports so its still unclear at this stage how many MTB's of the 408 type will mount riverine load out's or more conventional MTB armaments. Its quite likely that a "type 1" or "type 2" will be added to the class to distinguish the loadouts but for now "or" is going to be a common word in the starts again. I'm also going to add additional crew to the 408's.