The Large ASW Ship

But, I have several advantages over the mentioned ships:

First, I propose no armor so that is a massive reduction in weight. That in turn brings down the needed displacement considerably.

Next, the guns I propose would not need high velocity and they would be using lower weight high capacity shells only. This reduces the powder requirement per round and the shell weight. This in turn reduces the size of the magazines. Additionally, the ship would only be carrying about 40 to 60 rpg rather than 100 to 200 rpg like a monitor or battleship would. This is because I would be expecting to need fewer rounds for the mission intended rather than expect a firefight where high round expenditure would be required. This too reduces magazine size. The 10 to 12" size is required mostly to get a sufficently large ASW round to do the necessary damage and have a reasonable chance of success.

With only two screws and less engine and bolier requirement the size of the main spaces would be reduced too. After all, I don't intend the vessel to be particularly fast.

Secondary armament could be limited to just say 4" or 5" AA guns if necessary to reduce their footprint and weight too. But, generally speaking, pedistal mount single purpose guns don't require alot of space and weight to mount for some surface fire capacity. These are really an add on.

Now, the hanger and catapult will take up some space but very little weight so their displacement is nothing and mostly a topside superstructure issue.

I'll see if I can do a rough drawing of the proposed ship over the next few days to add to this.

 

There is a ship design utility out there that is suppose to be pretty good. Spring board or something like that I think. You might check the naval boards. I think it was used for some of the Tarrantry and Letterstime ships.

 

lwd - you from Delaware? How'd you hear about punkin chunkin?

 

The ASW ship would depend on conventional escorts for targeting, so a convoy including one would requre as many other escorts as one without to have the same probability of detecting and engaging a submarine. The sub would know that it was being pinged, but the arrival of a salvo of heavy projectiles would be a surprise - especially if the ASW ship is fielded before the deployment of ahead-throwing weapons like Hedgehog and Squid. Conversely, if escorts were armed with something like Squid, the "value added" of the ASW ship might not be competitive with the same investment in conventional escorts, say two frigates for the production cost of the large ASW ship.

The ASW ship would need accurate range and bearing to the escort; range in particular would require surface search radar. The escort's range and bearing to the target, which were far from perfectly accurate with WWII-era sonar, would have to be transmitted to the ASW ship and plotted in real time, and long range or high trajectory projectiles introduce potential ballistic errors. We would have to hope that the number and size/lethal radius of the shells would compensate for the likely inaccuracy of the system. Long range gunnery usually scored few hits and required corrections based on fall of shot, but the exploding projectiles would have the same disruptive effect on sonar contact as other depth charges.

Prior to the Type 147 asdic associated with Squid the only means of determining the depth of a submarine was the loss of contact as a ship ran in to drop depth charges. Part of the appeal of Hedgehog was that its contact-fuzed projectiles essentially took depth out of the fire control problem, but it would still be an issue for the ASW ship.

The ASW ship should have a few depth charges and throwers for the hopefully rare occasions when it came into direct contact with U-boats, but it would not seem the best platform for large DC batteries or the Mark X depth charge. An analogy would be the Squid-armed Castle and Loch class ships, which carried a mere 15 depth charges - stern rack, two throwers, total three five-charge patterns - as a backup to their primary weapon.

I wouldn't necessarily bother with a heavy AA armament. Most ASW action took place outside the range of attack aircraft. The RN evolved a good mix of ships, though it appears to have happened more by circumstance than design. Most Atlantic escorts like corvettes and frigates had only a few close-range weapons. There were a proportion of sloops like the Black Swan class which combined AS capability with a powerful AA battery for the size and the Hunt class destroyers with AA but limited AS weaponry. So in this respect I would consider the large ASW ship part of the convoy, to be protected by AA escorts on routes or locations where it was necessary.

The air capability would be a useful asset, though I too would question if this is a better way to provide it than a CVE or MAC. A fighter type to intercept Condors would be useful in a Battle of the Atlantic scenario. A short flight deck with catapult and arresting gear might be a useful option, or to put it another way, the large ASW ship might be the rare example of a useful carrier/gunnery ship hybrid.

 

A friend of mine who lives in Maryland has visited it a few times and been very impressed. I think I've also seen some references either on line or on the tube but don't remember where.

 

Look forward to your drawing, could clear up some things.

 

Or what about the Cavendish (Effingham) class?
Same size as the Kents, but the Cavendish (ex-Vindictive) had been disarmed and converted to a training ship in the 30's.
Or the Hawkins. The original design of 7 single 7.5" guns was not as useful as the Kents.
So you wouldn't need to remove a commisioned warship from service.

 

IIRC Cavendish before her conversion to light carrier was part of the Effingham class that also included Raleigh, Frobisher and Hawkins so we are talking of sister ships. A bad luck class (two Effingham and Raleigh out of five wrecked) their most notable distinction was being the "baseline" for the Washington treaty cruisers. IMO the ship, if built from scratch, would look more like a small (10.000t and 10" guns) pre-dreadnought battleship like Swiftsure, but with no armour, than like Cavendish that had a high speed requirement. If you are looking for relatively new large cruiser hulls to convert the C are probably too small but the two larger E could be converted using single mounts.

 

Did some research on HMS Dreadnought from a a book I have that contains some good line drawings and internal layouts. For what it may be worth the 2-gun turret (12' guns) ring base was 28 feet in diameter. In a 3-gun configuration it seems reasonable for 40-42 foot turret. So it may be that it could work on a 60" beam.

I am concerned about blast concusion over the fantail. If the aft main battery is fired within say 20 degrees of centerline, and with much shorter barrels, will there be blast concussion effets on the depth charge racks? Will the DC rack crew be able to man their post when operating aft main guns?

 

Why an ASW gunship? Why not the floating iceberg aircraft carrier that was proposed and even researched? A huge chunk of ice with a flat top and giant "outboard motors." Torpedoes would just take a chunk of ice off and do almost no damage to it. Aircraft were considerably more useful in detecting, detering and destroying submarines than gunships, and more useful against surface vessels as well.

Also remember, there were very few if any weapons or weapons systems perfected and used in the Second World War that were not started into development before the war. Such as the iceberg aircraft carrier. It was thought up near the beginning of the war. By the time the concept was studied, designed and pronounced as feasible, the Allied navies knew that it wasn't needed.

 

The reason for a "gun ship" is for the close-in ASW battle. That is, the sub is already at the convoy and either attacking or preparing to attack. Here aircraft are not as helpful. There is too much noise for sonobuoys to work efficently, too many ships in the area for MAD in many cases and just the confusion in trying to coordinate the action with WW 2 tactical communications.
What the proposed design does is give the ASW group a ship capable of engaging a detected sub with an ASW weapon up to ranges of about 8 to 10 miles even if the firing platform is not the detecting platform. Having one ship direct the fire of another is a fire control problem that has already been solved.

As to the fire itself. The guns while nominally about 12" in size are more akin to low velocity howitzers or mortars than high velocity naval guns. The propelling charge is far smaller so the blast and concussion would be far less. If it were a problem using a transom (flat) stern and mounting the depth charge racks a deck down inside the ship solves that problem. Additionally, the main battery would normally be firing at high angles of elevation as well to lob their rounds on the target rather than firing on flat trajectories like conventional naval rifles would do.