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What the USN did not like about the Iowa Class BB's


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Youtube vid by the curator of the USS Iowa. Talking about future plans for the class and other BB's

 

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Good video.  Compromising between competing needs and requirements can be maddening, especially as needs and requirements change.

I foresee Drachinifel having a very stimulating conversation with this gentleman when he finally makes it over...

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Poor quality audio, especially in the wind and in the part near the T.D.S. I might not have understood what he said but here are my takes on this. Per shep854 above all ships are a compromise. It has been said the Iowas were a South Dakota class with an additional 10,000 tons to make an extra 6 knots and some officers thought this reasoning was not worth it. The Iowa class was designed in the in the late '30s and  I don't think the author mentioned this and/or stressed this in why the Iowa class was designed as it was. 
As far as hull shape goes, the fine bow was necessary for the speed requirements in the design. I may have missed it, but the author did not state that the T.D.S. near the bow was a compromise, as all bow protection in all naval ships is, for the shape of the hull. One need only to take a quick look to see you don't have the space for bow -- or for that matter stern --  torpedo protection on any ship. To be fair the T.D.S. on an earlier class, the North Carolina, survived a bow torpedo hit from a I.J.N. submarine torpedo, but had to retire to repair said damage.  The author stated R.N. battleships did not have a flared bow, but H.M.S. Vanguard  did. The Iowas did have low freeboard and this coupled with the fine bow made rough seas a challenge. 
The U.S.N. was aware of the air threat, hence the dual-purpose armament at this date. No navy was fully aware of how many a.a. guns and directors would be needed for W.W.2. Arcs of fire, I think, are a bit misleading as the U.S.N. had the money, manufacturing, and manpower to place a.a. guns on about every space it could.  This is especially true of the Oerlikons. I think the author stated that later U.S. cruisers had one more twin 5" mount than the Iowas. This is not true, as these cruisers had a broadside of 4 twin mounts vs 5 for the Iowas. 
The U.S.N., and other navies, were not aware that the need for electrical power and the topside space for future electronics would be as great as it was. The length of the Iowas helped in this regard. 
I'm not sure were the author got his Panama Canal information and I may not have heard him correctly, but all U.S. ships, except the Midways and the planned Montanas, could transit the Panama Canal. 
Good point on the refueling station, but this was not a primary concern and the attending ships would need to go slower than n normal in order to refuel from an Iowa. 
My two cents. 
 

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Rather than widening them, they could have been lengthened by extending the bow, so even with it's fineness, the hull would have been approaching it's maximum near the front turret. That would have solved the front buoyancy problem and helped torpedo protection around the front turrets.

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It would then be wider though across the two front turrets, where the width of the barbette is the limiting factor to the depth of protection.

Like this:

9GhnsFg.png
 

Edited by KV7
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I see.

According to this pretty good paper, the length was determined by an empirical formula, considering the width of the Panama Canal.

 

Quote

(...)

The increased tonnage limits were quickly combined with beam limitations of the Panama Canal locks (110 feet) to design the fastest class of battleships ever contemplated. The IOWA Class was designed according to the speed being equal to 1.19 x the square root of the waterline length (Figure 5). Their beam limitation would be 108-1/6 feet, allowing less than 2 feet of clearance through the locks of the Panama Canal (Figure 6 left). Before the Second World War, passage through the Canal was an absolute necessity for America to maintain a two-ocean navy. Planners recognized that the larger navy yards were on the Atlantic Coast while the principal maritime threat lay in the Pacific Basin.

A second theorem, arrived upon empirically, related waterline length to maximum beam. This ratio was seen to be 7.96 for a battleship and 8.85 for a cruiser. The battleship's heavy armor and large draft reduced the ratio from what it would be for something sleek like a yacht or cruiser (the LEXINGTON/SARATOGA had been designed at 8.85 and their turning characteristics were poor).

The IOWA Class would achieve these higher speeds by lengthening the forecastle and amidships. Hull model tests proceeded with great success at the Navy's David W. Taylor Ship Model Basin near the Washington Navy Yard (King, 1971; Carlisle, 1998). A large, heavily armored object could cut through seas in an exemplary manner while maintaining high speeds (Taylor, 1912). The IOWAs were the first capital ships fitted with bulbous bows, as shown in Figure 6 right.

(...)

 

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15 hours ago, KV7 said:

Rather than widening them, they could have been lengthened by extending the bow, so even with it's fineness, the hull would have been approaching it's maximum near the front turret. That would have solved the front buoyancy problem and helped torpedo protection around the front turrets.

Which brings other problems. A longer bow means a slower ship (more mass on same power and more hull drag), a slower turning ship (more hull length), and more ship for a torpedo to hit. And there still is a "fine bow" no matter what length the hull is. All ships have this compromise. 

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58 minutes ago, Rick said:

Which brings other problems. A longer bow means a slower ship (more mass on same power and more hull drag), a slower turning ship (more hull length), and more ship for a torpedo to hit. And there still is a "fine bow" no matter what length the hull is. All ships have this compromise. 

Of course there is no free lunch. Thought the extended bow ahead of the barbette need not be armored as there need be nothing of great value or risk in that space. It may have even be possible to increase power, reorganise the machinery and compartmentalise it, via spending internal volume created by moving stowage (eg. of fuel) from spaces around the machinery into the new forward volume. 

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Read about the "all or nothing" armor scheme used by USN BBs, KV7. Only way to increase power would be to add another shaft, as the Iowas machinery had already reached the 50,000shp per shaft limit given by the technology of the time, according to the paper I linked yesterday.

However, it was impossible to add another shaft without making the ships beamier, then they could not go through the Panama Canal.

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