The USN Cherrytrees – The Lexington class Part 2/3

Near-Final designs

In it’s original form Design 150 had a 5”/127mm belt and eight 14”/356mm guns (nothing special so far) but could make an astinishing 35 knots with it’s 218.000 SHP and at the same time had a range of an excellent 12.000 nautical miles. The plans of the 32.000 ton ship were put to the backshelves until April 1916 due to other, higher prioirty war programs. After then it was named „Battlecruiser 1917” and got a new number, No. 169 and a redesign of course in good USN fashion.

The redesign included two additional 14”/356mm guns and a 4 layer torpedo defense system with an increase in length to 259 meters (in order to retain the 35 knots speed without increasing power). The 4 layer system was a reduced version of the 5 layer one then applied to the latest battleship designs (TENNESSEE and COLORADO classes, both around 32.000 tons). Displacement therefore rose to 37.000 tons despite the fact the two additional guns were put in by replacing two twin turrets with triple. The main cause for growth was clearly the TDS.

Displacement was unacceptably high for a non-battleline unit. (Note: high displacement counted as a negative thing in two ways: first it implied high price as in those days displacement defined the price and also it meant less room for improvement during the service life of the ship.) Moreover the design was very tight space wise as well which is indicated by the placement of the triple turrets at the inner positions – there was simply no room in the hull to accomodate the larger barbettes forward and aft –despite that being the better position CG wise! A radical diet was looked for but they did not want to cut down on hull strength which was already stressed to maximum – so reducing plate thicknesses and scantlings was out of question. They tried a few solutions, among them deleting the TDS and raising the armoured deck one deck higher – this reduced overweight to 760 tons instead of 5200. But giving up the TDS in a terribly expensive, very long, duck like manuvering ship that would be highly dependent on it’s speed for defense was a lot to ask. They also tried to fit the belt as a structural member and reduce structural weight this way but the different strength qualities of armour and structural plate made this a dead end. Designers also investigated the square turtle back armoured deck idea from 1912 but this seemed to be too bold a move to try first in such a costly and big ship.

8. Figure: the turtle deck variant; this design predates No. 169 as is shown in Fig. 9 below – and this was the first one with a TE drive and arrangement; it also had the triples yet in the lower positions and a much cut down sheer to allow low angle fire directly forward. This feature was appearantly discarded very soon after this as somewhat raised forward barbettes were adopted (Credit: John Jordan, Warship 2011)

Furthermore the problem was aggreviated by the high freeboard required at the bow because that was the only way to provide high sustained speed in bad weather. The only viable solution therefore seemed to be a non-flush deck arrangement with a foracastle deck forward that extended aft of the after barbettes. It could not be terminated more forward than that as the heavy barbettes with their very large diamter cuts in the structural decks meant potential weak spots – reducing strength by one deck was out of question. In May the designers came up with two ideas to save this not-so-easy birth to say the least. The first was to use three thinner armoured decks instead of one thick one: one at the topmost weather deck, one at the upper edge of the belt as the main armoured deck and a third one at 3 meters above the waterline acting as a splinter deck. Needless to say three thinner decks were less effective then one thick one.

The other idea was even more insane: put the boilers at two levels! This would have reduced the length of machinery (and in turn the length needed to be protected) and using internal space better. This was never tried on a warship before although unbeknownst to the US designers the Germans were experimenting with the same in their Grosse Kreuzer designs (notably design GK3022) – and actually the USN designers were contemplating the same as well in 1939 with variants of the BB-57 SOUTH DAKOTA class preliminary designs.

In the end a simple but brilliant solution was found with the two above mentioned ones implemented as well. It was the lengthtening of the hull by 15 meters again which allowed for the excellent 35 knots top speed to be retained. Weight came out at 33.000 tons with these modifications and what’s more the extra length reduced power requirements to 180.000 SHP. This still needed 24 boilers that could only fit on two levels in the tight hull

9. Figure: Design No. 169 as of June 1916- the first variant approved for production. This sketch was the first that really looked like the ships that were actually laid down later on.

The high horsepower requirement (comparative BBs had 25-35.000 SHP) made turbo electric drive desirable – it meant placing each boiler in a separate compartment around the two turbo generators in the very middle of the ship. This greatly enhanced torpedo protection but at the same time increased weight and reduced free internal space but TE drive offered a lot of advantages:

  • more economical operation (the steam turbines turning the generator could always turn at the optimal rate)
  • increased redundancy (no direct shafting, each generator could power each electric motor)
  • simpler structural layout (lot less steampipes needed and no need et all for separate high-pressure, low-pressure, cruising and reverse turbines)
  • better manuverability (full and immediate astern power on all shafts, even applied independently)

In reality the extra weight of the TE propulsion was only 2-300 tons out of a total machinery weight of ~5000 tons.

Due to the large number of boilers the huge weight concentrations that manifested in the form of barbettes were pushed towards the end of the hull which further exaggerated the hull strength issue. Therefore the dual level boiler layout made sense as it reduced machinery length somewhat. The lower level was protected by the belt armour and the water against shells and the upper ones were safe against torpedoes due to their placement (they were above the waterline and the main armoured deck). With this solution the designers spared enough weight that even the 4 layer TDS (2 layers only aside boiler rooms) could fit into the 33.000 ton displacement so that even the lower boilers had some means of torpedo protection. The upper level boilers in turn were offered some shell protection with the structural plates’ special arrangement (that is to have as many layers as possible).

This whole setup triggered sharp critics (even on international level from the brits) although Preliminary design offered an explanation, that the two level setup split the threats into two (lower row protected against shells, upper ones against torpedoes). In the end though when the opportunity was present the designers were more than happy to put all boilers below the main armoured deck. A prominent and well know feature of Design 169 was it’s seven funnels, easily the most of any dreadnought age warship. 3 out of seven served the upper level boilers and were located on the center line while the 4 other serving the lower level were placed in tandem a few meters from the ship’s sides.

In essence the design in this form was a battlescout on steroids that was protected against 6”/152mm shells as the main belt was only 5”/127mm thick and the two upper armoured decks 20-38mm and 25-39mms respectively. In conclusion the designers created a true paper tiger that was comparable to the real life Renown class – but here even the main battery barbettes and turrets had a maximum of 5-6”/152mm armour only! It has to be noted though that we are still talking about pre-Jütland times and with the shell technology of the day it was likely that even this moderate protection could offer resistance to high caliber shells if those were hitting from oblique angles – which again was very likely as the battlescout could choose it’s range and angle of engagement thanks to it’s exceptionally high speed.

Design 169 was approved for production on 30th June 1916 in this form. The ships’ price was an astonishing 16.5 million $ (battleship 1917, USS TENNESSEE cost 10M$) – as mentioned above Congress approved building of 6 ships two days later. The orders and the side numbers were given out probably at this time.

Funnily enough the ships were neither called battlescout nor battlecruiser but got the Capital Cruiser name and CC abbreviation in the end.


Schermata 2016-03-18 alle 18.13.28

The final version

War has it’s own priorities and so the building of the CC-1 class was not progressing too fast. The designers took the time to refine the far from perfect Design 169. In January 1917 BuOrd, that was the responsible branch for armaments of the US Navy’s design office suggested a bold step: replace the main battery with six 16”/406mm guns and straight away with the bigger, heavier and lot more powerful 16”/50 Mark 2 still on the drawing boards. The reasoning was that this would give the ships a punch that would be potentially lethal to anything then afloat so that these vessels could deter any enemy. Not to mention that the 16”/50 Mark 2 had excellent range, flat trajectory and therefore very good penetrating power even at maximum possible battle ranges (by then envisioned as 17-20kms). The 14”/356mm gun could hardly penetrate battleship belts above 18 kms and lacked the shell weight to be a threat to decks at those ranges.

Paralel to this BuOrd wanted the secondary battery of 5”/51 Mark 7 guns replaced with sixteen 6”/53 Mark 12 guns to give more punch versus smaller ships as well.

Fortunately for the design effort boiler technology evolved rapidly during the war and while in 1915 the best boilers had a heating surface of 557 sqm (though even with 24 boilers at least 700sqm would have been reuired) by April 1917 this number grew to 836 sqm. Combined with superheating even higher numbers seemed possible. Thanks to this and to some internal rearrangement the length of machinery spaces were reduced by 3,6 meters and 20 boilers were enough to produce the required amount of steam. What’s more all could fit below the main armored deck! 5 funnels remained from the original 7, the two after ones from the centerline funnels got deleted.  Since this change required the redesign only of the middle part of the ship the new version was ready by May 1917 already – but by that time the USA enter the war and this accelerated things a lot. It was almost taken for granted at the time that these ships would be completed so General Board, the highest level of the Navy’s design department approved the armament change to 16”/406mm guns, but they went a step further and wanted 8 guns! By June 1918 Preliminary Design absolved this obstacle as well at the cost of 1100 tons gained and 0,3 knots speed lost. The secondary battery was limited to 14 mounts only due to this.

10. Figure: the intermediate step with 8-16″/50s alreaady


At this point Preliminary Design was joined by the famous British naval architect Sir Stanley Goodall who brought with himself the plans of the battlecruiser HMS HOOD and reports of battlecruiser actions during the war. The HOOD, contrary to many urban legends and beliefs was probably one of the best protected ship from her era, especially considering her deck armour (but even at other parts she did not lack in protection) – it was the prototype of a new breed, the fast battleship which joined the high speed of the battlecruisers and the protection of a battleship. That is the best of both worlds.

It’s safe to say that the US designers had a lot to reconsider after looking at the plans and obviously started to sketch similar designs for a prospective 1919 naval program. They were meant as challangers again to the battlecruiser concept and there was one very interesting twist just surfacing regarding them:

“One very unusual aspect of these designs is that two parallel series of designs were created, one by the U.S. designers, led by civilian James L. Bates, and a second drawn independently by the British exchange officer Stanley Goodall, serving at this time in the Bureau of Construction and Repair.” (Quote from Navhist official comment on the relevant drawings)

11. Figure: Bates C and D on the left, Goodall C and D on the right


FastBBDesignDGoodall (2)
11A Artist concept of Design D by Stanley Goodall (by TZoli)

They all married the armament of the most recent BB’s (SOUTH DAKOTA BB-49) 12 X 16”/50 Mk 2 with ~10% less armour (11-12”/280-305mm on the belt instead of 13.5”/343mm) but retaining a relatively high speed of 29 knots. Naturally this again resulted in gigantic ships for the age, quite similar to the rejected No. 133 of 1915. An artifical limit was agreed to control growth somewhat at 54.500 tons and a lenght of 304 meters. Bates’ Sketches C and D competed with A (which was SOUTH DAKOTA BB-49) and B which was a beefed up version of the previously described battlecruiser 1917 (or LEXINGTON) – it was now at 45.000 tons since the belt armour was thickened from 5”/127mm to 9”/224mm: Godall’s report showed no thicker armour than that was penetrated at Jütland. Godall’s design C and D were left out as they were probably not ready in time (according to Friedman, but date stamps actually indicate a two days delay only). They showed marked British influence as can be expected, with tripod fore and pole main masts, heavy upper belts, secondaries all grouped high up in the middle superstructure and British style cruiser sterns. Their real peculiarity was a fully inclined side armor with a bulge like arrangement of the TDS.

12. Figure: Inclined armor and bulge integrated TDS


After lengthy discussions between Navy departments involved in the design process it was concluded that the specialized, huge and fast battleship is not wanted. Specialized they were in that due to their cost and size they can not afford to build only this type although due to their high combat value they would mean a revolution in capital ship’s histroy similar to HMS DREADNOUGHT. In turn this would make the US Navy’s then first rate battleline – 15 years worth of investment – obsolete in a few years. It can be argued though that HMS HOOD, that was already nearing completion at the time had already started this revolution.

Above all this reasoning the contra-opinions (Cpt. Dreyer, chief of naval ordnance) were right in that a substantially less displacing (and therefore much cheaper) normal battleship could have a lot better armour and bigger or more guns so that it would easily sweep such an expensive, great unit away in a fleet engagement– meaning that still the slow but very heavily armoured and armed BB was the final world in the world’s navies. In order to have both heavy armor, excellent firepower combined with high speed would have meant going to extremely large dimensions, just like what the MONTANA class preliminary design BB65-8 represented twenty years later with it’s 80.000 tons displacement.

The final nail in the coffin of the fast battleships of 1919 were the astronomical price: for 3 design Ds (that were the largest) one could have 7 (!) of the beefed up battlecruisers, even more with the original design.

Therefore it made sense to retain the classic battleship-battlecruiser combination as the core of the fleet and also it meant a continued developement for the capital cruiser designs. In the end the General Board bowed in to the many critics regarding the very light armor. This meant yet another redesign, named B-3 and dated June 1919. This time it was the armor that got substantially changed at the cost of 1,5 knots speed lost again. The 5”/127mm belt finally gave way to a more reasonable 7”/180mm one that was sloped at 11,5 degrees (shades of Godall) which meant about 9”/224mm of resisting power. The arrangement of the armoured decks remained but the uppermost deck was beefed to 57mm and the main deck was made uniform 32mm. Only the splinter deck remained unchanged. What’s more the turrets and barbettes were strengthened to 11”/280mm on the face, 6”/152mm on the sides and 5”/127mm ont he roof.

The boilers were changed to the most modern types with 1045 sqm heating surface therefore their numbers could be reduced to 16 now. This further reduced internal space requirements and allowed using two large centerline funnels. The ship arrived at it’s final form with a displacement of 42.500 tons, around 10.000 more than the last battleship class (COLORADO). Only the contemporary SOUTH DAKOTA class BBs overwhelmed this by 1000 tons.

13. Figure: Artist concept of the completed and fictional modernised ships (Credit: Abram Joslin)


Many consider the LEXINGTON class ships useless white elephants, paper ships even in their final form. Moreover by 1919 the originally intended role of scouting was threatened more and more by the ever improving aeroplanes and their seaborn base, the newly developed aircraft-carrier.

In reality (with hindsight of course) I don’t think these ships should be considered as unsatisfactory as their speed and firepower would have made them though opponents, even for HMS HOOD. Don’t forget that due to early AP shell’s unreliability meant penetrations in excess of 229mm not too likely, even at relaitvely short battle ranges The case of the 3 BCs sunk at Jütland turned out recently to be due to insufficient cordite stability and less then aduqate flash protection. From a range or torpedo defense point of view the LEXINGTON in it’s final form would have outclassed any built or planned battlecruiser.

In conclusion we can say that they would have been perfect for the role they were designed that is to conduct tactical scouting for the battleships: they could have penetrated enemy escort screens easily and could cause swift and heavy damage then retreat as fast as they came.

What happened was that after keel laying work only proceeded for 1,5 years before their conctruction was suspended then cancelled in accordance with the Washington Treaty of 1922. The two most advanced units were the USS LEXINGTON CC-1 and the USS SARATOGA CC-3, latter was completed up to her upper decks and even the barbettes were delivered for fitting. From the remaining ships USS CONSTELLATION (CC-2) and USS CONSTITUTION (CC-5) had substantial work done on them, USS RANGER CC-4 and USS UNITED STATES CC-6 barely progressed beyond keel plates and main bulkheads fitted. The majority of the 16”/406mm guns and a lot of the armour plates intended for these ships were manufactured though. The former were used as coastal batteries and at a point was even planned to be used for the BB-61 IOWA class main armament.

14. Figure: On the building ways. As can be seen good progress was made on Saratoga




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