On 25Mar2017 1143, Phil Pugliese (via tml list) wrote:

> I recall reading somewhere that it took a really, really massive
> increase in SHP to get the Iowa class BB's an extra, what, 5 knots
> faster than the NCarolina class. In fact, as I recall, most of the
> increase in displacement was due to the increase in power required.

That's correct. Power went from 120,000SHP to 212,000 SHP, speed from
~27 knots to ~33 knots, and displacement from a nominal 35,000 tons to
over 45,000 tons. The armour scheme was arguably worse (though it
weighed more, it had to cover more side and deck area, and compromises
had to be made to under protection of the fine bow), the guns basically
the same in performance (though lighter), but in more cramped turrets.

The Iowas were also even less seaworthy than previous US battleships,
which all suffered from insufficient freeboard at the bow and were thus
very wet - the Iowas very long, fine bows meant that they lacked
buoyancy forward and thus tended to plough into waves they should've
gone over.

Note that HMS Vanguard, of similar displacement and era, made 30 knots
on 130,000 SHP, and was rather more seaworthy. She was also (turret
faces aside) better protected, though her old 15" guns were inferior in
power and number to the Iowas' 16" guns (OTOH the 15" Mk.II guns and
mount were very reliable, and aside *possibly* from a slugging match
with a Yamoto, plenty powerful).

Those 6 knots were *very* expensive.

--
Rupert Boleyn <xxxxxx@gmail.com>
Chief Assistant to the Assistant Chief