Ship hull forms should be selected like armor schemes

[AiryW]

Just like armor schemes unlock over the course of the game, there should be several hull forms, representing the transition to longer and longer designs over the period.  It should be possible to refit a ship with a longer hull form, this is expensive but increases the displacement.  A hull form should have a maximum speed value, going above that value results in speed penalties from increased friction.  Less advanced hull forms would also have a percentage penalty to effective hullpower, representing displacement and wave resistance.  That means that it could be possible to have the historical outcome of some ships being rebuilt to be longer and attaining higher speeds even without more engine power.  However the benefits of a longer hull form wouldn't be realized unless a ship is fast enough to justify the length.  A longer hull form would also have more armor requirements.  If a player wished to have a short stubby design which is heavily armored it could be possible to do so in the late game by chosing an older hull form.  This could allow for some interesting possibilities with battleships and could also allow for cheaper, smaller ships like destroyer escorts which didn't use up to date engine power.

[Blothorn]

This is already in-game to some extent, just mostly hidden--there are some "improvements in hull form reduce HP requirement techs". (You can see this if you ever try refitting very early ships with much greater speed--advances in engine techs allow some increase, but it is generally prohibitive to push even lightly-armored early ships beyond the mid-20 knot range.) The game just abstracts that from the player.

I know several ships were retrofitted with different bows for improved sea-keeping (which typically increases LOA somewhat), but I don't recall any being rebuilt with substantially longer underwater sections--the structural changes required would be near-prohibitive.

[AiryW]

May 28, 2019 13:29:43 GMT -6 Blothorn said:

I know several ships were retrofitted with different bows for improved sea-keeping (which typically increases LOA somewhat), but I don't recall any being rebuilt with substantially longer underwater sections--the structural changes required would be near-prohibitive.

I think oldpop2000 mentioned some ships like that in a different thread.

[oldpop2000]

You can add a bulbous bow which generally will reduce underwater drag and increase speed, range and fuel efficiency along with stability. Information that I have states that large ships with a bulbous bow have 12-15 percent better fuel efficiency. You can add a torpedo bulge which can reduce damage from torpedoes but that will reduce the length to beam which can reduce speed. The Pennsylvania class battleships and the Yamashiro class battleships did have those bulges added to them in rebuilds during the interwar period. With the addition of proximity fuses for torpedoes, the addition of the bulges was superfluous. Sterns can be modified but generally are not changed much due to the configuration of the rudders and propeller shafts.