Colosseum Builders—Volume 3 of The Structure of the Iowa Class Battleships

What do model kits get wrong?

Model kits tend to get the bow, and especially the stern, way off. The Iowa-class battleships have a bulbous bow. Unlike modern ships with a bulbous bow, the Iowa-class have a knife edge extension above the bulb.

Sterns tend to have several errors. The first among them is that they tend to depict the Iowa-class as having skegs. Many books also refer to the extensions housing the inboard propellers as skeg. Yet the Iowa-class battleships do not have skegs. None of the plan for the Iowa-class use the term skeg. The actul plans call these structures twin keels.

Skegs

Historically, skegs are a (1) center line (2) extension from the keel that (3) mounts a rudder. The twin keels are not on the center line. In modern usage, a vessel can have skegs off the center line. However, the next issue is that the twin keels are not extensions from the hull. They are an integral part of the hull structure. Finally the twin keels do not mount a rudder.

When a kit tries to represent the twin keels as extensions to the hull, rather than an integral part of the hull, the result is a misshapen hull form. The most visible issue is the length of the outboard shafts outside the hull.

Docking Keel

Kits tend to omit the docking keel that extends into the tunnel between the twin keels. The docking keel supports the weight of turret number three when the ship is in dry dock.

Half Siding

Half siding is an area of the ship that extends horizontally and linearly from the keel center line. Half siding is either flat or it bends along the keel. The Iowa-class have half siding from the bow to the stern. The half siding descends at the bow, then it is flat for most of the ships' length. Then it narrows and rises upwards in the twin keel's tunnel. As it emerges from the tunnel, the flat siding widens to create a mounting location for the rudders. Moving it narrows and ends at the stern.  Kits tend to depict the area of the hull at the rudders as being curved but lengthwise and crosswise.

Knuckles

The hull form has two knuckles towards the stern. The upper knuckle is visible in photographs. The lower is below the waterline. Amidship the hull cross section is vertical. Aft of this vertical section, the hull form divides into three areas separated by knuckles. The upper two areas have a linear cross section forward. Moving aft, the hull form starts to curve and eventually the three areas return to a continuous curve at the stern.

Plating

Some kits have started to include seams between the plating strakes. The problem is that these seams are only visible above the waterline at the bow and stern where the strakes lap. Elsewhere, where the strakes butt, you have to get very close to the ship to pick the lines out. Even where the plates lap, they  are beveled and  the plates are about 1/2" thick. Even at a huge 1:96 scale, a lap is only about 0.005", making it nearly invisible.
At least one kit depicts plating lines between plates within strakes. Almost all of these joints are butted and are hard to see up close on the ships. Even if the strake divisions were visible in scale, the lines shown on kits tend to be a work of fiction. Why go to all the trouble of depicting strake divisions and then do it wrong?  

Bilge Keel

The outer edge of the bilge keels on the Iowa-class battleships do not form a continuous, second degree curve. The natural curves of the bilge keels are truncated at the side and bottom so they will not extend beyond the hull form. This gives the outer edge a distinctive wave that is clearly visible in photographs.