---
title: 'Cracks start at square corners: make corners round!'
url: https://propagandaarchive.org/collection/cracks-start-at-square-corners-1944/
description: 'Technical instruction sheet: a small ship silhouette is magnified in a red circle to show a crack running from a square corner.'
section: Collection
---

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3. Cracks start at square corners: make corners round!

[![Cracks start at square corners: make corners round!, 1944 US poster: Technical instruction sheet](https://propagandaarchive.org/collection/images/cracks-start-at-square-corners-1944.jpg)](https://propagandaarchive.org/collection/images/cracks-start-at-square-corners-1944.jpg)

# Cracks start at square corners: make corners round!

Technical instruction sheet: a small ship silhouette is magnified in a red circle to show a crack running from a square corner, with a diagram and formula for how round to make corners. It presents a single engineering fact plainly. The persuasive element is the visual link from one crack to a whole ship; no emotional technique is strongly present.

## Propaganda techniques used in this poster

[Card stacking](https://propagandaarchive.org/techniques/card-stacking/)

## Text on the object

Original (English) · read from the image, not independently checked

```
CRACKS
START AT SQUARE CORNERS
MAKE CORNERS ROUND!
HOW ROUND?
r
S
W
S
WHERE
r = RADIUS OF CORNER
S = DIRECTION OF PRINCIPLE
STRESS
W = WIDTH (PERPENDICULAR
TO STRESS)
THEN
r SHOULD BE NOT LESS
THAN 1/8 W - AND PREFER-
ABLY 1/4 W
[imprint: NAVY DEPARTMENT, BUREAU OF SHIPS   APRIL 1, 1944]
[imprint: PRINTING OFFICE 1944-O-581666]
```

[← Cover coughs, cover sneezes. Never give a germ a break!](https://propagandaarchive.org/collection/cover-coughs-cover-sneezes-war-department-1944/) [Cut Neglected - Soon Infected →](https://propagandaarchive.org/collection/cut-neglected-soon-infected-navy-1944/)

## More propaganda examples that use the same techniques

- [Fragments of the Abydos king list from Ramesses II's temple, in the British Museum: rows of royal cartouches](https://propagandaarchive.org/collection/abydos-king-list-ramesses-ii-temple-british-museum/) (New Kingdom Egypt · 0000 · Card stacking, Transfer)
- [Behistun (Bisotun) rock relief and trilingual inscription of Darius I: the king, two attendants and the bound rebel leaders beneath the winged figure of Ahuramazda](https://propagandaarchive.org/collection/behistun-relief-darius-and-rebels-521bce/) (Achaemenid Empire · 0000 · Card stacking, Name-calling, Testimonial). Content note: Shows bound captives before the king, and the inscription records the mutilation and public execution of rebel leaders, as the king's own account.
- [Tomb of Darius I at Naqsh-e Rustam: the king in relief beside his inscription DNa, c. 490 BCE](https://propagandaarchive.org/collection/dna-inscription-darius-i-naqsh-e-rustam-490bce/) (Achaemenid Empire · 0000 · Testimonial, Card stacking)
- [Line drawing of the Great Kadesh battle relief on the walls of the Ramesseum, from Breasted's History of Egypt](https://propagandaarchive.org/collection/kadesh-relief-ramesseum-breasted-drawing-1275bce/) (New Kingdom Egypt · 0000 · Card stacking, Transfer). Content note: A drawing of an Egyptian royal battle relief showing Hittite soldiers and horses killed and drowned, as the king's monument presented the battle; it is a one-sided image made by the winning side's own account.
- [Persepolis, Apadana staircase relief: a figure with an animal from a procession of delegations, early fifth century BCE](https://propagandaarchive.org/collection/persepolis-apadana-delegate-relief-500bce/) (Achaemenid Empire · 0000 · Card stacking, Manufactured consensus)
- [Alabaster relief, Assyrian troops storming a citadel, from Nineveh (reign of Sennacherib)](https://propagandaarchive.org/collection/relief-sennacherib-storming-citadel-nineveh-704bce/) (Neo Assyrian Empire · 0000 · Card stacking). Content note: An Assyrian palace relief of troops storming a fortified city, with a file of figures below; Assyrian royal reliefs and texts record killing, mutilation and deportation, shown as carved, with the historical context and scholarly dispute on the regime page.
- [Colour lithograph of the Latin text of the Res Gestae Divi Augusti on the wall of the temple of Roma and Augustus at Ancyra, with the heading in large letters (Perrot, Guillaume and Delbet, 1872)](https://propagandaarchive.org/collection/lithograph-res-gestae-ancyra-heading-0014/) (Roman Empire · 0014 · Card stacking, Glittering generalities)
- [Silver denarius of Vespasian, reverse IVDAEA with a trophy of arms and a seated mourning woman](https://propagandaarchive.org/collection/denarius-vespasian-judaea-capta-0070/) (Roman Empire · 0070 · Card stacking). Content note: A Roman victory coin showing a mourning female figure as the personification of the conquered province of Judaea after the Roman suppression of the Jewish revolt; shown as struck, with the historical context on the regime page.