In connection with the specific expression "scale-armour-clad[鱗甲]" appeared in an old document which was recently found in Chŏlla Province, the present review reveals the realistic features of the iron-armour-clad for the combat turtle-boats, based on the steady approach of the author's former works. This documentary record concerning turtle-boats has been confirmed as a draft (or copy) for the memorials to the court written by the Kyŏngsang Left Navy Commander in 1748, i.e., almost 150 years after the Admiral Yi Sun-sin's death, and 47 years before the edition of the Complete Works of Yi Ch'ungmu-gong (1795). In the memorials to the court, the importance of tactical role of turtle-boats is repeatedly emphasized, and the necessity of the replacement of conventional board-roofed vessels by turtle-boats is strongly proposed appreciating Admiral Yi Sun-Sin's merits of ultimate victory by use of turtle-boats. Also, the "scale-armour-clad" turtle-boat is well likened to an armoured war horse dashing into enemies. The most important phrase in the record for the present review is a part of explanation for the roof-deck shielding.—It reads "...The so-called turtle-boat is roofed with planking without any turret, and then covered additionally with the scale-armour-clad" [...所謂龜船則不以爲樓以板爲蓋仍作鱗甲]. Next, the scale-armoured roof-deck would be properly studded with iron-spikes as in Admiral Yi Sun-sin's turtle-boats. Then, what is the scale made of? The answer will be iron, i.e., iron-scale. Originally the letters 鱗 and 甲 mean "scale" and "armour", respectively, and the word 鱗甲 has meanings of Crustacea, hard crustacean shield, or scale-like hard shell. So it has been used to term the armour with metal scales. The expressive terms hereon would correspond to the iron-armour-clad, i.e., forged thin iron-plates. Because, the only fireproof hard cover available for the turtle's back at that time must have been thin iron sheets. The shape of the unit iron-plate-scale may be rectangular (or hexagonal with proper dimensions). It is well known that the unique patterns of iron-armour-clads in the form of scale-plating on thick planking doors exist at wall gates built in the early periods of the Chosŏn dynasty. This offers a reliable model concept to realize such an expression used in the above-mentioned record. The draft for the memorials written by a naval commander identified as Yi Ŏn-sŏp offers the first written evidence for the iron-armour-clad of the turtle-boats.