“And God said to Noah, I have determined to make an end of all flesh; for the earth is filled with violence through them; behold, I will destroy them with the earth. Make yourself an ark of gopher wood; make rooms in the ark, and cover it inside and out with pitch. This is how you are to make it: the length of the ark three hundred cubits, its breadth fifty cubits, and its height thirty cubits.” (Genesis 6:13 – 15)
The word cubit (′kyü-bǝt) in English appears derived from the Latin cubitum for elbow. It was πήχυς (pay′-kus) in Greek. The cubit is based upon a human characteristic – the length of the forearm from the tip of the middle finger to end of the elbow. (Stone)
“[I]t was from the members of the body that they derived the fundamental ideas of the measures which are obviously necessary in all works, as the finger, palm, foot, and cubit. These they apportioned so as to form the ‘perfect number,’ called in Greek τελειον, and as the perfect number the ancients fixed upon ten.”
“For it is from the number of the fingers of the hand that the palm is found, and the foot from the palm. Again, while ten is naturally perfect, as being made up by the fingers of the two palms, Plato also held that this number was perfect because ten is composed of the individual units, called by the Greeks μονάδεϛ.” (Vitruvius)
The Cubit is a unit of linear measure used by many ancient and medieval peoples. It may have originated in Egypt about 3000 BC; it thereafter became widespread in the ancient world. (Britannia)
The cubit was a basic unit in early Israel and the surrounding Near East countries. The Tabernacle, the Temple of Solomon, and many other structures are described in the Bible by cubit measures.
It is אטה in Hebrew (pronounced am-mah′), which can be interpreted “the mother of the arm” or the origin, that is, the forearm/cubit. (Stone)
To some scholars, the Egyptian cubit was the standard measure of length in the Biblical period. The Biblical sojourn/exodus, war, and trade are probable reasons for this length to have been employed elsewhere. (Stone)
The cubit, generally taken as equal to 18 inches, was based on the length of the arm from the elbow to the tip of the middle finger and was considered the equivalent hand measurements of 6 palms or 2 spans. (Britannica)
Fathom, old English measure of length, the longest of many units derived from an anatomical measurement, is now standardized at 6 feet, has long been used as a nautical unit of depth. A fathom equals four cubits.
The fathom originated as the distance from the middle fingertip of one hand to the middle fingertip of the other hand of a large man holding his arms fully extended. The name comes from the Old English faedm or faethm, meaning outstretched arms. (Britannia)
Hawaiians used a similar unit of measurement to the cubit – the ha‘ilima; it is the measurement from the tip of the longest finger to the elbow of the same arm.
Variants of this include:
Iwilei – (equivalent of two ha‘ilima) measuring from the center of the chest to the tip of the longest finger while the arm is stretched out to the side of the body, parallel to the ground
Muku – (equivalent of 3 ha‘ilima) resembling the hula stance, both arms stretched out to the side of the body and parallel to the ground, then bend one arm at the elbow inward to the center of the body; the measurement is from the bent elbow to the tip of the longest finger of the opposite arm.
‘Anana – (equivalent of 2 iwilei or 4 hailima) measuring from longest fingertip to the longest fingertip when both arms are stretched out and parallel to the ground.
Many people were taller or shorter to measure these lengths. Say Kamehameha who was tall said build a canoe twenty Ha’ilima (18”) long or 30 feet tall but a menehune short man measured it at 12”. It would be 20 feet long . A rope measure could have been a better consistent of say a yard or 36”. Making a constant of this type must have been done.