1 Samuel 17:4-7: And there went out a champion out of the camp of the Philistines, named Goliath, of Gath, whose height was six cubits and a span. And he had an helmet of brass upon his head, and he was armed with a coat of mail; and the weight of the coat was five thousand shekels of brass. And he had greaves of brass upon his legs, and a target of brass between his shoulders. And the staff of his spear was like a weaver’s beam; and his spear’s head weighed six hundred shekels of iron: and one bearing a shield went before him.
Goliath of Gath was the giant warrior champion of the Philistines. His height of six cubits and a span equate to a modern conservative measurement of nine-feet and six inches, whilst his coat of mail (or scale armor) whose weight was five thousand shekels, equates to a modern weight exceeding 125-pounds! With this in mind, it is not difficult to see that the estimated total weight of Goliath’s armor and weapons was about two-hundred pounds! Goliath was indeed one big and intimidating guy, and a formidable force to be reckoned with.
But it is the size of Goliath’s spear to which we want to give our attention. The Bible records that it was like a weaver’s beam and that the weight of the spear’s iron head was six hundred shekels. The ancient shekel was a unit of weight used in transactions before the wide use of coins. The weight of a shekel was .445 ounces or 12.9 grams, so the spears head had a total weight of 16-pounds, 11-ounces! A replica spear has already been made according to the biblical measurements and description of the weapon, and allows us to truly appreciate its size and weight. The spear head measures at 26-inches in length, 7.8-inches in width, and of course, 16-pounds, 11-ounces in weight.
In the time of David, the weaver’s beam of a warp weighted loom was between 2-inches to 2.5-inches in thickness, thus the biblical reference to the weaver’s beam is given to emphasize the unusual thickness and strength of the shaft. But for the physics of Goliath’s spear to work properly with a 16-pound, 11-ounce spear head, the shaft of the spear would have needed to be about ten-feet in length and two-inches in diameter.
The spear would also have needed a 6-pound, 1.2-ounce counterweight, giving the spear a total length of 12-feet and 7 inches and an overall weight of 33-pounds, 12-ounces! Goliath’s actual spear may have been longer, but conservative weights and measurements were selected in the creation of the replica. The calculated length of the replica spear would allow Goliath to have a good center of balance in order to hold the spear easily with one hand about 62 inches from the tip, and would have allowed him to thrust it directly at the enemy to achieve the best leverage and killing force.