Saturday, 28 November 2009


The innovative harpax or siezer as devised by Agrippa had three novel elements (according to Appian).
1)uncuttable fastening between grapnel and rope
2)catapult projection into the enemy ship
3)a mechanical traction to draw the ships together

The attachment of several ropes to the same grapnel may have been novel or not.
The business end was quite heavy, an iron grapnel, a main stem bound with iron and having rings at each end for fastening and the several ropes behind it. Appian says, however, that it was light enough to be projected a considerable distance into the enemy ship.

A 13Kg stone took a machine weighing up to 3 tonnes to throw it.
The Syracusia, Hieron of Syracuse's colossal 55m ship was equipped with exceptional bolt throwers which took projectiles of 18feet length.

The harpax projectile was 5 cubits long, (x45cm = 225cm or nearly 7feet. The common Scorpio or manhandleable oxybeles threw a bolt of 27"/67cm. The harpax projectile was bound in iron, fitted with iron rings and had a grapnel linked onto the front, in addition it trailed several strong ropes: whatever Appian says, it was not light.

This shows us that the engine part of the harpax system was of considerable size.

At Naulochus Appian describes both sides ships as being of similar size and appearance with towers on the deck. The smallest ships with towers I can find reference to are 4's.

Casson reckons a 4 could ship a handful of light bolt shooters and a pair of 3kg ball-throwers. 3kg is not enough to throw a harpax projectile. This limits the use of harpax to ships of 5 or larger, I would suggest, which could safely mount a large thrower and the winching gear on a superstructure strong enough to take the stresses of its use.

The siezer, like the other Roman innovation for sea combat, the raven, did not retain its tactical surprise advantage for long. Appian implies that by his time it was normal for ships to be equipped with scythes on long poles so that even the siezer's long projectile could be cut free of the trailing ropes. A simple solution to neutralise such a complex weapon system: but a weapon which functioned long enough to give Octavian an edge in sea fighting and help him gain supremacy.

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