To begin with, the concept of sinking a galley is a misconception. A galley has a lot of positive bouyancy and
even when full of water there is little chance of it disappearing beneath the waves.
A galley which had been at sea some time without being dried-out and was burnt-away to some degree above the waterline may have gone down but the usual occurrence was that the hull would just settle in the water.
The main effect sought by a ramming attack was to breach the hull of the target and render it unmanageable as it was flooded and swamped. The victor in an ancient sea battle preferred to recover damaged hulls for salvage rather than watch such expensive items sink or burn.
We have evidence of baling procedures and capabilities in ancient ships beyond that manual balers are known from archaeology
|Baler from Nydam ship c.300AD|
|'Well you said you wanted to be paid to screw for a living!'|
The post of baler was a lowly one for an older or duller crew-member. He used his antleteria or bucket to keep the bilge levels down. In a pinch he would be assisted by more men. On a trireme there were about 10 deck crew in two teams who could help before oarsmen would be called upon.
In a trireme it would have been no easy task to bale at a fast pace in the restricted space down even below the world of the thalamian oarsmen. The bucket had to be filled, handed up to a level where it could be dumped overboard and returned below.
|Roman bucket. Owner kicked it, down a well, long ago.|
HOW MUCH WATER COMES IN ?
To work-out how much water comes in-board we must determine the size of any expected hole. To determine the size of hole expected we can examine the size of the hole-maker i.e. the ram.
We now have about a dozen rams to measure and they can be associated with various classes of ship. This gives us an approximate range of holes to put into any calculation.
The amount of water coming in to a hole of a specific size is governed by the
Flood Rate per minute in tonnes =
[100 b (h3/2)]
where b= breadth, h= height in metres, of hole, for the part of the aperture below the waterline.
Here we can see how much flooding each ram can generate.
RAM DRIVING CENTRE DRIVING CENTRE FLOOD
HEIGHT BREADTH RATE
EGADI 1 22 41 4,2
EGADI 2 20 31 2,7
EGADI 3 22 37 3,8
EGADI 4 22 36 3,7
EGADI 5 22 32 3,3
EGADI 6 24 41 4,8
EGADI 7 24 38 4,5
EGADI 8 C.29 EST. 50 7,8
ATHLIT 35 65 CIRCA. 13,5
Capo Rasocolmo c.30 c.60 9,8
ACTIUM EPTEREIS(7) 95 C. 46 !
ACTIUM ENNEREIS(9) 110
ACTIUM DECEREIS(10) LARGER SCARY NUMBER
It is a little hair-raIsing to find that the rams of larger ships create holes that allow massively more flooding. The larger vessels displacement increases as a cubic value as their dimensons increase so they could tolerate damaging each other but if a larger class ship hit a smaller one we can see the effect would be catastrophic.
The Athlit ram is probably from a 3. This shows that the rams from egadi are from lighter warships. The Actium rams are from Anthony's monsters.
|ACTIUM MONUMENT : ENNEREIS LEFT, ATHLIT RIGHT|
If we take a standard bucket to have a capacity of .035 of a cubic metre or 33cm deep, wide and high(large bucket!) then with the ten deck crew working fast enough to each dump two buckets a minute - a back-breaking rate! - then they can remove 0.7 cubic metres a minute or 0.7 tonnes.
From this we can see that a ship's crew would rapidly appreciate the severity of a successful ramming attack on their vessel. They would rapidly realise the inevitable result. The ship's officers and the epibatai would have a difficult job to persuade balers to work at this Sisyphian task or to keep the thalamians at their oars as the water level rose!
WHAT IS THE EFFECT OF FLOODING ?
Within a minute of a successful ram attack from another ship of the same class we can say a trireme may have taken 5 tonnes of water onboard. With the deck crew baling, the ship will take on 4 tonnes each subsequent minute thereafter. The effects of this on a ship have been calculated by John Coates.
Firstly, the displacement of the ship increases, causing it to settle in the water.This leads to the vertical centre of gravity of the ship being lowered. It 'settles ' down into the water.
However, a more sinister effect is that the mass of water in the ship has its own centre of gravity and its own life, sloshing within the ships structure. The higher up the ship the water reaches the worse is the effect of the 'sloshing'. - the inertia of the water mass will accentuate any movement of the vessel and make slight imbalances in the ship create extreme rolling or pitching. This is a resut of the Free Surface Effect of an unrestrained body of water within the hull. Also, as the water level rises inside the ship it will settle deeper into the water.
|Va's up ? or, rather , down...|
This amount of water would be inboard less than two minutes after being rammed.
If the flooding continues for a further 5 minutes 30 tonnes of water is now inboard.
With 30 tonnes of water inside the hull of a trireme the settlement will now be 25cm. Looking inside the hull one would see water was lapping over the floor timbers. Maybe not such a threatening sight. But now the ship is totally out of balance and requires very careful handling. A sharp turn could capsize the ship. Rowing becomes ineffective except in a flat calm. The increased displacement - the ship now effectvely weighs 70 tonnes - would overload the hull and it could split open in a swell as it 'hogged' when the bow and stern sag into wave troughs.
|A weak-hulled container-ship hogs and breaks-up.|
Five mnutes after being rammed by a ship of its own class a trireme would be disabled.
The oarsmen could not propel the ship which now weighed 50% more than in battle order.
The ship would roll if turned or if many men move about. At some point the sloshing water mass inboard would probably throw the ship onto one or other side from which it could not recover . Water would enter the oarports and its fate would be sealed.
The capsized ship would not sink but steadily settle in the water. Oarsmen would emerge from their confines and their presence on deck would only add to the hulk's instability.
If there was a significant swell or the ramming impact and hole was large enough then the hull may split as the displacement exceeds its strength.
Once successfully rammed a trireme was doomed, and the crew well knew this ! Could onboard discipline keep order as the inevitable happened?
It is a sobering fact that the 150 crew of Olympias, after some training in forming-up in ranks on specific areas on the quayside and getting themselves installed at their oars in sequence with the thalamians first and thranites last, could be ready to sail in about 1 minute and thirty seconds from getting the word 'go!';
but that same crew when abandoning ship could leave the trierarch alone and pondering whether to flounder with his vessel in precisely 24 seconds !
The ancient galley sea battle was a high-stress duel between rapier-armed fighters who sought to keep their balance and poise, keep their guard up and look for the opening which could lead to a well-timed thrust into the enemy's vitals. Once pierced, the target was doomed and its combat role in the battle soon over.