Siege Equipment

Does anyone have a good understanding of how siege equipment works? Once a tower reaches a wall the units can move up it, so are they subsidiary to the tower or does the animation have them walking in mid air? Further more are units like onagers hardcoded, as in, could you make a unit which starts on the battlefield with say, a siege tower?
I'm loosely kicking around the idea of naval battles, which I think are more realistic in BI than RTW because of options such as swimming. I was thinking the best way to do it would be to have a unit of marines with a siege weapon shaped like a boat, with the capabilities onagers have to use special abilities different from those of the units using them originally.

the climbing animations for ladders are seperate from the ladders. What i mean by that is if you changed the distance of the ladder rungs the animations would not be affected and look very odd. The units however are not seperate from the ladders. One way to look at the ladders is a strip of land that requires a different animation to walk across it. The ladders in seige towers work the same way. The platforms within the seige towers are needed (the units actually stand on them). Also Im pretty sure that you cant change around the inside of seige towers as i believe the path the units take is hardcoded. Removing or changing the ladders and/or platforms may disrupt this path and cause the units not to be able to walk up the tower.

As for units starting with seige equipment im almost positive this is impossible but i cant say that for certain. I know you can get a unit to have a seige engine but i doubt if it could be used correctly.

Hmm. But if the ladders are considered a strip of land technically a ship could be a unit sailing, then when units are fighting between ships it would be like boarding another strip of land.

I see what youre saying but i dont think its possible. I dont think its possible for units to start the battle inside a seige tower (or on a ship). Also seige towers can only connect to walls. There would be no boarding from ship to ship.

I rememebr someone else was trying to tackle the problem of naval battles a long time ago. Nothing ever came of it sadly. If im correct i believe he replaced an elephant with the ship model and then placed archers on top. This works well with ramming and such and makes it relatively simple to craete a low tech naval battle. In this way however boarding is not possible nor is seige equipment on the ships. Ships will not burn either. Only archers and ramming. As well as the chance to run amok.

Thats all i can think of at the moment. Its late and im tired.

Did he manage to create a sea map then? Units can be killed within siege towers without the tower being damaged, therefore I think if an animation which could be used within the ship could be made, where units (hoplite marine type) fight between ships with spears, you could have a reasonably high tech naval battle. Also I don't see any reason why ships wouldn't be able to use catapults and balistas in the siege unit method, (btw why isn't it possible in the other method? If you have the ship as the elephant the catapult can be a top section animated to swivel and fire like an onager on a turret). I've already made a trireme model and some new marine units, does anyone remember how far the last attempt at this got?

Have you taken a look at descr_engines.txt yet? That describes a lot of the non-hardcoded stuff for siege engines.