[Low-Tech] Landing Craft at TL2 to TL4

[Icelander]

Originally Posted by Anthony

Unless you need to roll vehicles off the ship, any boat capable of landing will do the job.

This is true. On the other hand, the PCs need the capability to quickly land more troops than will fit into their existing ships' boats. Hence, the need for building more. And as these are being built for a single purpose, i.e. amphibious landing, it makes sense to adopt a design optimised for that role and not, for example, a design that needs to be small and light enough for it to be hauled in by larger ships.

Originally Posted by Anthony

Unless you need greater speed and/or stealth, barges are the easiest.

Both speed and stealth are extremely desirable, as the PCs must figure on the possibility that deception and covert strikes by supernatural special forces will not be enough to prevent the opposition from defending their fortified docks with priests, mages, archers, slingers and mechanical artillery launching magical projectiles.

[johndallman]

Originally Posted by Icelander

... actually capture the ports that the other side is using to supply their three great field armies

Originally Posted by Icelander

the PCs need the capability to quickly land more troops than will fit into their existing ships' boats. Hence, the need for building more. And as these are being built for a single purpose, i.e. amphibious landing, it makes sense to adopt a design optimised for that role and not, for example, a design that needs to be small and light enough for it to be hauled in by larger ships.

Both speed and stealth are extremely desirable...

OK, things are becoming a bit clearer now, but there's an open question. Are these craft specialised for landing troops in a port, or on a beach? Or do they need to be able to do both? The latter makes it harder.

For landing on a beach, you want something like a Thames sailing barge. At 25x6 metres, they should be able to carry at least 200 men for several hours, and they're reasonably easy to beach and refloat, providedyou know how the tide behaves off the enemy coast. The TL4 version may not have the leeboard (retractable keel) which will limit their ability to sail fast, and against the wind. If this seems too advanced, something based on a Norfolk wherry will certainly be possible - they existed at the historical TL4.

Note that while these craft will do fine for narrow seas - the English Chanel and North Sea were their habitats - sailing them across large oceans in bad weather is not a good idea. I presume this is happening in summer, before the summer storm season? When dealing with sailing ships, weather is always the primary unpredictable factor. Do the PCs have weather magic? If so, they need to be planning around that.

If you want to sail into a port and capture it, the requirements on the ship are less severe, provided you know how deep the port is and what the tides are doing. You can use larger ships with proper keels, which are much safer in bad weather. You need to provide some defence for the troops on deck, and you need to be able to land them rapidly, and you can combine these requirements by mounting timber movable bridges along the sides of your ships, using them for the troops to hide behind on the way in, and then swinging them out to the shore or wharf for the troops to run down. Of course, you need to know what wharfs are where and how high they are: there are reasons why professional navies collect this kind of information.

[Icelander]

Originally Posted by johndallman

OK, things are becoming a bit clearer now, but there's an open question. Are these craft specialised for landing troops in a port, or on a beach? Or do they need to be able to do both? The latter makes it harder.

They are meant to take ports, but will assume that the enemy will make it extremely hard to land troops on the wharves themselves.

The plan calls for landing troops on a nearby beach, bombarding the barracks from the air by magical means, dispatching summoned aquatic monsters and swimming polymorphed commandos to clear port defences and finally sending in several 'forlorn hopes' of boat-borne assault troops to seize the various floating docks, wharfs and natural landings along the river that runs through the port city.

Lightly equipped volunteers led by PC superheroes and magically-aided commandos will storm the walls of the city from the inside, after landing on the docks. Then they propose to seize a gatehouse and let the troops that landed outside the city in.

Originally Posted by johndallman

For landing on a beach, you want something like a Thames sailing barge. At 25x6 metres, they should be able to carry at least 200 men for several hours, and they're reasonably easy to beach and refloat, providedyou know how the tide behaves off the enemy coast. The TL4 version may not have the leeboard (retractable keel) which will limit their ability to sail fast, and against the wind. If this seems too advanced, something based on a Norfolk wherry will certainly be possible - they existed at the historical TL4.

Both look very nice for their purposes. They'd need faster assault craft to complement them, for the first wave of attackers, but these would do very nicely for landing the main force on a beach and along the river.

Originally Posted by johndallman

Note that while these craft will do fine for narrow seas - the English Chanel and North Sea were their habitats - sailing them across large oceans in bad weather is not a good idea. I presume this is happening in summer, before the summer storm season?

It's spring, in seas fairly equivalent to the Meditarreanean around Alexandria, Egypt.

Originally Posted by johndallman

When dealing with sailing ships, weather is always the primary unpredictable factor. Do the PCs have weather magic? If so, they need to be planning around that.

Both sides have weather magic. There are reasons to assume that the seas will be fairly rough, but there won't actually be a storm.

Originally Posted by johndallman

If you want to sail into a port and capture it, the requirements on the ship are less severe, provided you know how deep the port is and what the tides are doing. You can use larger ships with proper keels, which are much safer in bad weather. You need to provide some defence for the troops on deck, and you need to be able to land them rapidly, and you can combine these requirements by mounting timber movable bridges along the sides of your ships, using them for the troops to hide behind on the way in, and then swinging them out to the shore or wharf for the troops to run down. Of course, you need to know what wharfs are where and how high they are: there are reasons why professional navies collect this kind of information.

The PCs already have some forty warlike sailing ships and around a dozen galleys that could enter a port which they have already seized. Add to that some twenty cargo ships for logistical purposes.

But until the most powerful mechanical artillery pieces are seized or destroyed, it is extremely risky to sail such ships into the narrow confines of a port. Not to mention that aquatic monsters or swimming magic-users could sink them easily.

So the most valuable ships will not enter the harbour until volunteer assault troops in less valuable landing craft have cleared the way and stopped artillery from sinking them.

[benz72]

Originally Posted by Icelander

They've had some two months to construct more boats to aid in their amphibious operations

Here is the key to your answer...
Build as many of whatever type the construction crews are already familiar with and have timbers seasoning for. Don't try changing the design with a 60 day build window.
If it is only towed barges then so be it, but if you try to get fancy and introduce the 'newest greatest thing' as a last ditch defense against an invader who has got you on the ropes you are taking unnecessary risks, not least of which is construction delays while they figure out that bit that doesn't QUITE work.

[Icelander]

Originally Posted by benz72

Here is the key to your answer...
Build as many of whatever type the construction crews are already familiar with and have timbers seasoning for. Don't try changing the design with a 60 day build window.
If it is only towed barges then so be it, but if you try to get fancy and introduce the 'newest greatest thing' as a last ditch defense against an invader who has got you on the ropes you are taking unnecessary risks, not least of which is construction delays while they figure out that bit that doesn't QUITE work.

The PCs are from another realm, far to the west over the local analogue of the Mediterranean, and arrived with a flotilla of ships. They have complete command of the ocean between their homeland and the realm being invaded. They also have significant mercantile contacts in some five or six large cities along the sailing route from their homeland to where the war is.

The invaders no longer have the country for which the PCs are fighting on the ropes, really. They still control 80% of the land area of the country they are trying to take over, but their logistics are falling to pieces, their fleets have gone down in sea battle after sea battle and one of their three field armies just suffered a catastrophic and shattering defeat after the dragonic vassals of a neighbouring power entered the war on the side of the PCs.*

If the PCs manage to take the two cities they propose to seize by seaborne assault, then the majority of the invading troops will be trapped without any way of resupply from the mother country except by a torturous overland route. Which effectively means that they will be unable to hold any part of the country north of those ports they still control. And they'll probably lose thousands, if not tens of thousands, during the retreat.

If the PCs fail to take these cities, it means that the war stalls for both sides. Unless the invaders can win some sea battles in the near future, however, they are not likely to make any more advances and are, in fact, likely to lose some of the territory they now hold, even if the amphibious landings fail.

The sixty day window is because the PCs are impatient to deliver a knock-out blow to the northern armies of the invaders. They want to claim credit for victories even more glittering than that recently achieved by the Wyrm Princess Shudu-Ab, Breath of the Red Ravager, High Priestess of Tiamat, and her dragonic allies.

The PCs could have bought boats abroad and transported them to the theatre of war, but for security reasons, they prefer to have local tribes prone to pirantical ventures construct them on an island where pirates congregate. They'll be used to building small, swift galleys used to raid coastal settlements and the local pirate specialty, a catamaran raiding galley design.

An ideal vessel would be capable of moving something like 50-70 men fairly swiftly, using perhaps 30 rowers, for a total capacity of 80-100 men. Move 3 would be very desirable, with higher Move even better.

*Well, their own side, really, but at the moment, they and the PCs have a joint interest in defeating the invaders before they come to blows over power in whatever post-war polity succeeds the ineffectual and anarchic patchwork of resistance figures.