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Old 01-23-2015, 02:25 PM   #11
Icelander
 
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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Originally Posted by johndallman View Post
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.

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Originally Posted by johndallman View Post
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.

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Originally Posted by johndallman View Post
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.

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Originally Posted by johndallman View Post
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.

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Originally Posted by johndallman View Post
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.
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Old 01-23-2015, 03:54 PM   #12
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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Most ships, certainly most purpose built warships were capable of being beached. Perhaps not a giant roman bread vessel, or one of those monster warships of the Macedonian Succession Wars that they were so ridiculously fascinated with and did little good to anyone but Archeologists. But a typical Venetian galley or Norse longship, or a Macdonald Berlinn(Scotch galley) could do so and would routinely on various missions. No Ancient or Medieval power needed specialized landing craft as such very much.

What was needed was something that could carry the horses and heavy impedimenta of a first class army. But back country polities like the Norse and the Macdonalds wouldn't have such amenities, and powers like Venice that were chiefly maritime would place lower priority on them.
The PCs are using frigates, brigs and 'war caravels' that are TL3+1 or TL4+1 sailing ships. Their allies have TL2+1 galleys and liburnians, as well as TL2+2 catamaran raiding galleys.

The PCs have two large horse transports that are converted medievalish galleys and two more should be ready when the attack is launched.
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Old 01-23-2015, 05:32 PM   #13
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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I seem to recall several accounts of crusaders using ships fitted with ramps via which horsemen could ride directly onto the shore - probably the medieval version of an LST.
Four older war galleys that were captured by men under the PCs have already been converted to hippogogi/taridae, i.e. horse transports that can carry some 25-30 horses each, along with riders and war harness.

They'll be used in the assault againt the larger city, landing a cavalry force of around 100 men on a beach outside the city, meant to screen the advance of the army that lands outside.

They'll probably be packed with men as well, as many as can fit on them, as they'll only be sailing a distance of 25 miles to make the landing.

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In the C19, I also seem to recall accounts of shallow draft, square bowed boats being used to land troops - probably modified lighters and mainly used to land horses, guns and/or stores as troops can be landed in regular boats.
Yes, but what are reasonable GURPS stats for such larger versions of ships' boats like longboats and cutters?

I'm principally interested in what kind of Move one can expect, with maybe 12 rowers for the smaller versions, up to 30 for the largests.
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Old 01-28-2015, 07:32 AM   #14
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

Some of the best landing craft look to be captured galleys and the light coastal raiding vessels of local pirates, largely because they are already purpose-designed for landing warriors to loot and pillage.

However, the PCs most likely do not have enough of those to land all the thousands of troops that they need.

Assuming that you can get several carpenters and an infinite supply of semi-skilled labour to work on each craft, what is a reasonable vessel to build in 60 days?

How long does it take to build a TL2 galley like the bireme or any other type that's fairly simple to build (i. e. not the huge polyremes)?

What about the earlier heroic Greek penteconters, which are essentially just long open-decked boats?

Or a typical Age of Sail ship's boat, like the cutter or longboat?

And how much does it change stats to make the galley or boat wider, enough so it could hold maybe as many passengers as rowers?

That would obviously slow them enough to make them useless in ship to ship combat, but these are landing craft, not fighting ships.

How many passengers could one transport with 30 rowers while still attaining Move 3? What kind of vessel would you use?

If I want to transport ca 5,000 soldiers and not need more than 2,000 rowers and sailors*, but I want Move 3+ for at least a thousand of them and at least decent pace of landing for the rest, what size of boats, open-decked galleys or barges do I want?

*For the actual landings. The rest of some 10,000 sailors and about a hundred ships will be busy with the logistics that allow the landing and keeping enemy ships away by controlling the seas.
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Old 01-28-2015, 08:02 AM   #15
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

There doesn't seem to be much written up on shipbuilding for 4e. The nearest thing I can find is this sidebar in High-Tech for 3e:
Quote:
BUILDING A SHIP
A successful roll against Shipbuilding is
required to plan a sailing vessel.
Construction of a 50- to 100-ton vessel is a
task requiring about 2,000 man-hours of
labor (see p. B93), at least 500 of which
must be by laborers with Carpenter and
Blacksmith skill; a Shipbuilder of skill 12 or
better must supervise. Another 1,500 hours
of unskilled labor, and 500 hours of
Carpentry, are required if the timber for
construction must be felled. A final roll
against Shipbuilding skill will give the GM
an idea of just how good the finished ship
is. (Full shipyard facilities would give a +3
or so to Shipbuilding rolls.)
This means that a crew of a dozen men,
shipwrecked on an island with timber, could
build a seaworthy vessel in only two months
provided they had the necessary skills and
tools, and could salvage the metal fittings
and sails from their old ship.
Under 4e, Shipbuilding is replaced by Engineer (Ships), and Blacksmith with Smith (Iron).
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Old 01-28-2015, 08:04 AM   #16
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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Originally Posted by Icelander View Post
I'm principally interested in what kind of Move one can expect, with maybe 12 rowers for the smaller versions, up to 30 for the largests.
You might be able to use Ghostdancer's Sailing the Open Skies article (Pyramid #3/64) here. Briefly, a vessel can have up to 3 oar systems, with one giving it Move 1/3 and each additional increasing maximum speed by +1. An SM +5 (30 ton) ship needs 4 rowers per system, SM+6 (100 ton) needs 12 per system, and SM+7 (300 ton, the largest that can use oars) needs 40 per system. The article suggests, in a cinematic campaign, allowing strong characters to count as more than one rower - each doubling of BL from 20 counts as an additional rower (EDIT: If you want to allow characters to have a fractional effect, log base 2 of BL/10 will give you your multiplier. An ST 12 character thus counts as 1.5 rowers. Note this will mean characters with ST 7 or lower can't contribute).

In a highly cinematic setting, or one where humans can be superhuman thanks to magic, it might be appropriate to allow very strong rowers to function as though the ship had more systems than it does. That is, if you have a 30 ton ship with 4 ST 20 rowers, each of those rowers is functionally equal to 3 normal rowers (they double BL 20 twice), so the ship has Move 1/5 as though it had three systems. If the above ship did have three systems, and each of the 12 rowers had ST 20, they'd count as 36 rowers. That's 9 systems, for something like Move 1/11.

Last edited by Varyon; 01-28-2015 at 08:13 AM.
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Old 01-28-2015, 09:24 AM   #17
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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You might be able to use Ghostdancer's Sailing the Open Skies article (Pyramid #3/64) here. Briefly, a vessel can have up to 3 oar systems, with one giving it Move 1/3 and each additional increasing maximum speed by +1. An SM +5 (30 ton) ship needs 4 rowers per system, SM+6 (100 ton) needs 12 per system, and SM+7 (300 ton, the largest that can use oars) needs 40 per system.
I hadn't noticed that an article about airships had Oars as a system for the Spaceship design system. Neat.

I can't help but notice how excessively favourable it seems, compared to real life, though.

First of all, why would there be 144+ rowers on historical rowing ships, going up to 420 rowers or so for the biggest galleys that can't be explained as hyperbole in ancient sources, if 120 rowers could attain the maximum speed for a ship up to 300 tons in weight?

And why would the sole historical war galley design to demonstratably attain Move 5 use significantly more than 120 rowers (170) and weigh less than a third of 300 tons (less than 80 tons fully loaded)?

Also, what prevents a SM +8 ships from having oars, given that GURPS already gives the vast majority of historical galleys SM +8? Except the SM +9 'turtle ship', of course.

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Originally Posted by Varyon View Post
The article suggests, in a cinematic campaign, allowing strong characters to count as more than one rower - each doubling of BL from 20 counts as an additional rower (EDIT: If you want to allow characters to have a fractional effect, log base 2 of BL/10 will give you your multiplier. An ST 12 character thus counts as 1.5 rowers. Note this will mean characters with ST 7 or lower can't contribute).

In a highly cinematic setting, or one where humans can be superhuman thanks to magic, it might be appropriate to allow very strong rowers to function as though the ship had more systems than it does. That is, if you have a 30 ton ship with 4 ST 20 rowers, each of those rowers is functionally equal to 3 normal rowers (they double BL 20 twice), so the ship has Move 1/5 as though it had three systems. If the above ship did have three systems, and each of the 12 rowers had ST 20, they'd count as 36 rowers. That's 9 systems, for something like Move 1/11.
Realistically, attention needs to be paid to matching rowing power on both sides, but there is nothing inherently unrealistic or cinematic about scaling the motive power generated by each rower by his strength (or indeed, by some combination of strength and skill).
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Old 01-28-2015, 09:31 AM   #18
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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There doesn't seem to be much written up on shipbuilding for 4e. The nearest thing I can find is this sidebar in High-Tech for 3e:

Under 4e, Shipbuilding is replaced by Engineer (Ships), and Blacksmith with Smith (Iron).
Hmmm... thanks for that.

This would seem to allow the building of penteconters or even more advanced models of war galleys in quite a short time.

Good for the PCs now, as it means that their allies in Messemprar will have been able to make use of the months while their control of the sea ensured plentiful shipping to Messemprar to import as much wood as they require and basically build as much of a navy as they can afford.

Pretty bad for them later since it means that the empire they are facing will require about one third of the time I had estimated to put out a new fleet to replace ships they have sunk or captured. Spending a few dozens of GURPS $ millions on new galleys won't even cause them to blink, their annual naval budget is already some $60,000,000 and that was while they were winning the war and used naval ships just to defend their grain ships from pirates.

Of course, being able to build them quickly won't help the enemy man their ships, as they already suffer from not having had much of a native tradition of seamanship, ocean voyaging, seaborne trade or sea warfare* before this war.

Most of their foreign trade for the past century or two has been transported in foreign hulls and their navy has always been low-prestige and neglected compared to their army. The fact that several nautical disasters and some defeats at sea killed off some 80% of their experienced navy men a few years before the start of this war didn't help.

*At least within the past few centuries.
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Old 01-28-2015, 10:14 AM   #19
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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This would seem to allow the building of penteconters or even more advanced models of war galleys in quite a short time.
I suspect there's a limit to the number of men you can use on a given size of ship. Also, there's the question of the availability of seasoned timber. That doesn't matter much for ships that are expected to be expended in a current conflict, but it is important in peacetime shipbuilding, because seasoning takes months to years, depending on the kind of wood.
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Old 01-28-2015, 10:42 AM   #20
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Default Re: [Low-Tech] Landing Craft at TL2 to TL4

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I suspect there's a limit to the number of men you can use on a given size of ship.
Most certainly. But that limit will not be less than ten for even the smallest war galley, which means that working in shifts, it seems that most war galleys would take less than a month.

Of course, it is highly plausible that triremes or other very fast galleys are actually higher quality than simple cargo ships of comparable tonnage, requiring more hours of work and a higher proportion of skilled man-hours to unskilled.

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Also, there's the question of the availability of seasoned timber. That doesn't matter much for ships that are expected to be expended in a current conflict, but it is important in peacetime shipbuilding, because seasoning takes months to years, depending on the kind of wood.
This is indeed a significant limit for both sides.

For the PCs' allies, it merely means that good warships (as opposed to rafts or scaled-up boats from green wood) require fairly expensive imports of seasoned wood, which imposes the above limit of 'as much of a fleet they can afford'. Being able to trade with all the Inner Sea means not having to cut and season your own lumber, especially as you control rich mines, irrigated plains, coastal land, river valley, huge lake, hills and mountains, but no significant forests.*

The Empire on the other side, however, has already been using all the sources of seasoned timber that they can tap for the last five years. Huge building projects, exponential growth in naval tonnage, truly frightening amounts of ox carts, massive demand for bows, spears, arrows, scorpion bolts, etc.

Any more wood they import would need to be transported through quite a lot of sea lanes controlled by the enemy or alternatively, transported overland for a thousand miles or more.

I've already estimated that a lot of their emergency naval building will use green wood and they've also been scavenging wood from less vital sources to turn out sorely needed hulls to replace losses.

Of course, imperfect raw materials means heavy, slow and clumsy galleys, which leads to further losses at sea.

*The land has been settled for almost 4,000 years, they've all been utilised already.
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