Spelljammer Spelljammer: A 5E Fan Conversion

[guildsbounty]

I think I'm going to give this a try. I'd like to have some differentiation between Minor Helms and Major Helms, though, maybe limit the top speed of a minor helm to 5, even if you pump higher level spell slots into it? I also like the idea of being able to boost the ship's speed by sacrificing additional spell slots.

I'm not terribly worried about the cost since my group has only one PC out of 5 who can't use spells of some sort, so they have plenty of slots to go around. I also still don't plan on a bunch of tactical ship combat. I had a chance to do that for Skull & Shackles when we were playing Pathfinder and it didn't really float our boat, so to speak (well, ONE guy liked it, but he goes nuts for anything tactical and crunchy).

Yeah, I do differentiate between a Minor and Major Helm in terms of both top speed, and total size of ship they can move.

A Minor Helm can move anything between 1 and 50 tons, and has a top Speed Rating of 5. Spending zero or one spell level gives you SR 1, above that every two spell levels you expend increases the SR by 1 more. So, 8-9 spell slots produces SR 5

A Major Helm can move anything from 1 to 100 tons, and has a top Speed Rating of 10. Zero spell levels gives you SR 1, each spell level above that increases SR by 1.

There's also optional rules regarding acceleration in the guide I have written up so far...and a Major Helm gets to ignore those rules.

 

[Ulthur]

Divine rules

Divine Magic in The Phlogiston: The gods have no influence in The Phlogiston (def: the space that you travel through when moving from one Solar System to another, i.e. outside of the Crystal Sphere of any particular system), and thus prayers from within it are simply not heard. As a result, a Cleric or Paladin (or any future class that prays for their spells) are unable to prepare any spells of third level or higher while in The Phlogiston. They still have all of their spell slots and can cast a spell in a higher slot if they wish...but they may not prepare any spells that are of higher natural level than second. There is no workaround for this.

Divine Magic in Other Spheres: A god only has influence in a System in which they are worshiped. Thus, if a Divine caster prays for spells in a System in which their god has no influence, their god cannot grant them spells. As in The Phlogiston, this means that a Divine Spellcaster cannot prepare any spells of third level or higher (though they retain their spell slots as normal). There are two workarounds to this rule in the form of a pair of new 2nd Level spells: Contact Home Power allows a Divine Caster to create a connection to their home Sphere that lasts for one week, while this connection is open they pray and receive spells as if they were in their home Sphere. Detect Powers (cast on a Crystal Sphere) allows a Divine Caster to detect if there are friendly gods and/or other powers within that are similar enough to their actual god (in terms of purview) that they'd be willing to cooperate; if so, the Cleric may pray to that god for their spells whenever they are in that Sphere...additionally, the spell will let them know if their own god is revered within that Sphere.

I love the idea of a full 5e Spelljammer convert. I'm running a campaign that has evolved basically constantly since we were kids. It took a long hiatus as we all moved away and started careers and families, but now I'm reviving it from its 2e/3.5e roots into a 5e environment. Most of the villains were once player characters in the late 90s who got turned evil and taken over by the DM when teenage roleplaying shenanigans went too far. Spelljammer exists in the world, though right now the players aren't advanced enough to know much about it. Eventually I would love if they had that option though, so thanks for taking this on!

The basis I had been working on for cleric casting went like this:

- In the Phlogiston, a Pantheon no-mans-land, clerics need to carry an item blessed by their god that will open a channel to them for their spells. Optional rule might be to limit the level of spell slots they can access by the power of the blessed item, but if you want to make it transparent and let clerics cast normally (and thus consistent with other parts of 5e), just make it so they need the item. Make it as trivial or difficult to acquire as you wish.

- In a world ruled by a different Pantheon, clerics must achieve a pact with a local god similar to theirs for their casting. This could be handled dozens of ways: maybe they need to visit a temple and talk to senior clerics, or pray directly to a relevant god for help, or even offer a trade; your god gives me proxy-powers, and my god will help out one of your traveling clerics in the same way later. Or demand a service before granting powers the players can use on their own causes. A particularly powerful visiting cleric might find him or herself approached by divine representatives as soon as they arrive in another Pantheon.

What I like about it is it lets you move the problem of clerics being treated differently than other classes more or less to the background, tactically, while still paying homage to the thematic elements of gods and pantheons.

 

[Cleon]

I have plans for controlling that...though I haven't fully fleshed out how it will work with 'deck mounted' or other externally-set weapons.

Internal weapons are easy, as the tonnage of a ship dictates how much internal space it has, and these internal weapons eat up that space. (1 'ton' of ship is equal to about 1350 cubic feet)

External weapons are a bit trickier, as the tonnage of a ship doesn't dictate the shape of the ship, and so a ship could have either a tiny or enormous deck to cover in weapons...(though pre-made ships come with a 'deck plan' that shows how much space you have on the deck) and you could also just build platforms onto the side of the ship's hull to install a weapon. The Warcaptain's Compendium listed a rule that says "If you have weapons (internal and external) that exceed half the tonnage of the ship, they start displacing the air envelope, reducing the amount of air the ship can carry with it." So, if I keep that rule, a 40 ton ship could carry a max of 20 tons of weapons (10 bombards) before it started losing air capacity. That said, I feel like calculating air capacity is complicated enough already, and may do away with that rule.

Instead, the most natural restriction on the number of weapons a ship can carry is simply the size of the crew. A 'standard' crew capacity is 1 person per ton of ship. This provides them with breathable air for up to 8 months (though the latter 4 months are going to be deeply unpleasant as the air is starting to go bad). Given travel times in space...you don't want to go too far above this. So, again, assuming a 40 ton ship that gives you a standard crew capacity of 40 people...taking some off for people responsible for other tasks around the ship (maneuvering, helmsman, captain, etc) that leaves about 30 people available to man the guns. Which, given that a Bombard would like an 'ideal' crew of 3 people...still limits you to 10 bombards on the ship. And, naturally, this is assuming that you want a crew of nothing but gunners, and don't want any close-combat specialists for boarding actions.

I think this actually produces a pretty interesting ship design philosophy. Planetary defense ships could be more heavily armed because they don't need to travel, while traveling ships would have to trade armament for range.

In the real world, you can't just slap most siege engines onto a ship's deck and fire them - the recoil would smash through the decking or maybe even the hull. The hardpoint installation needs to add considerable tonnage of bracing and shock absorbers to prevent the weapon damaging the ship when fired. External mounted weapons likely require MORE such tonnage, since the braces and such would perforce need to be longer than those used for an internal weapon.

'Course some weapons have lower recoil than others - rockets, flame-siphons and the like. From what I've read, most ancient nautical forces got around this problem simply by only using comparatively light weapons such as cheiroballista. The heavy stuff was mostly reserved for solid ground.

 

[guildsbounty]

In the real world, you can't just slap most siege engines onto a ship's deck and fire them - the recoil would smash through the decking or maybe even the hull. The hardpoint installation needs to add considerable tonnage of bracing and shock absorbers to prevent the weapon damaging the ship when fired. External mounted weapons likely require MORE such tonnage, since the braces and such would perforce need to be longer than those used for an internal weapon.

'Course some weapons have lower recoil than others - rockets, flame-siphons and the like. From what I've read, most ancient nautical forces got around this problem simply by only using comparatively light weapons such as cheiroballista. The heavy stuff was mostly reserved for solid ground.

I would assume that is why a 'Light Ballista' consumes a full Ton worth of space, and heavier weapons take up to 3 tons of space. You don't need that much space for just the weapon itself, I imagine that a fair bit of that space requirement comes from the bracing and such needed to secure the weapon.

Of course, this being D&D where a Wizard could physically heft a portcullis over his head if he rolled well enough, you have to take your realism with a grain of salt.

 

[Cleon]

I would assume that is why a 'Light Ballista' consumes a full Ton worth of space, and heavier weapons take up to 3 tons of space. You don't need that much space for just the weapon itself, I imagine that a fair bit of that space requirement comes from the bracing and such needed to secure the weapon.

Of course, this being D&D where a Wizard could physically heft a portcullis over his head if he rolled well enough, you have to take your realism with a grain of salt.

Frankly, that's not enough. Some siege engines are BIG. Look at this picture of a ballista. That's a stone-throwing ballista, not the small spear-throwing engine assumed in D&D (that's more a cheiroballista), a much smaller siege engine that could easily fit within a Spelljammer "ton" and was well suited for mounting on a ship's deck.

The ballista in the first picture is more equivalent to a heavy catapult in D&D terms. You can see it's roughly 25 feet long and 20 feet high. If it's to turn sideways it'll need a space at least 25 wide too, obviously, to fit its length. 25 by 25 by 20 feet is 12,500 cubic feet. You'll also need some space for ammunition and parts stowage and for the crew to get around it. Let's say another 1,000 feet for a total of 13,500, since that's a nice neat 10 tons at the Spelljammer Tonnage of 1,350 cubic feet per ton.

...and that's not including the space in the hull needed for braces to prevent the ship being shaken to flinders when the thing fires.

I can see some light siege engines fitting within 3 spelljammer tons, but a heavy catapult or trebuchet should take up way more space.

 

[guildsbounty]

Frankly, that's not enough. Some siege engines are BIG. Look at this picture of a ballista. That's a stone-throwing ballista, not the small spear-throwing engine assumed in D&D (that's more a cheiroballista), a much smaller siege engine that could easily fit within a Spelljammer "ton" and was well suited for mounting on a ship's deck.

The ballista in the first picture is more equivalent to a heavy catapult in D&D terms. You can see it's roughly 25 feet long and 20 feet high. If it's to turn sideways it'll need a space at least 25 wide too, obviously, to fit its length. 25 by 25 by 20 feet is 12,500 cubic feet. You'll also need some space for ammunition and parts stowage and for the crew to get around it. Let's say another 1,000 feet for a total of 13,500, since that's a nice neat 10 tons at the Spelljammer Tonnage of 1,350 cubic feet per ton.

...and that's not including the space in the hull needed for braces to prevent the ship being shaken to flinders when the thing fires.

I can see some light siege engines fitting within 3 spelljammer tons, but a heavy catapult or trebuchet should take up way more space.

Unfortunately, this is where realism is going to have to take a back seat to playability. Unless I dramatically increase the max tonnage of ships, making them bigger, with more HP, etc...I cannot increase the size requirements of weapons without seriously reducing ship firepower.

And yes, Ballista in Spelljammer are the spear-tossers, regardless of what their proper name is in the real world. If it chucks a rock, it's a catapult. If it chucks a spear, it's a ballista, if it chucks a lot of rocks, its a Jettison.

 

[Cleon]

Unfortunately, this is where realism is going to have to take a back seat to playability. Unless I dramatically increase the max tonnage of ships, making them bigger, with more HP, etc...I cannot increase the size requirements of weapons without seriously reducing ship firepower.

An easy solution is to assume the ship's weapons in question are simply scaled-down versions of regular siege engines. That'd also help explain why they do comparatively little damage relative to the toughness of the ships.

And yes, Ballista in Spelljammer are the spear-tossers, regardless of what their proper name is in the real world. If it chucks a rock, it's a catapult. If it chucks a spear, it's a ballista, if it chucks a lot of rocks, its a Jettison.

Yes, I'm well aware of that. It's not just in Spelljammer of course, D&D has been calling spear-throwing siege engines ballista for decades and multiple editions. It's a bit late for it to change its ways.

 

[JediSoth]

I started my campaign a couple of weeks ago (you can follow session updates at DoctorStrangeRoll). Tonight we went into a little detail about how helms work for 5E. I used the suggestions from this thread that a caster could expend a cantrip slot for Speed Rating (SR) 1, a cantrip and a 1st level for SR2, Cantrip, 1st, and 2nd for SR3 and so forth. I'm using the Flow map by Nerik over at the Cartographer's Guild. It's a beautiful piece of work with travel times listed, but I don't actually know for what speed rating those travel times are intended.

The character right now can't really get their ship above SR4 with the system as I'm using it; they're only 6th level. I'm wondering if maybe I should let them spend extra spell slots per level for speed boosts in the flow, or if standard cruising speed is a pretty slow rating like SR1. According to the map, it's 22 days from Realmspace to Greyspace, plus another 10 days travel from the edge of the Crystal Sphere to Oerth. So, just over a month to haul stuff from Faerun to Greyhawk. That seems reasonable at normal cruising speed. But, just what IS normal cruising speed?

 

[guildsbounty]

I started my campaign a couple of weeks ago (you can follow session updates at DoctorStrangeRoll). Tonight we went into a little detail about how helms work for 5E. I used the suggestions from this thread that a caster could expend a cantrip slot for Speed Rating (SR) 1, a cantrip and a 1st level for SR2, Cantrip, 1st, and 2nd for SR3 and so forth. I'm using the Flow map by Nerik over at the Cartographer's Guild. It's a beautiful piece of work with travel times listed, but I don't actually know for what speed rating those travel times are intended.

The character right now can't really get their ship above SR4 with the system as I'm using it; they're only 6th level. I'm wondering if maybe I should let them spend extra spell slots per level for speed boosts in the flow, or if standard cruising speed is a pretty slow rating like SR1. According to the map, it's 22 days from Realmspace to Greyspace, plus another 10 days travel from the edge of the Crystal Sphere to Oerth. So, just over a month to haul stuff from Faerun to Greyhawk. That seems reasonable at normal cruising speed. But, just what IS normal cruising speed?

I you refer back to the original rules, and this is what I am maintaining as well...'SR' only matters for Tactical Speed. Tactical Speed is how a Spelljammer moves when they are near something they might run into (planet, other ship, etc). Otherwise, all Spelljammers (regardless of SR) can reach a 'Long-Range Speed' of about 100 million miles per day (approximately 4.17 million mph). When a ship is moving at Long-Range speed, it cannot really maneuver beyond minor course adjustments, and if it approaches any other object of significant mass, it drops down to Tactical Speed, which is the speed determined by SR.

 

[JediSoth]

I you refer back to the original rules, and this is what I am maintaining as well...'SR' only matters for Tactical Speed. Tactical Speed is how a Spelljammer moves when they are near something they might run into (planet, other ship, etc). Otherwise, all Spelljammers (regardless of SR) can reach a 'Long-Range Speed' of about 100 million miles per day (approximately 4.17 million mph). When a ship is moving at Long-Range speed, it cannot really maneuver beyond minor course adjustments, and if it approaches any other object of significant mass, it drops down to Tactical Speed, which is the speed determined by SR.

Ah, yes, I remember that now. It's been so long. Thank you!