The Steam Galley "Tiberius"

From Cloudships & Gunboats: "The 'Endtime' class are the most numerous of the Oenotrian medium screw galleys, and is the smallest warship to mount a lob gun. As with many of the larger screw galleys, the 'Endtime' has a limited operational range, and this puts it at a distinct disadvantage when engaged in any long-range gun duels with most British gunboats. Its slow speed further compounds the problem, making it difficult to close in on a speedy steamship. As part of a larger force involved in a general fleet engagement, however, the 'Endtime' is a useful vessel, and the lob gun is a potentially decisive weapon, once within range."
In Sky Galleons terms:
Endtime-class								screw galley				
Armor:  0	£31,500
Hull:  5	Speed:  3	
485 tons	Altitude:  High
Crew:  Captain, Helmsman, Trimsman, Signaller, 2 other Officers; 5 Deck, 15 Turncranks, 
9 Gunners, 1 Marine officer, 9 Marines
Armament:  1 rod gun forward; 2 heavy guns, in wing mounts; 1 lob gun amidships aft

(Sky Galleons crew conversion to 'real' numbers: 3 officers, 15 deck enlisted men; 90 turncranks; 36 gunners; and 80 marines. Length 130 feet; beam, 40 feet)

Conversion to steam galley

Costs reflect Martian yards and war situation; shipping base cost to Mars from Earth is £200 per ton loaded. Desired weight: 416 tons

Remove turncrank positions, flywheels and most associated machinery, saves 150 tons.
Install steam engine(s), size 5, results in Speed of 6. Engine weighs 50 tons, output is 625 HP, cost is £5000. Speed 6 = 30 knots (= 35 land miles per hour).
Prolly actually 25 tons water, 6 tons condenser, 4 tons engines, 10 tons boilers, 5 tons misc.
Install coal bunker for 30 days endurance: 150 tons (range 25,000 miles; Mars is 12,000 miles circumference; but remember coal is hard to find on Mars)
Remove lob gun, heavy guns, rod gun, sell for £2400, save 320 tons
Install two 4" long-barrel breech-loading guns, cost £3840
Pivot mounts for 4" guns, with Armor rating 1; weight 8 tons, cost £1680
Install 3-pounder Hotchkiss Revolver Cannon aft, cost £180 pounds, weight 10 tons
Install two rifle-caliber Maxim guns, cost £600
Install Edison dynamo, delivers 125 amps at 70 volts DC; 0.1 ton, £30

Engines, screws, water tanks and coal bunkers: 200 tons
Weaponry: two 4" guns, one 3-pdr HRC, two .303" Maxims, mounts and armor: 98 tons
Marine quarters: 50 tons (for up to 200 troops = a company)
Extra Swank for Captain, officers, and four guests: 18 tons, £1000 (piano, etc.)
Cargo capacity: 50 tons (includes potential slung cargo)

Presuming original "Endtime" vessel to have been provided free, the "Tiberius Auxiliary Trust" must have ponied up about £10,400, making the ship worth overall about £42,000.
The ship's lower deck houses the magazines and crew quarters (forward), coal bunker and water tanks (mid) and engine room (aft). The mid deck is taken up by the ship's marines. The former flywheel deck is now the cargo hold; aft is the wardroom and officers' quarters (on the level normally called the 'bridge deck' by Martian standards). The captain's cabin takes up the whole of the drag deck. The actual bridge area is a short tower on the main deck, over the former location of the lob gun; on each wing of the bridge is a pedestal mounting for a machine-gun. The 4" guns are mounted forward, at about where the heavy guns were previously fitted; the HRC is mounted at the stern on the main deck. Sky Galleons stats:
Tiberius							steam galley
Armor:  0	£42,000
Hull:  5	Speed:  3	
416 tons	Altitude:  Very High
Crew:  Captain, Mate, Helmsman, Trimsman, Signaller, Bosun; 5 Deckhands, 
5 Engineers, 5 Gunners, 2 Marine officers, 18 Marines
Armament:  two 4" L guns in armored (level 1) pivoting wing mounts; 
one 3" HRC amidships aft, 2 Maxim MGs on bridge wings

(Sky Galleons crew conversion to 'real' numbers: 1 captain plus 3 deck officers, 4 deck petty officers, 15 deck enlisted men; 3 engineers, 27 artificers, stokers and wipers; 1 cook and 3 stewards; 20 gunners; and up to 200 marines. Length 130 feet; beam, 40 feet)

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