Alba cruising on a wide English river at golden hour, three-quarter side view from astern, with a church tower, houses and trees on the bank and the sun low on the left. A gloss deep navy-teal hull with a sand-gold line along the sheer and a second gold line low on the hull, a crease rising towards the stern, and two long dark window slots in the hull side. A pale cream superstructure with a dark window band runs aft into a slim hardtop over the aft deck, where a wooden deco wheel stands at the helm and sand leather seating wraps a teak table. A red ensign flies at the stern and ALBA is lettered in gold on the transom above a teak platform. Off brief: the stern is an upright, squared transom carrying the name rather than a rounded sculpted tail, the superstructure starts behind a long flat foredeck and a raked windscreen rather than low with a softly rounded nose, and a radar dome sits on the roof.

Engines: twin diesel or hybrid

Twin Volvo Penta D4-300 diesels on V-drives, with an optional parallel hybrid for silent running on rivers. About 21 to 25 knots top.

The card

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Engines: twin diesel or hybrid

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The notes

rendered

Both options use twin Volvo Penta D4-300 diesels (300 hp each, about 580 to 610 kg with gearbox, V-drive available). V-drives put the engines aft under the aft deck, leaving the hull clear for the second bedroom. The hybrid adds an electric motor and batteries to each shaft line.

weight estimate

Approximate, loaded.

Item	kg
Hull, superstructure, framing	4,200
Twin D4-300 with V-drives	1,220
Shafts, props, rudders, steering, bow thruster	300
Fuel 800 L	670
Water 300 L, holding tank, plumbing	600
Interior fit-out	1,600
Electrics and house batteries	400
Deck gear, anchor, hardtop	450
Crew, 6 people	480
Total, diesel	about 9,900
Hybrid motors and batteries (extra)	about 600

speed

Using Crouch's formula with a semi-displacement constant of 130 to 150, 600 hp on about 9,900 kg gives roughly 21 to 25 knots top, or 18 knots cruising. The hybrid's extra weight costs about 1 knot.

comparison

	Twin diesel	Parallel hybrid
How it works	Diesels drive the props	A motor between each engine and gearbox (for example the Transfluid HM series, about 40 kW) runs on battery at low speed; diesels take over at sea and recharge the batteries
On rivers	Diesels idle at low load, which they dislike over long periods	Silent electric running at river speeds, roughly 2 to 3 hours on about 38 kWh of lithium batteries
At sea	Simple, proven	Same diesels, plus electric boost for acceleration
Extra weight	none	about 600 kg
Extra cost (approx.)	none	about £40,000 to £70,000
Complexity	Low	Higher: battery management, cooling, more to maintain
Marinas	Shore power for house loads	Charges from shore power; quiet arrivals

recommendation

Hybrid suits Alba's river-first life well: low-speed river running is where diesels are least happy and electric is most useful. If budget or simplicity matters more, twin diesels with a good silencing package are the fallback. Electric range and costs are rough estimates.

fuel and range

Approximate. At an 18 knot cruise the pair burn around 85 L/h, giving about 9 hours or 150 nautical miles from 800 L before reserve, enough for a Channel crossing with margin. At river speeds on diesel, burn drops to a few litres per hour.

The drawings

1 sheet

Side cutaway, bow on the left. Below, from the bow: the main bedroom, the ensuite, steps up to the saloon, the second bedroom under the saloon floor, and the shared bathroom. Above: the saloon with its convertible sofa and table, then the galley. A bulkhead closes off the engine room aft, where the twin diesels sit under the aft deck with V-drives turning the shafts back. The helm and seating sit on the aft deck under the hardtop, with the platform at the stern. — 01 · Side cutaway