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Hallberg-Rassy Monsun 31 · insideSail

Hallberg-Rassy · 1973–1982

Hallberg-Rassy Monsun 31

An Olle Enderlein design with a 9.36 m hull and published draft of 1.40 m. The archive gives a 4.2 tonne reference displacement and a Volvo Penta MD11C engine.

Overall length · LOA

—

Beam

2.87 m

Displacement

4,200 kg

Ballast

—

Draught

1.4 m

Enclosed cabins

—

Engine power

17 kW

Cockpit

—

Published values checked against their source; each individual boat's condition and configuration may differ.

What kind of boat is this?

An Olle Enderlein design with a 9.36 m hull and published draft of 1.40 m. The archive gives a 4.2 tonne reference displacement and a Volvo Penta MD11C engine.

Editorial interpretation. Categories overlap and are not certifications.

Understand sailboat types

Dimensions

Waterline length · LWL
Overall length · LOA Overall length · LOA	—	Data awaiting verification
Hull length Hull length	9.36 m	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Hull length Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.

Beam Beam	2.87 m	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Beam Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.

Draught Draught	1.4 m	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Draft Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.

Displacement Displacement	4,200 kg	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Displacement Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Original published value: 4.2 tons Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.

Ballast Ballast	—	Data awaiting verification

Published keel weight Published keel weight	1,900 kg	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Keel weight Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Original published value: 1.9 tons Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.

Hull material	—	Data awaiting verification

Sailing characteristics

Keel Keel	—	Data awaiting verification
Rudder support Rudder support	—	Data awaiting verification
Rig Rig	—	Data awaiting verification
Steering Steering	—	Data awaiting verification
Sail area Sail area	—	Data awaiting verification

Sail plan, sail condition and actual loading affect behaviour. A single number cannot predict performance.

Comfort and behaviour at sea

The indicators below help compare proportions. Interpret them alongside hull shape, mass distribution, loading, condition and sailing conditions.

Ballast / displacement Ballast / displacement	—	Insufficient compatible data
SA/D SA/D	—	Insufficient compatible data
D/L D/L	277.46	Calculation & limits (displacement_lb / 2240) / (0.01 × LWL_ft)³ conventional-monohull-v1 A conventional indicator calculated from this configuration's published data. It is neither a safety certification nor a prediction of an individual boat's condition. Input sources are shown with the corresponding specifications.
Comfort Ratio Comfort Ratio	—	Insufficient compatible data
Capsize Screening Formula Capsize Screening Formula	1.79	Calculation & limits beam_ft / (displacement_lb / 64)^(1/3) conventional-monohull-v1 A conventional indicator calculated from this configuration's published data. It is neither a safety certification nor a prediction of an individual boat's condition. Input sources are shown with the corresponding specifications.
Theoretical hull speed Theoretical hull speed	6.65 kn	Calculation & limits 1.34 × √LWL_ft conventional-monohull-v1 Conventional approximation for displacement hulls, not a rigid limit or a guaranteed cruising speed. Input sources are shown with the corresponding specifications.
Power per tonne Power per tonne	5.43 hp/t	Calculation & limits (power_kW / 0.745699871582) / (displacement_kg / 1000) conventional-monohull-v1 A conventional indicator calculated from this configuration's published data. It is neither a safety certification nor a prediction of an individual boat's condition. Input sources are shown with the corresponding specifications.

These calculations are not safety certificates. STIX and AVS require specific documentation; they are not estimated from these ratios.

Propulsion

Engine power Engine power	17 kW	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Power Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.
Transmission Transmission	—	Data awaiting verification
Fuel Fuel	120 L	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Diesel tank Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.
Water	160 L	View source Hallberg-Rassy Monsun 31 — official data sheet Hallberg-Rassy Monsun 31 data sheet — Fresh water tank Source type: Manufacturer documentation Hallberg-Rassy Varvs AB — Hallberg-Rassy Monsun 31 — official data sheet Evidence confidence: Medium Checked against the source: 2026-10-09 Transcription reviewed against the manufacturer's named public page; documentary confidence, not independent measurement or a guarantee for an individual boat. Source-linked documented reference. Source type and confidence remain visible; verify the configuration of individual boats. Documentary verification; this is not a measurement of an individual boat.

The original engine may have been replaced. Power, propeller, transmission and conditions together determine real use; consumption and range are not inferred from power alone.

Interior & layout

Cockpit Cockpit	—	Data awaiting verification
Enclosed cabins Enclosed cabins	—	Data awaiting verification
Heads Heads	—	Data awaiting verification
Aft cabin Aft cabin	—	Data awaiting verification
Internal walkthrough Internal walkthrough	—	Data awaiting verification
Aft double berth Aft double berth	—	Data awaiting verification
Galley shape	—	Data awaiting verification
Galley level	—	Data awaiting verification
Headroom Headroom	—	Data awaiting verification

Enclosed cabins and saloon berths are different information. An internal aft walkthrough needs confirmation in the individual boat’s layout.

Hallberg-Rassy Monsun 31

What kind of boat is this?

Dimensions

Sailing characteristics

Comfort and behaviour at sea

Propulsion

Interior & layout

Known issues

Market

Owners in the community

Experiences & questions

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