Review of Bostrom 37

Bostrom 37 anno 1982.

Basic specs.

The Bostrom 37 aka B-37 is a sailboat designed by the Swedish maritime architect Bruno Boström in the late seventies. Several hundred boats have been produced. The Bostrom 37 is built by the Swedish yard Porali Marin.

Looking for a new boat? Find a Bostrom 37 or similar boat for sale

Interior

The boat is equipped with 9 berths, a galley and toilet facility.

Rig

Rig of Bostrom 37 anno 1983. Photo from July 2022, Jomfruland, Norway.

The Bostrom 37 is equipped with a masthead rig. The advantage of a masthead rig is its simplicity and the fact that a given sail area - compared with a fractional rig - can be carried lower and thus with less heeling moment.

Keel

Unknown keel type

The keel is made of lead. Compared with iron, lead has the advantage of being 44% heavier, which allows a smaller keel and hence less water resistance and higher speed.

The boat can only enter major marinas as the draft is about 1.95 - 2.05 meter (6.40 - 6.70 ft) dependent on the load. See immersion rate below.

Engine

Bostrom 37 may be equipped with an inboard Volvo Penta diesel engine at 45 hp (33 kW). Calculated max speed is about 6.8 knots

Sailing characteristics

This section covers widely used rules of thumb to describe the sailing characteristics. Please note that even though the calculations are correct, the interpretation of the results might not be valid for extreme boats.

Stability and Safety

What is Capsize Screening Formula (CSF)?

The capsize screening value for Bostrom 37 is 1.99, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 7.7 knots. The term "Theoretical Maximum Hull Speed" is widely used even though a boat can sail faster. The term shall be interpreted as above the theoretical speed a great additional power is necessary for a small gain in speed.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Bostrom 37 is about 264 kg/cm, alternatively 1481 lbs/inch.
Meaning: if you load 264 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1481 lbs cargo on the boat it will sink 1 inch.

Sailing statistics

This section is statistical comparison with similar boats of the same category. The basis of the following statistical computations is our unique database with more than 26,000 different boat types and 350,000 data points.

Motion Comfort Ratio

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Bostrom 37 is 26.5.

Comparing this ratio with similar sailboats show that it is more comfortable than 50% of all similar sailboat designs. This is an average comfort value!

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Bostrom 37 is 2.74.

Compared with other similar sailboats it is more spacy than 92% of all other designs. It seems that the designer has chosen a significantly more spacy hull design.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Bostrom 37 is 40%.

This ballast ratio shows a righting moment that is higher than 50% of all similar sailboat designs. This righting moment (ability to resist heeling) is spot on average!

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Bostrom 37 is 222 which categorizes this boat among 'light crusers & offshore racers'.

66% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

SA/D (Sail Area Displacement ratio)

What is SA/D (Sail Area Displacement ratio)?

The SA/D for Bostrom 37 with ISO 8666 reference sail is 15.9, with a 135% genua the SA/D is 19.2.

The SA/D ratio indicates that it is faster than 38% of all similar sailboat designs in light wind.

Over- / underrigged

The Bostrom 37 has more rig than 34% of all similar sailboats, which indicates that the boat is slightly underrigged.

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Bostrom 37 is 46

The relative speed performance is 46 which means that a it is faster than 46% of all similar sailboat designs.

Maintenance

Bottom Paint

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 44m² (473 ft²).
Based on this, your favourite maritime shop can tell you the quantity you need.

Note: If you use a paint roller you will need more paint than if you use a paintbrush.

Rig

Dimensions of sail for masthead rig.

Are your sails worn out? You might find your next sail here: Sails for Sale

If you need to renew parts of your running rig and is not quite sure of the dimensions, you may find the estimates computed below useful.

**Guiding dimensions of running rig**
Usage	Length		Diameter
Mainsail halyard	37.3 m	(122.4 feet)	12 mm	(1/2 inch)
Jib/genoa halyard	37.3 m	(122.4 feet)	12 mm	(1/2 inch)
Spinnaker halyard	37.3 m	(122.4 feet)	12 mm	(1/2 inch)
Jib sheet	10.8 m	(35.5 feet)	14 mm	(0.55 inch)
Genoa sheet	10.8 m	(35.5 feet)	14 mm	(0.55 inch)
Mainsheet	27.1 m	(88.7 feet)	14 mm	(0.55 inch)
Spinnaker sheet	23.8 m	(78.1 feet)	14 mm	(0.55 inch)
Cunningham	3.5 m	(11.5 feet)	12 mm	(1/2 inch)
Kickingstrap	7.0 m	(23.0 feet)	12 mm	(1/2 inch)
Clew-outhaul	7.0 m	(23.0 feet)	12 mm	(1/2 inch)

Boat owner's ideas

This section is reserved boat owner's modifications, improvements, etc. Here you might find (or contribute with) inspiration for your boat.

Do you have changes/improvements you would like to share? Upload a photo and describe what you have done.

Finally

We are always looking for new photos. If you can contribute with photos for Bostrom 37 it would be a great help.

If you have any comments to the review, improvement suggestions, or the like, feel free to contact us. Criticism helps us to improve.

References

[Ref 1]: ISO 8666 Small craft — Principal data.
[Ref 3]: ISO 12215-5 Small craft — Hull construction and scantlings.