Review of BM Family
Basic specs.
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The hull is made of fibreglass while the deck is made of wood. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season. And outside the sailing season, just bottom cleaning and perhaps anti-fouling painting once a year - a few hours of work, that's all.
The interior is like many other boats made of mahogany. Mahogany belongs to the hardwood species, known for being water-repellent and resistant to decay. It has an attractive wood grain and holds wood polish and varnish well.
The boat is equipped with one cabin, 4 berths, a galley, 65.0 liter fresh water capacity and toilet facility.
Note: the boat has also been sold to be self-made/-interiored, which means that the quality of each boat may vary.
The BM Family is equipped with a fractional rig. A fractional rig has smaller headsails which make tacking easier, which is an advantage for cruisers and racers, of course. The downside is that having the wind from behind often requires a gennaker or a spinnaker for optimal speed.
Full keel
The BM Family is equipped with a long keel. A full keel provide a better directional stability than a similar boat with a fin keel; on the other hand, better directional stability means also that the boat is more difficult to handle in a harbour with less space.
The keel is made of iron. Many people prefer lead keel in favour of iron. The main argument is that lead is much heavier than iron and a lead keel can therefore be made smaller which again result in less wet surface, i.e. less drag. In fact iron is quite heavy, just 30% less heavy than lead, so the advantage of a lead keel is often overstated.
BM Family can enter even shallow marinas as the draft is just about 1.22 - 1.32 meter (4.00 - 4.30 ft) dependent on the load. See immersion rate below.
The boat may be equipped with an inboard Yanmar 1GM10 diesel engine at 9 hp (6 kW). Calculated max speed is about 4.5 knots
The transmission is a shaft drive. A shaft drive will in the long run require less maintenance than other types of drive e.g. a sail drive.
The fuel tank, which is made of stainless steel, has a capacity of 56.0 liters (14 US gallons, 12 imperial gallons).
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.
What is Capsize Screening Formula (CSF)?
The capsize screening value for BM Family is 1.71, indicating that this boat could - if evaluated by this formula alone - be accepted to participate in ocean races.
What is Theoretical Maximum Hull Speed?
The theoretical maximal speed of a displacement boat of this length is 5.9 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.
The immersion rate is defined as the weight required to sink the boat a certain level.
The immersion rate for BM Family is about 88 kg/cm, alternatively 495 lbs/inch.
Meaning: if you load 88 kg cargo on the boat then it will sink 1 cm.
Alternatively, if you load 495 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.
What is Motion Comfort Ratio (MCR)?
The Motion Comfort Ratio for BM Family is 24.0 - 25.1.
What is L/B (Length Beam Ratio)?
The l/b ratio for BM Family is 3.47.
The ballast ratio for BM Family is 42%.
What is Displacement Length Ratio?
The DL-ratio for BM Family is 277 which categorizes this boat among 'medium weight cruisers'.
Maintenance
When buying anti-fouling bottom paint, it's nice to know how much to buy.
The surface of the wet bottom is about 15m2 (161 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.
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.
| Usage | Length | Diameter | ||
| Jib sheet | 7.6 m | (25.1 feet) | 10 mm | (3/8 inch) |
| Genoa sheet | 7.6 m | (25.1 feet) | 10 mm | (3/8 inch) |
| Mainsheet | 19.1 m | (62.7 feet) | 10 mm | (3/8 inch) |
| Spinnaker sheet | 16.8 m | (55.1 feet) | 10 mm | (3/8 inch) |
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