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Review of Bianca 420


Bianca 420
Bianca 420.

Basic specs.

sail specifications
The Bianca 420 is a large sailboat designed by the French maritime architect Michel Joubert together with Bernard Nivelt also from France in the late eighties. Less than 100 boats have been produced. The Bianca 420 is built by the Danish yard Bianca Yacht I/S.

Looking for a new boat? Find a Bianca 420 or similar boat for sale

Hull
The hull is made of hand laid fibreglass while the deck is made of fibreglass. Generally, a hull made of hand laid fibreglass requires only a minimum of maintenance during the sailing season.
The hull is a double hull which improves the indoor climate. Especially when the water is colder than the air in the cabin, then the double hull insulates against cold water and reduce the condense water in the cabin.
The deck is a double deck which improves the indoor climate.

Interior
The interior is like many other boats made of mahogany.
The boat is equipped with 3 cabins, 6-8 berths, a galley and toilet facility.

Rig
The boat has more than one rig.

One option is 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 genaker or a spinnaker for optimal speed.

Another option is 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

The Bianca 420 has been built with more than one type of keel.

One option is a fin keel. The fin keel is the most common keel and provides splendid manoeuvrability. The downside is that it has less directional stability than a long keel.But be aware that even though a Ellipse keel is very good for speed racing, a fishing nets and the like in the water can easily make you into a troublesome situation.

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. As the surface of a fin type keel is just a fraction of the total wet surface, the difference between an iron keel and a lead keel can in reality be ignored for cruising yachts.

Bianca 420 can only enter major marinas as the draft is about 2.15 - 2.25 meter (7.05 - 7.35 ft) dependent on the load. See immersion rate below.


Engine

The boat is typically equipped with an inboard Yanmar diesel engine at 44.0 hp (32 kW), which gives a max speed about 6.9 knots.

The transmission is a shaft drive. A shaft drive will in the long run require less maintenence than other types of drive e.g. a sail drive.

The fuel tank which is made of stainless steel has a capacity of 140.0 liters (36 US gallons, 30 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.

Stability and Safety

What is Capsize Screening Formula (CSF)?

The capsize screening value for Bianca 420 is 1.97, 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 7.8 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 Bianca 420 is about 270 kg/cm, alternatively 1514 lbs/inch.
Meaning: if you load 270 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1514 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 Bianca 420 is 24.7.

Low High 24% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 24% of all similar sailboat designs. This is a comfort value significantly below average.


L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Bianca 420 is 3.27.

Slim Wide 58% 0 50 100
Compared with other similar sailboats it is more spacy than 58% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.


Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Bianca 420 is 41%.

Low High 62% 0 50 100
This ballast ratio shows a righting moment that is higher than 62% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.


D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Bianca 420 is 198 which categorizes this boat among 'light racers'.

Heavy Light 73% 0 50 100
73% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.


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 47m2 (505 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

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
Fractional rig
UsageLengthDiameter
Jib sheet 12.8 m(41.8 feet)14 mm(0.55 inch)
Genoa sheet12.8 m(41.8 feet)14 mm(0.55 inch)
Mainsheet 31.9 m(104.6 feet)14 mm(0.55 inch)
Spinnaker sheet28.1 m(92.0 feet)14 mm(0.55 inch)
Masthead rig
UsageLengthDiameter
Jib sheet 12.8 m(41.8 feet)14 mm(0.55 inch)
Genoa sheet12.8 m(41.8 feet)14 mm(0.55 inch)
Mainsheet 31.9 m(104.6 feet)14 mm(0.55 inch)
Spinnaker sheet28.1 m(92.0 feet)14 mm(0.55 inch)

Boat owner's ideas

This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.

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



Finally

We are always looking for new photos. If you can contribute with photos for Bianca 420 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