Review of RB 98

Basic specs.

The RB 98 is a sailboat designed by the maritime architect Roland Bergström in the early eighties. The RB 98 is built by the Swedish yard Rivalbåtar.

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Rig

The RB 98 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.

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 1.80 - 1.90 meter (5.91 - 6.21 ft) dependent on the load. See immersion rate below.

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 RB 98 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 7.1 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 RB 98 is about 184 kg/cm, alternatively 1032 lbs/inch.
Meaning: if you load 184 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1032 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 RB 98 is 22.1.

Comparing this ratio with similar sailboats show that it is more comfortable than 38% of all similar sailboat designs. This comfort value is just below average.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for RB 98 is 3.05.

Compared with other similar sailboats it is more spacy than 62% 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 RB 98 is 44%.

This ballast ratio shows a righting moment that is higher than 66% 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 RB 98 is 192 which categorizes this boat among 'light racers'.

76% 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 RB 98 with ISO 8666 reference sail is 18.2, with a 135% genua the SA/D is 21.0.

The SA/D ratio indicates that it is faster than 73% of all similar sailboat designs in light wind.

Over- / underrigged

The RB 98 has more rig than 50% of all similar sailboats, which indicates that this rig is spot on average!

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for RB 98 is 79

The relative speed performance is 79 which means that a it is faster than 79% 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 32m² (344 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 fractional 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	34.8 m	(114.2 feet)	10 mm	(3/8 inch)
Jib/genoa halyard	34.8 m	(114.2 feet)	10 mm	(3/8 inch)
Spinnaker halyard	34.8 m	(114.2 feet)	10 mm	(3/8 inch)
Jib sheet	9.8 m	(32.0 feet)	12 mm	(1/2 inch)
Genoa sheet	9.8 m	(32.0 feet)	12 mm	(1/2 inch)
Mainsheet	24.4 m	(80.0 feet)	12 mm	(1/2 inch)
Spinnaker sheet	21.5 m	(70.4 feet)	12 mm	(1/2 inch)
Cunningham	4.0 m	(13.0 feet)	10 mm	(3/8 inch)
Kickingstrap	7.9 m	(25.9 feet)	10 mm	(3/8 inch)
Clew-outhaul	7.9 m	(25.9 feet)	10 mm	(3/8 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 RB 98 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.