Review of Gib'Sea 105 Plus

Basic specs.

The Gib'Sea 105 Plus is a sailboat designed by the French maritime architect Michel Joubert together with Bernard Nivelt also from France in the early eighties. Several hundred boats have been produced. The Gib'Sea 105 Plus is built by the French yard Gibert Marine.

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Hull

Both the hull and the deck is made of fibreglass. Generally, a hull made of fibreglass requires only a minimum of maintenance during the sailing season.

Interior

The boat is equipped with 2 cabins, 8 berths, 320.0 liter fresh water capacity and toilet facility.

Rig

The Gib'Sea 105 Plus 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 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.

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 Gib'Sea 105 Plus is 2.18, indicating that this boat would not 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 7.3 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 Gib'Sea 105 Plus is about 215 kg/cm, alternatively 1208 lbs/inch.
Meaning: if you load 215 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 1208 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 Gib'Sea 105 Plus is 18.8.

Comparing this ratio with similar sailboats show that it is more comfortable than 15% 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 Gib'Sea 105 Plus is 2.90.

Compared with other similar sailboats it is more spacy than 79% 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 Gib'Sea 105 Plus is 37%.

This ballast ratio shows a righting moment that is higher than 31% of all similar sailboat designs. A righting moment (ability to resist heeling) just below average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Gib'Sea 105 Plus is 178 which categorizes this boat among 'light racers'.

82% 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 Gib'Sea 105 Plus with ISO 8666 reference sail is 18.1, with a 135% genua the SA/D is 21.5.

The SA/D ratio indicates that it is faster than 69% of all similar sailboat designs in light wind.

Over- / underrigged

The Gib'Sea 105 Plus has more rig than 82% of all similar sailboats, which indicates that the boat is significantly overrigged.

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Gib'Sea 105 Plus is 62

The relative speed performance is 62 which means that a it is faster than 62% 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 36m² (387 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	32.0 m	(105.2 feet)	10 mm	(3/8 inch)
Jib/genoa halyard	32.0 m	(105.2 feet)	10 mm	(3/8 inch)
Spinnaker halyard	32.0 m	(105.2 feet)	10 mm	(3/8 inch)
Jib sheet	10.4 m	(34.3 feet)	12 mm	(1/2 inch)
Genoa sheet	10.4 m	(34.3 feet)	12 mm	(1/2 inch)
Mainsheet	26.1 m	(85.7 feet)	12 mm	(1/2 inch)
Spinnaker sheet	23.0 m	(75.4 feet)	12 mm	(1/2 inch)
Cunningham	3.8 m	(12.5 feet)	10 mm	(3/8 inch)
Kickingstrap	7.6 m	(24.9 feet)	10 mm	(3/8 inch)
Clew-outhaul	7.6 m	(24.9 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 Gib'Sea 105 Plus 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.