Review of Forgus 31

The hull is made of fibreglass. 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 most other boats made of teak.
The boat is equipped with 6 berths, a galley and toilet facility.
The headroom is above average

The boat 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.

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 enter most marinas as the draft is just about 1.64 - 1.74 meter (5.38 - 5.68 ft) dependent on the load. See immersion rate below.

Forgus 31 is typically equipped with an inboard Volvo Penta MD2B diesel engine at 25.0 hp (18 kW), which gives a max speed about 5.6 knots.

What is Capsize Screening Formula (CSF)?

The capsize screening value for Forgus 31 is 1.91, 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 6.6 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 Forgus 31 is about 158 kg/cm, alternatively 888 lbs/inch.
Meaning: if you load 158 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 888 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Forgus 31 is 27.1.

Comparing this ratio with similar sailboats show that it is more comfortable than 69% of all similar sailboat designs. This comfort value is just above average.

What is L/B (Length Beam Ratio)?

The l/b ratio for Forgus 31 is 2.91.

Compared with other similar sailboats it is more spacy than 73% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.

What is a Ballast Ratio?

The ballast ratio for Forgus 31 is 42%.

This ballast ratio shows a righting moment that is higher than 58% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.

What is Displacement Length Ratio?

The DL-ratio for Forgus 31 is 330 which categorizes this boat among 'heavy cruisers'.

18% of all similar sailboat designs are categorized as heavier. A heavy displacement combined with smaller water plane area has lower acceleration and is more comfortable.

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

The SA/D for Forgus 31 with ISO 8666 reference sail is 13.9, with a 135% genua the SA/D is 16.7.

The SA/D ratio indicates that it is faster than 21% of all similar sailboat designs in light wind.

The Forgus 31 has more rig than 27% of all similar sailboats, which indicates that the boat is slightly underrigged.

What is Relative Speed Performance?

The Relative Speed Performance for Forgus 31 is 50

The relative speed performance is 50 which means that a it is faster than 50% of all similar sailboat designs.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 27m² (290 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.

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.

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.

We are always looking for new photos. If you can contribute with photos for Forgus 31 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.

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