Review of Finn Flyer 31

The hull is made of fibreglass. A hull made of fibreglass requires only a minimum of maintenance during the sailing season.

The hull is a sandwich construction 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 core material in the sandwich construction is balsa.

The boat is equipped with 6 berths, a galley, 100 liters (26 US gallons, 21 imperial gallons) fresh water capacity and toilet facility.

The interior is like most other boats made of teak. Teak has the advantage of being naturally very oily and therefore water-repellent, which is suitable on boats.

The boat has more than one rig.

One option is a fractional rig. The sail area for the mailsail + jib is 43.0 m² (462.8 ft²). 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.

Another option is a fractional rig. The sail area for the mailsail + jib is 38.4 m² (413.0 ft²). 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.

Fin keel

The Finn Flyer 31 is built with a fin keel. A boat with a fin keel is more manoeuvrable but has less directional stability than a similar boat with a full keel.

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.

Finn Flyer 31 can enter most marinas as the draft is just about 1.75 - 1.85 meter (5.74 - 6.04 ft) dependent on the load. See immersion rate below.

The boat may be equipped with an inboard Yanmar diesel engine

What is Capsize Screening Formula (CSF)?

The capsize screening value for Finn Flyer 31 is 2.13, indicating that this boat would not 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 Finn Flyer 31 is about 160 kg/cm, alternatively 900 lbs/inch.
Meaning: if you load 160 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 900 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Finn Flyer 31 is 19.5.

Comparing this ratio with similar sailboats show that it is more comfortable than 27% of all similar sailboat designs. This comfort value is just below average.

What is L/B (Length Beam Ratio)?

The l/b ratio for Finn Flyer 31 is 2.94.

Compared with other similar sailboats it is more spacy than 69% 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 Finn Flyer 31 is 31%.

This ballast ratio is higher than 8% of all similar sailboat designs. Since the ballast ratio and the righting moment (i.e. better ability to resist heeling) is strongly correlated, a ballast ratio significantly below average indicates a very low ability to resist heeling.

What is Displacement Length Ratio?

The DL-ratio for Finn Flyer 31 is 231 which categorizes this boat among 'moderate racers'.

62% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

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

The SA/D for Finn Flyer 31 with ISO 8666 reference sail is 16.9, with a 135% genua the SA/D is 19.3.

The SA/D ratio indicates that it is faster than 58% of all similar sailboat designs in light wind.

The Finn Flyer 31 has more rig than 92% of all similar sailboats, which indicates that the boat is significantly overrigged.

What is Relative Speed Performance?

The Relative Speed Performance for Finn Flyer 31 is 69

The relative speed performance is 69 which means that a it is faster than 69% of all similar sailboat designs.

As balsa wood is used as sandwich core material special care must be taken in relation to work that require penetration of the sandwich construction in order to to prevent water to get in contact with the balsa wood. Otherwise the balsa wood will eventually rotten and be expensive/impossible to repair.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 28m² (301 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 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.

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.

We are always looking for new photos. If you can contribute with photos for Finn Flyer 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.