Review of Seafarer 31 Mk I

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 boat has more than one rig.

One 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.

Another option is a yawl rig. A yawl rig is generally considered easier to handle, because the sails are smaller, and because it can sail on most points to the wind with one sail completely taken down for repair or while reefing. The sail configuration of a yawl allows for better comfort and stability when sailing downwind or on a broad reach.

Full keel

The Seafarer 31 Mk I is equipped with a long keel. A full keel provide a better directional stability than a similar boat with a fin keel; on the other hand, better directional stability means also that the boat is more difficult to handle in a harbour with less space.

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 1.52 - 1.62 meter (4.99 - 5.29 ft) dependent on the load. See immersion rate below.

Seafarer 31 Mk I may be equipped with an inboard Universal Atomic 4 gasoline engine at 30 hp (22 kW). Calculated max speed is about 6.3 knots

What is Capsize Screening Formula (CSF)?

The capsize screening value for Seafarer 31 Mk I is 1.70, 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 6.1 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.

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Seafarer 31 Mk I is about 114 kg/cm, alternatively 641 lbs/inch.
Meaning: if you load 114 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 641 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Seafarer 31 Mk I is 31.2.

What is L/B (Length Beam Ratio)?

The l/b ratio for Seafarer 31 Mk I is 3.57.

What is a Ballast Ratio?

The ballast ratio for Seafarer 31 Mk I is 38%.

What is Displacement Length Ratio?

The DL-ratio for Seafarer 31 Mk I is 424 which categorizes this boat among 'heavy cruisers'.

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

The SA/D for Seafarer 31 Mk I with ISO 8666 reference sail is 13.3, with a 135% genua the SA/D is 15.6.

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 20m² (215 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.

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.

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If you have any comments to the review, improvement suggestions, or the like, feel free to contact us. Criticism helps us to improve.