Review of SJ-30

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 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 genaker or a spinnaker for optimal speed.

The SJ-30 is equipped with a fin keel. A boat with a fin keel is more manoeuvrable but has less directional stability than a similar boat with a long 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.

The boat can enter most marinas as the draft is just about 1.62 - 1.72 meter (5.31 - 5.61 ft) dependent on the load. See immersion rate below.

The boat is typically equipped with an inboard BMW diesel engine at 7.0 hp (5 kW), which gives a max speed about 3.9 knots.

The fuel tank has a capacity of 30.0 liters (7 US gallons, 6 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for SJ-30 is 2.31, 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 6.7 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 SJ-30 is about 167 kg/cm, alternatively 937 lbs/inch.
Meaning: if you load 167 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 937 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for SJ-30 is 15.8.

Comparing this ratio with similar sailboats show that it is more comfortable than 12% of all similar sailboat designs. This is a comfort value significantly below average.

What is L/B (Length Beam Ratio)?

The l/b ratio for SJ-30 is 2.83.

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.

What is a Ballast Ratio?

The ballast ratio for SJ-30 is 41%.

This ballast ratio shows a righting moment that is higher than 50% of all similar sailboat designs. This righting moment (ability to resist heeling) is spot on average!

What is Displacement Length Ratio?

The DL-ratio for SJ-30 is 185 which categorizes this boat among 'light racers'.

79% 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 SJ-30 with ISO 8666 reference sail is 18.9, with a 135% genua the SA/D is 21.6.

The SA/D ratio indicates that it is faster than 82% of all similar sailboat designs in light wind.

The SJ-30 has more rig than 88% of all similar sailboats, which indicates that the boat is significantly overrigged.

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 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 SJ-30 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.