Review of Najad 520 DS

The boat is equipped with a galley.

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 boat can only enter major marinas as the draft is about 2.20 - 2.30 meter (7.22 - 7.52 ft) dependent on the load. See immersion rate below.

Najad 520 DS is typically equipped with an inboard Yanmar 4LH-HTE diesel engine at 135.0 hp (100 kW), which gives a max speed about 8.7 knots.

The fuel tank has a capacity of 690.0 liters (182 US gallons, 151 imperial gallons).

What is Capsize Screening Formula (CSF)?

The capsize screening value for Najad 520 DS is 1.71, 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 8.9 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 Najad 520 DS is about 417 kg/cm, alternatively 2338 lbs/inch.
Meaning: if you load 417 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 2338 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Najad 520 DS is 39.0.

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 Najad 520 DS is 3.43.

Compared with other similar sailboats it is more spacy than 66% 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 Najad 520 DS is 34%.

This ballast ratio shows a righting moment that is higher than 38% of all similar sailboat designs. A righting moment (ability to resist heeling) just below average.

What is Displacement Length Ratio?

The DL-ratio for Najad 520 DS is 224 which categorizes this boat among 'light crusers & offshore racers'.

46% 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.

SA/D (Sail Area Displacement ratio)
Indicates how fast the boat is in light wind:
- Cruising Boats have ratios 10-15
- Cruiser-Racers have ratios 16-20
- Racers have ratios above 20
- High-Performance Racers have ratios above 24
Sail-area/displacement ratio (SA/D ratio): 14.63

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 69m² (742 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.

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 Najad 520 DS 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.