Review of Southerly 470

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

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 boat can enter even shallow marinas as the draft is just about 1.00 - 1.10 meter (3.28 - 3.58 ft) dependent on the load. See immersion rate below.

What is Capsize Screening Formula (CSF)?

The capsize screening value for Southerly 470 is 1.74, 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 8.8 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 Southerly 470 is about 389 kg/cm, alternatively 2183 lbs/inch.
Meaning: if you load 389 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 2183 lbs cargo on the boat it will sink 1 inch.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Southerly 470 is 37.1.

Comparing this ratio with similar sailboats show that it is more comfortable than 66% of all similar sailboat designs. This comfort value is just above average.

What is L/B (Length Beam Ratio)?

The l/b ratio for Southerly 470 is 3.22.

Compared with other similar sailboats it is more spacy than 76% 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 Southerly 470 is 35%.

This ballast ratio shows a righting moment that is higher than 46% of all similar sailboat designs. A righting moment (ability to resist heeling) just below average.

What is Displacement Length Ratio?

The DL-ratio for Southerly 470 is 216 which categorizes this boat among 'light crusers & offshore racers'.

58% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

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): 14.64

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 74m² (796 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 is reserved boat owner's changes, 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 Southerly 470 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.