Review of Hydra 16

Basic specs.

The Hydra 16 is a small sailboat designed by the Swedish maritime architect Heinz-Jurgen Sass in the early seventies. Several hundred boats have been produced. The Hydra 16 is built by the Swedish yard Boo Marin AB.

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Interior

The boat is equipped with 4 berths.

Note: the boat has also been sold to be self-made/-interiored, which means that the quality of each boat may vary.

Rig

The Hydra 16 is 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.

Keel

Unknown keel type

The keel is made of iron. Many people prefer lead keel in favour of iron. The main argument is that lead is much heavier than iron and a lead keel can therefore be made smaller which again result in less wet surface, i.e. less drag. In fact iron is quite heavy, just 30% less heavy than lead, so the advantage of a lead keel is often overstated.

Hydra 16 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.

Sailing characteristics

This section covers widely used rules of thumb to describe the sailing characteristics. Please note that even though the calculations are correct, the interpretation of the results might not be valid for extreme boats.

Stability and Safety

What is Capsize Screening Formula (CSF)?

The capsize screening value for Hydra 16 is 2.09, indicating that this boat would not be accepted to participate in ocean races.

Theoretical Maximum Hull Speed

What is Theoretical Maximum Hull Speed?

The theoretical maximal speed of a displacement boat of this length is 5.6 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.

Immersion rate

The immersion rate is defined as the weight required to sink the boat a certain level. The immersion rate for Hydra 16 is about 72 kg/cm, alternatively 405 lbs/inch.
Meaning: if you load 72 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 405 lbs cargo on the boat it will sink 1 inch.

Sailing statistics

This section is statistical comparison with similar boats of the same category. The basis of the following statistical computations is our unique database with more than 26,000 different boat types and 350,000 data points.

Motion Comfort Ratio

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for Hydra 16 is 13.6.

Comparing this ratio with similar sailboats show that it is more comfortable than 62% of all similar sailboat designs. This comfort value is just above average.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for Hydra 16 is 3.00.

Compared with other similar sailboats it is slimmer than 82% of all other designs. It seems that the designer has chosen a significantly more speedy hull design.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Hydra 16 is 44%.

This ballast ratio shows a righting moment that is higher than 76% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly above average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Hydra 16 is 159 which categorizes this boat among 'light racers'.

62% 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)

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

The SA/D for Hydra 16 with ISO 8666 reference sail is 18.3, with a 135% genua the SA/D is 22.2.

The SA/D ratio indicates that it is faster than 50% of all similar sailboat designs in light wind.

Over- / underrigged

The Hydra 16 has more rig than 66% of all similar sailboats, which indicates that the boat is slightly overrigged.

RSP (Relative Speed Performance)

What is Relative Speed Performance?

The Relative Speed Performance for Hydra 16 is 69

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

Maintenance

Bottom Paint

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 12m² (129 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.

Rig

Dimensions of sail for masthead 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.

**Guiding dimensions of running rig**
Usage	Length		Diameter
Mainsail halyard	17.8 m	(58.4 feet)	6 mm	(1/4 inch)
Jib/genoa halyard	17.8 m	(58.4 feet)	6 mm	(1/4 inch)
Spinnaker halyard	17.8 m	(58.4 feet)	6 mm	(1/4 inch)
Jib sheet	6.0 m	(19.7 feet)	8 mm	(5/16 inch)
Genoa sheet	6.0 m	(19.7 feet)	8 mm	(5/16 inch)
Mainsheet	15.0 m	(49.2 feet)	8 mm	(5/16 inch)
Spinnaker sheet	13.2 m	(43.3 feet)	8 mm	(5/16 inch)
Cunningham	2.0 m	(6.6 feet)	6 mm	(1/4 inch)
Kickingstrap	4.0 m	(13.1 feet)	6 mm	(1/4 inch)
Clew-outhaul	4.0 m	(13.1 feet)	6 mm	(1/4 inch)

Boat owner's ideas

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.

Finally

We are always looking for new photos. If you can contribute with photos for Hydra 16 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.

References

[Ref 1]: ISO 8666 Small craft — Principal data.
[Ref 3]: ISO 12215-5 Small craft — Hull construction and scantlings.