Review of US 27 Mk I

Basic specs.

The US 27 Mk I aka Triton 27 is a sailboat designed by the American maritime architect Douglas Blair Peterson together with Daryl Watson from in the early eighties. The US 27 Mk I is built by the American yard US Yachts - Bayliner.

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Hull

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.

Keel

The US 27 Mk I has been built with more than one type of keel.

One option is a fin keel. The fin keel is the most common keel and provides splendid manoeuvrability. The downside is that it has less directional stability than a long keel.

Another option is a centerboard keel. A centerboard keel is a pivoting lifting keel, allowing to sail both coastal and inland waters.

The boat can enter most marinas as the draft is just about 1.57 - 1.67 meter (5.15 - 5.45 ft) dependent on the load. See immersion rate below.

Engine

The boat is typically equipped with an inboard Volvo Penta diesel engine.

The fuel tank has a capacity of 68.0 liters (17 US gallons, 14 imperial gallons).

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 US 27 Mk I is 2.07, 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 6.5 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 US 27 Mk I is about 137 kg/cm, alternatively 771 lbs/inch.
Meaning: if you load 137 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 771 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 US 27 Mk I is 19.5.

Comparing this ratio with similar sailboats show that it is more comfortable than 42% of all similar sailboat designs. This comfort value is just below average.

L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for US 27 Mk I is 2.89.

Compared with other similar sailboats it is more spacy than 69% of all other designs. It seems that the designer has chosen a slightly more spacy hull design.

Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for US 27 Mk I is 32%.

This ballast ratio shows a righting moment that is higher than 15% of all similar sailboat designs. A righting moment (ability to resist heeling) significantly below average.

D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for US 27 Mk I is 221 which categorizes this boat among 'light crusers & offshore racers'.

62% of all similar sailboat designs are categorized as heavier. A light displacement requires less sailarea and has higher accellerations.

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 24m² (258 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

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
Jib sheet	8.4 m	(27.5 feet)	10 mm	(3/8 inch)
Genoa sheet	8.4 m	(27.5 feet)	10 mm	(3/8 inch)
Mainsheet	21.0 m	(68.7 feet)	10 mm	(3/8 inch)
Spinnaker sheet	18.4 m	(60.5 feet)	10 mm	(3/8 inch)

Boat owner's ideas

This section shown boat owner's changes, improvements, etc. Here you might find inspiration for your boat.

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Finally

We are always looking for new photos. If you can contribute with photos for US 27 Mk I 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.