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Review of Grampian Discovery 7.9


Basic specs.

sail specifications
The Grampian Discovery 7.9 is a sailboat designed by the maritime architect Alex McGruer in the late seventies. The Grampian Discovery 7.9 is built by the Canadian yard Grampian Marine Ltd..

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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

Fin keel

The Grampian Discovery 7.9 is equipped with 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.

The boat can enter even shallow marinas as the draft is just about 1.14 - 1.24 meter (3.74 - 4.04 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 Grampian Discovery 7.9 is 1.94, indicating that this boat could - if evaluated by this formula alone - 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 6.2 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 Grampian Discovery 7.9 is about 112 kg/cm, alternatively 631 lbs/inch.
Meaning: if you load 112 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 631 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 Grampian Discovery 7.9 is 20.2.

Low High 54% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 54% 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 Grampian Discovery 7.9 is 3.12.

Wide Slim 66% 0 50 100
Compared with other similar sailboats it is slimmer than 66% of all other designs. It seems that the designer has chosen a slightly more speedy hull design.


Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for Grampian Discovery 7.9 is 45%.

Low High 73% 0 50 100
This ballast ratio shows a righting moment that is higher than 73% of all similar sailboat designs. A righting moment (ability to resist heeling) just above average.


D/L (Displacement Length Ratio)

What is Displacement Length Ratio?

The DL-ratio for Grampian Discovery 7.9 is 221 which categorizes this boat among 'light crusers & offshore racers'.

Heavy Light 58% 0 50 100
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)

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): 17.39


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 18m2 (193 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
UsageLengthDiameter
Jib sheet 7.9 m(26.0 feet)10 mm(3/8 inch)
Genoa sheet7.9 m(26.0 feet)10 mm(3/8 inch)
Mainsheet 19.8 m(65.0 feet)10 mm(3/8 inch)
Spinnaker sheet17.4 m(57.2 feet)10 mm(3/8 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 Grampian Discovery 7.9 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