x yacht 79

Sailboat specifications

• Last update: 3rd April 2020

X-79's main features

X-79's main dimensions, x-79's rig and sails, x-79's performances, x-79's auxiliary engine, x-79's accommodations and layout, x-79's saloon.

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• Sailboat Guide

X-79 is a 26 ′ 1 ″ / 8 m monohull sailboat designed by Niels Jeppesen and built by X-Yachts between 1979 and 1994.

Rig and Sails

Auxilary power, accomodations, calculations.

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311 Hull Speed = Max Speed/Length ratio x √LWL

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

SA/D = SA ÷ (D ÷ 64) 2/3

• SA : Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
• D : Displacement in pounds.

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Ballast / Displacement * 100

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

• D: Displacement of the boat in pounds.
• LWL: Waterline length in feet

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam 1.33 )

• D: Displacement of the boat in pounds
• LOA: Length overall in feet
• Beam: Width of boat at the widest point in feet

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

CSV = Beam ÷ ³√(D / 64)

The X-79 was the first boat built by X-Yachts. Thanks to Paul Keller for providing updated information.

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The X 79 is a 26.12ft fractional sloop designed by Niels Jeppesen and built in fiberglass by X-Yachts between 1979 and 1994.

468 units have been built..

The X 79 is a light sailboat which is a very high performer. It is very stable / stiff and has a low righting capability if capsized. It is best suited as a racing boat.

X 79 for sale elsewhere on the web:

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• Boats for Sale

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Review of X-79

Basic specs.

Both the hull and the deck 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. The hull is a double hull which improves the indoor climate. Especially when the water is colder than the air in the cabin, then the double hull insulates against cold water and reduce the condense water in the cabin. The deck is a double deck which improves the indoor climate.

The boat is equipped with one cabin, 4 - 6 berths, a galley, 17.0 liter fresh water capacity and toilet facility. Note: the boat has also been sold to be self-made/-interiored, which means that the quality of each boat may vary.

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 X-79 has been built with different keel alternatives.

One option is a fin keel. A boat with a fin keel is more manoeuvrable but has less directional stability than a similar boat with a full keel.

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. As the surface of a fin type keel is just a fraction of the total wet surface, the difference between an iron keel and a lead keel can in reality be ignored for cruising yachts.

X-79 can enter even shallow marinas as the draft is just about 1.33 - 1.43 meter (4.36 - 4.66 ft) dependent on the load. See immersion rate below.

Another option is a fin keel.

This keel is also made of iron.

The boat can enter even shallow marinas as the draft is just about 1.35 - 1.45 meter (4.43 - 4.73 ft) dependent on the load. See immersion rate below.

An outboard motor is often used on this boat. In that case the boat will typically require a power of 3 - 4 hp, alternatively 71 - 85 lbs thrust if you prefer an electrical motor. Electric outboards are becoming popular for sailboat owners who want clean instant power with less noise and no exhaust fumes.

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.

What is Capsize Screening Formula (CSF)?

The capsize screening value for X-79 is 2.48, indicating that this boat would not 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 6.1 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 X-79 is about 123 kg/cm, alternatively 691 lbs/inch. Meaning: if you load 123 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 691 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.

What is Motion Comfort Ratio (MCR)?

What is L/B (Length Beam Ratio)?

What is a Ballast Ratio?

What is Displacement Length Ratio?

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

What is Relative Speed Performance?

Maintenance

When buying anti-fouling bottom paint, it's nice to know how much to buy. The surface of the wet bottom is about 20m 2 (215 ft 2 ). Based on this, your favourite maritime shop can tell you the quantity you need.

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.

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.

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If you have any comments to the review, improvement suggestions, or the like, feel free to contact us . Criticism helps us to improve.

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X-79 6 Pages

Catalog excerpts

The interior of the X-79 is functional, light, and pleasant. The materials used here are e.g. maha-gony, cork, linen, horsecloth, and structure coat. At the table in the cabin there are seating for 4-6 persons. The quarter berths are deap and comfortable with a length of 1,95 m. In standard version the forward cabin can easily be used for sails and gear - maritime and suitable. As extra equipment a large double berth with room for chemical toilet can be mounted. During the Off-shore races the shelves are used as pilot berths. The combined chart table/galley can easily be operated while...

The X-79 is a sandwich construction of fibre glass laid-up by hand. Characteristic for the X-79 is the quality of finish. The cockpit is worked out providing optimum seating comfort at the 2 m long benches as well as on the side decks. The long mainsail cross haul secures a precise and easily operated mainsail trim. All halyards and reefs are led to the winch at the hatch garage so that it can be operated either from windward, leeward, or standing on the double step in the companion way. The X-79 design has practically become leading for modern designs of the eighties. An increasing number...

During the recent years X-79 has gained a footing as a very exciting racer class. "DA NSK X-79 KLUB" is every year together with "INTERNATIONAL X SEVENTY-NINE ASSOCIATION" (IXSNA) arranging large races with participation of 30-40 boats, e.g. the races "SKANDINAVISK MESTERSKAB" and "DS-KLASSEM ESTER-SKA B" etc. X-79 has since her start every year been in the lead of the world's largest race "SJ/ELLAND RUNDT" in easy weather as well as hard weather. One of the most success-full match-racing finals in Denmark was held by using the X-79 in extremely hard weather (wind force 22 m/s) where...

Niels Jeppesen Modern Yacht Design

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X-yachts X-79 resources

• Assembly/build manual
• German X79 Class association rules from 2002 (In English, source: x79.de)
• Some commercial brochures: first second
• X-79 specification february 1991
• Sample polar diagram .

Trim guides

• The most comprehensive trim guide ( local copy ) I've found is the one from North Sails in Denmark. (in Danish)
• Quantum Sails has a section (in Danish) as well, but more brief. ( local copy )
• Original (?) typewritten trim guide from Nils Jeppesen In German, from x79.de
• SWE-67 pages (in swedish)
• Danish X-79 club
• X-79 on Danish wikipedia
• North Sails recommended X-79 sails (dead as of 2018-05-18)
• X-79 on sailboatdata.com

Mirror this site!

Much content is originally mirrored from www.x79.dk . As of December 2015 x79.dk is dead, and the swedish x79.nu is also offline now. Yachts last longer than web sites! Please fetch a full copy (or a git clone ) of the content and make it available for future X79 owners.

Last updated 2018-05-18 by Lasse Karstensen.

The X-79 is no longer in production. To see an overview of the current range please visit the Yachts page. You can also visit the overview of Previous X-Yachts Models .

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