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Review of JPK 45


Basic specs.

sail specifications
The JPK 45 is a large sailboat designed by the maritime architect Jacques Valer in the mid 2010.

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Hull

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

The hull is a sandwich construction 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 core material in the sandwich construction is PVC foam.PVC foam core is a synthetic material which offers excellent mechanical properties and low weight. It is widely used and has a proven track record in marine sandwich composites.


Interior

The boat is equipped with 3 cabins, 8 berths and 499 liters (131 US gallons, 109 imperial gallons) fresh water capacity.

The headroom is below average


Rig

The JPK 45 is built with a fractional rig. The sail area for the mailsail + jib is 113.0 m2 (1,216.0 ft2). 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 gennaker or a spinnaker for optimal speed.


Keel

Fin keel

The JPK 45 is built with 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 boat can only enter major marinas as the draft is about 2.00 - 2.10 meter (6.56 - 6.86 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 JPK 45 is 2.22, 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 8.6 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 JPK 45 is about 379 kg/cm, alternatively 2127 lbs/inch.
Meaning: if you load 379 kg cargo on the boat then it will sink 1 cm. Alternatively, if you load 2127 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 JPK 45 is 18.9.

Low High 7% 0 50 100
Comparing this ratio with similar sailboats show that it is more comfortable than 7% of all similar sailboat designs. This is a comfort value significantly below average.


L/B (Length Beam Ratio)

What is L/B (Length Beam Ratio)?

The l/b ratio for JPK 45 is 3.00.

Slim Wide 86% 0 50 100
Compared with other similar sailboats it is more spacy than 86% of all other designs. It seems that the designer has chosen a significantly more spacy hull design.


Ballast Ratio

What is a Ballast Ratio?

The ballast ratio for JPK 45 is 48%.

Low High 95% 0 50 100
This ballast ratio shows a righting moment that is higher than 95% 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 JPK 45 is 118 which categorizes this boat among 'ultra light racers'.

Heavy Light 92% 0 50 100
92% 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): 27.58


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 61m2 (656 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 13.5 m(44.3 feet)16 mm(5/8 inch)
Genoa sheet13.5 m(44.3 feet)16 mm(5/8 inch)
Mainsheet 33.8 m(110.7 feet)16 mm(5/8 inch)
Spinnaker sheet29.7 m(97.4 feet)16 mm(5/8 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 JPK 45 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