Review of JPK 45

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.

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

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.

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.

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.

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.

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.

What is Motion Comfort Ratio (MCR)?

The Motion Comfort Ratio for JPK 45 is 18.9.

What is L/B (Length Beam Ratio)?

The l/b ratio for JPK 45 is 3.00.

What is a Ballast Ratio?

The ballast ratio for JPK 45 is 48%.

What is Displacement Length Ratio?

The DL-ratio for JPK 45 is 118 which categorizes this boat among 'ultra light racers'.

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

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.

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.

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.