WEB SERIES – Listening to our customers, we have created a new web series to answer all of your questions and expectations about the J/Boat difference. We share our expertise, advise and tips with you to improve your knowledge and settings on your boat.

All about – INFUSION

Infusion Process – Sandwich construction using infusion methods is one of the most technological and cutting-edge processes in the marine construction market. At J/Composites, all the build elements are created using the infusion technique so as to obtain maximum stiffness. Furthermore, it should also be highlighted that the scantlings of the infused composite structure meet the standards for offshore racing (World Sailing structural plan review), which is possible thanks to the very significant weight saving synonymous with infusion.


Deck Fittings and Layout – Sailing pleasure is improved with well positioned and equipped deck layout and fittings. Through this new video, we explain our choices of the standard deck fittings on a J. Whether the retractable mooring cleats, the end fitting for the pulpit or the highly ergonomics deck layout, every part of a J/Boat is well thought out for racing or cruising.


Sandwich Construction – what’s the difference?  We present the advantages of infused sandwich construction used in J/Boats versus the simple mono panel. Discover how a J/Boat offers the most solid and rigid construction on the market, whilst retaining its unrivalled lightweight design, which establishes its reputation as a high-performance yacht.

All about – MAST DETAILS

Mast Details – To maximize performance at sea and navigation pleasure, we create unique mast profiles and characteristics specifically designed for each model.

All about – FOAM LAYING

Foam Laying – Following on from the infusion and sandwich construction, it is important to highlight the know-how and attention to detail in laying up the boat. There are different levels of quality behind the word “infusion” and “sandwich” which is why it is important to explain how we utilise this technology to its utmost to create the best stiffness/weight ratio.


The pleasure of sailing a J/Boat – a yacht built with care, with a concern for lightweight yet robust quality design.  All this is possible due to manufacturing quality, construction materials and the architect’s designs – dedicated to all-round performance and build quality combining lightweight design and stiffness and an unrivalled mastery of infusion.

These three parameters define the weight and stiffness of the build, to offer a yacht with increased rigidity and generate improved performance when sailing. The upshot of this is a yacht which is easy to sail with less sheet loadings, less use of the engine and more time sailing.  

To achieve this, the boat’s construction methods utilise the infusion process pioneered by J/Boats. Some 30 years ago, the SCRIMP patent (Seemann Composite Resin Infusion Molding Process) was applied for in the construction of J/Boats, which was a revolution among shipyards. Today, this well-controlled technique is more widely known as ‘infusion’.


Resin Infusion in progress

What is infusion? Sandwich construction using infusion methods is one of the most technological and cutting-edge processes in the marine construction market. With traditional lamination, an operator applies the resin to the materials by hand. With infusion, there is less human contact with the resin, hence working conditions are improved and there is far better quantity control. In layman’s terms, having applied various layers of materials, or even added elements of predominantly foam-based sandwich, a plastic cover is stretched tightly across the materials, creating a hermetic seal. A pump sucks up any air between the cover and the materials, compressing these in the process. The compression creates suction and the resin is distributed around the materials, followed by a few hours’ wait for the polymerisation process to be completed. Result: Perfect distribution of the resin and optimum quantity, culminating in light and stiff decks, structural bulkheads and hull.  Plus it’s better for the environment.

Hull being infused in the mold

At J/Composites (builder of J/Boats), all the aforementioned elements are created using the infusion technique so as to obtain maximum stiffness. Furthermore, all the secondary bulkheads are bonded to the hull and deck throughout, as well as to the fit-out structure. It should also be highlighted that the scantlings of the infused composite structure meet the standards for offshore racing (World Sailing structural plan review), which is possible thanks to the very significant weight saving synonymous with infusion.  Additionally, it allows for a 5 year structural warranty and 10 year warranty against osmosis.  In short, this is construction at its best!

Infused hull being released from the mold


J/Boats have always been renowned in racing circles, monopolising the list of winners for decades.  Whether you’re racing around the cans or over longer distances, the Js have always demonstrated great prowess both offshore and inshore.

Js offer a level of performance that is easily accessible in shorthanded configuration thanks to their ballast stability and build optimisation, thereby reducing the weight in the boat’s topsides.


Note the finish on the solid wood carpentry. At J Composites, craftsmanship is still part and parcel of the fit-out on its yachts. Every piece of furniture starts off as a block of specially selected walnut. No reconstituted Alpi-style wood here, only solid wood in its original state. As such, the boat ages naturally and looks even more beautiful over time! A great deal of work goes into the selection process to ensure only the best pieces of wood are chosen. Carpenters and cabinet makers use it for lockers, cupboards, shelving, and tables adapted to each yacht interior, like the Elégance range penned by Roséo.  Another benefit of well-crafted construction is that it ages well hence the second-hand value remains buoyant.


Isn’t it essential to have all the necessary equipment as standard for making headway on every point of sail? A trademark of J/Boats, the famous carbon bowsprit with spinnaker fittings comes as standard of course. The hardware is optimised to the boat in both the Elegance and Sport series and developed jointly between the builder and the supplier. For example, the new Snubbair winch developed for the J/70 or the aluminium mast on the J/112 E and the J/99, are custom developed uniquely for these models with notable innovations. With regards to the deck hardware, it’s worth noting the size 40 winches on the J/97 E and J/99 weighing 4mt, are the same size as used on an Océanis 46.1 with a weight of 11mt!  Each year, our teams’ trial and put to the test the latest technological equipment innovations to offer you the most appropriate recommendations.

You’re on a high-quality yacht which will be a part of your dreams for a long time to come!



The measure of a good sailboat is how well it sails upwind and downwind with only 2-3 people aboard. The goal is VMG, Velocity-Made-Good, straight into the wind or away from the wind, considering both speed and sailing angle. Hull design, rig, sailing length and weight location greatly affect VMG. You see many cruising boats motoring upwind in both light and heavy air. Why? Not enough sail power for light air or stability for a breeze. These differences are inescapably locked in by design and construction.


Flying an asymmetrical spinnaker from a retractable, carbon-fibre bow sprit is safe, fast and easy To jibe, simply let off one sheet and pull in the other. Downwind VMG is doubled. Result? Less motoring and more sailing. It’s safer. The tack of the spinnaker is always secured to the bowsprit, eliminating wild oscillations. The sail has more slope to its leading edge with a centre-of-effort located further forward and lower. Wind gusts lift the bow, propelling the boat forward with finger-tip control. No more “white-knuckled” round-up broaches. Speed from the asymmetrical spinnakers greater power pushes the apparent wind 30-50 degrees forward of the true wind direction. In light air and lumpy seas, the sail’s added power steadies the boat. Deep sailing angles (160-170 degrees True Wind Angle) are achieved in a breeze. The luff, which is 8% longer than the straight line distance from tip of the sprit to halyard exit on the mast, rotates to windward as the sheet is eased – projecting area to the wind like a conventional spinnaker when pulled back by a pole.


Good upwind VMGs are only possible with a low, vertical centre of gravity (VCG). Top-heavy boats roll and pitch. This motion disturbs water flow around the boat and airflow past the sails, not to mention equilibrium of the crew on deck. The lower the weight of the boat relative to its waterplane, the greater the stability, the more sail that can be carried and the smoother the motion. This explains a J’s smooth, stable ride through waves. The VCG is well below the waterplane.

The best place to reduce weight is aloft. All spars are custom-designed for J/Boats, race-tested to ensure reliability with a good safety margin built-in. Running backstays aren’t required.

The best place to add weight is in the keel. A lead keel, fixed under a structural molded sump, having much of the weight in a bulb at the bottom, serves to optimize a boat’s stability without adding excess draft. J’s combine low VCG ballast with quality construction.


Sails are the horses. A light boat with clean lines and good stability can carry the sail power needed for lively performance. There’s no need for tall, scary rigs with heavy sheet loads and winches. Sail Area to displacement (SA/[DSPL/64]^.67) is a good indicator of how much horsepower the design can handle and what its speed potential might be. Look for ratios over 20. The J/122 is at 23%.


Too much weight usually means too much wetted surface (WS). The more WS there is relative to sail area, the quicker you stop. A good SA/WS ratio is critical for performance in light air conditions. For example, among 40 footers, J/122’s ratio of 3.1 is FAST. A boat with a ratio of 2.0 would be “glued.” Then there’s form drag. It’s usually faster to be long and narrow, but only when combined with greater stability and sail power. A length (LWL) to beam (BWL) ratio greater than 3 is desirable for good directional tracking in waves. J/122 has a healthy 3.6:1 ratio with flared topsides. Flare slaps waves down and keeps the crew dry. Vertical sided hulls bounce waves up on the crew.

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