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The Design.....

The J/160 is unique among all yachts over fifty feet in providing exceptional sailing performance, upwind and down, with ease of handling normally associated with yachts under 45 feet. Unique also is the J/160's combination of a comfortable sea-going cruising interior, sturdy ABS-approved construction, and the safest and most stable yacht that modern technology can provide. The hull, keel, rudder, and sail plan interact to achieve the speed, balance and sailing comfort that knowledgeable offshore sailors expect in a modern, high performance design.

Fast, Seagoing Hull
The J/160 is designed primarily for comfortable and fast ocean-going cruising for a short-handed crew.  Deep "V" forward sections and gently curved bilges amidships provide easy motion through waves and short chop. The combination of a narrow waterplane, fine entry, and low wetted surface optimizes comfort, speed, steering performance, and smooth motion in a seaway. Moderate flare in the topsides results in less spray on the windward deck. The aft sections show progressively tighter bilges toward a moderately wide stern, and very straight diagonals aft for optimum high-end speed on all points of sail.

The hull underbody profile displays ample fore-and-aft "rocker," characteristic of all J/Boats. This minimizes wetted surface and maximizes acceleration in light air. High freeboard and generous reserve buoyancy in the bow combined with low freeboard aft are designed to keep the bow up on high speed reaches, and handle the rigors of high-speed downwind sailing in large ocean waves. A low (but not too low) Displacement/Length ratio of 130 (in sailing trim) assures high top-end speed in heavy conditions, and allows enough displacement to achieve high stability for excellent upwind performance and safety offshore.

The J/160 becomes narrower through the water with progressively less wetted surface as it heels up to angles of 22 degrees. This accounts for the yacht's incredible speed and easy handling qualities upwind and reaching. In storm conditions the stable hull allows optimum steering control, and a smooth, slow, forward motion. Many yachts this size, including the J/160, are comfortable at the dock, but what distinguishes the J/160 is comfort at sea.

Advanced Keel Design
Two other important ingredients which enhance performance are proper keel and rudder size, shape and location. The J/160 fin keel design with long wedge-shaped tip places keel volume and vertical center of gravity (VCG) of the lead ballast very low. This shape distributes volume fore-and-aft to increase lift and reduce drag. Unlike conventional fin keels or a fin keel with bulb, lift is increased by placing a higher proportion of the effective lifting surface further away from the hull turbulence, caused by water flow around the hull and by pitching of the hull in waves.

The size of the keel and rudder depend on a yacht's displacement, beam, and height of Vertical Center of Gravity (VCG). A heavier, beamier, or less stable yacht requires a larger, deeper rudder and keel. This increases drag. If drag increases then the sail plan must be increased to maintain reasonable sailing performance. Because J/160 is narrow and relatively light, the keel and rudder are optimized for efficiency.

Superior Tracking and Control
With the keel located amidships, and airfoil-shaped rudder located near the aft end of the waterplane. The J/160 provides the best possible steering control. Her directional stability is unmatched by other configurations whether beating to windward in a following sea, "laying to" in storm conditions, or simply maneuvering around the dock. The easy cross-flow of water under the hull at low forward speeds, and the large distance between its keel and rudder, allow the helmsman to control steering, speed, leeway, and heel angle to achieve maximum comfort with minimal sail area . Similar control is nearly impossible with traditional heavy full-keel designs with an attached rudder.

The J/160 rudder is a deep, high-aspect, balanced spade with molded fiberglass shaft designed to rebound after deflection from striking underwater objects. This rudder configuration has survived groundings of the worst kind without rudder post failure in all larger J/Boats designs. The rudder and keel are both designed with enough leading edge sweepback to shed pot warps, and most forms of weed and kelp.

Stability
The J/160 is designed and built to optimize a low VCG. The deck and topsides are built strong and light using TPI's advanced resin-infusion SCRIMP® molding technology. Lower VCG means greater stability, which results in less heeling and a more efficient keel. This also allows for a moderate draft choice of 7.2 feet (standard) or 8.8 feet (optional). The designed limit of positive stability of J/160 is approximately 140 degrees, plus or minus three degrees depending on the loading. IMS calculated LPS (does not include deck) is approximately 125 degrees.

Short-handed Manageable Sail Plan
The triple-spreader masthead-rigged sail plan is moderate in size and height, and features a comparatively small high-aspect ratio forward triangle and large low aspect ratio mainsail. This rig configuration provides maximum sail area for the least possible rig height, and excellent sailing performance when cruising with main and roller furling #3 jib. The J/160 will perform well with this sail combination even in very light air.

This performance is the benefit of a high Sail Area /Displacement Ratio (22.0 for the J/160). Most cruising boats have SA/DSPL ratios of less than 20.0 which inevitably requires an inventory of at least two or more headsails to achieve acceptable performance in a variety of conditions. For offshore cruising a main and roller furling #3 is the perfect combination. A foam luff jib can be rolled to storm jib size. No need to change headsails or constantly reef while cruising on this yacht.  In fact, the J/160 can carry the same main and #3 jib combination in winds from 5-20 knots without need for reefing or changing sails.  This is a key example of where new design and technology combine to produce an easier to handle yacht.

The versatility of the large low-aspect mainsail and small headsail configuration is proven repeatedly in racing, cruising and ocean sailing. Whether you tack up a narrow channel under mainsail alone, race downwind with asymmetrical spinnaker this sail plan design allows for speed under great control. And unlike the cutter rig found on many yachts this size, the J/160 sloop configuration requires fewer and smaller headsails which cover a wider range of wind conditions.

The Asymmetric Spinnaker: Fast, Safe and Easy
Setting a spinnaker on a yacht this size is now practical and easy thanks to the asymmetric spinnaker flown from the retractable carbon fiber bow sprit. By using a cockpit operated snuffer no one must go forward on deck when the spinnaker is deployed, jibed or doused. To jibe, simply ease one sheet and pull in the other.

This system is safer than conventional spinnakers because one corner of the sail is always secured to the bowsprit, eliminating wild oscillations. The bowsprit extends and places the sail's low center of effort further forward. So a gust of wind tends to lift the bow and propel the yacht forward with "finger-tip" helm balance.

The shape of the asymmetric chute results in an efficient reaching sail in all conditions. When running downwind, deep sailing angles (down to 170 degree true wind angle) are achieved in over ten knots of breeze. The luff rotates out to windward as the sheet is eased, looking very much like a conventional chute pulled back by a pole.

-Rodney S. Johnstone, Designer

© Copyright 2004,  J/Boats, Inc., 557 Thames Street  Newport, RI  02840 - 401.846.8410  Email: J/Boats