Messing about in boats since 1975.  Online Since 1997.

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A 42' Ketch For Voyaging


The 42' Steel Ketch - Zephyr
Larger Sail Plan Image
| Alt Interior Profile & Plan | Newest Interior Prof & Plan
Side Perspective | Aft Perspective | Starb'd Above Perspective

Copyright 1996 - 2019 Michael Kasten


Shown above is a new version of my Zephyr design, originally created immediately following a rough and wet passage down the Pacific West Coast in the early 1990's. During that voyage the ideas for Zephyr came together in the form of several sketches which were eventually worked into the design you see here.

The Concept

The Zephyr styling was inspired by the excellent yachts from the mid 1900's such as those drawn by Alden, Rhodes, Crocker and others of the time. Those yachts were not only elegant, sleek and graceful, they also had a hull form that is known to behave well at sea. For blue water travel they have been proven to be comfortable, safe, fast, and weatherly.

My goal with the Zephyr design has been to combine the attributes of sleekness, grace, speed and comfort inherent in those designs with an easily built metal hull form. It also seemed desirable to have an interior layout that could accommodate up to four on a passage, though three is really the ideal.

With those design goals in mind, Zephyr was given medium displacement and the characteristic spoon-bow and counter-stern, a well balanced combination. Beam and depth were optimized for windward sailing without resorting to a high aspect fin keel or a tall Marconi sail. The ketch rig was chosen for its all-around sailing ability and a long fine run was provided for fast sailing.

Design Details

Zephyr was conceived primarily for ocean voyaging, therefore steel construction was originally chosen for its incredible strength and abrasion resistance. In steel, the rig had slightly less sail area, with the sails sized for easy handling. See below for rig details...

In order to achieve a lighter structure and a larger sail area, I recently re-designed Zephyr for construction in aluminum. The alloy structucre is equally strong and the lighter hull weight allows more ballast for enhanced sail carrying ability. Thus, even though the hull shape did not change, the sail area could be increased vs the original in steel.



  • Length on Deck: 42' - 0"
  • Beam: 12' - 2"
  • Draft: 5' - 4"
  • DWL Displacement: 26,370 lb.
  • D/L 323
  • Working Sail Area: 1,015 SF
  • Light Weather SA: 1,241 SF
  • Length on Deck: 12.8m
  • Beam: 3.72m
  • Draft: 1.63m
  • DWL Displacement: 11,958 kg.
  • Metric L/D: 4.46
  • Working Sail Area: 94 Sq Meters
  • Light Weather SA: 115 Sq Meters

Whether steel or aluminum, the single chine hull form is ideal for its simplicity, economy of construction, performance, and in order to blend well with the classic aesthetics of the design. To review the rationale for this, please see my article on Aluminum for Boats, originally published in Cruising World magazine.

The keel has been designed using a NACA foil shape, which provides the best combination of enhanced lift and low drag for windward sailing. The sweep-back of the forefoot and the "drag" to the keel bottom are key elements that provide for optimum steering stability. The keel profile can be seen here, and is the same as that of Highland Lass II. With this type of keel, the boat will not require a steering vane during passages, and can instead use a simple sheet to tiller steering arrangement. Many are skeptical on this point regarding self steering, however it has been proven through my own experience on several ocean passages with similar vessels.

The after-deck is raised to the height of the bulwark top in order to provide more storage in the lazarette as well as more leg room for quarter berths. A key benefit to the raised afterdeck is increased reserve buoyancy aft, thus a dry area for the helm and enhanced stability. A raised quarter rail is provided for security on the aft deck.

The heavy wall pipe davits aft are for carrying the skiff during day-sails, and for hoisting it up at night to keep the shore boat from disappearing, or getting into trouble. For longer trips in open water, the skiff is lifted aboard using the mains'l halyard and nested into the portside runway, halfway onto the cabin top.

The Interior

ORIGINAL LAYOUT: The original Interior Profile & Plan for the Zephyr is the same as that of the 42' schooner design, Highland Lass II. With Highland Lass' schooner rig, the mast positions determined what was possible with the interior. For example, in the forepeak there is a good sized chain locker and aft of that, a settee is located port and starb'd with a dining table hung on the mast.

Just aft of the settee, a large galley is located port and starb'd. Aft of the galley there is a head to starb'd and a chart table / hanging locker to port. Two quarter berths are located right aft, tucked under the raised aft deck. The engine box is located between the quarter berths, and is arranged to also serve as a bureau-top as well as being one of the steps on the way to the aft deck from below. This layout allows comfortable sleeping for four on a regular basis.

ALTERNATE LAYOUT: Due to the main mast position on Zephyr, an Alternate Interior Layout becomes possible, with a generously sized double "V" berth right forward. Aft of the "V" berth at the same height to port and starb'd are a pair of 4' - 6" long settees that extend aft to the galley, with a table between. Continuing aft of the settees, the rest of the layout is more or less the same as the Highland Lass, except that with the schooner's main mast removed from the main cabin, it becomes possible to re-arrange the head - all for the better.  

42' Ketch ZEPHYR - Kasten Marine Design, Inc.

NEWEST INTERIOR LAYOUT:  Many will prefer to have a true "Island Berth" up forward - one where you can swing your legs out to either side.  In this 'third' layout, we find an actual private stateroom forward with a walk-around double berth...  The settees in the saloon are a full 7 feet in length, and the galley is moved to be opposite the head.  In all, with the pull-out berth to port in the saloon, this could provide sleeping for 7 people. 

If it were preferred to increase the galley size, the 'midship settees could be shortened to 5 feet, and the added space donated to the galley on the port side - offering a genuine "U" shaped galley with a bit more foot room on the sole.  To starb'd, the added 2 feet could allow the head to move forward, making room for a chart table aft having its seat on the head of the starb'd quarter berth.

42' Ketch Zephyr - Island Berth layout
 Third Layout - Click for Larger Image


The Rig

All the spars are designed to be fabricated using aluminum pipe, with all fittings welded in place. All spars sealed at the ends and are therefore are air-tight and water-tight. They will actually float…! Aluminum is the strongest, the simplest to fabricate and the easiest to maintain of any spar material. If done nicely and painted, no one need know they are not made of wood!

The ketch rig works well for ocean cruising and provides a generous sail area, especially with the mizzen staysail - the "mule" as they say. A gaff mains'l was chosen in order to provide a relatively low-aspect, easily handled, robust and low-stress rig. The mizzen mast is located in order to provide a good hand-hold when emerging from the companionway, and also serves as the compass binnacle. An awning can be spread over the mizzen boom... a Bimini for the cockpit..!

The ketch rig provides quite a number of well-balanced sail combinations. For example, the main and stays'l when used alone have nearly the same balance as the whole sail plan, and will allow easy tacking in close quarters. With sufficient wind, the boat will also tack nicely with only the mains'l set. Another equally well balanced sail combination is just the mizzen and the jib, say to keep the foredeck clear while coming in to anchor so the jib can be lowered once anchored, and the mizzen will weather-cock the vessel - or while stowing the ground tackle when getting under way from an anchorage.

ORIGINAL SAIL PLAN: The Original Ketch Rig sail plan was developed for use with a steel hull and was less tall. Originally conceived as a passage-making vessel, off wind performance was given the highest priority, therefore a few additional sails were planned for trade wind sailing in the form of a square sail and raffee hung from a cross-yard located just above the gaff saddle, with those sails set flying from on deck. These two sails add a bit more than 500 sq. ft. yet still preserve a low center of effort - the perfect rig for voyaging on a steel hull.

NEW SAIL PLAN: The New Ketch Rig shown here is able to provide a larger sail area with higher aspect ratio sails for use with an aluminum hull. With the same excellent hull form, the lighter weight aluminum structure allows more ballast to be carried in order to achieve a lower center of gravity, therefore a higher aspect rig can be carried in order to maximize windward performance. With the addition of a mizzen-staysail for light airs, performance will be excellent in all weathers.

Another of the benefits of the rig as it is drawn is the manageable size of each individual sail. For example, the new mains'l is just 398 sq. ft. and it is well inboard where it can be handled safely and easily.

JUNK SAIL PLAN...?  See below for the Zephyr Junk Rig concept.  This is a good option for the Zephyr. In general, it is best when using the Junk Rig to avoid using any Western style headsails.  The reason for this is that the headsails will tend to blow the bow off the wind, and therefore reduce the ability of the vessel to sail to windward.  In addition, by comparison to the Junk Rig, Western type of headsails are much more difficult to handle.

Because the Junk Rig is much heavier than the ketch rig, it will require the maximum amount of ballast, therefore the Junk Rig version of Zephyr would necessarily be built in aluminum.

42' Zephyr Junk Rig - Kasten Marine Design, inc.
  Click for larger image.


Each of the attributes mentioned here emerged as the result of having wished for each one of them on our rough coastwise trip. What would I change...? Not one thing really. For other purposes, a Bermuda rigged main sail could easily be provided and would be a good companion on an aluminum hull that is intended for coast-wise sailing. It is all a matter of one's preferences, which once decided cannot be argued...

A smaller sister has been developed for construction in steel or aluminum: the 36' ketch 36' Ketch Grace, with all the excellent attributes of the Zephyr in a smaller package...

For more information about Zephyr, please inquire.