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The 112' Sailing Yacht


The 118' Alloy Sailing Yacht - LEAH
Perspective Starb'd | Perspective Port | Lines Perspective

Copyright 2006 - 2014 Michael Kasten

The Name

Leah the first wife of Jacob was the mother of Zebulun, thus the name reflects the relationship of this prototype to our 96' sailing yacht design Zebulun.

General Concept

The 112' yacht Leah is a stretched and slightly wider and deeper version of the Zebulun. The aim in this case is to create a large ocean sailing yacht with very open accommodations, with a focus on ultimate performance, but without sacrificing anything in terms of seaworthiness and sea kindliness.

Preliminary particulars are:

Construction Materials

Leah's scantlings would be according to the requirements of the ABS Rule. Aluminum has been chosen as the material for the entire structure. This is primarily for the purpose of extreme ruggedness; ease of construction; a very favorable strength to weight ratio; thus for sailing speed and efficiency under power. Interior materials would be light weight honeycomb panels wherever possible, further reducing weight. Interior finish would be finely done to superyacht standards.


Cockpit: A hard "Bimini" top is shown above the forward part of the cockpit, with windows opening forward. This could just as easily be eliminated, or could become a sleek canvas dodger. The cockpit is arranged with wrap-around seating around twin tables aft and a central helm. If the cockpit entry and helm were located farther forward, the aft seating would become larger.

Presently, in this configuration there is an open swim deck aft, with a centerline stairway. It could be easily rearranged though so that the transom would be an uninterrupted slope, having a flip-down center section. This would allow the transom to present a sleek appearance with the swim platform folded up, and when deployed the 'door' would become the swim-deck. Of course a variety of arrangements are possible.

In General: Standing headroom of 6' 10" is provided throughout the interior.

Aft House: house amidships would enclose a multi-purpose lounge and dining area, having an excellent all-round view. If desired, an indoor helm and nav station could be provided forward.

Midship House: Forward of that, amidships within the low deck house would be a large galley to port aft and formal dining area to starb'd aft. A large saloon would occupy the forward half. The goal with this layout is to create a luxurious yet cozy environment for everyday living, all on one level.

Below Forward: Beginning all the way forward, a large forepeak is accessed via a deck hatch and ladder. The forepeak is dedicated to sail and line storage, and for the anchor rode.

The forepeak and accommodation spaces are separated by a robust water tight bulkhead, immediately aft of which would be a day head with shower for use by crew or by other casual day guests.

Aft of the day head would be two smaller guest / crew cabins, each with sleeping for two and with access to the forward head. Aft of those cabins would be two large luxury guest suites, one to starb'd and one to port, each having en-suite head and shower, with a central king sized berth. Each luxury cabin would have a vanity cabinet with sink, desk, bureau, night stands, and generous closet.

A central hallway would provide access from the midships saloon to the forward day-head and each of the staterooms.

Below Aft: Just aft of the Pilot House, adjacent to the companionway is stairway leading to the owner's stateroom, located below the cockpit area. A 'Kong' sized 'island berth' is planned on center aft, with walkway access to the swim deck on either side. Outboard of the walkway to port and to starb'd would be a long bureau and desk, separated by a cozy love-seat in the middle. Forward to port would be a large en-suite head with Jacuzzi and shower. Forward to starb'd, a generous walk-in closet.

Engine Room: Forward of the owners stateroom and directly below the raised deck house is the engine room and mechanical spaces. A small 'control room' is located aft, and is sound proofed from the rest of the engine room. A sound-isolated mechanical space / machine shop is located to port, and a well insulated pantry / bosun's locker is located to starb'd. On center is the engine space itself, containing twin CAT diesels, a large gen, and a pony gen for use when the vessel is not fully occupied.

The engine space is thus thoroughly sound proofed not only from the interior of the vessel, but also from the working spaces around it. A forced ventilation system and air conditioning keep everything cool throughout.


For maximum economy, long range cruising speed under power for this vessel would be kept to around 11 knots. Top speed however is dramatically higher - and would be around 18 knots while motor sailing or while under sail in the right conditions - potentially even faster whilst surfing in good conditions. This is by no means slow...!

The Rig

Leah is planned to have a three mast rig, having the largest mast amidships, a smaller fore mast, and a much smaller mizzen - somewhat in the style of a yawl. This could easily be changed to being a ketch or two mast schooner rig, however the three mast configuration allows each sail to have a favorable aspect ratio, a more easily managed size, and a low center of effort - all in order to permit relatively shoal draft.

Sails would be fully battened to enable the use of a large roach and an elliptical plan form, while still allowing maximum draft control. Each sail would be cut differently in terms of draft in order to take maximum advantage of their relative positions in the rig. A large roller furling jib would be set to the forestay, and other light weather stays'ls could be set from the respective mastheads.

Of course the rig is a matter of personal preference, and would be so arranged. Other factors involve overall rig height and mast placement - for the maximum benefit of the interior.

Standing Rigging

The masts and booms would be fabricated of aluminum. All spars are welded shut in order to be air and water tight. Halyards are planned to be external. Reefing is planned to be slab type with hydraulic winch assist.

The rig is planned with swept back spreaders, allowing use of a single lower shroud and a single upper shroud per mast per side. This is very efficient. Running backstays would be arranged as needed - if needed.

NC Cutting

Hull and superstructure surfaces have been computer modeled and faired. For the sake of saving considerable labor during hull fabrication, the structure would be detailed for NC Cutting via our usual CAD Design Stream. Frames, girders, keelson, stem, engine beds, tank faces and tops, and all hull plating would be detailed and nested, ready for plasma or water jet cutting, then all components nested as required by the cutter.

Images of the NC files and the resulting structure for the 96' sister vessel Zebulun can be seen in the following links:

In Conclusion

At 112 feet, Leah is an ambitious project. With twin ballasted keels, Leah would be highly capable to windward even with her relatively shoal draft. Another bonus... she can sit on the hard when the tide goes out! Being of all aluminum construction, it would be possible to leave the hull and decks unpainted except below the waterline, thus making maintenance requirements minimal.

With generous accommodations, Leah would permit her owner to be an excellent host to the many friends and guests who have the good fortune to sail on her.

Being a prototype at this point, the size, layout, keels, houses, etc. could be varied as desired. For more information, please inquire.

Other Designs in This Series:

45' - 60' Zeb | 46' Dinah50' Sarah | 65' Rachel | 96' Zebulun | 118' Leah  |  120' Leah - II