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The 43' Motor Sailing Ketch

"White Buffalo"

43' Ketch WHITE BUFFALO - Kasten Marine Design, Inc.
Exterior Profile | Deck Plan | Interior Layout
Perspective Sailing | Perspective Forward
Perspective Aft  |  Perspective Far Aft

Copyright 2008 - 2018 Michael Kasten

General Concept

First, an explanation of the name is in order... 

Native American peoples consider the White Buffalo to be sacred and spiritually significant, in part because in nature the birth of a White Buffalo is an extremely rare occasion.  It has also been noted that finding the "perfect boat" is also an extremely rare event...   With the interior arrangement and overall dimensions shown here, this design has been considered to be the 'perfect boat' by the prospective owner.  Thus the name White Buffalo was a natural...!

The 43' White Buffalo is a modification of the 43' Roberta Jean, which was originally developed as a trawler yacht design. The hull form and the layout of the White Buffalo are identical to the 43' Roberta Jean except that the 43' White Buffalo has been given a true sailing keel and a good sized ketch rig. 

The ketch rig, borrowed from the Lucille 42, is slightly rearranged here and made larger in order to better suit the White Buffalo.  The result is a very capable motor sailing yacht... one that is not compromised by less than ideal performance under sail.  In other words, there is ample sail area.

43' Ketch WHITE BUFFALO - Kasten Marine Design, Inc.
Click for Larger Image


Shown below is the interior profile of the White Buffalo.  It is nearly identical to the 43' Roberta Jean, with the only differences being the mast locations, and that the White Buffalo Pilot House has been shortened slightly in order to make room for a larger aft deck seating area.  A walk-through of the White Buffalo interior is as follows:

There is a covered aft deck for part-time outdoor living, which can be screened in or enclosed by a canvas / vinyl dodger in cooler weather. A large open fore deck allows plenty of space for sun tanning and for stowing gear. A flat flat "cargo platform" / hatch is provided on the fore deck. The shore boat will go on the fore deck, over the cargo hatch, or it can be stowed on the house top.

Inside the pilot house is a dinette that can comfortably seat four on the settees, plus two more in the portable pilot chairs.  Below, to port aft there is a large U-shaped galley.  Opposite the galley is a large head / shower complete with - you'd never guess - its own bath tub!    Amidships is a cozy saloon, having plenty of room for a coffee table on center.  The forward owner's cabin has an island berth on center forward, plus ample hanging lockers and storage.  With a raised fore deck, there is quite a huge amount of space in the forward accommodation spaces.

The layout provides ample room for a couple and occasional guests. The saloon settee on the port side can be made into a double berth, as can the pilot house dinette. Combined with the aft-facing seat on the aft deck, conceivably there is sleeping space for seven...! If the aft deck table were able to be lowered to berth-height to create a double, there would be room for eight...!  Now that is really pushing it for more than a one night adventure, but it is possible. 

43' WHITE BUFFALO Interior Layout - Kasten Marine Design, Inc.
 Click for Larger Images


The choice in favor of aluminum for the structure has been made in order to keep structural weights as low as possible, and to make the vessel as rugged as possible within its weight budget. When built to the same strength as a steel vessel, a bare aluminum hull "as fabricated" will weigh roughly 1/3 less than an equivalent steel hull. However, if designed to the same weight budget for structure, the lighter weight of aluminum will permit a given hull form to be built with immensely greater strength than would be possible if building the same hull in steel.

In this case, we have struck a middle ground with the goal of achieving higher strength than the same hull in steel, while also saving weight in order to still have sufficient room in the weight budget for an ample amount of ballast for the sake of sailing ability.

The benefits of more robust scantlings are many. Among them are that the added plate thickness will preserve hull fairness to a much greater degree; the internal stringers and frames can be spaced farther apart, also contributing to fairness; or if the frames and stringers are not spaced farther, the strength will be increased proportionately.

In steel, it would be typical to build a vessel of this size using 3/16 inch steel plate, or if built in aluminum using 1/4 inch alloy plate – in other words it is normal to use approximately 50% greater scantling size for aluminum in order to achieve a similar overall strength. However, given the same weight budget as the steel vessel, it is possible to use 3/8 inch aluminum plate without much of a weight penalty – and that is precisely the approach we have taken with the scantlings throughout. Rather than having just 50% greater thickness, the plating thickness is double that of the steel vessel, achieving a roughly equivalent weight, and a structure that is approximately twice the strength. For a bit more info on this, please see my Aluminum vs Steel article.

All parts are intended to be NC cut by water jet or router. The NC cutting process leverages the work that has already been done to create the computerized design model. In other words, structure can be easily developed directly from the surface model of the hull and superstructure. The resulting "boat kit" makes for fast and accurate assembly. Once the parts have been pre-cut and delivered, the frames and other internal structures are quickly erected, the stringers placed, and the plating applied.

This not only saves considerable labor on the fabrication floor, it also vastly improves the accuracy of the fit-up. The result is consistent plate seams and much less distortion during the weld-up, yielding a much more fair hull. In other words, a higher quality result at a lesser cost for labor.  The reward is that the hull does not need fairing, and for that matter does not even need paint...!

ALTERNATIVES...  Many have asked if the White Buffalo can be built in steel.  Yes it can...  The reason for this easy transition is as stated above, i.e. the White Buffalo has been given ample displacement to carry a heavier structure, so a conversion to steel construction would be a relatively easy matter.  Please inquire for more information...

43' Ketch WHITE BUFFALO - Kasten Marine Design, Inc.
Click for Larger Image

The Rig

The ketch rig was chosen for its ocean cruising benefits, which are to yield a generous sail area, to provide a variety of well-balanced sail combinations, and to keep each of the sails to a manageable size. The mains'l - the largest sail - is well inboard where it can be handled with ease. Our Sail Plan shows a sail area of close to 1,400 sq. ft. in the working sails, and just over 1,700 sq. ft. if a mizzen stays'l is included.   Very nice indeed...!

Power And Range

The White Buffalo has a plumb stem in order to maximize the WL length within a given boat length. In addition to providing more accommodation space, this also provides the most boat speed for a given overall boat length.

For the sake of ocean voyaging, the White Buffalo has been given adequate fuel capacity to function capably as a motor vessel.   Per the Beebe algorithm for range calculations, the White Buffalo should achieve 2,000 NM at 7 knots on a fuel capacity of 520 USG with 12% held in reserve.  It should be noted however that with the sail rig, range is essentially unlimited.

A 4 cylinder John Deere engine has been specified. If one were to prefer a naturally aspirated engine, the JD 4045 DFM at around 75 to 85 hp should push the vessel along at S/L 1.2 to 1.32. If using the JD 4045 TFM (turbo version) at 105 to 130 hp there would be plenty left over to punch into the weather.

The propulsion gear shown in the drawings is the JD 4045 TFM mated to a Twin Disc gear and a Nogva controllable pitch servo with self-contained shaft system and a three blade controllable pitch propeller.  This is the ideal arrangment for fuel efficient motoring at any boat speed and at any loading, but also allows feathering the prop for sailing, and adjusting the pitch perfectly for motor sailing on all points of sail.

43' Ketch WHITE BUFFALO - Kasten Marine Design, Inc.
Click for Larger Image


With the masts lowered, the overall height is kept well under 3.4 meters (11.15 feet) and draft is less than 1.6 meters (5.25 feet).  This allows cruising the canals of Europe, including the fairly restrictive Canal du Midi.  This also allows cruising the ICW in the US, including the so-called 'Great Circle' route through the Great Lakes, down the Mississippi, and up the ICW back to the Great Lakes.

The White Buffalo particulars are very much the same as the 43' Roberta Jean trawler yacht:


In Summary

For a couple seeking a comfortable life afloat, the 43' White Buffalo combines all of the basic necessities with a spacious un-crowded interior -perfect for a personal motor sailing yacht... 

Our 43' Moxie - 43' Roberta Jean - 43' White Buffalo - 50' Renegade - 60' Peregrine designs all share similar attributes, with a plumb stem, fantail stern, cozy aft deck, ample pilot house, and generous accommodations below forward.  

To me, the primary appeal of these designs is the excellent accommodations for two, even in the larger sizes. Guests can be accommodated by various means, none of which require there being a separate dedicated guest cabin. A covered aft deck offers protection from sun and rain; a gourmet size galley and big saloon allow the luxury of fine dining afloat... Combine that with simple construction, economical powering, and in several cases capable motor sailing... we think it is a winning combination.

For more information on these vessels, please contact us.

43' Ketch WHITE BUFFALO - Kasten Marine Design, Inc.
 Click for Larger Image

Similar Designs and Prototypes in this Tug / Trawler Yacht Series

Tug Types
Boojum 22 | Boojum 25 | Boojum 30
Terrier 32 | Talisker 32 | Nidaros 38

Trawler Types
Sweet Okole 30 | Buster 30 | Boojum 43
Roberta 43 | Roberta Jean 43 | Roberta Jean 47
Far Horizon 40 | Far Horizon 43 | Far Horizon 46

Direct Quote from an aluminum boat owner... As an owner since 5 years of an aluminum boat I could not agree more with your preference for this material. She is a great boat and requires very little in the way of maintenance. I do a lot more reef snorkeling than the paint, polish, varnish and wax guys!

--Peter Kminek