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120 Foot Bahamian Schooner
"CHIEF SEATTLE"
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Starb'd Aft Perspective | Starb'd Forward Perspective | Side Perspective
Copyright 2010 - 2015 Michael Kasten
The following is an outline of how the prototype design of the Grand Banks Schooner "CHIEF SEATTLE" has been developed. This is a "first draft" based on a prospective client's mission statement, which outlined a classic vessel modeled after the Grand Banks fishing schooners of the early part of the 20th century, for construction in aluminum.
RESEARCH & INSPIRATION
It is not so often I get inspired to create a prototype prior to actually being asked to do so... but this inquiry definitely sparked my interest. That's primarily because of the prospective client's the wish to create a vessel that would have "an interesting historical past" and to have "a nice classic hull shape with long overhangs." The prospect of being able to create a new design that is born with a "heritage" is one of my favorite challenges. It is all in the details... In this case, the Grand Banks schooners of Newfoundland - a type that I've long admired - was the chosen paradigm.
The prototype design shown here has a profile and hull shape similar to the Grand Banks fishing schooner, Bluenose, a well known vessel built circa 1920 at Halifax, Nova Scotia. As noted in the book "American Fishing Schooners" by Howard Chapelle, "... the Bluenose was built to race and to fit the official measurements for competitors in the International Fishing Schooner Races, and her fitness for fishing, though required, was relatively superficial."
At 143 feet length on deck, Bluenose was one of the fastest schooners on the Grand Banks, winning nearly all of the races she entered. Several schooners of a similar size were designed and built in New England during the 1920's for the express purpose of trying to beat the Bluenose, but... They could not beat her even though many schooners tried...!
As such, Bluenose and the racing-fishing schooners of her time (late 1800's to early 1900's) represent the height of the development of commercial sail. Size for size, these were the fastest commercial sailing vessels ever built, and the most windward-capable. The last of these schooners were built in 1927 - displaced at last by steam.
HULL FORM
The model shown in these images is heavily based on the Bluenose, but is smaller at 120' on deck with slightly more spring to the sheer, slightly more rake to the transom, greater beam, and a shape below the WL that takes advantage of the best that the Grand Banks schooners had to offer.
The waterlines of the Bluenose reveal that she was very well balanced fore and aft. In other words, the transom was sufficiently narrow as to avoid a wedge shaped underbody when heeled. This prevents the stern from being lifted when heeled, thus avoiding the steering anomalies present in wedge shaped hull forms.
Notably, the Bluenose had very easy and slightly convex waterlines forward, thereby avoiding any possible added drag induced by the tendency of hollow forward waterlines to create a second bow-wave. The Bluenose diagonals were very fair without any tendency to form a hook astern. The buttock lines on Bluenose were very easy and fair forward, with a long straight run aft extending into a long counter stern with heavily raked transom. Combined with the long bow overhang, the heeled waterline will be much longer than the static waterline, and the vessel will be well supported on bow and stern wave. The combination of these factors are indicative of a fast sailing machine - a true greyhound of the seas.
The keel on the Bluenose was relatively short, with a knuckle roughly one third of the WL aft, and having moderate drag to the keel bottom - thereby having reduced wetted surface as compared to vessels of the day, and an underwater profile conducive to excellent directional stability at sea. The long easy entry profile will provide excellent handling down-wind, with no tendency to "gripe" when reaching the trough of a wave, as often is the case with a deep forefoot. In general, handling under sail should be excellent.
All of these features have been retained in the CHIEF SEATTLE model shown here.
Click for Larger ImageWooden craft require that the rabbet at the garboard be more or less parallel to and not too distant from the keel bottom. This is for several reasons, not the least of which is to reinforce the deep "blade" of the keel, especially aft. It was also beneficial in that the rabbet did not have to cross the deadwood timbers in the keel, which would have invited leaks and would therefore have required numerous stop-waters. This meant that there had to be a strong "reverse" curvature at the turn of the garboard, so that the planking could extend downward to a rabbet line parallel to the keel bottom.
Since the CHIEF SEATTLE is intended to be built in in aluminum, there is no need structurally for there to be a "reverse" curvature to the garboard in order to support the keel, nor to carry the garboard / rabbet down onto the keel aft to prevent leaks. Thus on the prototype presented here, the rabbet at the keel is able to follow the simple projection of the deadrise onto the upright face of the keel. This allows vastly simpler construction in metal and increases the effective "lateral plane" of the keel. Further, we are able to retain the same overall profile and provide a NACA foil shape to the keel - partly for the sake of increased lift, but very much for decreased drag.
Displacement of our prototype as-modeled is around 167 metric tons, for a displacement to length ratio of under 245 (calculated using Imperial units). In other words, displacement is very adequate to carry the structure, equipment, outfit, fuel, and the sail rig. It is possible that the displacement could be reduced on further analysis, perhaps via a reduction in beam.
SAIL RIG
The original request was for an easily handled, simplified rig, but one which still has "classic" appeal. The rig I've proposed is very much in line with Caribbean / Bahamian sail rigs, having masts raked well aft, each with a "Bermudan" style sail. Three masts should provide the most easily managed sail sizes, vastly simpler running and standing rigging, and reduced stress on individual rigging components. As shown, the rig is as simple as it can be made for the sake of sailing short-handed.
As a concept, I've shown the fore and the main sail loose footed, while the mizzen and jib are both shown with booms. The jib could easily be changed to a boomed staysail, with outer jib / Genoa, etc., but at the expense of added complexity as well as having to handle the jib when tacking. If it were desired to simplify further, the fore and main could also be boomed and the sail area recovered by use of taller masts, which the vessel would certainly stand up to.
As-drawn, the rig has quite sufficient sail area, at just under 600 square meters. As shown, the sail area to displacement ratio is over 20 and sail area to wetted surface is 2.7 (calculated using Imperial units). Both measurements are at the high end as compared to IMS racing vessels, indicating adequate sail area in the working lowers without the use of multiple light weather sails. This is as intended - a further step toward simplicity for short handed sailing.
With a conservatively assumed vertical center of gravity (not yet calculated but based on other similar vessels) the Dellenbaugh calculation yields a heel of around 8.5 degrees in 15 knots of wind - in other words, about right for this size of vessel - not too tender, and not so stiff as to be mean to her rig.
LAYOUT / SIZE
At 120 feet on deck (37 meters), the size should be adequate to achieve the requested layout - described briefly as follows:
Aft would be a helm with exterior seating / dining for 10 under a semi-permanent Bimini. The prototype model does not show those features, but it is apparent there would be plenty of room on the aft deck to achieve this arrangement. As an option, in order to augment visibility from the on-deck helm, it would be tempting to introduce a deck-step just forward of the deck house, so the aft deck would be at the height of the top of the bulwark, the quarter-rail becoming the aft deck bulwark. This was a very common feature on the fishing schooners. It would add storage space below and would enhance buoyancy and large angle stability. The idea is that the deck-house sole would not be raised, just the aft exterior deck, making it easier to see over the house top.
The deck house / chart house / saloon is intended to contain the following:
- Settee, easy chairs and coffee table for 10
- Dining table, settee and chairs for 10
- Desk and chair
- Instrument console, helm and main navigation station
- Day head
Freeboard is sufficient to provide below decks headroom of two meters throughout, and is intended to include the following:
- Master stateroom with en-suite head and shower, plus two large single berths, sofa convertible to a berth, and ample wardrobe and drawers for storage
- Four twin guest / crew cabins with en-suite head and shower to accommodate eight
- Well equipped galley with easy access to the deckhouse to include a dinette for four
- Laundry
- Engine room
- Forepeak and lazarette storage
Forward on deck will be stowage for a five meter tender. The cradle for the tender is planned to double as a salt water dip pool or Jacuzzi when the tender is not on board.
GENERAL NOTES
The classic Grand Banks type that I've chosen as a paradigm is from the height of the development of commercial sail. The last of these racing-fishing schooners were in fact built as yachts, even though they had to do at least a few trips to the Grand Banks to fish so that they could qualify for the International Fishing Schooner Races..! In my view these are very inspiring craft, the likes of which have rarely been seen since.
Inevitably, one might argue in favor of a split keel / skeg arrangement to reduce wetted surface. Possibly that would alter the historic aspect of the vessel - even though unseen above the WL - or possibly it could be seen as a natural step in the evolution of the type. In either case, it would be a simple matter of preference - the long full keel being more traditional, stronger, and better able to take the ground.
SUMMARY
As we have written previously in the Spring 1999 Editorial for the Metal Boat Quarterly, the materials of construction need not dictate the aesthetic presentation of a yacht. In the case of this vessel, the intent is to create a period-correct vessel in all but the materials of construction. In so doing, it is not necessary copy the details of exactly how such a vessel would have been built at the time, especially with regard to materials and structure.
Since we now have much stronger materials, a better knowledge of naval architecture, and vastly more robust analysis tools, we can make generous use of these technologies. Examples of new materials include the use of galvanized steel wire for standing rigging, Dacron for running rigging and sails, nylon for anchor rode, and... aluminum for spars and for hull structure - vastly stronger and much lighter.
In order to create a convincing period-correct "modern classic" design it is important to be sensitive to the aesthetics of the type, the general hull and deck arrangement, the presentation of the hull, its profile and elements of style right down to the carvings - yet not be so pedantic as to be opposed to marrying diverse hull and rig - as long as they seem to be a "good fit" aesthetically and functionally.
Inevitably, the question of authenticity comes up. In the Spring 1997 Editorial for the Metal Boat Quarterly we have outlined this rationale, summarized briefly as follows:
We have to keep in mind that the US colonial and post-revolutionary sailing vessels were made of what was most readily available on the East coast of the Americas at that time: wood. Today the situation is much different. We now have much easier access to metal than we have to wood.
Perhaps in order to approach the whole concept of building a highly traditional sailing vessel in the very most traditional of ways, we should ask our selves: "Would the colonial owner-skipper, keenly interested in turning a profit, have even remotely entertained the notion of building a vessel out of a more expensive, more difficult to find, more labor intensive, and weaker material?"
Without question, the answer would be a resounding "No!"
The aluminum hulled early 1900's vessel we have planned here will not only look like the real thing, it will in fact be the real thing.
It just won't be built in wood...!
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Home | Intro | Our Design Process | Stock Design Info | Motor Yacht Designs | Sailing Yacht Designs | Prototype Designs
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