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Click Image Above for a Much Larger Inverse Sail Plan Image
Spray Original Sail Plan | Spray Original Hull Lines | Spray Original Body Lines
Article & Screen Shots Copyright
2011 Michael Kasten
First, it should be known that I am a fan of the original Spray - i.e. the one that Joshua Slocum sailed around the world. However I am only a fan in a limited sense. Allow me to elaborate...
What the ORIGINAL Spray was able to contribute most notably for Slocum's voyage was excellent directional stability, i.e. outstanding and apparently infallible course keeping ability. This inherent self-steering ability was the result of several factors:
This combination allowed the vessel to behave somewhat like a dart, with the weight forward and the feathers aft. Alternately you can imagine a tear-drop shaped bomb with fins aft - the ideal shape for stability in a free-fall environment.
This made the Spray rather poor to windward, but superb off the wind.
The Spray was not slow, as many might think. On the contrary, the Spray was capable of
quite fast sailing when
off the wind or on a reach. This was due to her shoal draft, far forward CB,
long straight run of the buttock lines aft, extreme stiffness due to her
excessive beam and shallow draft, and
having a low aspect but very ample gaff yawl rig. In other words, a
slippery shape and plenty of sail area...!
As a long distance voyaging boat the Spray did have several drawbacks, the most important of which were excessive beam and extremely shoal draft. This combination resulted in the vessel being just as stable upside down as it was upright. In plain words, the Spray had zero self-righting ability.
It should be noted that the wooden oyster smack that Slocum named the "Spray" was presented to him as a gift, i.e. for free. At that point it was a rotten old hulk which Slocum then proceeded to restore on a very limited budget.
Due to Slocum’s extraordinary talent as a master mariner he had quite a successful voyage despite the limitations of the vessel, which was never intended for sailing offshore in the first place, but rather intended as an inshore “dragger” with ample sail area for that purpose.
This is a prime example of a commonly shared characteristic amongst many of the well known long distance sailing accomplishments... they were not the result of long arduous planning to create the "ideal" voyaging boat. Instead, the most spectacular individual sailing achievements occurred when a determined sailor encountered a more or less suitable craft that they could acquire inexpensively and put to sea in without too much fooling around. In other words, they were opportunists who made expedient use of what was ready to hand... It is a good lesson!
Slocum's spectacular voyage with the Spray was no
exception.
The above comments apply to the ORIGINAL Spray, as rebuilt by Joshua Slocum, which has subsequently been reproduced by others such as Pete Culler and Gilbert Klingel, often with good success. Most of them were highly faithful to the original.
I was fortunate enough to go aboard a very good replica of the Spray in Hawaii in 1979, built by Bob Carr in Vermont, and single handed from there to Honolulu. He had been some 180 days from Panama to Hawaii, possibly a record for the slowest passage for that route..! However Bob had encountered long periods of calm, and a number of storms. His mains'l was blown out, and he was nearly down to the bottom of his "bean barrel" even though he did catch a lot of fish..! It was impressive to see three large garbage pails in the store room: one for beans, one for rice, one for wheat.
A friend, Michael Colfer and I helped Bob Carr paint the boat's bottom while he was hauled out at Keehi Lagoon, near Honolulu. We heard several good stories during that time and we were well fed, albeit on chicken stew of questionable vintage. There being no refrigeration aboard, this was cause for concern. Like many before him, Bob Carr sailed without an engine so he used kerosene for lights and for cooking. We were fairly certain that the only electricity aboard was inside his flashlight and transistor radio...!
Another friend, George Maynard, built a faithful replica of Slocum's Spray in Noank, Connecticut, Slocum's original locale. Maynard named his vessel "Scud" and subsequently sailed it around the world with his wife and young children - a daughter and two sons. Maynard's voyage, like that of Slocum and Bob Carr, was accomplished without the aid of an engine or any fancy electronics...
Recently I have read about a sailor who
purchased Maynard's "Scud" and who has once again circumnavigated in the vessel, also without
an engine. Quite a number
of Spray replicas have achieved similar success. Others have met with shipwreck or loss without a trace, as in fact
happened to the original, which took along Mr. Slocum himself.
In recent years the name “SPRAY” has been used by a few boat designers in order to take advantage of name recognition for marketing purposes. Most notably, several steel "Spray" models have become popular among amateur steel boat builders despite those designs not being at all faithful to the original Spray design. This is so in terms of the rig and the hull shape as well as other parameters, but most notably it is so in terms of their appearance.
I regard these so-called “Spray” designs as being extremely crude attempts, especially in terms of capturing the beauty of the original Spray. In my opinion these “Spray” poseurs have little if any relationship to the original except to say that they have borrowed the "Spray" name and that they are fat, overweight, and total dogs to windward - nothing else has any semblance to the original.
Those vessels have not improved on the very poor ultimate stability of the
ORIGINAL Spray. As insult to injury, the structure of these vessels is
inordinately complex, in other words poorly adapted to amateur construction, as
is typically their claim. I am quite sure you know the vessels of which I speak... I
do not need to name names.
Having said the above, I have always been curious about the SPRAY, in particular to understand and possibly replicate its excellent course keeping ability for use on other designs. In order to know more about the SPRAY, I went to the trouble to model the design so that I could investigate its hydrostatics, stability, balance and sailing performance in greater detail. Images that show the results of that modeling effort can be seen in the following links and the image below:
Original Spray Above Aft | Original Spray Above Forward
Click Image for Larger View
Particulars of Slocum's Original Spray are:
Commentary: Looking at the above, a few comments are in order.
My conclusions are that the original SPRAY model would benefit greatly by being made deeper and longer, with possibly slightly greater freeboard, but done without changing the favorable attributes of the hull. With that accomplished, the ratio of beam to length will be brought more in line with traditional cruisers, as will be the ratio of beam to depth.
These changes would be introduced primarily for the sake of enhanced large angle stability (greater length and depth), but also to improve the windward ability of the hull (greater depth & outside ballast). In so doing, ideally the Center of Buoyancy would not be moved aft, but the CB would be lowered as would the CG. This combination would preserve a measure of the vessel's excellent stiffness without degrading its voyaging capabilities.
After I created a good NURBS surface model of the original SPRAY, I then made the above mentioned modifications to see what they might offer. Though my mods may not be easy to detect in the images linked below, they have indeed produced the desired result...
Modified Spray Perspective Forward | Modified Spray Perspective Aft
Length on deck is increased to around 40 feet; beam is unchanged; depth of hull and draft are increased; displacement is increased to 21 long tons; and sail area is increased. As a result of having been made longer but not wider, the Displacement to Length has been reduced to around 315, which is still a robust hull shape but not overly heavy.
The Prismatic Coefficient is down to .59 including the keel and stem, and .62 for the hull body only. This is still a little high for optimum performance at typical sailing speeds, but is indicative of a high speed potential and buoyancy in the ends for better support in heavy weather. The Center of Buoyancy remains approximately amidships, therefore is unchanged.
The rudder was made wholly external, which required that the transom rake be changed slightly, and that the deadwood be extended slightly farther aft. The aft deck was given an overhang just sufficient to house and protect the rudder, and to create a convenient landing for the mizzen mast.
In the image above, you will notice that I have also raised the aft deck to the height of the bulwark top, then introduced a toe rail around the aft deck. Raising the aft deck is not at all necessary, but it does provide advantages in terms of reserve buoyancy and self righting, as well as considerably greater interior space aft.
Along with those hull refinements, a few improvements will ideally also be made to the rig – not to change it from Slocum's Yawl rig, but to increase the relative size of the rig for the sake of improved performance. Ideally the SA / Displacement ratio would be above 18, preferably closer to 20. This implies a Sail Area of around 1,500 sq. ft.
The amount of lead from the CE to CLR should stay the same, i.e. approximately 9%, or possibly it could be reduced slightly due to the reduced beam ratio. By increasing sail area, a higher CE will result, but this will be offset by the lower CG inherent in the deeper hull. The result of having less beam will be an increased amount of heel vs the original SPRAY. The result of having a lower D/L ratio, increased sail area, a deeper hull and external ballast will be better performance on all points of sail, especially to windward. All of these changes are possible without having to degrade the inherent excellent tracking of the vessel on a passage.
My primary goals in making such tweaks to the SPRAY
have been to
see what could be done make the design safer and more seaworthy and to show that such improvements
could be made without screwing up the excellent traditional aesthetics of the original, nor
to adversely affect its excellent tracking ability and its consequent value as an
ocean voyager.
Many are attracted to the SPRAY simply on the basis of it having been the first vessel to carry a human around the world, sailing single handed. It is quite an achievement to say the least. What must be realized however is that the voyage was accomplished by a determined and very experienced professional sea captain, not by your ordinary beach bum.
Just like many other world-voyaging sailors who have also achieved extraordinary sailing feats, Slocum was an opportunist who made excellent use of what was available to him, in his case a freely provided old wreck which he rebuilt on a shoe-string, and which he then quite stunningly sailed into permanent fame and an honored place in our history of the sea.
Before Slocum left on his historic voyage, dockside wags said of the SPRAY, "It'll crawl...!"
When he returned, his dockside advisors would only deign to say, "You were lucky...!"
Luck or no, one cannot deny Slocum's extraordinary achievement, which was accomplished more or less in spite of the tool that he was given, i.e. the SPRAY. In other words, it was Slocum's WILL and long experience at sea that allowed him to achieve this feat, rather than it having been some sort of caprice conferred upon him by magical attributes inherent in the vessel on which he sailed.
Copyright 2011 Michael
Kasten
Helsingborg, Sweden
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