Joshua Slocum's boat 'Spray'

skodster

skodster

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I am 2/3 the way through his classic book and have been truly astonished at his boats ability to sail its course without self-steering gear. During a leg across the Pacific, he sailed 2700 miles with only three hours on the tiller. It didn't seem to matter what the conditions were or the set of his sails, the boat just ploughed on regardless.

I read that many marine architects have examined the design of the Spray and have concluded that it is perfectly balanced in all respects. The question is, how come modern boats can't achieve the same directional stability?

She also had a top speed of around 8 knots!
 
skodster said:
I read that many marine architects have examined the design of the Spray and have concluded that it is perfectly balanced in all respects. The question is, how come modern boats can't achieve the same directional stability?
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According to Wikipedia:

"Years later [after his death], an analysis by Howard I. Chapelle, curator of maritime history at the Smithsonian Institution and a noted expert on small sailing-craft, demonstrated that the Spray was stable under most circumstances but could easily capsize if heeled beyond a relatively shallow angle. He felt that Slocum was merely lucky that his unstable vessel had not killed him earlier."
 
skodster said:
I am 2/3 the way through his classic book and have been truly astonished at his boats ability to sail its course without self-steering gear. During a leg across the Pacific, he sailed 2700 miles with only three hours on the tiller. It didn't seem to matter what the conditions were or the set of his sails, the boat just ploughed on regardless.

I read that many marine architects have examined the design of the Spray and have concluded that it is perfectly balanced in all respects. The question is, how come modern boats can't achieve the same directional stability?
She also had a top speed of around 8 knots!
Click to expand...

Modern racing design doesn't have a full length keel- nor anything like one. There are cruisers and they are more than a handful in confined conditions, especially marinas. In this life one can't have everything.
 
Slocum was a seriously skilled seaman and a very good teller of tales. The fact that he kept tweaking the rig (even adding a mast) indicates he was altering things to improve self-steering. Most modern "replicas" of "Spray" sail like bricks, and have very dubious ultimate stability, as did the original. Although the hull lines were taken after his circumnavigation, personally I strongly suspect the original may have had a centreboard, which would have greatly improved self-steering abilities off wind. Centreboards were so common in US NE coast shallow draught boats around that time that it would almost have been odd not to have had one, and if the boat was sat ashore on it's keel a C/B may not have been visible when the lines were taken.

Slocum made his famous circumnavigation in what he had (been given free) rather than a boat designed for it's task. I don't really hold that he was lucky to make it round: rather that many years of experience in all sorts of vessels allowed him to get away with it, but there is no doubt that a serious ( maybe 120 degree ) knockdown in "Spray" would have killed him - and perhaps it later did.
 
Spray was immensely beamy but a very shallow hull. She relied almost entirely on form stability so the AVS is very low by today's standards. It is relatively easy to self-steer with a gaff yawl as you have so many sails to balance the steering with e.g. crank in the mizzen to head up, hand it to bear away.

Here are the lines: http://www.kastenmarine.com/_drawings/spray_lines.gif You can see she has nearly 2:1 length beam ratio, far tubbier than any modern design.

Lots of people build replicas based on his stories of self-steering. A wind vane or auto-pilot would do the job more easily on a boat of less extreme shape.
 
Regarding Spray's self-steering ability, there is a book by Lee Woas titled "Self-Steering without a Windvane" that provides an explanation. When sailing off the wind, Slocum would set-up an extension to the bowsprit from which he flew a flying jib sheeted flat. This would prevent Spray from rounding up. Lee Woas demonstrates in his book that he can accomplish the same on a modern boat.
 
Slocum's book is available as a series of online web pages. The appendix < http://www.bluemoment.com/slocum/appendix.html > describes Spray in some detail and includes a description of the approach for making her self-steer.

In a sloop-rig the Spray made that part of her voyage reaching from Boston through the Strait of Magellan, during which she experienced the greatest variety of weather conditions. The yawl-rig then adopted was an improvement only in that it reduced the size of a rather heavy mainsail and slightly improved her steering qualities on the wind. When the wind was aft the jigger was not in use; invariably it was then furled. With her boom broad off and with the wind two points on the quarter the Spray sailed her truest course. It never took long to find the amount of helm, or angle of rudder, required to hold her on her course, and when that was found I lashed the wheel with it at that angle. The mainsail then drove her, and the main-jib, with its sheet boused fiat amidships or a little to one side or the other, added greatly to the steadying power. Then if the wind was even strong or squally I would sometimes set a flying-jib also, on a pole rigged out on the bowsprit, with the sheets hauled flat amidships, which was a safe thing to do, even in a gale of wind. A stout downhaul on the gaff was a necessity, because without it the mainsail might not have come down when I wished to lower it in a breeze. The amount of helm required varied according to the amount of wind and its direction. These points are quickly gathered from practice.

Briefly I have to say that when close-hauled in a light wind under all sail she required little or no weather helm. As the wind increased I would go on deck, if below, and turn the wheel up a spoke more or less, relash it, or, as sailors say, put it in a becket, and then leave it as before.
 
There is a steel Spray being fitted out in the boatyard where I am. It is a monster, I was looking at it the other day and couldn't help thinking it reminded me of something off the Dutch canals, like a Botter...without the Lee Boards. It's all beam and blunt bow and little draught. He tells me the keel is full of steel punchings but to me anyway, it looks as if it will sail like a milk crate, but with less buoyancy..
 
Downsman said:
There is a steel Spray being fitted out in the boatyard where I am. It is a monster, I was looking at it the other day and couldn't help thinking it reminded me of something off the Dutch canals, like a Botter...without the Lee Boards. It's all beam and blunt bow and little draught. He tells me the keel is full of steel punchings but to me anyway, it looks as if it will sail like a milk crate, but with less buoyancy..
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Sounds about right. The original was an oyster boat designed for shallow water, so you have large beam and displacement for carrying the catch and relatively shallow keel. Not an especially good hull form for ocean sailing, but Slocum used what he had available. The daft thing is everyone copying it.

The original (in fishing trim) would have had a large gaff rig with plenty of sail area to push that fat heavy hull along. The typical modern Bruce Roberts interpretation has a standard bermudan rig and is notoriously slow.

Pete
 
mel80 said:
A shipping container with a sail on it has a top speed of 8 knots...
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Hmm, interesting idea. But imagine if you were on board your container, ploughing along at top speed, when you hit a semi-submerged object...like...maybe a half-sunken yacht...
 
It's always worth remembering that Slocum was a professional master mariner, having been master of several sailing ships prior to his round the world trip. I find it interesting that on his first voyage in Spray, he brought her into harbour single-handed under sail and did it pretty much perfectly. In his usual self-effacing manner he puts it down to luck, but its the sort of luck that has many years of practice behind it!

Another aspect is that Slocum was writing for a world where sailing was still the ways a lot of the word's commerce worked. He didn't go into a lot of detail about techniques and so on, because it was "of course" for him - just as Marryat's books don't give as much detail on the operation of a sailing warship as Forrester and O'Brian do; Marryat was a Nelsonian officer, and it was all "of course" for him!

The other thing worth noting is that I doubt if Slocum cared very much about his exact heading. He was sailing the trade-wind routes; as long as he was within plus or minus 20-odd degrees of the "right" course, I think he'd have thought that was fine. His navigation was only capable of providing positions to maybe 30 miles or so (I understand he used lunars for longitude, which is why he didn't need an accurate clock).

Given that it is pretty much certain that Spray killed Slocum because of her marginal stability and his declining mental state, it is a) a tribute to Slocum's skill that he made it round the world and b) concerning that she is held up as an epitome of design!
 
My ketch under Genoa and mizzen will quite happily keep itself on course given constant wind conditions
 
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I love the way people are criticising here but none have done what he achieved. Blunt noses dont matter, its hull length that decides speed, and he built the boat based on a working lifetimes experience. To suggest he was given the boat for free, means that person did not read the book, it was rebuilt from the ground up. I'm in admiration of the man, I could not do what he did.
 
He made use of bowsprit extensions ,bamboo poles lashed to the existing bowsprit,the sail area although small had tremendous leverage that could be played with to get a balance plus the hull shape meant it kept its areas balanced unlike a more modern yacht hull.
 
I can now, after lots of experimenting, sail hands free from 40 to 80 degrees TWA. Anything beyond is still work in progress but sheeting my storm jib flat on the centreline works pretty well when off the wind. Not quite at the set and forget stage but another seasons worth of testing and I'm sure i'll get there.

It's what i spend most of my time tinkering with when I'm sailing.
 
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