BACKGROUND...
My first homebuilt boat, in 1981, was a Bolger Teal rigged with a 59
square foot sharpie sprit sail. Next boat was the Bolger Jinni with a
96 square foot main and small mizzen, both sharpie sprits. Later came
Birdwatcher with a 126 square foot sharpie sprit. I've used the
sharpie sprit on lots of my own designs thinking it about the best
sailing cheap rig (although it has its disadvantages too). In this
essay I'll pass along what I think I've learned about it.
THE BASIC ELEMENTS...
Figure 1 shows the basic elements of the sharpie sprit rig. We'll
talk about them one by one. The basic elements are the MAST, the
SAIL, the MAST/SAIL ATTACHMENTS, the SPRIT, the SPRIT ATTACHMENTS.
Here we go...
THE MAST...
The sharpie sprit mast is actually one of its main
disadvantages...the mast needs to be long compared to something like
the mast of a balanced lug rig. For example my 12' Teal needed a 16'
mast to set enough sail to be interesting, the Jinni needed a 21'
mast on its 15' hull, and the Birdwatcher needed a 24' mast on its
24' hull. In general the mast needs to be longer than the boat,
sometimes by a goodly amount. That causes problems in trailering and
cartopping, especially with the smaller boats. It's at its worst with
a small row/sail boat like Teal. If you have to row the boat after
sailing, you need to leave the rig standing. Where are you going to
put a 16' mast in a 12' boat? If there is any wind about, rowing the
boat with the rig standing is very difficult. On Jinni I put a set of
crutches fore and aft to stow the rig. The crutches were off
centerline so I could launch and row the boat with the rig still
stowed - very important. Never stow such a rig on centerline if you
don't have to. Actually the mast length problem would be no different
for any triangular sail rig.
As for mast material, low tech wood is the way to go. I've tried
aluminum and other pieced together solutions and I'll report on them
some issue. But the single straight stick seems to be the best. The
three boats I mention all had masts with square cross sections (even
though the Birdwatcher was supposed to be octagonal). The square
masts are a lot easier to build than the octagonal or round masts. I
suspect they work about as well. They are stiffer for the size and
can easily be built hollow like a box if you want, although if you
crank through the numbers you might find that a hollow mast in the
size we are talking about saves very little weight. But I don't think
a mast should ever be made of a single piece of wood, at least not
the wood my sources carry. Always laminate from at least two layers
to minimize warping.
Sharpie sprit masts are usually unstayed, that is they have no
supporting guy wires. That means a heavier mast but a simple and
easily assembled structure. I think a stayed mast would work as long
as you were on the lookout for interference between the wires and the
sprit as it projects forward.
I might add that from a practical standpoint the 24' Birdwatcher
mast, which weighs perhaps 35 pounds, is about all one man can put up
by himself with repeatable ease. Even then you must use care,
practice and patience and be in control of the thing all the time.
You must really rig the boat on shore. The small skiffs often don't
have the stability needed to allow you to stand up in the boat trying
to balance a 16' stick on end. In rough water it is not possible
without good luck. And with the larger ones you may have the
stability to try to raise the mast while afloat but any passing wave
that rocks the boat as you stand a 24' mast on end will invite
disaster.
THE SAIL...
Up until a month ago all the sharpie sprit sails I had made were of
real Dacron sailcloth using instructions from SailRite books. As far
as I'm concerned they all went quite well. The SailRite books contain
all the information you need although the book I used, written 20
years ago, was a bit jumbled. But since then I think I've learned a
few things needed to tweak the general instructions to sharpie
spritdom.
For one thing, almost any sharpie sprit sail will benefit from having
its leech (trailing edge) hollowed out. If you don't do that the
leech will flutter with a loud motor boat sound in higher winds.
Usually 2 or 3" on a 20' leech might be enough. I don't think there
is any special number, but you do have to hollow it out.
Next, the foot of the sail should be cut more or less as if the sail
had a boom which is to say with some "round". I've always use the
SailRite instructions for getting the round. I've seen Phil Bolger
write that the foot should be cut straight. But I can't see that if
you are looking for shaping in some camber. My feeling is that the
tension in the foot of these sails is so high that the foot is going
to straighten out due to the load no matter how you shape it, so it
ends up as if you had laced it to a straight boom.
Next, the luff of the sail needs a lot of "round" mostly to allow for
the backward bend of the unstayed mast, which can be considerable.
Here again SailRite gives good guidance in suggesting the mast be
supported at it ends, a weight equal to half the sail area suspended
in the middle, and the resulting deflection "mapped" and applied to
the luff. The "round" needed to allow for sail draft shaping is added
to the deflection round but it is usually a lot smaller than the
deflection round. You might be surprized how much round the luff may
need - a 14' luff may need 5" or 6" of round, especially if the mast
is limber!
As for allowance for draft, I think a camber of 7% to 10% is fine. I
recall somewhere that Marchaj, who wrote the book on scientific
testing of this sort, said there is no reason to ever give a sail
more than 10% camber by any testing he has seen.
Lastly, I've been experimenting with a small polytarp sharpie sprit
sail recently and should have a full report with "how to" within a
few months.
MAST/SAIL ATTACHMENTS...
This is where the sharpie sprit sail starts to get interesting.
Because the sprit must be attached to the mast well above the foot of
the sail, the sharpie sprits of old could not use a regular halyard.
If they did so, the sprit attachment would interfere with the normal
sail attachments of the time - hoops or lacing. As the sail is
lowered with the halyard, the hoops or lacings needed to pass over
the sprit attachment and there is no simple way to do that. So
traditional sharpie sprits had no halyards! The sail is tied to the
mast head forever. You can never raise and lower sail in the usual
way.
Once you accept that you have no halyard, some economies become
apparent. Not only are the halyard and block eliminated, but the mast
compression that results in the downward pull of the halyard is gone
(as it is in high tech rigs where the halyard is secured over a stop
at the top of the mast as with a Hobie cat). And the mast can be
thinner up top for that. I think the top of the Birdwatcher mast, 24'
long overall, is no more than 1" square.
Not needing a halyard allows for a very simple sail/mast connection,
indeed. Bolger likes best simple ties every 18" or so around the
mast. If one tie fails it is of little consequence. This is what the
Birdwatcher used. The sail stays tied to the mast at all times.
Bolger suggested a way to furl and stow such a rig.
Here is a photo of my Birdwatcher with mast and sail furled. The
sprit has been stowed, the sail rolled up like a sausage and the roll
secured to the mast with a bungee. (On a small boat you can actually
roll the sprit up inside the furl.) Looks great and simple doesn't
it.
There were two problems with this method of stowing. One is that wind
can get into the roll high above the tie and unroll the sail making
for uncontrolled thrashing and noise and danger. It can undo you with
its violence if you try to furl the rig say at the approach of a
thunderstorm which later produces very strong wings. I found a nice
easy solution. I tied a light line to the masthead which led down the
side of the mast to a cleat near the deck. After I had the sail
rolled up I would uncleat that light line and wrap it around the
sail/mast working from the deck and spiraling the line around and
around. Tug hard and recleat the line and the sail was secured from
tip to toe. And that is how the rig was stowed for trailering too.
Never came loose.
But I never solved the second problem with this furl. A sail rolled
like this will eventually take a permanent curl at its trailing edge.
It can't be good for the sail shape. The only thing I could think of
to solve this was to roll the sail a different way each time.
Simple lacing works well too. There are lots of lacing schemes but
here are two I tried with Jinni and both worked well. Actually these
lacings can work with a halyard given some tricks which we'll look
into next time.
I found the masthead lacing to be a special challange. The sail needs
to be pulled up at the masthead and also pulled close to the mast.
With simple ties, two separate ties will do the job. But with lacing
you need to try to give a special extra loop around the mast at the
top grommet so that the lacing pulls both up and into the mast. Be
ready to tinker.
After I had tried all of the above with Jinni I went to the method
the plans called for - standard sail track. I found an oldster in
selling 20' of sailtrack for $20 in Messing About In Boats
classifieds and scooped it up because now the stuff costs $5 a foot
if you can find it at all. It worked perfectly, better than all the
lacing schemes. But if I had to pay retail for the track, I would go
back to lacing. I think in many ways that the old traditional ways of
rigging boats are coming back because the materials, like sailtrack
and Dacron sailcloth which made the traditional ways obsolete, are
now getting too expensive to consider.
As for the tack attachment, like the masthead attachment it is best
done with two separate lines, one around the mast to hold the sail
close to the mast, and another pulling down on the sail. The one that
pulls down is best done this way: Have a line tied through the base
of a cleat near the bottom of the mast. Run the line up through the
tack grommet and back to the cleat where you belay it. This way you
will have a two-to-one advantage here (ignoring friction) and can
really crank in some luff tension if you need it. If you see the luff
of your sail starting to pucker between its luff grommets in higher
winds, you can remove the puckers with more tension on the tack
attachment. This way is a lot easier that trying to retension any
halyard, if you have a halyard. In fact it might be worth setting the
tack line to a spring loaded cam cleat instead of a regular cleat to
allow for instant adjustments. Like this:
THE SPRIT...
In a lot of ways the sprit makes the rig into a bow-and -arrow affair
and makes the sharpie sprit a high performer. The sprit itself is in
compression and can usually be fairly light. I used a 1-1/2" square
sprit for Jinni's 96 square foot main and a tapered 1-1/2" x 3-1/2"
sprit for Birdwatcher's 16' sprit.
The sprit itself sort of floats free with its aft end tied to the
sail's clew, and usually attached to the sheet there. The fore end is
attached to the mast with a tackle called a "snotter" More on that
later.
But if you put tension in the snotter you put compression in the
sprit which forces the clew aft. That tensions the foot and leech
which in turn pulls the masthead aft. Here is what happens.:
By varying the tension in the snotter you can preload the mast bend
to what you want and that varys the draft of the sail to something
you want. It's actually quite adjustable although there are limits to
it all. So this very simple rig can do things for which other boats
need adjustable stays, etc. I always found the thing works very well.
I have a feeling that, as with most "preloaded structures", the
preloaded bendy mast retains the shape that you put into it until the
wind force overcomes the preload. So the sail shape will stay
constant until that wind force is attained, the sail shape does not
change with the wind below that threshold. So I've always felt that
the rig should almost always be preloaded to some degree. I never
bought into the idea that one should set the snotter tension light
for light winds and high for high winds. I kept the snotter tension
high all the time and hoped for a constant sail draft and shape.
One major point about the sprit geometry is how high up the mast the
snotter attachment should be. The higher up you go the greater the
tension in the leech and foot and the more rigid in general the
arrangement. I should mention now that another advantage of the
sharpie sprit is that it is "self vanging" which is to say the clew
does not lift up as sheet tension varies as with a normal sail. With
a regular boomed sail, the sheet pulls downward on the sail and boom
to resist the upward pull of the leech. When the boom is swung
forward as when running downwind, the sheet usually no longer pulls
downward and the boom usually lifts up. That allows the leech to go
slack, the sail looses its shape and sometimes its control. So often
regular boomed sails have a vang that runs from boom downward and
forward to the mast to eliminate the lifting of the boom. The sharpie
sprit doesn't need a vang because the sprit is always pushing the
clew down. The greater the angle between the sprit and foot, the
greater the affect. So sometimes you might see the snotter tackle
attached up quite high to take full advantage. I suppose the optimum
would be when the sprit sort of bisects the angle formed by the leech
and foot.
But it can be overdone from a practical standpoint and here is why.
On both Jinni and Birdwatcher I've had the snotter attachment break
or rattle loose while underway. It only happens in bad conditions,
course. You need to repair it quickly because you won't have control
of anything until you do. If the snotter attachment is more than
chest high, you will be in danger at repairing it. Having to stand on
a deck to effect the snotter attachment is a total no no as far as
I'm concerned. You won't be able to do it in the bad conditions that
caused the failure to start with. So that's why I place my snotter
tackles somewhat lower than some other designers and builders.
SPRIT ATTACHMENTS...
One thing to keep in mind about the sprit is that it sometimes must
be rigged very quickly. Another thing to keep in mind is that if it
comes loose you loose everything!
Here is how I like to connect the sheet and sail to the sprit's aft
end. A simple open based cleat is attached to the sprit there. The
sheet has a stopper knot about two feet from its end and is led
through the base of the cleat until the stopper knot bears against
the cleat, then through the sail's clew grommet, and the belayed back
on the cleat. Be sure there is enough rope beyond the stopper knot to
do all of this quickly. Variations on this are that on smaller boats
it can be nice to leave the sheet permanent to the sprit, in which
case a second stopper knot can be tied in above the cleat, capturing
it. Another variation is to have a snap hook tied in to the end of
the sheet so that instead of having to belay the sheet after looping
it through the clew, you simply snap the hook into the clew.
Here is how I like to connect the snotter tackle. In my opinion all
snotter tackles should be at least 2:1 to allow power to easily
preload the mast. So a small sail, say less that 100 square feet,
should have something like in Figure A. Again an open based cleat is
attached to the fore end of the sprit. A snotter line is prepared
with a stopper knot and passed through the base of the cleat, around
the mast and back to the cleat where it is belayed. Some sort of
eyepad will be needed on the mast to keep the snotter located on the
mast. For larger boats, the multi part tackle shown in Figure B is
suggested. It can be put on in an instant with the snap hook. The end
of the sprit is slotted to take the loop holding the block and the
slot needs to be just the right width to allow a press fit of the
loop rope. This is the rig I use on Birdwatcher. The snotter lead is
then lead down to a belaying pin near the base of the mast.
Contents
Sportdory
LIGHT ROWBOAT, 15' X 4', 70 POUNDS EMPTY
SPORTDORY
Sportdory is an attempt to improve upon the Bolger/Payson dory I
built about 15 years ago. This boat is slightly smaller than my old
dory. In particular the bow is lower in hopes of cutting windage.
the stern is mostly similar. The center cross section is about
identical. This boat has slightly more rocker than the original
Bolger dory.
The hull is quite simple and light, taped seam from three sheets of
1/4" plywood, totally open with no frames. The wales are doubled
3/4" x 1-1/2" pieces to avoid the wale flexing my first boat had.
I've added an aft brace to stiffen it up and give the passenger a
back rest.
Mine once covered 16 statue miles in four hours. In rough water you
will feel the waves are about to come on board but they won't. But
if you try to stand up in one it will throw you out with no prayer
of reentry.
The prototype was built by John Bell of Kennesaw, Georgia. Here is
a photo of John's Sportdory under construction. You can see the
sides and bottom, precut to shapes shown on the plans, wrapped
around temporary forms and "stitched" together with nylon wire ties
in this case. I'm quite certain that with this design one must
leave the forms in place until all the structural elements like the
wales and cross bracing have been permanently installed. If they
are removed before then, the assembly will change shape and you
won't get the same boat. In particular I think the nose will droop
to no one's benefit.
One might wonder about a comparison of Sportdory, Roar2 and QT.
They are all about the same size and weight, a size and weight I've
found ideal for the normal guy. They are small enough to be
manhandled solo yet large enough to float two adults if needed.
They are all light and well shaped for solo cartopping. Roar2 is
probably the most involved to build and the best all around of the
three. Sportdory is simpler and lighter, at least as fast and as
seaworthy, but most likely will feel a little more tippy and less
secure. You shouldn't really try standing up in either of these
two. QT will be the least able of the three as far as speed and
seaworthiness but may be the easiest and cheapest of the three and
is stable enough to stand up in. So take your pick.
Sportdory plans are $20.
Contents
Prototype News
Some of you may know that in addition to the one buck catalog
which now contains 20 "done" boats, I offer another catalog of
20 unbuilt prototypes. The buck catalog has on its last page a
list and brief description of the boats currently in the
Catalog of Prototypes. That catalog also contains some articles
that I wrote for Messing About In Boats and Boatbuilder
magazines. The Catalog of Prototypes costs $3. The both
together amount to 50 pages for $4, an offer you may have seen
in Woodenboat ads. Payment must be in US funds. The banks here
won't accept anything else. (I've got a little stash of foreign
currency that I can admire but not spend.) I'm way too small
for credit cards.
I think David Hahn's Out West Picara is the winner of the
Picara race. Shown here on its first sail except there was no
wind. Hopefully more later. (Not sure if a polytarp sail is
suitable for a boat this heavy.
Here is a Musicbox2 I heard about through the grapevine.
This is Ted Arkey's Jukebox2 down in Sydney. Shown with the
"ketchooner" rig, featuring his own polytarp sails, that is
shown on the plans. Should have a sailing report soon.
And the Vole in New York is Garth Battista's of
www.breakawaybooks.com, printer of my book and Max's old
outboard book and many other fine sports books. Beautiful job!
Garth is using a small lug rig for sail, not the sharpie sprit
sail shown on the plans, so I will continue to carry the design
as a prototype boat. But he has used it extensively on his
Bahamas trip towed behind his Cormorant. Sort of like having a
compact car towed behind an RV.
And the new Down Under Blobster is out sailing, report soon.
A view of the Caroline prototype showing a lot of the inside,
crew on fore deck. Beautiful color:
And here is another making I think its maider voyage in the
Texas 200. (I'm told the Chinese rig will be replaced by the
blueprint rig.)
I gotta tell you that on the Caroline bilge panels I made an
error in layout and they are about 1" too narrow in places on
the prototype plans. I have them corrected but it always pays,
even with a proven design, to cut those oversized and check for
fit before final cutting.
And a Deansbox seen in Texas:
A Twister goes together in good shape. He moved the cabin
bulkhead aft for more cabin, less cockpit:
Contents
AN INDEX OF PAST ISSUES
BACK ISSUES
LISTED BY DATE
SOME
LINKS
Mother of All Boat
Links
Cheap
Pages
Duckworks
Magazine
The Boatbuilding
Community
Kilburn's Power
Skiff
Bruce Builds
Roar
Dave
Carnell
Rich builds
AF2
JB Builds
AF4
JB Builds
Sportdory
Hullforms Download (archived
copy)
Plyboats Demo Download (archived
copy)
Brokeboats (archived copy)
Brian builds Roar2 (archived
copy)
Herb builds AF3 (archived copy)
Herb builds RB42 (archived copy)
Barry Builds
Toto
Table of
Contents
