The Development of the Keel
In Star Boats
By David Bolles
When the Star was designed in
November 1910 in the office of William Gardner, there was no thought given to
the idea that the Star boat would outgrow its being used as a local
F
I T T I N G S.
All fittings, including fin
keel, rigging, blocks, cleats, deck and spar fittings, rudder‑post,
tiller‑jaw, and sails, to be furnished by William Gardner & Company,
and put in place by Builder.
At
the time the Star was designed it was natural for the
However,
it should be remembered that castings made from cast iron is not an exact
process. There is a certain amount of shrinkage which takes place as the cast
iron cools, so the end result will be a keel which is smaller than the pattern
which was used to make the mold. William Gardner undoubtedly knew the vagaries
in the casting process, and perhaps that was why originally the specifications
required that the keel had to come from a pattern supplied by the
However, during the next few
years two things happened. The Class began to expand to areas beyond
As regards the fittings ‑
It would be foolish for you to make patterns of same, as the patterns alone
would cost you three times as much as the fittings. If you wish, we can furnish
you the fittings, which are the ones used on all the boats here. The prices two
months ago were as follows ‑ ‑
Bronze blocks and sheaves, $16.50
Iron keel, 50.00
Deck and spar fittings, 29.64
Sails, 70.00
Rigging, 25.00
Track, slides, etc., 13.50
--‑-----
$204.64
If you desire them, will get these
prices verified, and they will probably not differ very much from the above
figures.
As regards the fin ‑ ‑
You could probably do a great deal better by getting this from the Rocky River
D. D. Co., as they, I understand have made a pattern for it, which is a very
expensive thing and very difficult to make. When the freight is taken into
consideration, they could probably furnish you the fin at a much lower price
than the above. If, however, you wanted an absolutely correct fin and didn't
mind the slight increased cost, it would be better to get it here, as the fin
pattern was checked up very carefully by myself, so there in no question about
its accuracy.
Since
this was the war time era, perhaps the
Thus,
while it appears that the original intent of the Gardner office was that
Gardner & Co. was to be the only source of fittings for the Star, including
the keel, because of various circumstances, including the distance from a
central distribution point and war time restrictions, the Gardner office
changed its policy with regard as to where Star fittings such as the keel could
be manufactured. Almost certainly, if the Gardner office, and later the Star
Class Association after it had acquired the rights to the Gardner plans, had
continued the stipulation that the keel be provided by only one source, the
Class would not have grown into being a worldwide Class at a time when shipping
such items as keels was very prohibitive.
The Star keel, as shown on the
The Star Keel as shown on the
Gardner Plan of November, 1910
However, if one looks closely at
the keels on boats from various periods there is a noticeable refinement in
shape, especially that of the bulb. A couple of items of note in this plan are:
1)
In the drawing of the cross section there was a gradual widening of the
bulb with the widest part of the bulb being within a couple of inches of the
bottom of the keel. This is in contrast to some bulbs of today which flair out
very quickly near the top of the bulb.
2)
There were no wood fairing strips around the flange of the keel to make
a smooth transition between the hull’s bottom and the keel. Fairing strips came
some time later, and by the 1950’s were in universal use.
After World War I the Star
started to evolve. The first change was for the rig to change from a gaff rig
to the short Marconi rig in the early 1920’s. The Star’s keel, along with the
rest of the boat and rigging, also went through a process of evolution over the
nearly 100 hundred years of the Star’s existence.
Change in the Keel Position
One item that has long been
played with is the fore and aft positioning of the keel. For two years running,
1922 and 1923, Bill Inslee of the Western Long Island Sound fleet was the
Champion of the Star Class. Bill wrote an article about boat preparation for
the April-May, 1924, issue of Starlights. This article is very illuminating in
letting us see what a top skipper considered to be necessary to tune up his
Star. Bill begins with a description of how to get the smoothest bottom. Then
he deals with getting the proper balance in the helm when going to windward. He
mentions the importance of the proper position of the keel, the placement of
the mast, the rake of the mast, the position of the jib fairleads, and backstay
tension as various components which went into getting a balanced boat. In the
original design of the Star the keel was a little too far forward and it became
quite common to move the keel as part of the process of getting the boat tuned
up. Since the hull was sitting on top of the keel flange, as shown in the plan
above, and there were no fairing strips, moving the keel aft was not an
especially difficult project.
In the 1925 Log there is the
first attempt at giving specifications for Star boats. As shown in this Log, it
was allowed to move the keel “forward or aft 4 inches from position shown in blue
print”. In 1939 this was changed to allow 6” fore and 4” aft of the position as
shown on the plan. At the present this allowance is much more restrictive,
being 51 mm or about 2” fore or aft of the point known as dimension E.
In the 1925 Log there is also
the earliest comment about keel shape: “Must be cast from a pattern approved
and registered with the association.” This wording was soon changed to read
“Must be cast from a pattern recorded with and approved by the Measurement
Committee.” This second wording was used for a number of years until the 1945
Log when the wording was changed to read only “Must be cast as per plan…”
The first time keel dimensions
are listed in the “Table of Limitations” was in the 1954 Log. Only three keel
dimensions are given: the vertical distance from the bottom of the hull at
Station 6 to the bottom of the keel, the thickness of the keel fin at the
thickest point, and the thickness of the keel bulb at the thickest point.
The earliest known existing keel
drawing which gives details on the various keel contours was made by Skip
Etchells in July, 1946. This was the original Drawing No. 4. There is no “Table
of Limitations” given on this drawing. It does however include a “Table of
Drawing Board Offsets for Bulb Sections” plus numerous other dimensions.
In July, 1979, during the period when the Star Class was
tightening up on hull tolerances, Drawing No. 4 was redrawn by Carl Schumacher,
showing the same shape and dimensions given in the Etchells drawing but now
including data in both English units and Metric units. Furthermore, a “Table of
Limitations” for the keel was added to the plan. The number of measuring points
on the “Table of Limitations” increased from 3 to 14. This is in addition to
the various points (53 in number) given in the “Table of Drawing Board Offsets
for Bulb Sections”. Also added were various “General Notes”. Some of the more
pertinent ones to this article are as follows:
5. Except for bulb station 1, maximum width of bulb shall occur
between 77 (3”) and 127 (5”) above keel base line.
6. All
keel radii, when viewed in profile, shall be as shown here plus or minus 33% of
value shown.
8. No
keel waterline when viewed in plan, shall have a concavity.
9. Drawing
for all new keel patterns must be submitted to the chief measurer for prior
approval.
Position of the keel flange relative to the hull
One
significant change made in the Schumacher drawing from the earlier plans of
Clarification on Keel Fairings
The hulls
of some Sune Carlsson boats are recessed only 6 mm. for the keel flange, so
that the flange still protrudes below the boat bottom. The mold has been
corrected to remove excess fairing forward of the keel, but fairing all around
the flange within the control dimension is allowed.
On Buchan,
Gerard, Lippincott, Mader and other hulls that have a complete recess in the
hull for the flange, it is the opinion of the Measurement Committee that keels
cannot have any “fairings” as discussed in Article V, section 7, of the
Specifications. William V. Richards, Chairman
The 1979 “Table of Limitations” for the Keel
As
stated previously, castings made from iron is not an exact process. There is a certain
amount of shrinkage which takes place as the iron cools, so the end result will
be a keel which is smaller than the pattern which was used to make the mold. By
the 1970’s it was recognized that there was a need to have a “Table of
Limitations” giving an envelope into which the Star keel could fit.
Thus,
during the 1970’s efforts were made to tighten the hull’s “Table of
Limitations” and create the keel’s “Table of Limitations” to bring construction
of these two key components to the Star under tighter control. The hull’s
“Table of Limitations” underwent further tightening during the 1980’s. This
tightening was in part in response to the fact that during the last years of
wooden boat construction as builders became more adept at carrying the hull lines
to the extreme limits of the limitation envelope hull shapes which were
obviously not the original intent of the Gardner lines became prevalent. A good
example was the late Eichenlaub boats which had a very pronounced V bottom.
There were many complaints about a continual “arms race” in which each builder
tried to out-do the others in introducing innovative features in their boats.
Boats were very distinctive from builder to builder and one could often say at
a glance who the builder was. Now with the present fairly restrictive “Table of
Limitations” for the hull one now has to look elsewhere on the boat to have
some idea which builder built the boat. Such things as deck construction and
layout, and keel features, are tip-offs as to what company built the boat.
The Kimble Keel of the late 1970’s
Starting with the July 1977
Starlights there began to be a series of notes about keel shapes. The first was
in 1977’s Resolution 5, which in its preamble stated the following: “Whereas certain new keel shapes have been seen which
appear to differ in substantive degree from the keel plan, and whereas it seems
appropriate that keel shapes be variable only to a reasonable degree and
consistent with Class policy, therefore be it resolved that additional keel
dimension tolerances be adopted as follows:” The resolution then went on to
give specifics. This was followed up by a note in the November 1977 Starlights:
“Resolution 5 … was withdrawn by the sponsoring fleet because the Technical
Committee had not yet reported on it. President Parks commented that the IGC is
assigning the keel problem to the Measurement Committee because we are dealing
with a tolerance problem, not a Specifications change. Regarding Kimble keels:
New information available to the Measurement Committee suggests a stop order be
issued on Kimble keels. The Measurement Committee will recommend new (i.e.
additional) keel measurements immediately. Existing boats with these keels and
with a measurement certificate will be grandfathered. This will be reviewed at
the IGC meeting on Sept. 3, 1977 for final decision.”
Further discussion on the topic of Kimble keels
followed in the December 1977 issue: “A different shaped keel made an
appearance in
For the next year and a half
Starlights was silent on what was happening with the keel issue, but then the
May 1979 issue came out with interim guidelines introducing temporary
limitations K-11, K-12 and K-13. These limitations were further refined and
incorporated in the 1979 Drawing #4.
The significance of
the Kimble keel is that it had a concavity longitudinally along the bulb. Jet
fighter designers noticed an improved high-speed performance when the body of a
jet fighter had an hourglass shape. This was called the “coke bottle effect”,
and it was decided that this should be tried out on Star keels. Thus the need
for note 8 in Drawing #4: “No keel waterline when viewed in plan, shall have a
concavity.”
The final chapter in the Kimble
keel episode was written up in the December 1979 Starlights:
1.
Keels. Bill Gerard, Technical Committee Chairman, reviewed the new keel
drawing. He noted that few keels had been built strictly according to plan over
the last ten years. He said that the new plan is an attempt to narrow the
tolerances and prevent extensive development…. President Burnham reminded the
meeting that the last three major regattas. Kiel Week, Bacardi Cup, and the
Western Hemisphere Spring Championship, were all won with the old keels….
Burnham added that … the new keel drawing is being made up. In addition, a new
K measurement has been added to try to ensure that no major keel development
can occur in the future. The final official drawing will be available 1 January
1980.
2.
Class keel pattern. Friedrich Krieger investigated costs and found that a
master keel pattern would cost $7,000 and moulds would cost $200. Bill Gerard
noted that a Class pattern would not solve the basic problem of tolerances
because much work is done in finishing and puttying the keels, which changes
the shape of the bare casting. The Committee voted to postpone the introduction
of a Class pattern.
Keel Cross Sections
In note 2 to the original
To give some idea of the changes in bulb shape here are
some keel cross sections:
Relative to the original
Milled Keels
As stated in the comments about
the 1979 Drawing No. 4, a Table of Limitations for keels was introduced in
1979. Recently, the milling of keels using a computer to determine the finished
shape has become possible. The result of this is that it has become possible to
pour over-sized keels and then mill off the excess to a desired shape. This
allows the boat builder to take any point on the table of limitations to the
maximum or minimum, depending on the desired keel shape, and produce a keel,
which while falling within the bounds given in the Table of Limitations, still
has a bulb shape which was not the original intent of the keel drawing.
Of course, the process of
milling a keel adds significantly to the cost of building the boat. Builders
charge anywhere between 3,000 € and 9,000 € for this extra service.
A Couple of Recent Developments
One of the most recent
developments is the flat-sided bulb seen on some of the newer Maders. This is
shown above in the last depiction of keel cross sections. One of the results of
carrying this feature all the way to the trailing edge of the bulb is that the
trailing edge is mostly vertical with almost equal radii at the top and the
bottom of the trailing edge. While visually this is not the intent of Drawing
No. 4, given General Note # 6 which states that “All keel radii … shall be as
shown here plus or minus 33% of value shown” and taking the upper and lower
trailing edge radii to the 33% limits, then in fact the radii can be close to
being the same at about 4 ½”.
Another recent development is
what some have called a “drooping keel”, in which the aft end of the keel bulb
is significantly lower, and conversely the forward end of the keel bulb is
significantly higher, than what is shown on Drawing No. 4. This can be achieved
by taking the forward keel measurement K-6 which is shown as 30 ⅜” to its
minimum which is 30” and taking the aft keel measurement K-9 which is shown as
32” to its maximum which is 32 ½”.
Keel Coatings
and the problem of rusty keels
One of the more bizarre things to happen in the last
ten years is the reduction of the amount of coating on the keel so that the
overall density of the keel is as high as possible in order to obtain the
maximum righting moment. Carrying this concept to the logical extreme, milled
keels in which the keel is milled to the final shape so that no filler is
necessary have become fashionable. As mentioned above, the process of producing
milled keels is quite costly. While this concept is correct and all very well,
it would seem that applying a coat of protective material which is so thin that
water penetrates it and begins to cause rust after only a short time is
carrying the concept too far. Surely, having the proper amount of a protective
barrier coat applied on the keel cannot increase the overall volume of the keel
significantly enough to affect the righting moment.
On keels receiving this treatment it is quite common
for the original coating to bubble up and flake off the keel due to rust. This
is an unfortunately common problem with boats built by one company in
particular, and boats as new as only 4 years old have had to have their keels
recoated, usually at a cost of between $3,000 and $5,000.
Leading Edge
One of the subjects not touch on
in this article is that of leading edge in keels. While this may seem minor
compared to what has been talked about above, in fact there is reason to
believe that this factor has more to do with the keel’s performance than other
factors such as bulb shape and orientation.
In the Spring 2001 issue of Starlights there appeared an
article by Paul Bogataj which addresses this topic. In it he shows three
different leading edge shapes and gives a graph showing the up-wind and
down-wind performance for each of these leading edges. Briefly stated: A
rounded leading edge has good lift for up-wind performance but high drag for
down-wind performance. The opposite is true for a fairly narrow leading edge.
He gives a third leading edge which he suggests is the best compromise between
the two extremes. Although seldom talked about, for years top skippers have
paid attention to this detail, and today practically all of the variations
mentioned here can be found on Stars. The preference is related to what type of
racing the skipper plans to do most, whether short course racing where high
lift is needed, or traditional long Star course racing were speed is more
important.
SOME FINAL THOUGHTS
There are two points brought up in the December 1979
Starlights comments about keels which deserve further consideration:
1) That few keels are built according to Drawing #4.
2) That there should be a Class keel pattern.
At the time when wooden boats were being built all
over the world it was common sense to allow foundries local to where boats were
being built to produce keels. During that period of the Class’s development it
not only made sense but it was necessary in order to accommodate home-built
boats to have a fairly lenient “Table of Limitations”. Once the Class switched
to fiberglass boats then the idea of home-built boats was no longer feasible,
and as a result the hull’s “Table of Limitations” was tightened up during the
1970’s and 1980’s.
Added to this fact, at the present time there are in
effect only three builders of Stars, all located in relative close proximity to
each other. This fact makes it possible for there to be a single foundry which
could provide keels to all three builders. Further, with the advancements in
foundry practices it is now possible to pour keels with much greater precision,
thus eliminating the need for the costly process of milling keels to a desired
shape.
Taking these various factors into consideration,
recently there was a renewed effort to reign in the variety of keel shapes and
costs associated with milling to accomplish these shapes. During the
correspondence concerning crafting a resolution which would attempt to solve
these problems the observation was made that Drawing #4 was way out of date and
does not reflect present-day keel shapes.
This being the case, it seems that an effort should be
made to redraw Drawing #4 to reflect what the Star keel should be, and at the
same time, given today’s better casting techniques, the keel’s “Table of
Limitations” should be further tightened consistent with present-day foundry
practices. Carrying this idea further, the Class should settle on a single keel
shape and have a pattern built which would produce the desired keel.
Thus:
1) A study should be made to see what the best
all-conditions keel shape is and Drawing #4 should be redrawn to reflect this
ideal keel shape.
2) A pattern should be made which will produce keels
which conform to this shape.
3) The leading edge of this keel should have a narrow
entry, and builders and/or owners should be allowed to build up the leading
edge according to what they believe is best for the type of sailing they are
going to do.
4) The Class should stipulate that builders apply a
protective coating to the keel which will last the lifetime of the boat.
I
believe that it is time for the Star Class to return to the original principle
concerning keel construction; that is that all keels come from a single
pattern.