Celnavitis. A rare, progressive and incurable disease.
Celnavitis is a rare, progressive and incurable psychiatric disorder that usually affects male scientists
over 50 years of age, although isolated cases have been diagnosed in females, non scientists and the
young.
There are several variant forms of the disease and the majority of patients are unaware of the diagnosis.
Many nevertheless seek help from web based support groups such as Navlist. Occasionally the disease
progresses to the even rarer and more serious “lunar” form .For these patients there is little hope
except for Frank Reed’s web site which provides regular cognitive therapy exercises involving
prediction and clearance of the most severe symptoms which include parallax distorted sensations of
distance, time and altitude sickness.
I describe below a particularly severe case (myself) as an example.
Case History
The patient is a 62 year old physician with a life-long passion for the sea and the sky, usually expressed
as aberrant behaviours such as sailing, SCUBA diving and staring at the heavens through telescopes.
In 1982, the patient dived on the wreck of Sir Clowdisley Shovell’s flagship H.M.S. Association which
sank in the Scilly Islands in 1707 while lost in thick fog with no idea of correct longitude. The patient
then developed an intense and uncontrollable interest in celestial navigation and in particular, the great
scientific challenge of the 18th century: The discovery of a method to find a ship’s longitude. At this
stage, the symptoms were mild and could not be classified as pathological.
A chance visit to a nautical second hand bookshop in Falmouth however, exposed the patient to a
collection of some extremist subversive literature, including the 1970s books by Hewitt Schlereth, and
John Letcher. This precipitated the first major pathological crisis, the purchase of a beautiful sextant. His
condition was then exacerbated when he inherited his father’s antique Fuller cylindrical slide rule and
his grandfather’s 15 jewel Swiss watch.
Slide rule disease and mechanical watch disease are separate and equally incurable psychiatric disorders
which occasionally affect patients with celnavitis. In its most extreme form, patients are compelled to
construct the most dangerous form of cylindrical slide rule known as the Bygrave and navigate across
the oceans with nothing more than that, the sextant, the watch and Schlereth’s book. A small sub group
of Bygrave sufferers even deny that the slide rule is cylindrical and genuinely believe that it is flat.
Fortunately, this patient’s condition has not deteriorated to that extent.
Over the last few years there has been a steady but gradual deterioration, the condition moderated
slightly with the occasional use of new, potent replacement therapies such as the GPS, quartz watch and
electronic calculator, usually when there are family aboard and you really should know exactly where
you are, especially as his favourite sailing grounds are the rock- strewn Scilly Islands. Unfortunately
these marvels of modern science, which he admits are crystals of the best achievements of western
civilisation, were associated with side effects such as button- pressing -boredom and hunger of the soul
and he slowly slipped back to his old addiction.
Two years ago he suffered a major relapse. His disease entered the probably terminal “lunar “phase.
He genuinely believes that he can tell the time by measuring the distance between the sun, some stars
and the moon. Last month, he thinks he found his position within 5 miles without a watch using lunars
to find the time, then a LOP fix from the sun and moon altitudes. He is now clearly deluded.
He recently made a pilgrimage to the holy of holies, the Royal Observatory at Greenwich, in the hope of
a cure. He stood on the zero meridian line at exactly noon GMT (minus the equation of time) and spent
hours with Flamsteed’s telescopes, Maskelyne’s Almanacs, Hadley’s quadrants and Harrison’s clocks, the
first 3 still ticking and tocking after over 250 years. All to no avail. His condition deteriorated. He cannot
decide who was the greater genius, Harrison or Maskelyne? He has now started on Cooks’s Endeavour
Journals, so little hope remains.
Summary of the patient’s symptoms
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An irrational urge to locate, roughly, within a few miles, his position at sea using a mechanical
watch, sextant, Bygrave replica cylindrical slide rule and a little book by Hewitt Schlereth,
containing a permanent almanac. This despite having 4 independent, robust, waterproof GPS
devices on board, 2 enclosed in tin box “Faraday’s cages” to protect against EMP from lightning
strikes and, God help us, nuclear attack. These locate the ship within a few meters. GPS can be
jammed by bad people, but so can the sun and moon by a wondering cloud and the darkness of
the night.
An irrational urge to measure time with a mechanical watch which looses up to 20 seconds per
day (albeit the going rate is regular). This despite the presence of 4 cheap, reliable, robust,
waterproof quartz watches which between them provide accurate GMT. Two of these reside in
“Faraday’s cages”.
An irrational urge to navigate even without the mechanical watch. He takes several lunars and
altitudes of the sun and moon over a period of 5-8 minutes and drafts the readings on a graph
using a homemade water drip clock or counting (1 thousand, 2 thousand e.t.c.) to measure the
time between readings. He selects the best fit, “simultaneous “readings, to establish GMT from
the lunar distance and then uses the Bygrave to obtain a LOP fix using the moon and sun
altitudes at that time. Even Maskelyne needed a “good watch” for his pre-LOP method in 1763.
The fact that this no- clock method actually works has just strengthened his delusions. His soul
leaps and he feels good. (Some of his fixes, so done, have been up to 30 miles out, but he is in
denial over these.)
An irrational urge to calculate his lunars with a Fuller slide rule using the formulae in John Karl’s
excellent book (which he nearly understands from the pictures of the navigational triangle) and
that in Letcher’s (which he doesn’t). This despite the presence of several cheap, reliable, robust
and waterproofed calculators which can do it quicker and more accurately (but with less
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soul).He finds something tactile, organic and beautiful about the sextant and slide rule. The
buttons on the black boxes, despite the miracle of the chips inside, do not move his soul. He
generally checks everything later on the Frank Reed web site, but not out in the wide open sea.
He would now like to use his Bygrave to do this, but cannot master the maths. He is going to
seek counselling from Frank Reed and John Karl. (the Bygrave is a lot more compact than the
bulky Fuller.)
An irrational urge to wake up at 5am to find his latitude by Polaris, using a homemade
“Nocturnal” for the correction. The unexpected accuracy and ancient simplicity of this method
also lifts his soul to incurable heights. Three years ago, he sailed across the English Channel a
hundred miles from Brittany to Penzance, steering only by Polaris, the North Star, lighting the
way home.
An irrational urge to check the accuracy of his mechanical watch by timing the eclipses of
Jupiter’s moons. One of his heroes is Galileo. His best so far has been a few minutes out. He has
asked for a better telescope for Christmas.
Prognosis
The long term prognosis is clearly hopeless. However, there is no evidence that the condition is
associated with reduced life span or even pain. Most patients report that they feel better when ill than
when in GPS or computer induced remission. A few have become addicted to high tech replacement
therapies and have irrational and uncontrollable urges to locate their position using digital cameras and
artificial satellites. This may well be a separate disease and beyond the scope of this paper.
Conclusions
Celnavistis is a serious, incurable illness, but it is not life threatening (except where a miss of a Scilly Rock
may not be as good as a mile). Most patients appear to be happy and contented with their illness and it
would probably be unethical to enforce electric shock therapies such as GPS treatment on them.
Government plans to ban the sale of sextants would not work, since it is quite easy for the average
patient to build one himself. A homemade watch may be beyond the skills of the average patient, but
who needs a watch when you have lunars?
Dr Francis Upchurch. September 2013. Physician and Celnavitis sufferer with severe lunar
complications.
(Health and Safety warning. Celnavitis sufferers may be 2- 30 miles out and tend to be in denial
about numbers over 5. They are usually skipper of the boat. If you are a “normal” crew member and
anywhere near land, cheat and sneak a look at the GPS, chart plotter and radar. If you are near rocks,
take command and throw the skipper in the brig.)
Acknowledgements and references.
I would like to thank a host of Cnav and slide rule experts for infecting me with this wonderful disease.
Most seem to be still active via Navlist. My apologies for anyone I may have missed.
Hewitt Schlereth for his book “Common sense Celestial Navigation” which started me off on low tech
CNav.
John S Letcher .Jr. For his wonderful book.
John Karl for his book, in particular the chapter on lunars, but the whole thing is brilliant.
Frank Reed for his lunar web site and Navlist expert postings and general all round wisdom. Totally
brilliant.
David Burch for his wonderful book, Emergency Navigation which contains numerous tasty soul food
recipes .
Gary LaPook, G Kolbe, R. Van Riet and Zvi Doron for help with my early Bygrave prototypes a few years
ago. Gary also introduced me to Chichester’s early aviation Cnav achievements. Inspirational!
Wayne Harrison (slide rule lists and Google web site.) for his authentic replica Bygrave and Fuller scales.
My replica homemade slide rules are used at sea, the originals stay locked safely on dry land.
Nevil Maskelyne: 1)Nautical Almanacs 1767-now! (but no longitude prize for him!). 2) British Mariners
Guide 1763. (Lots of bad press from Dava Sobel et al. I’m not so sure? ) All available on Google. Several
as paper book copies (Ecco).
Dava Sobel: Longitude. Pure Poetry summarising the whole thing. Gorgeous book. A bit biased against
Maskelyne I would say. Harrison was a difficult character and he did take 40 years to get it right! (at
£500 pounds a time, (over £30.000 now, taking 3 years to make!) Maskelyne’s Almanac + good sextant
cost about £15 at the time.
James Cook Journals Endeavour. (unabridged). Free on Google.
Dennis Fisher: Latitude Hooks and azimuth Rings 1987. If you want to make your own quadrant or
nocturnal. (easier than you think.)
Tony Crowley : Lo-Tech Navigator 2004. Also good for homemade quadrants, nocturnals and other soul
food recipes.