Celestial Navigation for Yachtsmen: 13th edition

Written by an expert. Thorough and well explained. A very practical treatise.

I first read read Celestial Navigation for Yachtsmen in the 1970s and learned to take sights from it. The updated version is much improved, and will become a classic also.

I know this is a classic. I bought the kindle version and found it hard to flip back and forth between the text and the figures. I found some easier instruction on the web.

The definitive guide to using a sextant & theory behind it.Short, clear, concise.

Comprehensive, clear and practical explanation of celestial navigation, easily understood by the novice.However, purchase of accompanying tables is necessary.

Nice revision of a classic

I have an active interest in celestial navigation and I have been studying on Mary Blewitt's book as well as many others. I think the book can be a useful resource AND it has some pros, but ultimately I don't think it's a great book and I probably wouldn't buy it again if I had a choice. The praise that it is "The 'bible' of navigation for generations of yachtsmen... worth its weight in gold" reported on the back cover is making me cringe and want to cry.I think Henning Umland's "A Short Guide to Celestial Navigation" is vastly superior to this book in all aspects -- and it's a FREE download. Henning is just better at explaining things. If you like to pay for your books, get David Burch's books on celestial (and non-) nevigation... any of them: they are all superbly written.The only prospective customers to whom I feel I could recommend Mary Blewitt's book are people who don't really care much about the subject, are ok with learning it procedurally and mnemonically without too much insight, and want to be done with it quickly. Possibly, somebody who *has to* take the subject in some kind of certification program and they need to "be done with it" and move on to something else. Anybody who has true curiosity for the matter will be left unsatisfied by the paucity and poverty of this book.A more detailed analysis of Mary Blewitt's book follows.Pros:1) conciseness -- it has only 51 pages of contents (tables and indices excluded) and its entire contents can be mastered in a few afternoons;if brevity matters to you, this is probably the best book for you;2) the material is presented in a very clean and well-thought order. You are presented only the material you strictly need to understand in order to solve the problem at hand. Then, new material is introduced to allow you to solve a new problem, of increasing complexity. It feels like the book comes from notes that the teacher has been handing out to his student, and the teacher has delivered the course many times and optimized the order of presentation that is easiest for the students to absorb;Cons:1) briefly said, the book does not explain things well. It would probably work well as a handout to accompany a classroom course where the teacher gives you the *actual* explanation... but as a stand-alone learning tool, it is insufficient. The section on "Spherical Triangles" (p. 23) is an example of a poor explanation: the author is slowly building up to the need for the intercept method, but the explanation is all over the place, and the transition from the "why we need this method" to the "here is how the method works" is abrupt and confusing. Any reader who already learned the intercept method from another source would shake his or her head at these pages, wondering how much of the explanation remained in Mary's head and how little made it to the page. The math "Calculators" section in the Notes chapter is some of the worst typeset math I have seen in my life, and I can't imagine anybody understanding that section unless you are already familiar with it. It's not just ugly to look at, it's aggressively confusing and missing all the necessary basis that make it understandable. I would bet my money on the fact that the author does not know trigonometry enough to prove any of the formulae she provides. There's nothing wrong with that, but as a customer, I'd rather get a book written by somebody who actually knows trigonometry.2) Mary probably is part of those people who teach navigation and celestial navigation to students that don't know math and fiercely resist learning it. I know that kind of teacher and that kind of student... sadly, I was in a coastal navigation class where a student asked if he could use a smartphone app to compute time, distance and speed from one another. This kind of teachers tend to replace all the math they can with mnemonic rules and casuistry. I think it can help in some cases, but in others it's disastrous. I argue against the way it's done in the book. Latitude can be N or S, Longitude can be E or W, Azimuths also come in two variants. All angle additions and subtractions can deliver results out of the 0...360-degree range. If you start considering all these outcomes as different cases, you end up with a law book or a telephone directory, and it's nonsensical. Math involving angles simplifies A LOT if you introduce reasonable sign rules and enforce them. Most "cases" disappear, and formulae collapse in fewer, simple ones. It's ok to keep the figures of the various "cases" just to show how angles can occur in relation to each other in practical cases, but the *one* formula still holds. Umland's book is quite better in this respect.Blewitt introduces a lot of material just to circumvent using a tiny bit of math at the right time, and the explanation ends up being longer, more convoluted and more confusing.3) Figures are insufficient. When you explain geometry concepts to people who are unfamiliar with them, you can't expect them to visualize those concepts correctly, entirely in their mind, on the mere basis of brief word explanations. Draw those concept. Use clear, large, well-thought figures. If you don't, you are a lazy and sloppy teacher. Example: when explaining that lines of position appear straight when plotted on a large-scale (detailed) map but are in reality circles on the earth's surface, you MUST include a figure to show how those circles. It's figure 1-5 in Umland's book, but it's nowhere to be found in Mary Blewitt's book.4) If you have any curiosity about the celestial navigation that roams outside the bare practice of "doing it on paper", there is NOTHING for you in this book. Nothing on the historical birth of celestial navigation. Nothing on the math behind it. Nothing on the mathematical basis of the operations you do on paper. Nothing on different methods used through history. Nothing on how to solve exactly and analytically the intercept method (as opposed to solving it graphically by drawing it on paper). Nothing on sensitivity analysis to determine the impact of input errors on final estimate error. Nothing on celestial dynamics. Nothing that could help you write simple celestial navigation software.If celestial navigation is a great drama movie, Mary Blewitt's book is a 20-second excerpt where the characters have intercourse and their faces are not even shown. The first is art, the latter is pornography.

This book has all of the technical aspects of celestial navigation, but cannot be read as one's first book on the topic. In order for this short book to helpful, it's necessary to have a foundation in the subject. It's inconceivable that this topic could be properly taught in 63 pages.

Great book that has stood the test of time helping many budding astro navigators achieve acceptable results in small boats at sea

Manual básico para la navegación astronómica que guía sobre el uso de la técnica de posicionamiento. No es un libro de texto, sino un manual de aprendizaje para navegación. El único inconveniente es que esta escrito en inglés.

Contents is great, would give a paper copy a 4star, this e-book not all that user friendly

I bought this particular book on astro-navigation as a result of numerous recommendations. The common thread of the recommendations was "It is clearly written in terms that anybody can understand".It is (clearly written) and I do (understand).Now I really must get a sextant!Thank you Mary Blewitt.

This is a small book that is packed with just the essentials of celestial navigation for sailors. This is just what I wanted but it may leave others unsatisfied and wanting more. Fortunately, there are tons of other books on the subject but I suspect that none will come close to this book in information density. Read carefully and repeatedly.