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kitcrazy

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hi, been reading up on basic navigation and i've got myself some charts to pratice on, but i need to get a parallel ruler and dividers. I've noticed there's diffent types, does it matter which ones or is it just down to personal choice?
 
Dividers are fairly standard; the type with a semi-circle (or 'bow') near the hinge, so that you can open and close it with one hand. Never stick the points into the chart, but lay the dividers almost flat against the paper to take measurements.

Go for brass with a stainless set of points - feels really good !


Parallel rulers are a different fish kettle. Lots of different types and some non-parallel ones as well.

The roller rule will wander all over the chart table and is pretty useless on a small boat under destroyer size.

I prefer the ones which are like two plastic rulers, joined by a couple of thin metal plates, so that you can zig zag them over the chart from a compass rose. They remain stationary when flat on their own.


Plotters
There are lots of other bespoke devices: e.g. Breton plotter, Portland plotter, etc., which all have a compass with deviation / variation adjustments, graticules, distances markings etc.

They can be quite addictive, and each has its army of followers. Probably the best all-round device, and cheapest !
 
On the whole it's a matter of personal preference. I have Capt Field's parallel ruler (the one with a protractor drawn on it), but haven't used it for years. When I use one, which is not often these days, I have a gizmo attached by parallel tapes to a corner of the chart table which is easy to use, even one-handed (and also has a protractor built-in).

I don't use a Breton type plotter, though we have one since SWMBO went to classes. I only ever use it to line up screw holes before drilling, but I know a few people, some of them sane, who use one for navigation.

As a general rule get the best quality stuff you can afford. That goes for most things on board, if only for the greater pleasure in their use.
 
Portland plotter and dividers were recommended at our nav course - have served us well and never needed anything further. You can get some nav exercise books which might give you some focus - nothing quite like the real thing though.....
 
As a recent 'dazed kipper' theory and practical student. I can vouch for the brass/stainless dividers and Portland plotter. IMHO they work well in the classroom and also for real when rolling around off St Alban's Head in the pitch black with no GPS.

I have worked with parallel rules as well but just find the compactness (is that a word?) and convenience of the Portland pretty good.

Tim
 
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Absolutely Personal Choice - But Some Are Better Than Others Depending On The Job

A good Parallel Rule, a Douglas Protractor and a so called Breton Plotter (the rectangular device with the circular protractor in the middle). I actually prefer Standard Dividers as opposed to the bow type. My reasons are as follows: -

Parallel Rule
Easy to use for transfer of positions lines - running fix is a classic example.
Very easy transfer of Lat and Long from GPS to chart.
Buy the 12" size

Douglas Protractor
Great for setting up position lines directly from the object on the chart. Simply put the centre over the object (protractor aligned North) and mark the angle on the chart. Draw position line from object through mark.
No need to slide or position device to transpose angle.
Buy the 6" size

Breton Plotter
Great for laying off a course and measuring the bearing. Simply align on the course, twiddle the dial to North (make sure it overlays a Lat or Long line) and read the bearing.

Standard Dividers
I have never navigated in such a contorted position which only allows me to squeeze the bow types. The bow types allow you to squeeze to open and squeeze to close. However they always open up just short of the distance you want to measure. Bow type, in my opinion, have limited functionality compared to Standard Dividers.
Buy 9" size

Why
Any of the above tools can do any of the plotting requirements when navigating so you only need to have one type and just practice. I have found that each of the angle measuring devices can be used in an optimal situation as described. This has been observed over many years of so called traditional Navigation.

If I Only Had To Choose One
12" Douglas Protractor. No moving parts, big enough to place in a useful position on the chart, long enough to use as a straight edge rule; 9" standard dividers.

Don't get too hung up about it. As another poster says, just practice.
 
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Just get a pair of STRAIGHT navigational dividers, as found on all ships' bridges. For people with the normal complement of fingers, these are much easier to use with one hand than the "bow" type, which look the part but don't do the job anywhere near as well.

Parallel rules belong on a large, flat and relatively steady ship's chart table - not much use on a yacht at sea. A Breton plotter or big Douglas Protractor will do the job better.
 
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Personal preference, but it's worth trying with all of them until you can establish a preference, rather than using one and then slagging off all the others.
Personally, I prefer bow dividers (the big ones -- forget the fiddling little ones) over straight ones, and I prefer 12" or 15" Captain fields parallels over a Breton plotter. (a proper, thin flexible Breton, not the heavy, thick, brittle copies).
Most of the other contraptions come way down my list but I did have a fairly long-standing infatuation with an 8" douglas protactor look-alike.
But get what *you* like, and *enjoy it*: navigation is a hobby -- not a "chore".
 
timbartlett said:
Personal preference, but it's worth trying with all of them until you can establish a preference, rather than using one and then slagging off all the others.
Personally, I prefer bow dividers (the big ones -- forget the fiddling little ones) over straight ones, and I prefer 12" or 15" Captain fields parallels over a Breton plotter. (a proper, thin flexible Breton, not the heavy, thick, brittle copies).
Most of the other contraptions come way down my list but I did have a fairly long-standing infatuation with an 8" douglas protactor look-alike.
But get what *you* like, and *enjoy it*: navigation is a hobby -- not a "chore".
Click to expand...

Spot on Tim. Find what you like. What works for you. If it works & you find ease using it & get the correct results then end of story. Each to their own...........as long as it works.

One correction. Navigation is not a hobby, it is a necessity. IMHO of course. Hee hee.
 
kitcrazy said:
hi, been reading up on basic navigation and i've got myself some charts to pratice on, but i need to get a parallel ruler and dividers. I've noticed there's diffent types, does it matter which ones or is it just down to personal choice?
Click to expand...

Very much personal choice - mine is for the ultra-simple and cheap two largish triangular setsquares. I find that holding one down firmly and sliding the edge of the other against it is very esay to know if anything slips, and you can usually move from compass rose to chart point or vice versa in one go, at worst two shifts. With parallel rules you often have several 'steps' to go, and each step increases the chances of something moving, as it's rather fiddly.

My second choice is a square portland protractor - the one with a hole in the middle. I've also tried the currently fashionable Breton plotters with adjustable buits in the middle, but reverted to the two setsquares.

As for dividers - I have a big brass pair, but actually prefer a good quality large compass with a pencil at one end. For some traditional nav tasks you need to draw arcs, and you can't do that with dividers.

In practice however nowadays I first LOOK carefully at the chart, then navigate on an electronic plotter, but I write down a GPS position every hour and I can go back to absolute basics if I need to.
 
I've taught nav for years. If the class want me to buy equipment in bulk for them, I always go for the bow type dividers and the Breton plotter. This plotter has the biog advantage that it works out the way to apply deviation and variation for you, and some people have difficulty remembering how to do that. I have occasionally had people turn up with Capn Fields or parallel rules and even one of those useless on a yacht roller thingies, but most have ended up using the Breton plotter.

Which is why the RYA provide them to students.
 
As above, PORTLAND plotter (Breton is the original name), plus Dividers. Whichever dividers you prefer, beware the plastic type with no screw in the hinge, you want brass with stainless points, they will last forever. There are good deals on ebay for a Portland plotter and dividers - about £23 inc P&P.
 
All wonderful stuff for working in the classroom & planning courses to within a 1/2 deg.

However, when working in the cockpit of a small boat at sea when singlehanded, it's all about as much use as a chocolate teapot. By all means learn that stuff and make sure you understand the principles.

Then you can use your eyeballs, brain & chart folded on your knee to get a position & plot a course as you steer. Identify a landmark, point at it & then transfer that "bearing" to the chart, already orientated on your knee. Remember that & do the same for another landmark. Where the 2 cross is obviously your position - with a decent circle of uncertainty. You know where you want to go so use your eye & hand to transfer that bearing off the chart to the horizon & steer it. You will need to make some allowance for tide & leeway etc, but it works and you don't even need a pencil or a compass.

Of course, if you have the time & support to use all your equipment & books, then great, do it. It is very satisfying to navigate from below & hit a mark on the nose in fog, but safe singlehanding without instruments is not difficult & very useful. It can also provide a quick & simple "sanity check" on the info yoru navigator gives you.
 
'scuse my ignorance - but is there any difference between a Breton and Portland plotter?
 
The first question is - why are you doing this? Is it for an exam, to use on board or just for interest?

If it's for an exam you need to be able to show you can do it the traditional way with parallel rules. In a real situation the Breton-type plotter where you set magnetic variation then forget it is far quicker.

The best instrument I ever had was a 24" gunmetal roller parallel rule but it needed a full-size chart table. Since those were stolen I now use a breton plotter for coastal work and a douglas protractor for plotting astro position lines.

I have seen all sorts of equipment used for plotting - parallel rules (roller or pivot-arm), Breton/Portland plotters, Douglas protractors and even a pair of set squares. Anything you can get on with is OK.
 
Sinc said:
'scuse my ignorance - but is there any difference between a Breton and Portland plotter?
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In principle, nothing at all. That type of plotter was originally made in France, and called the 'Breton' plotter. When made in the UK by a different firm they had to use a different name.

A word of warning on dividers. As others have said, you want brass dividers with stainless points. I have seen brass dividers where the ends of the legs have been chrome plated; they look very similar, but the points rapidly bend or blunt. Look for a definite discontinuity between the brass and the stainless bits.
 
kitcrazy said:
I need to get a parallel ruler and dividers.
I've noticed there's different types, does it matter which ones or is it just down to personal choice?
Click to expand...

forget parallel ruler!
Get two pairs of dividers.
For plotting a position on a chart, I use two pairs of dividers (bow type). One to transpose Lat and one to transpose Long. It saves a lot of faffing around altering it for Lat and Long.
Plotters - as you say, it just down to personal choice.
 
LadyInBed said:
forget parallel ruler!
Get two pairs of dividers.
For plotting a position on a chart, I use two pairs of dividers (bow type). One to transpose Lat and one to transpose Long. It saves a lot of faffing around altering it for Lat and Long.
Plotters - as you say, it just down to personal choice.
Click to expand...
Puzzled as to how you draw water track, tidal set & drift and ground track with dividers. ;)
 
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