You look up and see the stars. But your Suunto Core sees an approaching squall. And it tells you with the Storm Alarm - one of several intelligent features that can help you make consistently good decisions. Building on the success of the venerable Suunto Vector, the Suunto Core keeps you informed with an accurate altimeter, barometer, digital thermometer, Weather Trend Indicator and digital compass.

This is the product description given by Suunto. I have known about the brand for a while now but have not had any hands on experience with any of their products before. The closest I came to using a Suunto was using the interactive demos on their site. That is until recently when I had the chance to take the Suunto Core for a test drive. The following review is going to look at its features and usability and gives a general run down of what I thought of the product.

Aesthetics, Ergonomics and Usability
Firstly the whole unit is quite large in diameter, about 5cm across and 1.5cm deep. I have quite skinny wrists so I was concerned that it would be too big to fit comfortably. This however didn’t turn out to be an issue at all, it sat pretty stable on my wrist. The straps are excellent, robust and the adjustments are well spaced, with a good quality closure buckle. The menu buttons are a good size and are well spaced so you wont be pressing the wrong buttons accidentally. With a textured surface the buttons are easy to press and to keep pressed for the menu button. At first the rotating collar for the compass was very stiff, but once I had rotated it around a few times the stiffness eased. The display is very clear, all the numbers are large and legible. The back light works well but is only really noticeable when it gets quite dark.. The battery is really easy to change, all it requires is a coin to open up the back panel. The manual is well laid out and informative, and can be seen in pdf format here.

Features
The core has 3 different modes, these are time, alit&baro (Altimeter and Barometer) and compass.

Time
The Core has all the standard features common to most digital watches like time, date, stopwatch and countdown timer; and has an adequate alarm with snooze. It also has dual time which will let you set the time for a different time zone. The Core will also give sunrise and sunset times, you have to select the location nearest to you under the menu. I set my sunrise location as Europe>Western>Manchester.

Altimeter and Barometer
Both the barometer and the altimeter are closely linked. I think that its important to get a rough idea of how they work to give a better understanding of what settings to be used in different situations.

An Altimeter measures your height above sea level
A Barometer measures air pressure which is caused by the weight of air above you.

Air Pressure varies with altitude, the higher you go up the less air is above you so the pressure decreases. There are some maths we don’t need to go into that would tell you what the air pressure would be if you were at sea level. This value is used for weather information.


There are 3 parts that the Core takes into consideration, and they are all connected.
• Altitude
• Absolute Pressure – The air pressure where you are stood
• Sea Level Pressure – If you were at sea level what the air pressure would be. This value is what weather forecasters use. Most people are familiar with this value as it is seen on weather maps. As a rough rule; if the sea level pressure drops the weather is expected to worsen, on the other hand if it rises the weather is more likely to be nicer and more stable.

The Core is always measuring absolute pressure, it uses your altitude to work out sea level pressure. And it uses sea level pressure to work out altitude. This is why you cant have the altimeter and barometer working at the same time its either one or the other.

If you set the Core to Altimeter, it will fix the sea level air pressure, so any changes in absolute pressure will be displayed as changes in altitude. However the sea level pressure may also be changing with the weather, but as the core assumes its fixed when in altimeter setting your altitude may become a little out of sync, especially if the weather is changeable. This is why you can put reference points in to the Core, so that it can recalibrate itself.

If you set the Core to Barometer, it will fix your altitude so that any change in absolute pressure will change the value of the Sea Level Pressure, so if you do go up or down in this setting the Core will assume it’s a change in weather.

This means that if your activity involves changes in height switch to altimeter, if you are stopping in one location or at a fixed altitude (sailing on a lake) then you will want the barometer profile.

I forgot to change the setting to barometer from altimeter and I left the Core overnight on altitude setting at my house, this means that the changes in pressure measured by the Core were put down as changes to altitude, so next day I was a little confused at first to find that over night my house was about 50m higher up. If had selected the barometer setting the altitude would have been fixed and wouldn’t have had this problem.

The Altimeter Profile
Under this profile, as you would expect, it will give you current height above sea level. There are also two modes that you can select from to look at any differences in altitude made or lost. The basic one is the Altitude difference measurer. You select this option and from then on, until it’s reset along with the current altitude, a figure will be shown with the difference in altitude from the starting point.

A more complex version of this is to use the Logbook function. You start it off just like a stop watch, and at each time interval you have chosen (1s, 5s, 10s, 30s, 60s) it will record your current altitude. At the end of activity you can stop the log and refer back to it. It will give you the following information

• Length of Log recording
• A Basic graph of altitude through this time
• Peak Altitude
• Total Ascent and total ascent time and average ascent time
• Total Descent and total descent time and average descent time
• Lap times
• Playback. This plays back the graph moving along at each time interval and shows the altitude at that time.

Whilst you cannot download this information it can be locked and stored on your Core for future reference.

The Barometer Profile
If you are staying at the same altitude for a long period of time you can set the Core to Barometer mode. This will fix your altitude, so any difference in air pressure measured by the Core will be because of changing weather.

The Core will display the sea level air pressure and will start to log any changes in this value and provide information for the weather trend indicator. This is a great tool. If you leave it overnight you can get up in the morning and see what the trend has been. The weather trend indicator is displayed as a line in 2 parts. Its gives an indication of change in sea level pressure over the last 3 hours and 3 hours before that. See diagram taken from the manual.

Temperature
The Core will also will give a temperature reading in degrees Centigrade or Fahrenheit, (depending on which you prefer). You will have to take it off your wrist to get an accurate reading though.

Storm Alarm
When the core is under the barometer profile and the storm alarm is switched on, if the pressure drops rapidly the display will flash and a short 20 second alarm will go off. It's a pity that this feature doesn't work in altimeter setting, as when climbing the mountains it would be good if the storm alarm went off, but it won't. It will only go off in Barometer profile which you would select if you were at the same height for a long period of time.

Depth Meter
The Core also has a depth meter that will work upto 10m underwater. It will give your current depth and also enables you to log your depths.

Compass
The compass on the Core is easily calibrated, it just requires you to rotate it. You can set the declination value (difference between true and magnetic north). The direction of north is shown by two lines on the outside edge of the display (just right of the 'Start Stop' in the picture). The line at 12 o'clock represents the compass direction arrow. The outside rim with N,E,S and W can be rotated.

There are 2 different views in the compass mode:

1. Point the 12 o'clock line at the target and then rotate the rim so that N matches up with the two North marks. If you keep N on the rim and the moving North mark, you can follow the 12 o'clock line to your heading.

2. Another way that you can use the compass is to point the 12 o'clock mark at the target you want to head to and lock this bearing. This is setting I have in the image. It shows that my current bearing is 39 degress but I need to turn left as I am slightly off course. You can also see a small triangle above the bearing, this turns into an arrow and gets longer the more you are facing the incorrect direction. Under this setting the compass will tell if you are aiming towards your destination, although there is a slight amount of variation of a couple of degrees either side of your bearing.

Trying out the altimeter and Log Function
A couple of weekends ago I decided to take the Core on a walk in the lakes. I wanted to see how accurate the altitude measurements were and I wanted to test out the logbook function. Cass from work also came along and we made the decision to go up the Old man of Coniston from the Seathwaite side. The weather was showery and windy.

I have roughly plotted our route on the Google map image. I have also made a graph of our altitude against time graph. As mentioned you cannot download this info so I just copied the values whist playing back the log.


View Larger Map



On the way up to the Old man I recalibrated the Core a few times - as is recommended by the manual when you know a suitable reference point (in this case the top of the pikes). As you can see the values were a little bit off the actual height but not by much.

Also on this particular day the values were fluctuating slightly when we were stood still, for example at the top of the Old Man there was some fluctuation in the readings. The highest reading was 806m, but the readings were between 803m and 806m.

On the way back down I wanted to see how accurate the Cores readings would be if I didn’t calibrate it. The Core was reading 803m before we left the summit of the Old Man. The journey down was slightly steeper than the way up and back at the car the core was saying 173m instead of 190m. The actual altitude drop was 613m and the Core was saying a drop of 630m. So it had gone out by about two and a half percent over two and a quarter hours. Which I personally think is very good and an acceptable level of difference.

Overall Impression
I have taken the Core out with me on quite a few days climbing. In regard to the accuracy of the altimeter other days gave similar results to my example above. So not the 1 metre perfect as suggested by the Suunto's blurb, but I have still been suitably impressed. I was expecting to see that the values would differ a lot more than they did, but didn't expect metre perfect readings. I would be very confident in using its readings in situations such as going up a face 'x' metres before traversing off. With the compass, again I wouldn’t use it if I required degree perfect accuracy. However its readings are still tight, and a very useful aid that will be with you even if your normal compass is not. The Barometer is great, as shown when looking at the bar graph of the recent trends, and has tied into the weather well. The storm alarm going off has often preceded a downpour in some of our recent thundery/showery weather. So okay, it's not an essential piece of kit that everyone should have but if you are looking for an ABC (Altimeter, Barometer and Compass) wristop or a tool to aid in your activities then I can highly recommend the Core.

Links
Suunto Homepage
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