With either one it is important to have an easy to read layout. This includes large digits and florescent hands and a good backlight. Digital is better to set a countdown timer easily and you can buy them with a large display scene make no mistake in the battle at start time.
If it's not water resistant don't wear your watch sailing. With that being said, water resistant numbers or water resistant to 30 m doesn't actually mean that it can be worn down to that depth. This mainly has to do with the watch being initially tested in ideal conditions with water pressure and temperature not changing rapidly. The seals are brand-new in the watch itself is in perfect condition.
If you get your battery replaced, make sure that your watch is again pressure tested to verify its integrity.
You must have a good countdown feature if your watch is for sailing. Another handy feature is an option to sync the countdown, so if you miss the five-minute gun, you can sync it easily when it's coming up to the four-minute mark.
Another feature, which is excellent, is having an audible alert during the countdown sequence. In addition to the alert at the start time, a good sailing watch has an extra alert tone that goes off at various intervals. This allows you to focus on watching the water, sails and other boats versus having to drop your eyes to the watch all the time.
You also want a watch that is easy to use. There is nothing worse than being on the start and trying to navigate through the watch menu to set the countdown timer but you are having difficulty. The easier it is to use, the better. Spend some time at home before your next race to get up to speed with how the watch works. Spend time familiarizing yourself with the features and how the watch works and it will be time well spent.
Watches can be like miniature Swiss Army knives. They can have all sorts of features. They can come with a GPS, compass, barometer. Some features are nice to have but many are not worth the money. Work out exactly what you need and make sure your watch does it all well. You can check out reviews on YouTube and browse for other opinions to check out a specific watch.
Some sailors like to wear watches over the top of their short jacket so they can check the time. If you prefer to do this you want to be sure that the band size is large enough to accommodate this. You will one the band to be comfortable so that the watch will quite likely not get totally knocked about while sailing. It has to be strong and the watch has to be secure. A strap that is made of silicone or rubber is a good choice since it does not absorb water making it more comfortable to wear even when it is wet.
A sailing watch is a vital sailing instrument and a serious implement that any skipper cannot do without. If you are a long-distance sailor you may not realize that they can now come in with a barometer and detect variations in pressure, all-important factors in predicting the weather. Some racers love to have chronograph movements and compasses that detect line bias and bearings. These are all nice but they can be more than the basics that you really need.
It is not so much about the functions that can help you with sailing but more about the look when you're back at the bar. Whatever your reason is for having a favorite watch for sailing, these items above should have you covered.