However, getting a dock line made of nylon rope is always recommended. This is because it doesn't get degraded in the sun and has the capability to stretch whenever the need arise. Try braided rope that generally has a stronger breaking strength.
Selecting a dock Line that serves your sole purpose is very essential to get the best from it. Hence, always be careful to choose the right make and model. Talking about this, it needs to be mentioned that getting one in the right size is also a matter of great importance. The general norm applicable for selecting the size is 1/8' of line for every 9' of boat. Never ever pick one that is bigger than the size you want, because otherwise your purpose would not be served. This is unlike boat anchors where selecting bigger size is recommended.
After size comes the length of the dock line. It is suggested that it should be 2/3 the length of your boat. This helps in keeping your boat snugly to the dock, while maintaining its flexibility. Though one rope is enough to tie your boat to the dock, you should keep two for emergency situations like heavy/stormy conditions. You can consider doubling your lines for more effectiveness.
However, to get the best from your docking lines, it is suggested that you use chafe guards. These protective gears are good for extending the longevity of your dock/spring lines. This is quite important as you all know that these ropes don't come cheap. For this protective quality of theirs, these are also known as 'sacrificial' chafe guards, as they themselves wear to save your dock lines. These are available in many different configurations, style and make. Apart from being super functional, they also add beauty in your marine vessel. Hence, get one of these if your line dock is exposed to high abrasive conditions.
The online destination is a great source for getting the best ropes including the climbing rope, cable pulling rope and dock lines that are suitable for your applications. Here, you can get nylon rope lines that have great strength and are resistant to all types of abrasions. Get an 8 Plait rope that is stronger than traditional three-strand lines.