How Many Fenders Do You Need For Your Boat?

Fenders do a great job of protecting your boat from docks or other boats. However, making sure you know which ones to get, how many you need, and where to place them is very important.

You should have 1 fender per side for every 5-10 feet of boat, and no boat should have less than 3 fenders per side. Meaning a 15-foot boat should have 3 fenders per side, and a 50-foot boat should have 5-10 fenders per side. The amount you should use depends on factors such as where you are mooring, weather conditions, etc.

If you are permanently docking at a marina slip, It’s generally best to use as many fenders as possible on both your boat and the dock, but if you’re just tying up to someone’s boat for a few hours on a calm summer day, not many fenders are needed.

Also, Make sure you have properly sized fenders and that they are positioned correctly.

Below is a table that shows how many fenders you should have on each side depending on the size of your boat:

Size of BoatFenders Per Side
20 feet3
25 feet3
30 feet4
35 feet4
40 feet5
45 feet5
50 feet6
55 feet6
60 feet7
65 feet7

Here are a few examples of boats with the proper amount of fenders, proper size, and positioning:

If you are at a dock, it will make your life a lot easier if you install permanent fenders on the dock (known as boat bumpers). This way you won’t have to constantly put your fenders up and down off the side of your boat. Here’s an example of what this looks like:

What size fenders should you get for your boat?

Obviously, the size of your boat plays a big role in how large of fenders you should get. However, the larger the fender, the more difficult it is to tie it up. So it’s best to use very large fenders for permanent spots such as on the dock and smaller fenders for on the boat.

The general rule of thumb is that the diameter of the fender should be 1″ for every 5 feet of your boat (2″ for ball fenders). So that means a 25-foot boat requires a 5″ diameter fender or a 10″ diameter ball fender.

For larger boats, I also recommend you’re fender closest to the stern should be 1″-3″ thicker than the other fenders used. This helps protect the larger surface area there usually is in this area. Or you can double up on fenders in this area.

Here is what I recommend depending on your boat size:

For A small boat 25′ or less, you can get away with small 5.5″ diameter fenders such as these on Amazon.

For a medium-sized boat between 25′ and 40′, you’ll want to use fenders with a diameter of 6.5″ or 8.5″ such as these ones on Amazon.

For large boats over 40′, you will want to use fenders with a diameter of 8.5″, 10″, or even more. Here are some large fenders you can purchase on Amazon.

How to tie a fender?

Tieing a fender to your boat may be different depending on what you are tying it to. However, most will be tying to a railing, which the video below shows how to do:

You can also tie fenders to cleats or really anything as long as the fender stays put.


Should I always leave boat fenders on?

No, once you get moving, pull up your fenders and store them somewhere they won’t move around. Not only do fenders create additional drag that will slow your boat down, but they will also rub against your hull leaving marks and taking off wax.