How Many Boat Fenders Do You Need?

How Many Boat Fenders Do You Need?

Part of owning a boat is understanding how to take care of it and everything it might interact with. A boat is a big investment and neglecting to learn how to make the most out of that investment isn’t a good idea. Protecting your boat from easily avoidable damage should be one of your top priorities, and luckily, it isn’t too difficult to do if you take the right precautions. Fenders are an essential part of protecting your boat from avoidable damage and knowing how many boat fenders you need is something we’ll help you with to get you settled on the water.

Determining How Many, What Diameter and Length of Fenders for Your Boating Needs

There are very simple rules of thumb to follow when you want to know what size and how many boat fenders you need. Remember these rules, and you can accurately predict your fender needs no matter what boat you have or may get in the future.

To determine how many fenders you’ll need - for every 10 feet of boat length your boat has, you’ll need one fender to protect it. However, it’s also important to remember that the minimum number of fenders should be three, no matter what size boat you’re on. A 20- to 25-foot boat would still need three fenders as a minimum. A 40-foot boat would need four fenders, one for every 10 feet of boat length. A 50-foot boat would need five fenders, and so on from there.

To determine the diameter of fenders, a general rule is that for every 4-5 feet of boat length, the fender should increase 1-1.5” in diameter for cylindrical fenders, and for round fenders, the diameter should increase by 2 inches. As an example, a 40-foot boat should have cylindrical fenders with diameters of 10 to 12 inches, and for a 40-foot boat with round fenders, they should be a minimum, 10-inch round diameter fenders.

To determine the length of fenders, you must take into account the area of the hull that will be generally contacting the docks, as well as any design elements on the hull that protrude, which will make first contact with the dock. Considering that fenders are typically available in various lengths for each diameter, once you know the fender diameter you need, simply analyze the dock contact area of your boat to determine best lengths for best fender protection.

Positioning Fenders Correctly

Having the right number of fenders is only the first part of protecting your boat. You also need to be sure you position them correctly to ensure they provide adequate protection. When you go to position your fenders, allow the bottom of them to just touch the surface of the water. Then you can raise them one or two inches away from the water to position them correctly. Always be sure that you tie your fenders to a solid anchor point, such as a cleat. You want your fenders to stay as low as possible to reduce the amount of swinging they can do. If experiencing unusually high wind conditions and your fenders are swinging around, you can always tie a small sand bag to the bottom of the fender, or fill the inflatable fenders with a little bit of water to weigh them down, then drain water when fenders are not in use.

Useful Accessories for Boat Fenders

You can get many accessories for your fenders that make them easier to store and deploy when you need to. For inflatable fenders, hand pumps can be very useful to quickly get them inflated when you need them. Lines and fender rail hooks made specifically for fenders can help to ensure they stay secured properly and do not chafe your brightwork. You can even buy bags for your fenders to make them easier to store.

If you need fenders, or any number of other boating accessories, Innovative Marine Group has a wide variety of them in our shop. Make sure you have enough for your boat and get yourself something fun as a reward for focusing on safety first!

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