How To Clean Barnacles from a Catamaran (in the Water) and Why?


I have seen YouTubers Nikki and Jason Wynn talking about cleaning the bottom of their boat and wondered, how do you clean barnacles from the bottom of a catamaran, how often does this need to be done, and why do barnacles attach themselves to the bottom of a boat?

So how do you clean barnacles from the bottom of a catamaran in the water?

Well, come to find out it isn’t rocket science. It is, however, hard work and best practices for removing barnacles from the bottom of a catamaran in the water includes a pair of gloves, a snorkel and mask and a scraping tool.

Well, there are some other important tips and information on how to remove barnacles from the bottom catamaran, what tool works best for doing it and the question of why it needs to be done and why are they there in the first place. So, let’s dig in.

Why Do Barnacles Need to be Scraped Off Sailboat Bottoms?

Barnacles need to be scraped off boat bottoms because they cling to the bottom of boats, reproduce often and will slow down your boat (a lot). They also can get into the water intakes and water discharges and clog them up.

Should the Scraping Tool be Made of Metal or Plastic?

There is some debate on this topic. I have visited forums on this topic and read numerous results. About half of the responses say you need a metal scraping tool while the others say plastic. One even recommends a metal tool with a plastic handle. Let’s find the arguments for each type of tool.

Why the Scraping Tool Should be Metal? 

The answer to why the scraping tool should be metal is a simple one. You see that scraping the bottom of a boat is really hard work. The strongest and most effective tool for removing the barnacles from the bottom of a boat is one made from metal. The metal has a smaller edge (like knife), is strong and effective and doesn’t wear down. Sure, the edge can get dull from using it, but it’s not going to wear down or break like plastic.

Why Do these Sailors Say Wood or Plastic Scraping Tools Work Best?

Not so fast you say. There are plenty of sailors that say wood or plastic is better. But why you ask? Well, here it is. Plastic is better because it isn’t as sharp and won’t damage the bottom of your boat. The plastic is strong enough to remove the barnacles from the bottom, but it isn’t going to dig into the boat and scrape off your nice bottom paint job that just cost you thousands of dollars. Having to replace the plastic scraping tool from time to time is much more cost effective than having to repair the bottom of the boat. This answer may also be influenced by the type of boat you have.

Why We Need Experienced Sailors to Set Us Straight?

We didn’t find conclusive evidence on one method or the other. One thing we did learn is that if you keep up with your boat cleaning, you may only need a cloth or a 3m pad for most of the boat.

If you are a seasoned sailor, with experience in this matter, we want your opinion. Please comment at the end of this post. Tell us which method works best and why. Also tell us about your boat, where it is anchored or docked (or roaming) and how often. Any or all of the above comments are more than welcome. Let the debate begin!

Why are Barnacles on the Bottom of our Catamaran?

Barnacle babies float in the water until they find something to cling to – like the bottom of your boat. They like water that is moving. They mostly live in more shallow water, though some species can live in water up to 2000 feet deep.

What Are Barnacles Anyway?

Barnacles are crustaceans; cousins to crabs, shrimp and lobsters. They latch on to boats while they are in the water. Their feather like legs move with the current and act like little filters. As water passes over them, they filter the food and nutrients out of the water. Barnacles can reproduce up to six times each year. Babies float until they latch on to something solid. Barnacles can live up to ten years and can grow up to ½ inch. No wonder boats require constant scraping to keep them free of barnacles.

What Other Tools Can be Used to Remove Barnacles from the Sailboat Bottom?

Other tools like brushes, drywall knives, putty knives and pretty much any type of scraping tool can be used. Screwdrivers are used to scrape around recesses and water inlets and outlets. Some sailboat owners use power washers both in and out of the water. A cloth or 3M pad may also be used on areas where barnacles have not yet attached themselves.

What Other Equipment is needed to Remove Barnacles in the Water?

Other equipment in addition to scraping tools needed to remove barnacles in the water may include a good snorkel mask, snorkel and flippers. If you have scuba gear, you will have an advantage to a snorkel and a mask as you can stay under water longer. Flippers are highly recommended and will help to propel you to the deeper parts of the boat and keep you in place when scraping. Some boat owners will wear a bathing cap while scraping to keep particles out of your hair and ears. Next, a rope can be helpful to hold onto while scraping. Make sure to remove the rope when you are finished so that it doesn’t get tangled in the prop. Finally, suction cups are available which attach to the bottom of the boat and work as a hand hold to keep you in place while cleaning.

Cost to Pay a Diver to Scrape Barnacles from Your Boat in the Water

Costs for scraping barnacles from your boat in the water will vary greatly by location, size and type of your sailboat. I checked a few areas and listed them below.

One diver in Central California charges; Monohulls; $3.25 per ft, Catamarans $3.75 per ft; Trimarans; $4.00 per ft. In Jacksonville, Fl, we are seeing from $2.75 to $4 per ft. In Tampa, Fl $2.50 per ft to $5.50 per ft depending on the condition of the boat. We noticed that some divers charges a flat fee from $75 per hour to $100 per hour in the US.

Many dive companies will charge less the more often you have the bottom cleaned and offer a regular maintenance schedule for those keeping your boat in a marina. Check with your local marina for prices.

How Often Do You Need to Clean Barnacles Off the Boat?

How often do you need to clean the barnacles off the bottom of your boat all depends on your boat, how often it is in the water and where it is located. As we mentioned earlier, barnacles reproduce up to six times each year. That’s a lot of barnacles floating about ready to attach themselves to your boat. If you keep your boat in a marina, the marina staff will have a general idea of how often this can be done. You or they can dive in and check the bottom to visually inspect it for barnacle growth and some dive companies offer a service to provide you with video footage. Certain environmental factors based on location like nutrients in the water will affect how often you should clean the bottom of the boat. In Florida, a sailboat that is in a marina in Pompano will have different barnacle growth than one in Palm Beach.

The More You Scrape – the More Efficient You Will Sail (or motor)

Remember, the more often you scrape, the easier it will be to maintain and keep the barnacles off, and the less damage there will be to the bottom of your boat, which could mean fewer haul outs and bottom paintings. Also, the more often you clean barnacles off your sailboat, the less drag and the faster you will sail and less fuel you will burn when motoring.

While researching in the water bottom cleaning, I learned a lot about how different it is to clean the boat bottom out of the water. I’ll be doing another blog post on out of water bottom cleaning, treatments and coatings, costs and how often you need a haul out for maintenance. If you are interested, you should subscribe so that you don’t miss it.

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