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One thing you will hear across marinas in Southwest Florida is a collective groan when bringing up the subject of bottom cleaning. Our water here is some of the most aggressive, high growth seawater around. It is dark, high in nutrients and it appears that the stronger the current your boat is in, the higher the growth rate.
I’ve been diving my own boat for the last 7 years in Southwest Florida and also dove commercially for a year in the marina we lived in. I dove roughly 10 boats per month and learned a lot about our waters and growth rate. Our location is a particularly tough area to combat organic growth, slime and barnacles that grow on the bottom of your boat. Whether you plan to dive your own boat, or hire a commercial diver I’m hoping I can share a few observations and tips that might help keep that bottom clean.
Observations in organic growth rate
The growth process begins with an organic slime that grows on the hull. After a week or two, barnacles and oysters begin growing on top of this slime. From my experience many things like location, current, and water content (i.e. fresh/brackish vs all salt) can affect how quickly this growth progresses. It seems the more clear the water (like Key West), the less aggressive the growth is. Since our water is darker and higher in nutrients it seems to produce bottom growth much faster. Summers are brutal because the higher the water temps the faster the growth. When we lived at Snookbight, we would see barnacles appear within 2 weeks from the last cleaning during the summer months. Because of where our boat was located at Snookbight, we were directly affected by the current which meant much faster growth on the bottom. If your boat is protected by the current, you may see slower growth.
Even in Southwest Florida our bottom growth rate can vary from location to location. When we lived at Cape Coral Yacht club I didn’t have to dive the boat as frequently as I do on Fort Myers Beach. This is because we had more brackish water from the river and perhaps because we didn’t have any current. On Fort Myers Beach, the salt water seems to have more nutrient content and with the swift currents it seems to be teeming with life.
There are different types of bottom paints to consider like a hard paint or ablative. We’ve only ever used a hard paint on our boat bottom. Supposedly, ablative paint has better anti-fouling properties, but as I understand it, the ablative paint will wear out faster and you will need to repaint every year. I have cleaned a few sail boat bottoms in our area that had ablative paint and they still had barnacle growth. On Blue Turtle, we prefer to push the limits and only paint our bottom every 2 years or so. We only do this though because I am maintaining my bottom myself and constantly know the condition of the bottom and zincs.
A newly painted bottom shouldn’t need much scraping. All you should need is a Scotch Bright cleansing pad to lightly remove the slime build up from the hull. The paint toxicity is higher so it shouldn’t have as much growth as a bottom that is in need of a paint job. Areas such as propellers, rudders, shafts and thru hulls will see the most growth as well as the paint typically wears off quicker. Barnacles tend to grow faster at the AC intakes where you have water moving through them quickly so those need to be checked regularly if you want to keep your air conditioner running. Even with a regular bottom cleaning, your AC intakes can still get clogged. From my experience, this typically happens around 3am. Not wanting to don a wetsuit and get in the water at that hour, I learned of another trick that works. Inside the boat, you can use an air horn to force the clog out. Disconnect the rubber line from strainer and put the blow horn on the rubber line. Making sure the thru hull is open, and the horn and line is above the water line, press the horn. The high-pressure air will typically blow out whatever is clogging it.
While ablative paint may have anti-fouling properties, it doesn’t mean you can neglect diving the boat. We have a friend who once told me that he got his sailboat bottom painted with a 1 year ablative paint and that since it should last 1 year, he wasn’t going to have it dove. I mentioned to him that he might still get growth and it cause him some trouble down the road. Late in the summer, he decided to get off the dock for the weekend with his girlfriend. He got out of his slip ok and headed out of the marina with the current. About 2 hours later they were returning to the marina driving backwards! Apparently once the current changed direction, the boat would barely move forward but they went faster in reverse so that’s how they returned to the marina. After he tied off the lines, I dove his props and they looked like a planetary system of round balls of barnacles. I was able to scrape them off but it was difficult because they were so large. Moral of the story: even the best bottom paint doesn’t get you out of diving your bottom in Southwest Florida.
Diving your own boat is no picnic
First of all, if you plan to dive your own boat, let me tell you there’s nothing really fun about it. Most of the time it is dark and cold and I am in a mild stage of hypothermia when I am finished. Diving our 40’ trawler, typically takes me about 2 hours and it can be pretty taxing on the body. At times, I am out of breath and many times I am sore the next day with muscles I didn’t know existed. Even in warm waters you get cold after being submerged for that length of time it takes to do the full bottom.
Diving your own boat is tough work but if you are located in a high growth area, it might be worth it as you know your boat is ready to go, know the zincs are in good shape and have peace of mind that your thru hulls are all clean. You will also have the added benefit of saving costs of not needing to pay a hired diver and the benefit of exercise.
You should definitely be confident with scuba diving and comfortable under the water. There are certainly risks involved such as running out of air, becoming snagged, being hit by another boat or possibly electrocution from docks with power.
If you’re still up for the challenge of diving your own boat, keep reading and I’ll share my method of diving my boat and some of the things I’ve learned over the years.
How I dive my own boat
- I dive our boat at least every 30 days. In the winter, you can get away with a little longer as the growth rate is much less. In a fast current location I would dive every time we were planning to leave as hard barnacle growth normally starts in 2 weeks. If I don’t have time to do a full cleaning I would clean the prop rudder and thru hulls.
I use a hookah rig with 60′ hose connected to a dive tank. I place the tank about ¼ of the way back from the bow. This tank position seems to be effective in being able to clean the entire boat as well as prevent snags or fouling of the hookah line in the props and rudders at the aft of the boat.
- I start on the props and rudder first because these are usually the most fouled and one of the most important parts to clean. Then, I start from the bottom aft and work my way forward.
- I work on the deepest part of the boat and reach as far up as I move forward. I prefer to do all the deepest parts of the boat first while I am fresh and warmest.
- Light conditions determine whether I start cleaning on the port or starboard side. I like to start on the well lit side of the boat first so I can get my bearings and rhythm. Sometimes the shaded side offers very low visibility that is completely dark and I can only feel with my hands and scraper.
- I will I position myself with the 14” scraper and suction so that as I can run the scraper from the bottom to as far up as I can reach. The suction is always on the clean side after I scraped that area. I try to have the current going away from me as I scrape so that the barnacles and hard growth floats away and not in my wetsuit.
- After I finish the bottom port or starboard I will go aft and work my way forward scraping from where I could reach on my first pass up to the waterline.
- As I move along the hull I will stop and use my brush, 14-in-1 tool and screw driver to clean thru hulls. These tools are attached to my hookah belt and easily accessible. I will also inspect and clean the zincs. Even the zincs will get barnacle growth in the summer.
- After both sides are finished I clean my bow thruster with the suction for stability and my 14-in-1 tool.
- Then I’ll clean the stern, swim platform and stern thrusters.
- After everything else is finished I’ll remove my weight belt and hookah and swim around the boat with a brush and clean the waterline.
- When I’m finished I rinse all my gear and tools with fresh water and allow them to dry before storing for the next time.
For the record, I have never seen a shark while diving the boat in a marina or protective anchorage. I have seen lots of catfish, snappers, sheep head and a Goliath grouper. I heard dolphins but never seen them. I never seen a manatee while cleaning although I know I will someday and it will spook me.
Below is a list of some of the tools I use to dive the bottom of my boat. There are also some links [affiliate] to the products or similar products on Amazon to give you an idea of what I use.
- Hookah rig with 60′ hose – The 60′ hose gives me enough leeway to clean the whole bottom leaving the tank on deck
- Dive Flag – You definitely want to let other boats around know you’re in the water
- 14” scraper
- Suction handle – The blue and yellow suction handle that I use (pictured below) is no longer available. I like this one because it slides easily. Most of the suction handles out there have locking mechanisms that can be difficult to operate underwater holding your gear. If you look for one try to find one that is easy to move.
- Scotch-Brite Light Cleansing Pad
- Wire Brush
- 14-in-1 tool