The Bottom Line

 

 Here in the Crystal River area where we keep our boat, underwater fouling is minimal. This is due to the amount of fresh water we have. Our canal is "brackish" with not alot of salinity and the closer you are to King's Bay and the springs the salinity goes way down. Out to the Gulf and further south, hull bottom fouling becomes worse. Go to the Keys and the Bahamas and it is very aggressive.  Wintertime when the water is cold, the growth is minimal, but when the water warms it is alive with billions of tiny organisms ready to cling to something and start reproducing. Now that our boat is in Tampa Bay and the water temperature is moving into the 70's the growth is accelerating. 

How do we combat this? The list of ways is endless but the basic method is to apply Anti-Fouling coatings. Bottom paint. There is a whole science and tons of info about anti-fouling coatings so I won't go into all of it but basically there are 2 types of paint. Hard & Ablative. Both coatings contain chemicals such as cuprous oxide and other biocides mixed in with the paint that release to kill the growth of those underwater organisms. Hard paint is just as it's name implies, it dries hard and the additives leach out of the paint but the paint stays in place. This type of coating has some drawbacks. The first is, the boat must be placed into the water shortly after painting otherwise the paint becomes ineffective if left out of the water. When exposed to air the paint loses it's anti fouling ability. Secondly, it builds up over painting sessions and must be removed from time to time to start fresh. The other type is Ablative. Ablative paint works like a bar of soap wearing layers off while providing a fresh layer of biocides.  When the paint is gone, so is the protection and it is time to recoat. Another advantage is that the paint can be applied without having to launch the boat right away. You could paint your boat in the winter, store it and "splash" it in the spring with a fresh ready to go coating.  This covers the fiberglass hull. When it comes to underwater metals, these cuprous oxide paints should not be used. There are special coatings used just for metal gear and metal hulls. For my underwater gear I use simple galvanize spray paint. It has performed very well and goes on smooth and even which is a must when it come to precision parts like props. 

So now my boat is in the evil waters of Tampa Bay. Before leaving I dove on the hull and scrubbed the fine layer of slime that grew over the winter. I knocked off the few barnacles on the rudder shoe and the bow thruster. The prop I might add was clean (galvanized paint worked like a charm).

I did some research on "ultra-sonic" hull cleaners. The systems use transducers similar to the transducer in your depth finder to send signals through the hull that are supposed to interrupt the collection and growth of marine organisms. The technology is not new and has been used by the Navy and large vessels. Do they work? The answers I got were both positive and negative. Some said they work, others said they did not. In fact if you do some research you will see that when the question is posed on many forums the discussion got down right nasty and negative. I was on the fence and decided to not go that route. Then I got a couple private responses from folks that had them. They didn't want to post their support because of the open attacks on the forums. Two boat owners that had them reached out to me to say they worked and extended their haul out and bottom recoat times considerably. I ran into a third individual that I knew personally who said all he could say was that his son had one on his boat and it sat for 4 years in the canal and when they hauled it, it was "pretty darn clean".

P.T. Barnum supposedly said "There is a sucker born every minute" Is it me this time? I went for it. I found a couple companies and decided to go with Hull Shield in South Carolina. Three reasons. 1 It was less expensive (if I was going to get screwed, I wanted it to be minimally). 2 Hull Shield is based in the US and it seemed like it would be easier to get technical help and not have to fool with an overseas company.  3 the Hull Shield system used multiple transducers where some of the others used only 1. The system costs about $750.00. 

The installation is pretty straight forward. 1 transducer goes aft on one side and the other goes forward on the opposite side. The transducers are epoxied to the inside of the hull. They only work with solid fiberglass or metal hulls. They do not work on cored hulls or wood hulls as the coring and/or wood absorb the signal from the transducer. The control box is wired to the 12 volt system. I wired mine to a 20 amp breaker instead of directly to the battery.  The first breaker I installed was too small and started to trip each time the system came on. The literature (not that I could find anyway) did not specify a size breaker. Only after communicating with the company did I find out what size I should use.  A little odd as the installation manual says connect to battery & doesn't mention a breaker or fuse. I fuse everything!

I had 2 issues. When the package showed up, it did not have the 12 volt cord. I contacted the company, they apologized and sent it to me. The second issue was that the breaker kept tripping, then the unit went dead. After contacting Hull Shield, they asked for some information and pictures of the install. They apologized and sent me a new control box no questions asked. Great folks to deal with!

The unit is installed and working fine. How do I know? Inside the boat you cannot hear anything and the only indication is that I can see the green light on the box when switched on and I can see the DC amp meter fluttering as the transducers send out signals. I dove under the boat and could distinctly hear the pulse signal. So much so that it actually was annoying.

I had my bottom cleaned in Tampa by a diver to start with a fresh bottom. The next time he cleans I will get a report and see if the system is doing any good. In speaking with the diver he indicated that there were a couple of boats in the marina that had them and the bottom was very clean....where the transducer was only. Will it work better in a less hostile environment like Crystal River?  Will it help when we leave the dock for an extended period with no diver to clean? Time will tell. I will update this post in a few months.

    Well it has been about 4 months with the boat in Tampa Bay. I sent an email to my diver asking if he noticed any difference in the amount of bottom growth, here is his response: “ Unfortunately, I do not see much of a difference. You are still getting about the same amount of barnacle growth as the other boats on C dock. I have cleaned a few boats with the ultrasonic cleaner installed and have not noticed a difference.”

   While I haven’t personally viewed the hull (it is underwater) At this point I can only go by what my guy, who by the way cleans the hull every 2 weeks. Now, with that being said, I have heard comments from others that basically say, why would someone who’s business is diving & cleaning hulls be in favor of a product that could essentially put them out of business? Food for thought. All of the sailors & cruisers I have talked to that own an ultrasonic hull system say they work. I will leave it going as it seems like good insurance to me & when I can actually gauge the results with my own eyes then I can say whether or not it works.

I look forward to any comments both positive & negative.

UPDATE: 12/1/21

    It is still hard to tell if the system completely works or even if it partially works. I was never able to get in the water and see how the bottom looked in time. I just performed a haul out (See Haul Out 2021) after having the boat home from Tampa for 30 days. The diver in Tampa cleaned the hull October 25th and now December 1 - 36 days, 7 days in salt water (most of which were traveling home for 4 days) and the rest in brackish waters at my dock sitting still.

    The bottom was clean with the usual very light green slime on the sides, but this wouldn't be unusual for 65 degree winter brackish water. So the test goes on.

                                                      UPDATE: 1/31/23

    From what the diver relays to me at regular cleanings, I think the Hull Shield is working. Barnacle growth is light but the fine "dust"/slime on the hull happens no matter what. It seems it will make the bottom paint last much longer as there is not as much scraping going on. The ultimate update will be at the next haul out, perhaps at the end of this year when we finish the Loop.