 |  |
| Boat Design Forums | Boat Design Directory | Boat Design Gallery | Boat Design Book Store | Thanks to Our Site Sponsors |
| ||||
|
#62
08-21-2011, 01:27 AM
| |||
| |||
| Excerpt from Capt. Alan Hugenot's Blog . . . http://madmariner.com/blogs/alan_hugenot/640 "ALUMINUM HULLS: The choices in bottom paints for aluminum hulls are dependent upon the boat's prior paint history, and its compatibility with the new paint system under consideration. This is because copper is not compatible with an aluminum hull. As I mentioned in yesterday's post, most bottom paints contain copper. However, copper is more noble than aluminum, and the aluminum loses electrons to the copper when the boat is immersed in salt water. This means the paint can corrode the hull unless it is properly isolated with primer and barrier coatings. Generally speaking, the problems are the same no matter what kind of aluminum the boat is made of, because both 5052 series used for inland boats and the 5086 series found on ocean boats have the same corrosion resistance characteristics. To find out if the prior paint on your boat is compatible with the new paint you would like to use, investigate your hull's history by contacting the previous owners. They may have paint receipts from the last haul out, which can tell you what is on the hull. Another idea is to find out where they had it painted and ask the yard which paint systems it was using. If that fails, then you need to scrape off the bottom paint and see what is underneath, or have it evaluated by an expert. For many years we enjoyed anti-fouling paints specially formulated for aluminum and steel hulls, which used TBT (tri-butyl-tin), a wonderful biocide that killed all marine growth and lasted from four to eight years between paint jobs. But it also killed all the marine growth in the marina and the surrounding waterways, so it is now permanently banned on recreational boats by most maritime nations. Although, TBT is still approved for use in U.S. waters on larger commercial vessels over 24 meters (81 feet) long, we are left with only two choices for aluminum hulls. The best choice is a modified epoxy, co-polymer incorporating cuprous-oxide. This is long lasting and has the best anti-fouling characteristics, but it requires a new hull or one that has been sand blasted down to bare metal. Then a proper epoxy barrier coating is applied, followed by a paint such as Interlux Fiberglass Bottom Coat or Interlux Super Bottom Coat. These contain enough copper to last two or three years without renewal. Going this route – a barrier coat followed by a copper paint – also requires a well constructed and functioning zinc galvanic protection system. The second choice, which is the only economical choice for use with a previously-painted boat, is a soft sloughing paint like Trilux II, which uses a Copper Thiocyanate that is more compatible with aluminum. However, it only lasts about a year, and must be renewed annually. For more information on aluminum painting systems read chapter 14 of Boatbuilding with Aluminum by Stephen F. Pollard and the Interlux Boat Painting Guide." Capt. Alan Hugenot is a naval architect and marine surveyor based in San Francisco, where he operates an 81-foot motor yacht converted from a Navy patrol boat. His column appears here weekly.
__________________ If you want to build a ship, do not drum up the men to gather the wood, divide the work, and give orders. Instead, teach them to yearn for the vast and endless sea. ~ Antoine de St. Exupéry  |
|
#63
08-21-2011, 02:39 AM
| |||
| |||
| My objection to e-paint is more in that I have seen no studies indicating it is effective at preventing marine growth. It may be, but I haven't seen anything but advertising copy from the manufacturer. They are making some very impressive claims but before I believe them I would want to see independent laboratory testing. And remember that just because a paint works great in one area doesn't mean it will work equally well everywhere. Different waters have different temperatures, salinity, animals, and plants that like boat hulls. As for painting aluminum with copper paint... This is a very well understood process that any half decent yard can do easily. Failing that any boat owner that can follow directions and a paint roller can do it as well.
__________________ ******************** Nothing is half so much fun as screwing around with boats, except screwing around in a boat. |
|
#64
08-21-2011, 03:25 AM
| |||
| |||
|
__________________ If you want to build a ship, do not drum up the men to gather the wood, divide the work, and give orders. Instead, teach them to yearn for the vast and endless sea. ~ Antoine de St. Exupéry |
|
#65
08-21-2011, 02:14 PM
| |||
| |||
| Again, very interesting stuff, I just want to see some scientific research on the stuff. It is easy to claim that a product does X, much harder to show it in independent testing. Though I would note that the intersleek, has some pretty good anecdotal recommendations. Major shipping companies coming back to it and expanding their investment is a good start to convince me. Though I would point out that all of the boats they use as examples cruise well over the speed available to a sailboat. It may be this speed is a critical part of the paint system, as it might be needed to wipe away the growth over time.
__________________ ******************** Nothing is half so much fun as screwing around with boats, except screwing around in a boat. |
|
#66
08-21-2011, 08:32 PM
| |||
| |||
| Stumble, they have a detailed report from an independent agency listed on the site. http://www.international-marine.com/...ettReport.aspx http://kitsu.org/International_Paint_Report.pdf The report seems to focus more on the fuel savings from the slick surface the paint presents that how it preforms as a foul release technology.
__________________ If you want to build a ship, do not drum up the men to gather the wood, divide the work, and give orders. Instead, teach them to yearn for the vast and endless sea. ~ Antoine de St. Exupéry |
|
#67
08-21-2011, 09:15 PM
| |||
| |||
| The report you linked to confirmed my question. On page 5 it indicates that boats need to maintain at least 10kn for the fouling release paint to work effectively, since that is the speed at which the gripping power of the growth fails and they get blown off the hull. This speed pretty much eliminates the use of the product for recreational sail boats, and even most powerboats, since the planing surface would see these speeds, but any portion of the hull that isn't washed by water speeds in excess of 10kn will never slough off the marine growth.
__________________ ******************** Nothing is half so much fun as screwing around with boats, except screwing around in a boat. |
|
#68
08-22-2011, 06:10 PM
| |||
| |||
| Interlux Pacifica Plus Antifouling Boat Paint http://www.yachtpaint.com/usa/pro/pr...fica-plus.aspx http://www.janssenpmp.com/bgdisplay....me=antifouling http://www.janssenpmp.com/content/ho...pdf/Econea.pdf
__________________ If you want to build a ship, do not drum up the men to gather the wood, divide the work, and give orders. Instead, teach them to yearn for the vast and endless sea. ~ Antoine de St. Exupéry |
Linear Mode
