As per my previous posting I’m going to start posting these weekend updates to summarize the various boat projects that I have underway for the major refit I have underway on Learnativity here in Fiji. It is all consuming for me so it is all I have to report on right now and might help you realize that as wonderful as this life of living full time on a sailboat is and how great it is to be in the likes of Fiji surrounded by nothing but colourful people, food and nature, there is a price to all of it. Though let me add that it is a price that I am more than willing to pay and is still the bargain of a lifetime for me!
I suspect that these updates will not be that interesting to many of you as they are really just going to be about my weekly progress on all these various boat jobs. However enough of you have written or called and asked for more details and so many seem to find it quite interesting that I figured it will be a good way for me to have this as a record in the future and that you are best to decide what and how much you want to read. So here is the update for you from week #1 of 2012.
The transition to the new year has been one filled with challenges as I more fully assessed the situation with the rust in the hull on Learnativity that I noted in my last posting with the background and context of the boat projects I have underway here. A steel boat always rusts from the inside out and after some very thorough examinations of every bit of the bottom of the hull I was able to find two areas where the rust had set in and was now starting to make its way all the way to the outside. I can normally keep watch of over 90% of this area as I can get at them through access panels or in the main bilge area in the large engine room, but there are a few spots up in the front of the bow and aft of where the propeller shaft exits the hull that are inaccessible due to the built in wood floor and other equipment and of course it was in these areas that the rust had gone undetected and seems to have been at work since not long after the boat was built back in 1994.
In order to fully check the hull and be sure that I had found all the problem areas I had bought a neat little ultrasonic digital thickness gauge just before I flew from from the USA. These fabulous tools enable you to measure the thickness of solid materials like steel that you can only access from one side and are used in such instances as large steel storage tanks and the like and with the help of eBay I was able to find one online and get it delivered to LA just before my flight out. To use them you press a small stethoscope like probe that is wired into a little black box with a digital readout meter tightly against the steel, wait for the meter to show that it has full contact and then it reads out the thickness under the probe in 0.1mm increments. The good news is that it works very well and is very accurate as I tested it on steel panels that I could measure accurately with a micrometer or vernier calliper. The bad news is that it only tells you the thickness in that one small spot and I have a VERY large hull! You also often need to wet the end of the probe to make a good contact and they provide some glycerine gel to do so but that proved to be very slow and tedious. So I figured that any liquid will do the job of filling in any air gaps between the probe and the steel to let the ultrasonic waves get through and so I came up with the technique of wetting the probe with my tongue, holding the probe against the steel, getting the reading and then writing this number on the wet spot with a pencil. Now just a few thousand more measurements to go!!
So I spent the next few days making my way all around the hull testing about ever square inch or smaller and covering then entire length of the hull with my little wet spots and penciled in numbers. Fortunately the majority of the hull was fine as it is all covered with spray on polyurethane foam for insulation and has stuck to the metal very well and prevented an air or moisture from getting in so no rust. But I needed to fully check an area about 50cm/18 inches on either side of the centerline of the hull from stem to stern. What this revealed was the two areas I note earlier, one on the port side of the bow just below the waterline and about 8cm/3in from the centerline that had holes or thin spots stretching back about a foot. There was another small area just under the bow thruster tube up in the bow area but the largest damage was in the rear of the hull just in front and behind of where the propeller shaft comes out of the boat. There were several areas over about a square meter/yard in this area that were thin and a few places that had already started to rust through. Yikes! I’ve got holes in my boat!! Not a good thing!!
What to do? I mulled it over for a long time and spent a lot of hours trying to find anything that might have caused the rust to accelerate and seemingly happen in such a short time. Electrolysis or galvanic action was the major suspect for me at first but after several days of exhaustive checking revealed that there was no stray current or other causes of such reactions and that my zincs of which there are 18 bolted to the hull to be sacrificial anodes for just this purpose, were all fine and wearing away at their usual rate.
So out with my big grinder with a thin metal cutting blade attached and taking a deep breath I cut out the sections you can see in the pictures. It felt VERY strange to be cutting holes in my boat and almost like I was violating my dear Learnativity, but I needed to cut out these rusted areas both to replace them as well as to get a good look at them and figure out what was going on. In the end I’ve determined that the rust is all due to “natural causes” and can be traced back to some less than ideal build quality back when the hull was welded up in about 1992. The boat was launched in 1994 but building stated in 1992. I found two things which I believe caused the rusting to set in. One was that the drain holes or slots cut into the sideways running ribs where they are welded to the lengthwise center stringer were too small and over the years they had filled in with dust, debris and rust which prevented any water which got in or due to condensation from being able to run down the hull into the bilge sumps and be pumped out. The other problem is that it doesn’t look like they had thoroughly cleaned, ideally sand blasted all the steel inside the hull after it was welded up and then covered it in several thick layers of epoxy paint. There was some primer in this area but it had long since broken down and these two factors had allowed moisture to build up in a few spots and started the rusting action which over the years advanced to that flaking layered type of rust which never dries out as the moisture wicks in between these flakes and continues the process slowly but continuously.
What I’m in the process of doing now is cutting out any and all areas where there is any of this flaking type of rust and cutting them back till I get to a steel rib or stringer. This will ensure that I have cut out all the rusted areas and quite a bit more past them and that I can weld in new steel where these stringers and ribs intersect the hull. I must admit it is a bit daunting to be adding this on top of the already major amount of work I had underway with the 20 year refit of Learnativity that involves redoing all the exterior paint, but the good thing about steel is that it is relatively easy to work with and welding enables you to create good as new patches of any size.
I’ve been working steadily on assessing the situation with the hull since Ruby and I returned back on Dec. 23rd and I’ll gladly admit it has been a real challenge and often quite defeating to deal with the depth of this rust situation. The biggest impact is how it has damaged my confidence in my boat so I simply need to put together a solution which will restore all that confidence and more. All problems can be solved and this one will be too and both Learnativity and I will be all the better for it when we do. Next week should be much better as I figure out the details of how to repair the hull, ideally how to improve upon it. My very able painting crew will also be back from their holiday break on Monday (Jan. 9th) and so we can pick up on all the preparations of the topsides and the deck for their eventual new coats of paint. I’ll be back to you next weekend with another update on how it all goes in week #2.
Wayne
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