Several years ago I became well acquainted with hundreds of blisters on my previous boat (18' Renken) while spending my spring vacation reworking the bottom. After reading all the literature I could find, I committed to doing the absolute best possible back yard repair job I could. In the process, I learned, in no particular order: 1. The blisters started and were largest where the boat sat on the trailer bunks. I believe that moisture is held by the carpet/fabric on the bunks even when the boat is on the trailer, and that this is a potential problem area for any boat kept on a bunked trailer over the winter. 2. After sandblasting the blisters, I knew there had to be a better way and found it when I tried the Dremel tool with a cone shaped cutter. About ten times faster, but you have to have a steady hand. 3. Some sources say to locate the blisters as soon as the boat is pulled because they shrink and are harder to spot later. You say they grow larger after the boat has been out of the water for a while. I think both are correct - I have seen larger ones appear to diminish with time, and small ones appear only after the boat has been out a couple of weeks. The important thing is to mark every one you see when you see it - I use a pencil or chalk, and circle every one I can. Marking them makes the process of cutting them out much quicker. 4. A real good way to spot blisters is to get under the hull at night and shine a flashlight beam (or headlights) obliquely along the bottom. Every little bump will show up and you'll see imperfections you'd normally miss. 5. I used CopperPoxy for the final coat on the bottom, and have been well pleased with it. It's not easy to apply smoothly, but forms a super hard coat. It is primarily intended for resisting hard growth in salt water situations, and as my boat was in fresh water it would still accumulate a thin layer of slime if not cleaned. However, when hauled, the boat was easily cleaned for two bucks worth of quarters at a car wash on the way home. CopperPoxy is expensive, but if it lasts 10 years as claimed (the manufacturer recommends ScotchBriting it every year to uncover fresh copper on the surface) then it pays for itself several times over.
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Really Good Information!
EXCELLENT write up, Bob! Two bucks worth of quarters to pressure wash the bottom???? Don't remember what the yard charges to pressure wash but it's mega-bucks more. Makes me want to go back to a trailer boat! Not to mention they go faster.
EXCELLENT write up, Bob! Two bucks worth of quarters to pressure wash the bottom???? Don't remember what the yard charges to pressure wash but it's mega-bucks more. Makes me want to go back to a trailer boat! Not to mention they go faster.
Need a source for copper-epoxy
I had seen the ads a year or so ago and mentioned in the trilogy III but would like a contact so as to get some literature etc. Also my boat is about due for a bottom job! Thanks Jim Willis
I had seen the ads a year or so ago and mentioned in the trilogy III but would like a contact so as to get some literature etc. Also my boat is about due for a bottom job! Thanks Jim Willis
CopperPoxy Application
It is perhaps appropriate to point out that CopperPoxy is not easy to apply, especially for the backyard guru. It has the consistency of grainy peanut butter, must be mixed with a catalyst (that's why it's a "poxy"), and thinned very precisely, and kept stirred so that the copper particles stay uniformly distributed. I tried roller and brush application, finally settling on careful brushing. It is difficult to apply a uniform thickness, but I found that keeping a separate container of thinner (xylol) handy and dipping the brush lightly in that and then "tipping" the thicker appearing brush-strokes gave me an acceptable result. When finished, the bottom will knock your eyes out - it has the color of a brand new penny. However, sanding it or letting it oxidize causes it to look like an old penny. Still, there are benefits to that: in freshwater, the normal brown slime that accumulates over time is about the same color, so no one can tell if you haven't cleaned it. Unused product keeps well - I think they claim a one year shelf-life, but I've been able to touch up with left over product for 3+ years.
It is perhaps appropriate to point out that CopperPoxy is not easy to apply, especially for the backyard guru. It has the consistency of grainy peanut butter, must be mixed with a catalyst (that's why it's a "poxy"), and thinned very precisely, and kept stirred so that the copper particles stay uniformly distributed. I tried roller and brush application, finally settling on careful brushing. It is difficult to apply a uniform thickness, but I found that keeping a separate container of thinner (xylol) handy and dipping the brush lightly in that and then "tipping" the thicker appearing brush-strokes gave me an acceptable result. When finished, the bottom will knock your eyes out - it has the color of a brand new penny. However, sanding it or letting it oxidize causes it to look like an old penny. Still, there are benefits to that: in freshwater, the normal brown slime that accumulates over time is about the same color, so no one can tell if you haven't cleaned it. Unused product keeps well - I think they claim a one year shelf-life, but I've been able to touch up with left over product for 3+ years.
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