Curious Bottom
- Thread starter Scott T-Bird
- Start date
You could take a sander & just hit a small section of the hull to get a better look at the red color to determine what it is.
Other than that I'd just let her sit for the winter. Fair the hull/keel in the spring, barrier coat, bottom paint & you should be good to go.
Other than that I'd just let her sit for the winter. Fair the hull/keel in the spring, barrier coat, bottom paint & you should be good to go.
Bingo, I saw the ballast weight listed for shoal draft in 2 different places as 2,200 lbs & 2,300 lbs. so they must have marked the actual weight. The ballast weight for the fin keel is listed to be 2,000 lbs. The shoal draft keel has that heavy bulb on the bottom. (I've never been known to think of the obvious
)
Lead will oxidize like any metal will. There are types of metal oxidation that you can't even see with the naked eye. The scale you see is most likely produced by a combination of the lead an other metals present in the alloy like antimony. Other trace metals can be included like tin or copper to increase hardness or reduce metal fatigue, but who knows. It is doubtful that you really need worry about removing the scale completely, just sand with 80 grit to level out the surface and remove any stubborn flakes the blasting missed, the sand blasting should already have given you a nice grippy substrate for the barrier coat. The Interprotect is very good at filling to a degree, but fairing all the tiny pocks with the epoxy filler will do most of the work. There is a good deal of argument out there about how to fair the hull to keel joint, it usually depends on the type of keel. Since you have a keel stub that connects to the lead keel 1/3rd down from the hull you shouldn't have to worry about flex there so fairing with the epoxy filler is just fine, a flexible epoxy like G-flex or 'softer' adhesive Sika shouldn't be needed.
Well, the color only matters to the extent that it helps identify the laminate layer, I think. I'll have to verify, but I think Gunni helped illustrate and clarify my confusion!
. Thanks to All U Get for showing his bottom, too! 
Way back when I got the Seidelman, and pulled it the first time, I had thousands of these little blisters. Looked a lot like yours. But mine were all on the port side, and mainly forward of midship. I figured at the time that some way in layup, something happened in this area. I filled and faired with epoxy. Every time it's been out of the water since then, looks good. And mine stays in brackish water year round.
Scott, as CloudDiver noted lead will oxidize and paint will not adhere to lead oxide. So prepare your keel as follows to seal it and for good paint adhesion. Take a belt sander and sand it down to bare lead doing one side at a time. As fast as possible, apply a coat of west epoxy to the bare lead keel making sure to get it completely covered. Now do the other side. The reason for the speed and one side at a time is the lead will oxidize almost instantly as lead is a very conductive metal and will react very quickly with free oxygen in the atmosphere. Overlap the keel joint with the epoxy and try to get the bottom as best you can but you will need it hoisted in a lift and slings to really do the bottom. Now hot coat a second coat of West epoxy on the entire keel meaning once it sets up but before it fully cures, put on a second coat. Now hot coat two barrier coats of Interprotect as it is a good base coat for paint adhesion. Now hot coat your paint to optimize adhesion and reduce sanding needs. I did this to my keel that had bad paint adhesion when I bought the boat and it has been great for about 18 years. I think these instructions are from west system, but it worked great. They also recommend using a wire brush on the first coat of epoxy to make sure it bonds to pure bare lead, but I question adding iron from the brush into the lead. I skipped that step and it didn't seem to matter. The idea being bare lead oxidizes almost instantly at a microscopic level. Check the West website to see if they still have this posted.
Great tips. I appreciate the comments. I'll have to work it out with the yard to make sure it gets done correctly, or I'm there to do the work myself in this regard. It sounds like it takes some effort to make sure the layers get timed correctly.
Phil, there is a nice S37 in the yard and I think it is for sale. I've been looking at it from a distance lately!
Stainless steel is just steel with a high chromium and nickel content usually about 28 percent of the total or so. For 304 stainless the chrome is about 18% and nickel another 9%. The 70% +/-that is steel is iron with some carbon and other alloying elements in very small percentages. So the stainless is around 70% iron and again microscopically (at the atomic level) some atoms of iron will be imbedded in the lead potentially causing galvanic corrosion. I'd suggest using some type of a non metallic abrasive brush that would be inert if you go to this effort. Maybe a nylon brush imbedded with some kind of ceramic grit that will scratch the lead and expose the surface.
Use all recommended safety precautions with lead as it is very toxic.
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Your keel is blasted clean. If you epoxy coat the keel and scrub it with a wire brush to work the epoxy onto the lead prior to set, the job is done. No need to sand it.
After it is epoxy sealed, you can fair it nicely. Just don't use the micro-balloons, they aren't designed for BWL. Do that and have your tradesman apply a final barrier coat with
After it is epoxy sealed, you can fair it nicely. Just don't use the micro-balloons, they aren't designed for BWL. Do that and have your tradesman apply a final barrier coat with
Hey Scott,
When they blasted the bottom of my O'day I had several areas that looked the same as yours, just not as many. Some here suggested a little to aggressive on the blasting.
I used 2 coats of penetrating epoxy, sanded, barrier coated then applied hard ablative. Mine didn't require a lot of fairing.
Ward
When they blasted the bottom of my O'day I had several areas that looked the same as yours, just not as many. Some here suggested a little to aggressive on the blasting.
I used 2 coats of penetrating epoxy, sanded, barrier coated then applied hard ablative. Mine didn't require a lot of fairing.
Ward