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Core Sound 17 keel maintenance

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Dynel was intended mostly to be an alternative to canvas for decking because it would print through the resin a pattern much like canvas printed through the oil based paint.  I bet it works well for Don's lounging panel.

 

Not sure why the videos Jamestown Distributors has made show it for sheathing a hull, but you might find the techniques useful Walt.
https://www.jamestowndistributors.com/userportal/search.do?freeText=dynel video&resultPref=all&page=GRID&history=

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Dynel is easier to find, though about the same price as Xynole. Both "drape" well and conform to compound curves without difficulty, which is why it's used. Additionally, because it needs so much goo to wetout and fill, it dramatically improves waterproofing on surfaces. I find Dynel used on decks more than anything else, but given a choice, I'd use Xynole for its 2 times better abrasion resistance.

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On 2/28/2017 at 9:20 AM, PaulSmith said:

" And a metal strip full width on top.  That forces the roller away from the outer corner of the keel."

 

@PaulSmith The keel on this is 1.25" wide. Looking at online metals for the SS 316 flat and wondering if I should use 1/8" or 1/4" X 1.25". (https://www.onlinemetals.com/merchant.cfm?pid=651&step=4&showunits=inches&id=27&top_cat=0 vs https://www.onlinemetals.com/merchant.cfm?pid=661&step=4&showunits=inches&id=27&top_cat=0

 

Here is my concern: 1.25 is pretty wide but is it thick enough for that width so that I don't risk it bending side to side? 1/4" is pretty beefy though and maybe overkill? 

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316L stainless is ideal in salt water and very durable, but you'll payhell to drill and countersink this stuff for fasteners. 1/4" stock is way over the top for thickness, with 1/8" still being way more than necessary, but easier to work. Edge set is difficult to do with this stuff, as you have to intentionally try to move it sideways, which it will resist. A chalk line, laser level, taut string or a simple guide clamped to the side of the skeg can keep it aligned during installation. For boats of this size I prefer aluminum strips, which is way easier to cut, shape and machine for fasteners. Both aluminum and stainless can be buffed and polished up to lovely standards, depending on how anal you'd like to get about it. This is mostly elbow (or DA buffing pad) grease. Admittedly, the aluminum isn't near as tough as the stainless, but the usual types of damage these see, is directly related to momentum and light, relatively slow moving objects don't generate a lot of momentum. 

81.thumb.jpg.75ea99c1f9fa359e279fcdf9cbfb8f83.jpg

Shown here is a 2" wide length of 5052 alloy (aluminum) 1/8" thick. The image isn't great, but you can see I've radiused the edges (belt sander initially), I've shaped it to fit the outer stem taper and even rounded it over the stemhead. You can see it's bedded and I fastened it down with #8 stainless oval heads. It looks like a factory made piece and swells around the centerboard slot under the boat too. This stuff was rough cut with a metal cutting blade in a jigsaw, then fine tuned with several different sanders, eventually getting buffed out with 2500 grit pads, before polishing.

   I'd hate to tink of the amount of work this would require in stainless.

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That's pretty. I see the no-skid on the deck too. That's nice. Was that one cloth or did you mask with non-skid in the goo?

 

I'm not concerned about aesthetics on this part. On the keel, I want to accomplish 2 things: First, make the strip the same width as the keel. As Paul pointed out, this protects that front edge that was especially getting mashed previously by the trailer. Second, I'd like it to be thick enough so that the weight of the boat on keel where the trailer roller meets it gets better disbursed than previously. The rub strip I removed was aluminum 1/8" X 3/4" and flexed enough that the keel got a little squashed. This might have been from it simply sitting too long on it without proper maintenance. I am also considering tweaking the trailer config a bit so that the weight is on the keel less and on the bunk rails more. The bunk rails are ramped higher in the front than the back and if I increase this just a hair more, when I pull in that last 12 inches on the winch, the weight should come off the rollers a little. so mostly my concern is #1: width flush to the keel. 

 

From what I read earlier here and elsewhere, the trick with aluminum in this application is the corrosion with non-aluminum fasteners (SS for example) It had SS before. Can I just do that again? If so, I'm not committed to SS. There might have been some corrosion on the old one but it didn't seem that bad. And the aluminum is pretty cheap. I could replace this periodically without breaking the bank. 

 

The plan is to only go as far as the front of the keel, which stops about 3' short of the bow eye. For the gap (because the radius is tighter) I'm looking for a 3' SS  3/4 hollow back half oval. This part may be prettier and am trying to find a local source since shipping is about as much as the part for most of the places I've looked. 

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The texture was done in the goo, with a roller just before it "gelled" up. Three coats of neat epoxy that was left to dry, then taped off for the waterways and a slightly thickened application of goo rolled on. When this was near the gel stage, I ran a roller through it to get a consistent textured pattern (you can see a few roller lap marks on the starboard side of the bow). Because the goo was very near becoming a non-liquid, it couldn't lay back down and self level, leaving the epoxy coating textured. This was lightly kissed with a DA, to knock off high spots and semi level the texture (dull it a bit), then prepped for paint.

   Corrosion can be a concern though with most trailer boats, if you keep it clean and dry, not really much of a concern for the first decade of ownership. Grab a small length of the stainless you'd like to use and drill/countersink several holes in it, before you make this decision. Aluminum can be shaped with many woodworking tools, not so with stainless. 

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You recommended 6061 Al awhile back for corrosion resistance, which is basically aircraft or gun aluminum.  Aren't there coatings you can put on aluminum that reduce corrosion? 


I was thinking about buying a countersink and drill for some flat 316 SS stock but you could also have this fabricated.  They could tap the holes at the same time.  TACO sells round SS hollow-back in 6' sections that's already countersunk for the stem.  Of course, this could require some hammering to the correct radius if you're installing it from the flatter forward edge of the keel up the stem.  The flat stock could alternatively be hammered rounder, but this wouldn't be fun either.  You'd probably need some thick round stock to beat the flat stock against.   

 

With shipping costs and tooling costs and tool setup time, I think it's probably cheaper to go to a local metal fabricator and have them cut, radius, drill, tap, and countersink everything for you if you're going to use SS.  Bending the whole thing around the stem sounds like a lot of work too. 

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I recommend 6061 for above the LWL applications, which typically are in the rig or fittings. 6061 is commonly available as is 5052, which is better for immersed exposure. I agree most home builders would be best advised to have a local welder/fabricator cut, drill and countersink anything but very thin stainless. This is one reason I recommend aluminum bar stock for these sort of things, as wood tools can be used and it's fairly easy to work, bend, drill, etc.

   An example of this type of work is attached. This rudderhead has a lot of shape and more flat bar stock bent around. There's some slight compound curves involved, which were pounded into it with a leather hammer. It's a precise fit, bedded in 3M-101 and again screwed down with #8 stainless oval heads. Also attached is more of the same flat bar stock, this time bent to serve as a below deck, halyard sheave bracket. Simply bent in a vice, over a small pipe to get a good radius. Working custom pieces of hardware like this is easy in aluminum and once polished up, makes you look like a pro. The polishing process is a bit tedious, but not hard and you likely have the tools to do it already. Compared to bending and machining stainless, no contest.83.thumb.jpg.4bf6ada322d03e0534736ac9f419537e.jpg64.thumb.jpg.4bdd1310846911d8c17469bbd40ca579.jpg

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Walt,

It is "How to Use Epoxy, Part 3 – Sheathing Wood with Fiberglass and Dynel".   So far, I'm happy with my job.  Here's where I am so far.  The "Panel 1" is when I ironed the fabric, to get it nice and flat.

Panel 3.jpg

Panel 4.jpg

Panel 1.jpg

Panel 2.jpg

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That sure is a pretty boat, PAR!  You do beautiful work.  Next time I'm in Leesburg, I'm gonna drop in.  Hope you don't mind.

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@ Walt S. -- it's nice and rough!  (But not overly so.)  The key is to only put on one coat of epoxy, and squeegee off most of it.  Then, one coat of primer and one (or two at most) coats of paint.  If you gob it up with those things, you lose your texture.  But right now it's lovely.

 

@Chick Ludwig -- it's what I call a "lounging panel" for my first mate.  Once we get under way, Terri loves to take a nap.  This will pay homage to those wishes.  I will also use it for camp cruising, if I do that.  It'd make a neat platform for sleeping.  It occupies the area forward of the mizzen, going all the way up the the forward bulkhead.  My "boom tent" will cover just this area.  I plan to make an awning for the area aft of the mizzen, too.  Right now, though, I'm prepping all my toys for our messabout next weekend.  No tent or awning work will be done until after that event.

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Sigh I feel relief. I epoxied the keel down and managed some very small radius fillets from the ooze to ensure complete coverage. With that, I officially feel like I have turned the corner on what I set out to do: replace the keel. First thing in the morning I'll remove the screws. I just have the skeg section to put down after that, then on to filling and fairing. Feels good. Thanks to all for the assistance and input to get me this far. 

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Here's a closeup of the final surface.  This is with one coat of undiluted Totalboat primer and one coat of thinned Brightside topcoat.  I'll stop applying finish at this point.  If I were doing it over again, I'd thin the primer a little.  There were little pinholes in the valleys of the weave, which is one reason I thinned the topcoat more than usual.  This method did take a lot of epoxy to wet out the Dynel.  I ended up squeegeeing out about a pint of goo, before allowing it to cure.  And I did take some sandpaper to the cured epoxy, to knock off some high, sharp points of fabric.  But I'm happy with the job.  We'll see if my mate's bottom agrees.

IMG_8102.JPG

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So the final coat of epoxy is on. the bulk of the gray area is the first layer of glass cloth and filling the dips forward of the seams. You can pick out the triangle of Xynole inside of this gray patch. Now to wait for cure, scratch a bit and prime. One step at a time...

bowfinallayerofepoxy1.jpg

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A fairing trick I'm not a big fan of, but many are is, to use a small notched trowel to spread the first layer of fairing compound. It's really handy around tape seams where the area raised is slight and hard to see. A uniform smear of goo (all over) with the trowel and let it dry. Next you come back with the long board and start knocking it down. Blowing off the surface you'll see the little ridges left by the trowel, but some will be deeper than others, which is what many like about this technique. Because you can literally see the low and high spots in the valleys of the notches, you know where to focus filling and knocking down efforts. Once you've got it pretty much fair, you simply come back with more fairing compound and fill the grooves, flush to their neighbors. What I don't like about this technique is the amount of waste in used filler, but it is an effective method, that many pro's employ. It can also be pretty fast. A buddy of mine is a metal boatbuilder and he uses this method exclusively. I can understand why with metal builders, as there's always a considerable amount of fairing with plate distortion and such, so it makes sense for him. For a small boat a 1/16" V-notch trowel is fine, unless the surface needs major low spot filling.

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Getting there. Was planning to go with the yellow again but am waffling. Other than personal preferences, are there more objective considerations for color choice? Obviously dark colors would tend to absorb heat. But others?

IMG_4957.JPG

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I painted my hull dark blue, which I like, but if it gets a scratch, the white primer shows through.  I guess if the topcoat was white or the primer dark, the scratch wouldn't be so obvious.  So the moral of the story might be to use primer and finish coat that are the same color.  Except I really like dark blue.

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@Paul356 - yes, I thought about that yesterday. I should have had the primer tinted. Gray probably would have been the better choice. Even with yellow (which I will most likely use) the white will show but gray not as much I think. And for any color, gray would just be less noticeable except if I went with white of course. 

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