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Spindrift 12 build log


Walt S.

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I'm finishing the forward compartment today.  I'm putting 3 coats of epoxy on all surfaces.  The best method I've found for removing the selvage edge of the fiberglass is to use a carbide scraper.  I cut the handle off of a Husky carbide scraper and have used it on all the tapes I've laid.  For the most part, I've been able to put on the tapes and subsequent coats of epoxy inside the cure window of the fillets so that I don't have to sand.  I'm not sure if I will be able to do this for the next step. 

 

The next step will be the center interior between the seats and aft of the forward bulkhead.  This is a lot of filleting and may require multiple sessions spread over multiple days.  I'm not a fast filleter.  I may have to sand these fillets, but that wouldn't be the end of the world.  I suppose another option is to take a half-day off and try to fillet the whole center compartment in one session, but then I doubt I'd have time/energy for taping that evening, especially considering the wife/kids.

 

I'm also starting to run out of the B&B wood flour/cabosil.  I might have to wait for another shipment.  Duckworks has both wood flour and cabosil.  You guys use a 50/50 mixture of it, correct? Can I just pour the components together in a bucket and stir? 

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The balls are actually pretty common. The first ones I stole from some broken ball valves, but they're available at a number of places. US Plastics, Online Metals, etc. all carry them. I'll bet even Hobby Lobby or Joann Fabrics has them.

 

I use wood flour only for color matching now. Silica (Cabosil) is a thickening agent and will make really hard to sand fillets, if you use much more than enough to control viscosity. Generally there are three basic types of fillets, light or heavy structural and cosmetic. The structural fillets I simply apply as needed, without worrying so much how they'll finish out, knowing they'll be covered with tape or a thin cosmetic mixture afterward. Cosmetic fillets are as the name suggests and decorative in nature, such as cockpit seating where it lands against the hull shell. These would typically be light weight fillers (microballoons, quartz spheres, etc.) with just enough silica to permit it to not sag, under its own weight.

 

The percentage of one filler to another is application/environment specific. I do have jars of pre-made up combinations, but these are without silica, which I use per application, depending on the requirements. I've done the same thing with structural fillers, just adding silica as needed, per batch.

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I either use B&B's pre-mixed thickening powder (good price and convenient) or 2:1 cabo:wood.  That is the ratio I used to build the Willow kayak (per Thomas' direction), and have stuck with that ratio ever since.  It might be interesting to more cabosil next time, though.

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I beat the bushes for wood flour out here and apparently none of the marine suppliers read the Gougeons or Devlin.  All of their fillers are a mixture of cabosil and microballoons.  I'll order from Alan when he gets back tomorrow.  In the mean time, there's plenty of sanding to do.  

 

I've decided that I can avoid sanding by filleting and glassing one seam at a time with a 1.5" fillet into the seam I'm not working at the moment.  This will leave enough room for the tape to lay down on the seam but leave bare wood adjacent so that I can pick up the fillet where I left off with minimal sanding where the tapes would overlap at a corner.  There will be a mechanical bond at the overlap, but that's better than a mechanical bond on the entire fillet due to waiting for each fillet to dry, sanding, then taping.  THis isn't making much sense.  I'll try to post a picture. 

 

Devlin likes to use peel-ply on tapes to eliminate sanding.  Personally, I think I'd have a hard time finding air bubbles if I used it and it's a lot of money.  I was hoping Action Tiger was going to use it in his latest build but it looks like he didn't.  

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Check out folks in your area that refinish wood floors. They may save sanding dust from their floor sander for you. Also, furniture manufacturers that use stationary sanding machines. How about cabinet shops? Maybe there are other industries that use sanders.

 

I create a lot from my stationary belt sander, and even my d/a sander. It may be worth having a "dedicated" shop vac to attach to your sanders just for this purpose.

 

But for the price and convenience, B&B is a great source!

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Recent tests have shown what may of us have long suspected, wood flour can vary to say the least. Sometimes you can make a nice heavy, non-sagging mix and it looks pretty until it's cured. On other occasions, an hour after you've applied it, the top of the fillet looks dry and a puddle of diluted wood flour colored goo, is pooling at the bottom of the fillet. Different batches of flour, different species used, how fine it was ground, hardwood or soft, exotherm, moisture content, etc., filled our heads. Testing has confirmed that exotherm can decrease the viscosity, of the freshly applied resin/wood filler mix, causing it to go from a seemingly non-sagging mix, to a pretty sloppy one, in time. You have to have mixed/applied several gallons of wood flour fillet goo, to notice this.

 

My first discovery was that hardwoods make much better fillet bulking agents. Softwoods don't seem to suck up as much, usually aren't ground as fine, compairtivly and can be less consistent, especially the lighter colored pines. More specifically found that nut shells make the best, if ground fine enough and you avoid the oily versions, like Pecans. There's big difference between the stuff you buy and the stuff you get out of the sander. Sander dust is good for fillets you'll never see again, but require a lot of sanding, cursing and fairing compound to make neat. Talc (yep, baby powder) works very well and is usually ground finer, so use a sifter. Cooking flour works as good if not better, than some real wood flours. To this the three usual choices (white, wheat and rice), wheat has the best tensile strength, with rice having better compressive strength. Bulk talc (with or without fragrance) is cheap, but I haven't compaired cooking flour to store bought wood flour, though I'll bet it's cheaper too.

 

Now, as I mentioned I use wood flour only as a colorant. My mixtures to insure something stays stuck usually has micro milled fibers ('glass), a talc/rice flour mix and enough silica to control viscosity. This is a hard to sand, strong and stiff mix, good for gluing, filleting and filling holes, plus reasonably smooth applying. If I want the mix to still be strong, but easier to sand (and smoother), I'll decrease rice flour and increase the talc. Even easier sanding by deleting the milled fibers from the mix, maybe skipping the wood/cooking flour and using microballoons or quartz spheres. 

 

Most would be well advised to get some gallon jugs, with a wide mouth and mix up the basics for the three usual fillet/glue/fairing mixtures. Don't add the silica, as you'll do this to control viscosity on each specific batch. 

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Good grief, Paul, let's just KISS it. Mix some wood flour from one of the sources I suggested, along with some Cabosil, and see how it works for you If it sags, add more Cabosil, if dry, add less. Keep track of how you mix it so you'll know what to do next time. If you like a light color, use light colored wood flour. If you want it darker, use darker wood flour. To vary how "thick" it is, add more or less poxy.

 

Most amateurs aren't gonna have a bunch of different thickening agents around. Cabosil, Q-cell, and wood flour outa cover their needs. Later on, they can start getting more exotic.I really like the B&B mix, so why worry with all that other stuff. That along with a little bag of Q-cell to make an easily sanding putty when needed, will serve well.

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I used the West brand stuff and it worked fine. It was localy available so that's what I got. I don't recall the numbers but I used the one recommended for filleting, and a lighter one for fairing. The fairing stuff was way easier to sand, the filleting stuff set pretty hard.

I worked with wood flour before and I found this stuff easier to work with. It was easier to mix and I got smoother fillets. But either would work, and it you're better at it than me you can probably get really good fillets with wood flour, I just found the West stuff easier.

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I ordered everything from Alan which saved me a lot of time and worry over whether or not different brands and types of epoxy and filleting blend would work as well as what I've been using.  This is my first build and I don't want to deviate.  

 

I checked my hull for twist again yesterday and found that the level method I used several pages back gave identical measurements from the bow to the corner of the port stern knee and the bow to the corner of the starboard stern knee (Devlin's method of checking for twist).  

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Welp, there were high winds today and my tent blew over, despite all of my attempts to shore it up and reinforce the poles.  The grommets actually pulled out of the canvas and the tent poles broke.  I'm going to move it into the garage where it will be easier to work on it anyway.  The keel still isn't filleted so I'll have to re-level everything.  I have to carefully lift the entire boat over my fence and bring it into the garage.  Providentially, my wife is strong.  I'm going to get a neighbor to help also.  

 

I think this will actually enhance my progress since the lighting's a lot better, power is much easier to get, and it's attached to my house rather than across (at this point) a marshy backyard. I just wish I'd done this from the beginning.  Hindsight is 20/20. 

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That foam block in the CS15 video is leftover divinicell foam (boatbuilding foam) but often times I use blue board insulation foam. The blue board insulation foam is fine for flat areas but for rounding over chines I think it's too soft. I rectangle of 1/4" plywood works pretty good. So would a bit of door skin ply. 

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Going along with my lazy approach to boat building tools, I try to add power to any kind of operation. I do like Alan says in the process of fairing the chines, but I use an in-line air sander - air file -  like they use in auto body shops. I move it in the 45 degree motion that Alan shows in his video.

One of these guys: https://www.amazon.com/Ingersoll-IRT315-Piston-Straight-Sander/dp/B00004XOT5/ref=sr_1_1?ie=UTF8&qid=1484143253&sr=8-1&keywords=air+file+sander

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That foam block in the CS15 video is leftover divinicell foam (boatbuilding foam) but often times I use blue board insulation foam. The blue board insulation foam is fine for flat areas but for rounding over chines I think it's too soft. I rectangle of 1/4" plywood works pretty good. So would a bit of door skin ply. 

 

What grit were you using on the chines?  

 

What grit do you guys use for fairing the hull and fairing paint?  

 

I'm getting ahead of myself here but other people on the forum will shortly be in the same stage. 

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