Monday, May 28, 2012

Who needs a workout program?

 When you have a boat to sand, fair, sand, paint, sand, fair, sand, paint, . . .
 Second coat - with a touch of graphite powder added to tint the paint gray.  I took the boat outside so that I could see the imperfections.  I also took the opportunity to clean out the garage under the boat.
 Second coat after sanding and fairing - I finally filled in just about all of the pin-holes and glass weave
Third coat - after sanding the bottom again of course.

Saturday, May 19, 2012

First coat of primer

I applied the first coat of primer today to the hull using using Interlux Primekote epoxy paint.  The photo to the left shows the boat bottom with the primer.  I spent most of the time trying to make sure that all of the glass weave and the "pin holes" were filled in and didn't worry too much about complete coverage.  I did this by rolling on the paint with a foam roaler and then by going over the wet paint with a bondo spreader to make sure that the holes were filled.  Tomorrow  I'll sand the bottom and start filling in the low spots with fairing compound.  Overall the hull looks very good and I don't think that I'll need to do too much fairing

The picture on the right shows the keel after priming.  The keel surface actually was pretty smooth so the primer covered pretty well.

Monday, May 14, 2012


 All of my work on the boat this weekend revolved around the keel.  I first widened the slot in the bottom of the hull (which I cut some time ago), using the keel sleeve as a template and a saber saw for the cutting.  I then laid some carbon fiber cloth into the sides of the slot, and onto the surface of the hull.  Next, I inserted the keel sleeve into the keel box using thickened epoxy to glue the sleeve to the bottom of the hull.  At that point, the keel sleeve protruded from the bottom of the hull a bit, but was level with the top of the keel box.  Once the epoxy dried, I then cut off the excess keel sleeve using a multi-tool with a flush cut-off blade on it.  I've found this tool to be invaluable in this project.

Next, I applied two layers of fiberglass cloth over the bottom of the keel sleeve.  I used masking tape and plastic to cover the inside of the sleeve so that no unwanted epoxy got into the sleeve.  

The photos to the right show the results.  The top photo shows the bottom of the hull.   I haven't cut the fiberglass over the slot yet, but will do that soon.  I've put a first layer of fairing compound over the edges of the glass cloth.  The other photo on the right shows the top of the keel sleeve inside the keel box.  I'm planning on filling the gap between the two with expanded polyurethane foam.  

I also joined the keel foil to the keel bulb this weekend.  Rather than using bolts to connect the foil to the bulb, I bought threaded stainless steel rod as well as stainless washers and nuts.  I used rod since the length that I needed varied from front to back.  I could have bought bolts of a given length and then changed the depth of the countersink to fit but I thought that the threaded rod would be easier.  The picture to the left shows the holes drilled through the bulb and the countersunk holes to make room for the washers and bolts.  I'm not sure where I read this, but someone suggested using milk as a lubricant for drilling the holes in the lead instead of cutting oil.  That actually worked very well.  Using milk avoids having to clean the oil off of bulb with degreaser prior to coating the bulb.  

The final photo shows the assembled foil (before cleaning up the epoxy mess).  When putting these two parts together, I first poured in a few ounces of epoxy / colloidal silica mix (West 406).  I then pushed the foil down into the slot in the bulb (which of course caused the epoxy mixture to rise up), and then put the rods through the holes and attached the washers and bolts.  I then made a thinner mixture of epoxy and 406 and filled the slot to the top.  Finally, I made some fairing compound (a mixture of epoxy and West 407) to cover the washers and nuts.

As it turned out, at 175 lbs. my keel is slightly under weight (the class limit is 185 lbs.).  I made the slot in the bulb larger than it needed to be because I didn't want to have to trim the foil to fit.  I think that with a bit tighter tolerance there, I would have been right on the 185 lb. weight.  

If you notice, just about all of the photos of the keel bulb on this site show the bulb sitting on a pile of sand.  The sand makes it very easy to put the bulb in almost an orientation while I scrape, fair, and sand it.  My wife is looking forward to my cleaning up the mess soon now that I'm almost ready to prime and paint the keel.

A final note on mixing thickeners, whether for bonding, making filets, or fairing:  I find it much easier and a whole lot less mess to do all of my mixing in zip-lock bags rather than using cups and a mixing stick.  Some of the thickening materials are very fluffy and light weight and float in the air pretty easily.  Virtually all of them are very bad to breath in.  I just measure out an appropriate amount of thickener into the zip-lock bag (you have to use the heavier freezer bags), and then pour in the right amount of mixed epoxy resin and hardener.  I then mix the filler with the epoxy mix by just squishing the bag around for a while.  When it's mixed, I let out the excess air and then cut off a bottom corner of the bag.  I then apply the mixture just like you would frosting when decorating a cake.  The "recipes" for the mixtures vary by type of filler, but in general, a cup and a half of filler with an 8 shot mix of epoxy/hardener is a pretty good starting point for a mixture with a mayonnaise consistency.

Monday, May 7, 2012

Keel Sleeve

I created the keelbox structure out of wood and carbon fiber quite a while ago (described below).  However, I always intended to put a foil shaped liner inside of the rectangular keelbox.  The liner extends the full height of the keel-box structure will be attached to the hull at the bottom and will be water-tight.

Take 1

I had some luck in the past with hand molding Carbon Fiber cloth around items and then just wrapping it with release cloth.  So in my first attempt, I wrapped several layers of plastic around the keel foil and then applied a four layers of 11 oz CF cloth over the plastic.  I then covered that with release cloth and clamped the bottom of the cloth with spring clamps.  Unfortunately, the sleeve that resulted was really lumpy both on the inside and the outside.  Even though no one is ever going to see this thing once it's installed, I just couldn't use something so ugly on the boat.  

Take 2
So I started over on the sleeve with a few changes.  1) I used alternating layers of glass cloth and CF instead of straight CF, 2) I mixed epoxy with graphite powder for the inside layers, and 3) I vacuum bagged the whole thing.

The graphite powder is supposed to make the inside of the sleeve much more slippery and to make retracting the keel much easier over the life of the boat.  I've also learned a thing or two about vacuum bagging while doing this boat project.  Using release cloth between the "bag" and the item yields a much nicer surface.  The second picture here, shows the sleeve while the vacuum was being applied.  I put the absorber cloth underneath the whole sleeve and wrapped the entire thing with the peel-ply.

The final picture shows the result.  The sleeve came out beautifully.  The next step is to open up the trailing edge the sleeve and then re-seal it with CF tape.  This is to give a bit more room inside the sleeve so that the foil doesn't bind.