Glassing the Hull - Part 1... Prep

Long time, no post....
Its not that we haven't been doing much, its just that we were hoping to get this hull finished and flipped a lot quicker than it has happened. I was holding off on the posts so that I would have a true "transitional point to bring this blog up to (the "flip" seemed perfect) but that will be postponed a little.  I have had a setback in the "elbow department" that has thrown a wrench in things.  Seems that about three weeks ago I somehow tore about 2/3's of the

triceps tendon off the end of the elbow. rare injury I am told by the orthopedic surgeon.  I never felt anything at the moment but within a day or so of the injury (best guess), it swelled and hurt and became hard to use (pushing).  Finally had the MRI and I am scheduled to have it reattached to the bone on Tuesday the 18th.
Dad and I worked off and on the past three weeks but were not able to make too much progress on final sanding and prepping for the paint.  At this point we are limping along.  As of today I am trying to sneak in a little left handed sanding (literally with the left hand) and figure it will be a good week before I can pick it back up with help.  As of today 11/16/2014 we are on the final skim coat of epoxy filler and are really close to paint.
Prepping for glass...

Cured patch ready for sanding

Areas like this are best handled
with the RO sander

Looking back at the blog it looks like we were up to patching and filling screw holes with epoxy filler and getting ready for an all over sanding and shaping prior to laying the xynole fabric over the hull and wetting out.  Lots to cover so here we go. Using a mixture of fillers, specifically phenolic micro-balloons (accounts for the brown color) and silica for its thickening and non-sagging properties; we went around the hull patching all the screw holes and joints.  Once fully cured it came time to sand and level these surfaces.  Folks, do what you want but we don't mess around trying to fine sand at this point and find a random orbit sander the wrong tool for the job.  Instead, reach for your trusty belt sander and if you don't own one,stop and go get one.  They are not cheap, but with the right technique, they are great at leveling and prepping a surface. Fast too.  The belt sander is your friend!!! Remember, you are getting ready to build a thick surface of epoxy and fabric over this surface so level it, fair it even, but don't waste your time making it baby butt smooth.


Belt Sander technique and expectations...

1. Keep the sander pointed in the direction of the grain (in this instance front (fore) to back (aft) and keep it moving.  the sander is aggressive and that is what scares most folks off, but as long as you keep it moving in lazy figure eights and keep the platen (flat piece that the belt rests on) flat and let the weight of the sander do the cutting. You will find the time it takes to accomplish what a RO sander will to be diminished nearly half or more. Moreover, the surface will be much fairer and flatter, basically emulating what a long-board can accomplish to a point.
2. Expect a lot of dust...  I mean a lot of dust. It would be a good idea to go ahead and find a 1" tool hose and adapter to attach to a Shopvac.  The epoxy/wood dust buildup can overheat the belt and get in the motor. Strap or tape the cord 
3. You can use the belt sander in other ways as well...  Fun tip! your sander has a "slack belt" portion than can be used for shaping outside curves.  Between the front of the plate and the front drum is an unsupported portion of belt that will assume a natural arc.  Two things to note: One, the belt may tend to wander left or right.  If it does, it only means that you are applying too much pressure on the opposite side of the belt.  Two, most sanders have a portion of the housing that extends down to protect this portion.  You will have to remove this before you can use this technique.  We relied on this, in combination with a 45 degree chamfer router bit to remove the bulk of the edge, to help create the rounded-over edge at the chine (where bottom meets side).
4. Grit... On a tabletop that we are leveling we are cautious about going too coarse in grit and creating more work for ourselves down the road as we try to sand out scratches.  At this stage were are not worried about it.  Start with a fast cutting 36 or 50 grit belt and keep it moving. Sand wood and patch alike to a fair surface.  It will go quick and you will be ready for the cloth in no time.

Epoxy fillet around end of keel

Final Filling and Sanding...

Bondo squeegee with cut radius  edge.

Following the techniques and suggestions above, we finished pre-glass sanding of the hull.  The only step left was to round the joint between the keel and hull bottom so that the cloth would smoothly flow between the two perpendicular surfaces. Xynole drapes better than just about any cloth out there, but it has its limits.  This was basically a matter of filling up a Ziploc pastry bag with thickened epoxy and laying a generous bead along the joint.  Once accomplished, run a bonding spreader with a radius corner along the joint to create a fillet.  Let it set and clean up the excess squeeze out with a sander.  An RO would be fine for this work if the joint is pretty clean.  Just a suggestion: Feather sand the radius cut on the squeegee.  The trailing edge of the squeegee is done this way as manufactured and we think it would help out when trying to press it hard into that  90 degree corner.

At this point we are ready for cloth.  On to Part 2.