March 28, 2008

The construction team has been busy working on the race canoe.  We poured our canoe in the middle of February and cut the prestess tendons after 14 days of curing.  The form was removed a few weeks ago, and patching and sanding has been ongoing.  Initially, the team planned to place an inlay inside the canoe in the shape of our logo.  However, the impression left in the bottom of the canoe did not look very good when the canoe came off the form, so we decided to stain everything instead.  We are in the process of researching stains and deciding on a color scheme for the canoe.  Only four weeks left to finish sanding, staining, and sealing!

One innovation of this year's team was to tie the pre-placed reinforcement to grade screws.  The screws were left in the concrete to act as depth gages during placement, patching and sanding.  They were removed from the concrete before the tendons were released.  We used 157 screws, and had to ensure that all of them were removed before attempting to take the canoe off the form.  Although the process was time consuming, it dramatically helped quality control.

January 25, 2008

The past few months have been difficult for the construction team.  The application of drywall mud was a long, repetitive process of patching and sanding.  In addition, the team had to find a new sealer that would prevent fiberglass resin from eating through the form.  In previous years, Elmer's Glue was used, but it was difficult to apply and impossible to sand.  Finally, fiberglass was applied to the form.  To see pictures of every step of the form construction, CLICK HERE .

Although there were hopes of pouring a practice concrete canoe, the long finishing process made the team unable to do so.  Once the holidays passed, the team decided to cast a fiberglass canoe for the paddling team to use.  That was finished a couple of weks ago, and the team is finally close to having the form ready for concrete.  A little more body work must be done on the mold, but most of the work ahead entails cutting the form into pieces (so it may be removed from the concrete canoe), applying a final gel coat, constrcuting the anchorages, and tying the reinforcement.

The team hopes to pour the final race canoe on Saturday, February 16 in the basement of the structures lab.  Since the similar casting methods from last year will be used, we hope that the canoe will come out well.

Applying drywall mud to the form

Attaching the foam for the bow of the canoe

Aplying Kilz latex sealer to the mold

Cutting strips of fiberglass mat

The first layers of fiberglass

Applying cloth to the form

Pouring resin onto the mold

I think those scisors may be ruined...

November 12, 2007

This weekend, the construction team made a lot of progress on the form.  They finally put the form on the table and began the initial sanding process.   First, the pieces of the form were glued together with spray-on adhesive and then sanded to a rough finish.  To ensure that the keel line was straight on the form, the team set up a laser level and sanded the keel in the dark.  After the rough shape was in place, the team went back through and fine sanded many areas to remove the waves in the form.  Next, the locations of the ribs were marked off with painters tape and cut into the styrofoam with a janky hot wire.  Finally, the team began sanding the body line that wil be incorperated into this year's hull design.  The form is beginning to take shape and actually looks like a canoe!

Cross-sections of the form

Rough sanding of the mold

Fine sanding to remove the waves

Sanding the keel line in the dark

Marking off the locations of the ribs

Cutting the ribs into the mold

Initial sanding the body line

November 2, 2007

The construction team has almost finished the steel build table.  Actually, they put the plywood on the table top last night, complete with steel spacer blocks (that create the needed sheer).  The only problem is that some of the steel pieces weren't square prior to welding and the table is not straight.  Although the ends are perfectly level, everything in between is not.  I think "torsion" is a good way to describe it, even though that still implies that plane sections remain plane.  Either way, there is a serious problem and we had to fix it by shimming the plywood with pieces of PVC pipe across the entire length.  Of course, this required the use of a laser level and some highly complicated mathematics to determine the vertical offset needed at 34 different locations along the table.  As engineers, we tend complicate everything.

Regardless, we hope to get the mold on the table this weekend and finally begin the sanding process.  The team has decided that they would like to try and pour a full scale practice concrete canoe this year, and they are aiming for December 15th as the first pour day.  We have a lot of work to do before then, and there will be many late nights and long weekends spent in the lab.  Below are some pictures of the table construction.

Welding the table together

Assembling the pieces

The new steel table

These two-foot sections are located in the middle and are removable

Spacers between the table and plywood that create sheer

Using a laser level to fix the table top.  Does it look crooked to you?

October 24, 2007

Over the past few weeks, the team has been working hard to cut out all of the pieces for the form; last weekend, we finished cutting out the cross-sections, putting us well on our way to creating this year's concrete canoe.  The other task at hand is the construction of the table.  This year, we decided to fabricate a steel table that can be used from year to year for construction purposes (reducing the construction time in subsequent years).  The table is 26' long with three removable sections (2' each), so that its length may be adjusted.  This year, we will be using 20' of the table to accomodate the length of our canoe.  In addition, the table has been designed with adjustable sheer; plywood will be attached to the top of the table as a build surface and the spacing of the plywood can be adjusted along the length of the table to meet the sheer requirements of any canoe.  The other reason for making a steel table was to resist the large forces placed on it by our prestressing tendons; last year the canoe had 16 prestressed tendons--each loaded with 165 lbs--that almost bent our wood table in half.  We designed the new table to resist these forces in anticipation of a prestressed canoe again this year.  This weekend, we hope to weld most of the table together and begin sanding the styrofoam form by next week.

Two-Inch Cross Sections of Foam

Cutting the Big Block of Geo-Foam

The Basis of Our Concrete Mold

Cutting Steel for the Table

How to Measure an Angle on a Cheap Chop Saw

Prepping Steel for Welding

How Many Engineers Does it Take...

September 29, 2007

Last night, we began setting up our hot wire apparatus so that we may begin cutting out cross-sections for this year's mold.  Initially, we were looking into the possibility of getting the mold CNCed, but none of our options worked out; the only company in Reno that had the capability to CNC our styrofoam decided not to do the job because of their inexperience CNCing 3-D objects.  This means that we have to fabricate our own form (as usual), and we began the process last night.  We set up the hot wire apparatus and began slicing our large pieces of styrofoam into 2" segments.   This year, we wil also use 4" and 6" segments along the straighter parts of the hull to minimize the number of pieces we will need to shape.  To accomodate these various sizes, the hieght of the hot wire was made adjustable by welding threaded rod to a piece of square tubing.