Keel box is in

 Memorial Day weekend - Sunday was the day that I was going to install the keel-box.  I had previously reinforced the floor of the boat between frames 110 and 124 with an additional layer of 1/4" hydrotek.  Yesterday I then glued on a template for the keel sleeve using a NACA 0012 shape.  The template was 2" wide by 14 1/8" and fit perfectly between the 110 and 124 frames.  

As the picture on the left shows, I then glued on the sides of the keel-box which were made out of three 1/4" ply laminated together (it would have been nice to have some 3/4" Hydrotek.  Note that I glued on some pieces outside of these boards so that i can create a recess in the deck for the keel top plate.

Once the Keel-box sides were in, I reinforced the floor of the boat further with another piece of 1/4" ply and then glued angled supports on to frames 110 and 124 which provide further support for both the keel-box and the floor.  If you zoom into the pictures you'll get a better view of these supports.  


Finally, I used the West System scarfer to angle the edges of the floor reinforcements so that there is a nice smooth transition.  


Next up for tomorrow, is to fillet and glass in all of the frames.  I had previously put mini-fillets on the frames to hold them in place more securely than with just the zip ties.  

More gluing and shaping

 All of the frames were stitched in, however after reading some of the entries on the i550class.org forum, I decided to remove the three center frames (89, 110, and 124) and double them up making each frame 1/2" thick instead of 1/4".  This should give me substantially more strength in the center of the boat where the majority of the stresses are concentrated.  While the frames are out, I filetted and taped the chine seams with glass biax tape.  I'm in the process of gluing on the shear clamps.  Once both sides are done, I'l put zip-tie the frames back in and then filet and tape the seams.  Should be done this weekend. 

In the mean time, I continue to work on the keel, and almost have the final shape set.  Of course, I'm expecting to have to do quite a bit of fairing with this item.  It will be a shame to cover up the mahogany with carbon fiber cloth.


The keel by the way uses a NACA 0012 shape.  I plugged the formula for a NACA foil into Microsoft Excel, and plotted the results.  I then adjusted the size of the plot in the spreadsheet until the print-out was "life sized".  I then used those print-out as a template for the foil.

Frames are in

I have to admit, I'm a bit obsessed with this boat.  I spent quite a few hours today (a Sunday)  cutting out all of the frames, and stitching them into place.  I still need to filet all of the seams on the hull (except the center seam which I taped last night).  I debated fileting and taping the chines before I put the frames in, but I decided that it would probably be better to get the true shape of the hull before doing any of the fileting

A couple of the other builders of i550's suggested putting castors on the cradle.  I have to thank them profusely for that idea.  It made building this thing a whole lot easier.

Front and back attached

Tonight I glassed in both the transom and the bow stem.  The transom was made up from two laminated 1/4" sheets.  The bow stem was cut out of a 1-1/4" solid mahogany.  Again, this material was chosen for some level of rot resistance.  The place that I bought the Hydrotek plywood (Homestead Hardwood near Sandusky Ohio), had an incredible selection of hardwoods.  Actually the left-over pieces of Mahogany will make some nice woodworking projects.  

Cutting the angles on the bow stem created a challenge.  The plans show only the front of the piece with a shape tapering from 2" wide at the top to 0" at the bottom.  However of course the back has different dimensions due to the hull taper.  The Watershed people did indicate the appropriate angles on the Tyvek paterns that they sent to me (23 deg at the top and 20 deg at the bottom), but getting the bow stem shaped with a varying angles was a bit of a daunting.  Ultimately, I created a simple jig that allowed me to rip a 3" X 27-5/8" board with a 2% angle in the long direction and a 23 deg taper.  I then used a Stanley Sureform planer to "twist" the angle of the taper to 20 degrees at the bottom.


Gluing in the bow stem wasn't that hard.  After wetting out the hull panels and edges of the bow-stem with a West System (105/207) epoxy mixture, and then applying a peanut butter consistency mixture thickened with 403 filler, I simply held the bow stem in place, drilled some small holes through the side panels into the mahogany, and used small brass screws to hold it all in place.  This was much easier than trying to use clamps.  

Wood in the shape of a boat

 We now have a boat-shaped object in the garage.  I've chosen to use the 1/2 inch PVC pipe technique in order to align the panels on the boat.  The basic idea is to wrap the zip-ties around small segments of PVC pipe in order to more closely align the edges of the plywood.  This worked very well where the panels meet at oblique angles, however near the bow where the bottom meets the side at almost 90 degrees, it is harder to maintain exact alignment.  I think that putting in the bow stem will take care of some of these issues.

If you look at the picture closely, you'll notice that I chose to build the side panels "backwards" with respect to the plans, with the seams closer to the stern rather than the bow.  I did this for two reasons: 1) so that the side panel seams don't align with the seam on the bottom panel, and 2) I really think that there is less stress on the plywood at the back of the boat.

Parts that look like a boat

 Worked hard on the boat this evening.


Using the West System scarfer worked out really well, although one of the joints that I created was misaligned so I had to cut the boards apart, re-cut the angle joints and re-glue the boards.  Today, I cut the bottom and sides from the three 24 X 4 sheets of Hydrotek.  

The picture on the right shows the bottom piece.  and in the foreground are the folded up tyvek sheets for these large components.  Like most people of the other i550 builders, I just taped them onto the long sheets and used spray paint to outline the appropriate shapes.  After I cut out these shapes, I did a bit of destructive testing on the long angle (8 to 1 I believe) joints made using the scarfing device, with the scraps that were cut off of the long parts.  As I had hoped, in every case the plywood broke on either side of the glued joints.  In fact the joints were so strong that I have delayed reinforcing them with fiberglass.  Really this wasn't a conscious decision - I just ran out of epoxy resin.  However I felt comfortable cutting the components out, without the reinforcement.

To the right is the cradle that I've built to hold the boat during construction. 

Getting Started on Hull 381

Having read just about all of the blogs linked to www.i550class.org and a bunch of the forums on that site and the old one, I'm hoping to avoid some of the mistakes that were made in building the early boats, and only have to deal with my own mistakes.  In any case, I've started with 22 sheets of Meranti Hydrotek and some really beautiful Philippine Mahogany from http://marine-plywood.us/index.htm .   I realize that the plans called for only 19 sheets, but I figured that it was cheaper to buy some extra than to drive back to the lumber yard when I need more.  

the next picture shows sliced and glued Mahogany strips that are going to be used for the keel.  I've followed some of the discussions about using lighter weight materials for the keel, but I figure that I'd rather have some rot resistant material here, and the point is to put heavy stuff in the keel anyway (even though eventually we want most of the weight as low as possible.



Next up is to scarf together 24 ft. of Hydrotek (three times).  I decided to use the West System scarfer to have angled joints rather than just blocking the panels together.  I bought a sheet of moderately priced birch plywood from Home Depot in order to practice making these cuts.