Tuesday, August 9, 2011

Tuesday, August 9


The class accomplished a lot today. This (and most boats) are constructed on a building frame, which in simplest terms, looks like a wide ladder, turned on its side, with short legs added. So this morning, using construction lumber, we started this phase.

Geoff quickly put together a cut list and various groups, using the chop saw, cut 2x4's, 2x6's, and lighter stock to the correct lengths. Since the 2x6's weren't long enough, two shorter pieces had to be joined using a short overlaying length of 2x6 (butt block). The two long (18+ feet) boards were placed on the floor standing on edge. Shorter 2x6's (think of them as the rungs of a ladder) were then screwed between them. A few 2x4's were then added to the ends to eventually receive the stems. Short legs were added (initially clamped). The whole structure was checked to make sure it was rectangular (instead of rhomboidal) and bracing was added. Careful attention was then paid to leveling the frame and permanently fastening the legs with deck screws. The whole thing was then screwed to the floor.

Next, the flatness of the tops of the long 2x6's was checked and adjusted. Geoff agreed it wouldn't have been a bad idea to run these through the jointer; it would have made life a little easier. We also ran a centerline string from one end of the frame to the other.  To see the sequence of photos showing the construction of the building frame click here

Next we discussed how molds patterns are represented on the plans and various ways of building them.  Photos are here. To make this project feasible in our two week period, Geoff let us use his molds. These are attached at specified “stations” along the two side rails. The plywood molds obviously have two faces; only one, however, is the station face and needs to sit precisely at the station marks. These are screwed to the frame (the have a 2x2 on the bottom edge to allow this), making sure that the centerline string crosses at the vertical centerline of the mold. Next the molds have to be made perfectly vertical using a level and light bracing.

At this point, two of the students took a piece of douglas fir and milled it to the correct specifications for the keelson. The rest of us released the inner and outer fore and aft stems from the jig on which we bent and epoxied them yesterday. Voila! The stems came free, even the double one, on which the outer and inner inner stems were fabricated together, separated by a strip of polyethylene. Next we cleaned them up by running a power planer over the sides and sanded with 36 grit sandpaper glued to a piece of formica (which is a neat sanding block that has the flexibility to conform to the curves). Finally, they were run through the thickness planer to achieve the correct width. Some of us thought that if we did this on our own we would laminate somewhat wider strips to give us a little more leeway in this final shaping. A total of three stems were made: bow (inner and outer), and stern (inner). The stern outer stem will be fabricated from lumber later.   It should be noted that all of the appropriate markings, which are indicated on the jigs, should be carefully transferred to all of the stems.  We had to go back and do this later.

The next step involved beveling the inner edge to the angle specified in the plans. This angle varies along the length, but Geoff gave us a compromise angle for the entire length to make life easier. The bevel was cut with a hand power plane, but some dressing up was done with block planes and spokeshaves.  The inner stems were then dry fitted on the molds along with the newly dimensioned keelson. A line was drawn on each stem where it met the keelson to insure an appropriate landing. This took a lot of adjusting, using the bandsaw, and power and hand planes. When Geoff was satisfied, the stems were screwed to the frame at their tip, and they were adjusted to make sure they landed on the molds at the right point.  As stated earlier the stems had been marked from reference lines while they were still in the jig to give as these calibration points. A few countersunk screws were placed on the stem where it meets the keelson, but only driven in to just touch the keelson. Finally, epoxy was mixed (peanut butter thickness), and was slathered into the space between the stems and keelson. They were  clamped, and the screws driven home.  Click on stem photo sequence and go through it be clicking on "next" from the first photo.

A few other students, working from Geoff's patterns, cut out the floor timbers. These are the structures that run from side to side, stiffen the garboard, and provide a surface for the boards that you actually stand on. These were temporarily fastened to the molds and checked for fit. Once the fit was satisfactory, usually involving a bit of filing (or is it rasping?) with a Nichols #50 rasp.  Click here for photos of this.

Wow! It looks like we're building a boat.


End of the Day Progress

All photos of the Ness Yawl 2011 class may be viewed at: http://www.flickr.com/photos/21597525@N00/collections/72157627358772597/ 



2 comments:

  1. Sounds like fun! Keep up the posts. It will be cool to review the whole process from start to finish. I'm going to check out the Flickr pics now.

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  2. Wow, this sounds really complicated but can't wait to see all the progress! Keep up the good work! Kai sends hugs and kisses to his Pops :)

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