Sunday, December 02, 2018

First steps for the new design

Today I modified the previous drawings for the 14 guide boat frames (2 each of 7 different shapes) and made an estimate of how much lumber will be required.  I want the frames to be 1/2" thick and will need some 1" to 2" wide pieces to bond and trim into the required shapes.  I already have a 12' x 7 1/4" x 1/2" beautiful piece for the plank keel which required some careful trimming to remove a slight curve.  My full-size drawings of the frames, keel ends, and plank keel were made on rosin paper.  I like that the rosin paper comes in three-foot wide rolls and is fairly strong and stiff.  I think I may want something even stiffer when I make patterns for the planking.  I just discovered a new candidate for patterns- Ram Board, it is stiffer, smoother, and has a lighter color (so pencil lines show up better), but it is also more expensive.

Once I get the frames almost done, I will be looking for material for the ends and for the battens at chines and sheer.  Sheathing decision will wait; I can always use thin plywood, but would like to incorporate some solid but thin planking.  I just need to see what will take the required curvatures.  With developable hull surfaces, many options exist for sheathing it.

Below is a print out of the essential dimensions for a slightly revised guide boat.  The previous published dimensions will produce a good result with a few less details, but I made a small revision, creating one more chine, to create a smoother, more refined, visual shape.

The blemish on the photo is due to an internal "floater" in the camera.  The numbers are still legible, but I may be looking for a new camera.

Below is a drawing of several stations in the series of cross-sectional frames for the new hull shape.  As you can see, adding an additional chine allows a more rounded hull shape.

One of the advantages of this design is the low seating position it provides; occupants are seated very close to the level of the 4" waterline.  This provides great ultimate stability.  The level of the oarlocks has to be coordinated with the level of seating; thus, the low seating position also facilitates less required freeboard and a lighter hull .  I have started cutting out pieces for the future frames but won't post an pictures until things start being joined together.