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Mike Seibert
11-17-2016, 09:06 PM
This is a message to J. Madison, Senior Member.

I just ran across a thread from 2013 discussing Herreshoff lines and plans. In that thread, you indicated that your roommate had the plans for a BB 15 and was planning on building one. I was wondering if that has happened yet? If there is a build in progress, I would love to learn about that . . .

I too have the drawings and other materials that I got a couple of years ago from MIT, and dream about building one. It appears that each frame may have a series of measurements in a kind of workbook, but so far I haven't been able to break the code. I would appreciate guidance on how to understand the notations in the workbook.

Thanks, Mike

BBSebens
11-17-2016, 09:46 PM
You might be better served sending him a private message.

rbgarr
11-17-2016, 10:36 PM
Contact the Herreshoff Museum for guidance on reading the offset booklet, which may be what your 'workbook' is.

WI-Tom
11-18-2016, 07:51 AM
It appears that each frame may have a series of measurements in a kind of workbook, but so far I haven't been able to break the code. I would appreciate guidance on how to understand the notations in the workbook.

Thanks, Mike

Sounds like a table of offsets. HERE (http://bateau2.com/howto/foam4.php) is an example and basic explanation of how that works.

Basically, the table gives a set of coordinates for a number of "slices" through the hull--and each "slice" becomes a temporary building mold or frame giving the shape of the hull for planking. So every set of numbers in the table gives you either a height or a half breadth (half the width of the boat at that point). Half breadth is measured from the centerline. Heights are measured (in the example linked above) up starting from waterline 1 (WL1). Other designs might measure up from the keel--but there will be a reference point used to measure all heights.

Traditional offsets are given in feet-inches-eighths, with a + or - indicating an additional 1/16". So, 1-9-4 is 1' 9 1/2", etc.

Does that sound like what you have?

Tom

Mike Seibert
11-18-2016, 11:44 AM
In the materials I got from MIT, I don't have a table of offsets in the traditional sense. I have two pages of drawings that give me lots of info, but no offsets. However, the drawings include a ruler, and indicate that 1 inch is equal to 1 ft on the drawing, so I can get close to the offsets for the bottom and sheer from the profile, etc.

The drawings provide five waterlines for reference, with the load water line labeled Waterline # 3. They also provide three lines that appear to be diagonals, but that is just a guess because I haven't worked with diagonals in lofting yet.

And then there is the workbook. It is arranged with a set of notations that appear to correlate to the Frame numbers. For example, here is what the workbook looks like for # 14:

4.1.0 2.11.4 (I assumed this is the sheer)
4 2.11.4
3.6 2.11.0 1/2
3 2.9.0
2.7 2.6.7 1/2
2.6 2.3.4
2.2 1.9.7 1/2
2 1.1.6
1.9 0.3.7
1.8.0 1/2 0.1.0 1/2 (there is a letter "R" to the left of this notation)
1.7.6 0.0.0 (I assumed this is the bottom height at the CL)

Today I made an attempt to loft those notations, using the left column as the height and the right column as the half-breadth from the CL. It worked pretty well . . . the points I lofted gave me a general hull shape . . . In addition, four of the points landed on Waterlines 2-5, which was comforting. However, a couple of the points were off and I don't know why. But, when I skip the points that are obviously off, the hull shape looks very much like the drawings.

The BB 15 has 36 frames in the space of a 24'10" boat, which I assume will need to be lofted individually and then plotted together to get the overall hull shape. I am tempted to loft one out of every 4-5 frames and to plot the general shape of the boat from them. I am also beginning to think that I would like to cold mold this hull with a layer of strip planking inside of a couple of layers of cedar veneer. I understand that you don't need nearly as many frames for a cold molded hull, and wonder if 12 frames spaced about 2 ft apart would be enough?

Mike

Mike Seibert
11-18-2016, 11:53 AM
I tried to edit the above post . . . the notations in the workbook don't reflect the spacing that I tried to put in there . . .
The left column is: 4.1.0, 4, 3.6, 3, 2.9, 2.6, 2.2, 2, 1.9, 1.8.0 1/2, and 1.7.6. And I believe these are heights above the base line.
The right column goes: 2.11.4, 2.11.4, 2.11.0 1/2, etc.

Hope this helps,

Mike