Joel White Flatfish 20'3"

[andy81563]

Has anyone here built a JW Flatfish 20'3"? I am starting one and working on the lofting and had a question or two.

Thanks

[113bob]

Re: Joel White Flatfish 20'3"

I built a Flatfish. The lofting was a few years ago, but I'm happy to help if I can.

Bob

[andy81563]

Re: Joel White Flatfish 20'3"

I built a Flatfish. The lofting was a few years ago, but I'm happy to help if I can.

Bob

Bob,

Thank you for your reply.
Admittedly, this is my first attempt at lofting, but I understand the process and have gotten the profile and half-breadth lines faired. However, in doing the body plan, I am struggling. Do you lay it out from the table of offsets or use the already-faired profile and half-breadths to do it?
Also, in the table, what he refers to as the “profile” is that the same as the bottom of the keel, face of stem, etc?

Many thanks,
Andy

[jpatrick]

Re: Joel White Flatfish 20'3"

Andy... lofting pretty much any boat is the same process. So if you post some photos and share the build I'm sure many of the experienced will be happy to help. I, for one, would love to watch the build of this boat.

Jeff

[Jon Etheredge]

Re: Joel White Flatfish 20'3"

Bob,
...in doing the body plan, I am struggling. Do you lay it out from the table of offsets or use the already-faired profile and half-breadths to do it?
Also, in the table, what he refers to as the “profile” is that the same as the bottom of the keel, face of stem, etc?

Pick up the dimensions for the body plan from the lines you have already drawn. This gives you further opportunity to check if the lines are actually fair. If one of the curves has a kink in the body plan then you will need to decide where to change the line (which view/views) to give a smooth curve in all views at the same time. That is the process of fairing the lines.

As to what point is being referred to as the profile in the table of offsets, you will need to figure that out by looking at the drawings. If the lines are to the outside of planking then the "profile" might be the rabbet line (the intersection of the outside of the planking and the backbone). Or the "profile" might be a line that is not on the planking at all and is instead the outside of the backbone members (keel, stem, etc.). I don't think there is one single correct answer to this question. Some designers will use "profile" one way and another designer may use it differently.

[113bob]

Re: Joel White Flatfish 20'3"

Andy,

The answer to both your questions is yes. By that I mean you want to draw the body plan from the lines you've already faired while checking the table of offsets as well. The goal is to end up with all lines fair and in agreement, so don'ttry to stick to the table of offsets at the expense of a fair line.
Keep in mind that the boat wasn't designed from the table of offsets. It was created by scaling from the lines plans that the designer drew. That's why you'll find some discrepancies. Scaling dimensions from a hand drawn pencil line is really tough - especially if you're looking for eighths of an inch...

And yes, you are correct about what "Profile" means on the Flatfish drawings - it's the outline - the farthest line from the construction base line.

Bob

[andy81563]

Re: Joel White Flatfish 20'3"

This is a shot of the body plan portion of the drawing. Does anyone know what the dashed line and the statement "curve of areas..." mean?

Thanks,

Andy

IMG_2138.jpg

[nrs5000]

Re: Joel White Flatfish 20'3"

The curve of areas plots the areas described by each station.

[andy81563]

Re: Joel White Flatfish 20'3"

Ok, gotcha. So, what is that nomenclature; 1”= ?

[nrs5000]

Re: Joel White Flatfish 20'3"

It looks like 1 square something, which stands to reason since it is expressing an area. Measure up one of the nearly triangular sections forward (#2 or #4) for approximate area and see if you can back into the units.

[Rob Hazard]

Re: Joel White Flatfish 20'3"

I think the Curve of Areas is useful to the designer as a means of assessing the shape of the hull for predicting performance, but it's not a line that you need to loft for the purpose of building the boat.

[andy81563]

Re: Joel White Flatfish 20'3"

Thank you for these responses. I am slowly working out my lofting issues, realizing that all the information I need is somewhere on the drawings.

Andy

[nrs5000]

Re: Joel White Flatfish 20'3"

Do you have a good reference book, such as Vaitses's book "Lofting" or Bud Macintosh's How to Build a Wooden Boat?

[andy81563]

Re: Joel White Flatfish 20'3"

Yessir, I have Macintosh's book and Greg Rossel's book.

[andy81563]

Re: Joel White Flatfish 20'3"

In this design, all dimensions in the table of offsets are to the outside of the plank. I realize that the thickness of the plank (5/8" in this case) must taken into account when making the station molds. But, what about the ribbands? Should the molds reflect the ribband thickness also? It seems like somewhere I have seen someone cutting notches in the mold outer profile to accept the ribband.