Lines

[Raykenn]

I need a little help. I think I am at the stage that I don't see the forest for the trees.

I am working on developing a set of lines for a small powerboat. My problem is the "communication" between the section, profile and plan views. Everything measures out correctly except where the chine crosses the DWL. At this location, I end up with about a 1 - 2" variation between the three.

Any suggestions on how I should work out the devience? I have tried using each view seperately as the baseline to compare with and though I am able to lessen the variation, it's still there.

Thanks in advance.

Raykenn -

[SailDesign]

A-Hah! The curse strikes again. This is what really bugged me at first (about 40 years ago), and is what really persuaded me to take this cr*p up for a living. I just couldn't bear to not know how this worked......
The only way out is to ignore the sections until you have the "long" lines worked out. Draw the "perfect" chine line, centreline and sheerline in plan and in profile, then draw sections and see how they look. If tweaking is required, tweak the long lines, and redraw the sections. This way you will be sure that everything will match.
WARNING - this only works with chined hulls - round hulls need a different mojo....

Enjoy - Steve

[gonzo]

I agree. You select a line and make the rest work to it. Going back and forth between lines is normal. However, your section may show that the chine that looks great in profile doesn't work too well. If you want to keep the chine as it is, it may be necessary to change the keel or sheer. It goes around and around

[SailDesign]

Gonzo says:
>It goes around and around

That's why it's called the "Design Spiral" The problem is that sometimes you are going out on the spiral, when you are supposed to be going in. ;-)
Steve

I agree.
Remember that the stem is the result of the long lines. You don't draw the stem in profile, it resolves from the sheer, diagonals and waterlines. If the stem resolves in a way that you don't like, change the long lines just as if you were building the boat stick by stick.