Calculating square footage

[jameshogan]

Im trying to calculate square footage of my sport fisher from my paper plans. I need this for estimates for building molds. Anyone know how to do this?

Thanks
James Hogan

[kmorin]

jameshogan, it might be more helpful if you could be just a little more specific about what areas you're trying to calculate- surfaces of the areas for bottom, topsides, decks? 'Molds' as in the term used for a female version of the FRP hull? or 'molds' as the term is used when framing up temporary sections to plank a hull prior to building final frames?

Areas of the waterplane, deck sole, cabin top? I'm not clear from the post's description what you have or need to calculate. Are you working from lines- alone? or do you have in hand full building plans? are you trying to get a hull mold surface area and a deck insert or cabin and foredeck mold's overall surface area? Sorry, I'm not informed enough from the inquiry to form a response.

Cheers,
kmorin

[PAR]

Area is a simple geometry problem. All depends on the shape of the area(s) you need totals for.

Triangle:
1/2 any height x it's base (height is perpendicular distance to opposite vertex or corner).

Irregular Quadrilateral (like a gaff sail):
Divide figure into two areas (corner to corner) and it's the sum of these, using the formula above.

There is a formula for many shapes like; trapezoid, parallelogram, parabola, circle, ellipse, polygon, circular segment or section and probably a few I've forgotten.

More complex shapes can use a few rules such as; Simpson's, Trapezoid or Durand, or you can use a relatively simple device called a planimeter. The math is basic stuff, the rules take some getting use to and the planimeter comes with directions.

This isn't the best venue for math lessons, can you be more specific about what you're trying to figure out?

[lewisboats]

A Planimeter- a tool to measure areas

Steve

[jameshogan]

What I am trying to do is get a price quote for a set of female molds. Hull mold, deck mold and house mold. In order to do so, I was asked "what is the square footage of the yacht?" This I would think this is the hull, topsides/deck, and cabin house surface area.

I have full drawings including lines. The shapes are not regular and I figured it was going to be some type of integral formula to get it correct, at least for the hull section.

Hopefully this is clear now?

[kmorin]

James, its much more clear now, and the simple answer is you can get a very close area approximation using the body plan half girths by station combined in either Simpson's, Trapazoidal, or Durand rules, as mentioned by PAR, above.

In the event your shapes are so radical that a 0-10 station table won't catch the intricasies of your design's surface; decrease the common intervals to move closely follow the area changes.

Cheers,
kmorin