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LOFTING

Many people get quite nervous at the thought of lofting. However although it is important to get it right it is not as difficult as it seems at first sight. The most important thing is relax, and take your time. Double check everything, and you should have no problem.

First Question is probably what is lofting. Lofting is the process of converting a small diagram and instructions in your plans into a full size diagram on your plywood that you can cut out. It is done because with inexpesive plans such as the weekender it is not practical to send full size diagrams of the components for you to cut out.

Okay how to loft. Take a look at the diagram below, and we'll walk through how we would loft this diagram.


1. First we would have to draw the CenterLine. This is generally drawn in the center of the plywood or board. It is usually parrallel to the longer edge of the plywood sheet. However read the plans carefully to determine where this line goes. The center line is also called the reference line.

2. Next we have to draw the Station Line. These line are drawn at a 90 degree angle from the center line. This are NORMALLY drawn 12 inches apart. Each station line is given a number so if you ever hear of a problem in lofting at station 13 then you know the problem is at that station line. Another thing to watch is that the first station line is not always at the edge of the board you are lofting. Study the diagram and instructions carefully.

3. On each station line you will see a measurement. These are the Offset Dimensions. You carefully measure away from the center line the distance of the measurement and put a mark in this spot. Once you have done this at all the points double check everything. This is one job where it pays to be paranoid.

4. Put a small nail at each point where the offsets are marked on the station lines. Then you use a batten (usually a 3/4"x3/4" stringer) to mark the curve. You do this by placing the stringer against the nails from the inside of the curve. Push the batten against the nails. Mark the curve by drawing along the batten. You will probably need someone to hold the batten while you draw. If alone you can use a second small nail at each point to hold the batton in place. The curve when lofting should be smooth. If it is not you may have to move a nail a very small amount. If the nail has to be moved more then 1/4" look for a error in your lofting. For tight curves you can use a metal ruler or a thin batten. I've used pieces of cardboard for very small sharp curves. The best way to check the smoothness of a curve is too put your eye close to the surface near one end of the curve.


LINKS


DUDLEY DIX YACHT DESIGN(THE CASE FOR LOFTING) -A comprehesive page detailing lofting. It may be a bit advanced for the flat bottum boats that are detailed in this site. Still worth a look. It is the first of three pages. You have to pay to see the other two pages.

Sailing with Kathleen McKoon-Hennick (Lofting) -Not a lot of information, but worth a quick read.


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