Lofting - 4.Angled Flat Transom

Tramsom is the surface that forms the stern of a vessel to which outboard could be attached to. Until now, we built all the hull except transom.

This time we draw 10 degree flat angled transom.
Before we go on 10 degree angled transom, we have to check the characteristics of 575mm Trammel Arm.

Length between the center of the hole to another is 575mm. If you draw a cirlce with 100mm radius on the othe end of hole and draw a line from the center of the other hole to the tangent of the circle, then, its angle is 10 degree.
With same logic, line to the tangent of 120R cirlce makes 12 degree angle, 200R makes 20 degree angle.

Now, with Trammel Arm(575mm, length between the center of the holes), you could make 10 degree angled line.


1.Drawing New Grid Line for Tramsom(Half)
First to draw a Tramsom is to draw Grid Lines for it. Before you draw Grid Lines for Trasom, if there's no space for it, you attach a piece of paper to it.

* With 575mm Trammel Arm, Draw outer transom line with 10 degree.
* Draw a line which is parallel to the 10 degree transom line, this will be the Center Line for the Tramsom. Then, draw buttock lines which are parallel to the Center Line.
* And now we have intersects between Transom and all the lines in Profile. Draw lines from all the intersects, which are perpendicular to the Transom(or Transom or all the buttock,,the same.)
* Now, Grid Line for Tramsom is completed.


2.Defining Beam(Width) of Tramsom.

* Now it's time to use Tick Stick(Pick-Up stick) again.
* In Profile View, using Tick Stick, measure the distance from AP to each intersect between Tramsom and all the lines in Profile. Then, mark the value on each line in Half Breadth.
For example, if you measure the distance between AP and WL200 intersect, then, mark it on WL200 in Half Breadth.
* When you measure the distance(mark it on the stick), it should be perpendicular to the FP.
* B200 and LWL were so close to each other, it just looks the same, but it is not.
* Then draw a fair line connecting all the marks in Half Breadth. This one has a chine, make sure that you draw the line separately.(Once from an end to chine, then, chine to the other end, or not, it's impossible to draw the line,,no batten for the stiff angle.)
* Then we get the fair line as below.

3. Drawing Beam
From the fair line in Half Breadth above, we could get the value of Beam(Width) of each point(line). So we mark it the Tramsom Grid line as below.

Draw fair line connecting all the marks above then, we will have transom as below.

Now we have the transom but it's not done yet. What we did is the shape of transome outside. Since transome is a plank with thickness, it has thickness and bevel. So we have to draw it too.

4. Transom PT
We will make a Tramsom with 30mm thickness, so draw a line which is parallel to the 10 degree tramsome line with 30mm difference inside as below.

Then, it's the same as we did before. We have another tramsom line(inside) and thus, new intersects and new grid lines.
So all we have to do is do the things all the way again with those new transom and intersects.

Cheers.