inflatable boat drafting help

[hardchina]

Hi all, I'm looking for help with drawing some paper plans for an inflatable boat.

 

the problem i have is working out the curves for a tube mitre joint, that can be drawn on a 2d pattern that relates to its 3d shape- is there an easy mathematical formula for drafting this?

 

I'm really bad at explaining things so have taken a couple of pics....

 

 

the cut in this pic below is an s shape, doesn't show up well.

 

when in 3d the cut is a perfect straight line.

 

the only method i can think of is to use a 3d template (piece of pipe) cut to the required angle and mark out the fabric in its inflated state.

 

Cheers

Simon

[psychlone]

Yes, there is an easy mathematical equation. Here are 3 hints!

 

1. First, though your shape is 3D, the template to create the 3D shape is still only a 2D template.

 

2. Think more in terms of geometry.

 

3. Also, try and think about using sine or cosine functions to determine the 2D template’s shape.