Are you good at Trigonometry ?

I am not !


But it sure looks like some kind of a dificult trigonometry experiment...

Actually, I just applied wht Josh-Shazza told me to do to find the exact location of the chainplates. It works perfectly. Thanks dude.

Ben-Booger also helped me out with another way of finding the angle but since I am going for the same alu rig as the Aussies, I decided to got with the exact same angle for the chain plates and therefore the same method to place them.

If you carefully look at the picture , you will get what this method is all about. It is really straightforward for a 22,5 degrees angle.






First of all you should have a staight and plumbed F89 set at 90 angle from your boat CL. Thanks God mine was...!


1-I placed a string across the boat from stem to stern.That is the pink string on the photo.

2-I dropped a plumb right in the center of F89 where the compression post will be. That gave me an intersection with the pink center line string.

3-From that intersection (which was squared vertically, plumb /CL) I projected a 90 degree angle onto the side of the boat. That hit the inner edge of F89. I marked that point and measured the distance to the center line string.

4-I measured the exact same distance from the intersection point on my CL string. By doing so I was now with 2 sides of a perfectly leveled square.

5-I then pulled a string from those two points to "draw" a 90 degree triangle.

6-Marked that string right at its center and pulled another string from the squared angle, passing on that mark ang going all the way to the sheer clamp. My 90 degree angle triangle was now divided into 2 equals 45 degree triangles.

7-I divided that triangle once more using the same method, pulled it all the way the the sheer clamp and ended up with a line at exactly 22,5 degrees from compression post.

Et voila !

I now it sounds a bit complicated but that is because I suck at explaining ! Josh email to me was much clearer.
Anyways, it is easy and since a picture is worth a thousand words, I will say no more....






















Maybe just a last one : I did exactly the same thing for the other side. Then, just to check how symetrical my hull is, I measured the distance from bow to chain plate gusset mark on on side and compared it to the distance on the other side. Spot on ! I could not be happier !!!