Thursday 3 June 2010

Daggerboard

I started the daggerboard about 18 months ago, but gave up on it for a while, partly because it is rather tedious and partly because I was not sure how to maintain the correct profile up and down the board. The core is shaped from Western Red Cedar. Once you have started shaping, there is very little in the way of refference points to keep you on track.

I removed as much material as possible using a router, but this is a bit limited as you get up to the non shaped area. The only refference point I really have is a good center line up and down each side .I thought if I could get the correct profile (at the right angle) on the leading edge and trailing edge, this would at least be a start.

The shape is on a sliding piece of wood that should hold it perpendicular to the side and on the center line aadn at the correct angle..




The trailing edge is straight for about the last  12 inches which is  easy to shape.

When I started the daggerboard, I did not know that it was possible to buy a ready made blank, (Phill's Foils,or I think I would have gone for that.option. I had already bought the wood and glued up the board, so I thought I might as well try and finish it. The only plus side is that as the wood has been indoors for about 18 months, it is very well seasoned and lighter now than when I left it before.

I found an interesting article about designing and making foils here: http://www.gurit.com/core/core_picker/download.asp?documenttable=libraryfiles&id=1113 , actually from SP systems who manufacture the Ampreg resin I am using. It seems that for the stiffest board with minimum tip deflection, carbon UD either side of the board is the way to go.


Laminating the Carbon, centered on the widest part of the foil shape. I wish that I had sealed of the wood first as I had some bubble trouble under the UD. Before laminating the rest of the board I sealed the wood off with 2 coats of resin, and this put a stop to that.


 To avoid any distortion across the tressels I stood the board on its side before the Carbon UD layers were fully set, and did the same with the glass layers.

The trailing edge is very thin and prone to damage. (especially on the undersized blank.) I think it would only take a small ding on this edge,  and there would be wood and water contact.  To avoid this I replaced 2 inches of the trailing edge with a HD putty mix.


 I would have liked to have done the same on the leading edge, but I should really have done this before shaping. To compensate a bit I have arranged it so that there are 2 layers of glass over the leading edge and also over the tip.




Wrapping the board up.


Board glassed all over. The shape is not yet 100%, but I thought it was best to get the Carbon and glass on first and then do the final tweaking. I am pretty sure that it is a little undersize, and will need a bit of filling and fairing to perfect the shape. Weight wise I reckon it must be in the 18/ 20Kg area. I can just about lift it on and off the tressels on my own.


Sealed holes for the pull up/down lines

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