Monday, March 8, 2010

Shaping the daggerboard, rudder design dilemma

Today and yesterday I spend predominantly tackling my nemesis, the daggerboard and it's subsequent shaping.  For some reason I have held a slight amount of apprehensiveness towards working the rudder and the daggerboard, I don't know why, but I get the sneaky suspicion that they don't like me, and I don't like them, and we're going to fight.  Meanwhile, my Goat Island Skiff languishes in the garage waiting for a rudder, waiting for gudgeons, waiting for the rear seat to be glued down, etc etc etc, as I suspiciously eye the squared off blanks that will be my blades.  See the previous post to view the blanks.

A disclaimer:  You will notice SUN in these pics.  The garage doors are OPEN for the first time months!  It hit 50 F. deg. here at the homestead, the first time in months and months.  I worked without a hat or jacket!  It was nice indeed.  

First, using the template included in the plans I kind of traced the shape of the foil onto the blank.  I roughed it, because I would use the template later to match the shape correctly.  Then, the first pass on the plane down the trailing edge side... and away we went.  Remember that the trailing and leading edges are cherry, a hardwood.  I sharpened my planes before this project and also during when I would swap sides.  It made my life much, much easier.


As time progressed, I slowly worked inward, taking off the wood and feeling the idea of the shape rather than mechanically proceeding.  It's kind of difficult to explain, but I knew the shape I was going for and went for it, with checks to the rough outline to keep me true.


As the planing progress, I would check my jig for appropriate foil shape.  Here, I have achieved the desired shape, OOF!

Now, I will be the first to tell you that the entire blade doesn't necessarily have this nice of a fit the entire time.  It is, however, close enough for this amateur! We all build to our own goals.  The foil shape I got is very even, nice, and for all purposes close enough without whacking out a giant mistake and having to start over... something I definitely do not want to do since the cedar in these blanks cost me a pretty penny indeed.
The blades were notched on the trailing edge per the plans.  On retrospect,  I could have probably left them how they were because it just made for a more complicated shaping project.  I wanted to keep the shape of the foil through the transition to the end of the blade, and therefor got this kind of neat compound curve (see below).  It worked, but it almost didn't, and for a few moments I thought I had taken off too much and really screwed myself.  Also, this is a good spot to let the reader know about the trailing edge width.  It's supposed to be squared off, but I didn't know how wide.  A quick journey over to my compatriot in CA gave me the answer.  He had finished his blade to 3/8", mine was 1/4".  Apparently, it's supposed to go to about 1-2mm, or a 1/16".  HA HA HA  Sorry, I got mine down to 1/8" and I'm very very pleased with that.  Again, I don't want to risk breaking through the back of the board, I'm looking for durability, and the alignment of the centerboard trunk with the hull will make more difference than the 1/8" I'm off.  I'm not saying you can't go to 1/16", I just didn't want to.

The leading edge was next.  I took off a 45 deg. edge first, and then added subsequent degrees from there, until I got a nice rounded leading edge.  It worked out very well, and with a sharp plane, the work was precise and enjoyable.


I still have to sand everything down, cut off the top, and get things nice and smooth, but the blank is now shaped and I have a daggerboard worthy of some sort of aero-hydro-dynamic performance.  It's not perfect, but I'm happy with it.


Next up is the rudder.  This is important because I'm waiting on several other issues until I finish the rudder.  First and foremost is answering the question if I'm going to go with Storer's design on the rudderbox.  I am not a fan of it.  First:  The rudder is never permanently attached to it, it slides up and down the box with no rear, bungee cords hold it in place  I don't like bungee cords, the degrade in UV and salt, and I'm not interested in having to replace parts like this.  Second and most importantly, the box and the tiller are permanently attached, which means I can't remove the tiller without removing the rudder and the box from the transom (now I have to put them somewhere-- think sleeping aboard).  I could design some sort of device that folds the tiller up, but then it gets in the way of a theoretical boom tent or something else, or it comes crashing down in the middle of the night on my head.  No thanks.  Give me a tiller that dismounts from the box, so I can throw it on the floor.  Third, with a permanently attached tiller-to-box, I will either have to enlarge the hole in the transom to use the pintles and gudgeons I want to use, or use Storer's suggestion which is two gudgeons on top of each other with a pin running between all them.  I have spent more than enough time struggling with rudders and bizarre attachments that I know, in waves, with current, with wind, it's going to be a total pain in the ass trying to thread a needle through a million holes (of course the rudder wouldn't be attached which might make it easier).

Anyway, call me a curmudgeon, but I'm not a fan of the back-less, bungee cord, permanent tiller design.  I may have to come up with something else.

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