I just want to second Christians recommendations and add a couple of
comments that might be helpful to the mix.
The rudder box does get a lot of torsion stress. Also when the rudder hits
the bottom it will tend to stress the back edge and the lower gudgeon bolts.
Use large washers here if you always launch from a beach..
Christians explanation of wrapping the blade is a good one. I would suggest
that you could substitute some of the carbon for hybrid in the lay-up. The
Kevlar will handle some of the loads the carbon doesn't like. When you are
making it, pad the blade in some packing that is almost as thick as the
packing you finally will use in the box to cushion the blade. I am using the
female part of Velcro. So my packing needs to be about 1/16th thick. The top
part of either the NYC Skiffs Blade (that you make from a foam core) or the
49er blade do not taper so you don't need to worry about not getting it out.
It does help to spray under the plastic with some silicon though. I use
Saran wrap as a parting plastic layer and it tends to get sticky but not
impossible to remove. It is important for feel and loading that the pin of
the rudder is not too far in front of the leading edge, but must have
clearance from the pintles as Christian explains. You could use s-glass
under the braided tube if you make the pintle tube Christians way. It is
also possible to buy some rudder bearing straps that will bend around the
rudder cassette. Look in the APSLTD.com online catalog. BTW, APSLTD.com are
a good alternative source for all your parts needs. For the tiller, using
aluminium (aluminum for the septics) tube (straight only) as a core works
nicely. Aluminium expands if warmed with hot air (e.g. from a hair dryer)
stretching the lay-up. When done, if cooled, it will shrink but the lay-up
wont and you can pull it out with ease. Else use your car jack..
The NYC Skiffs Tiller core is a tapering foam core from 1.5inches to 1 inch
over 42 inches long. You just roll wrap it in hybrid. The core is purposely
cut a little long so you can suit yourself as to how and where you attach it
to the rudder cassette. There are no rules governing where you put it on the
cassette or how you attach it. Whatever looks nice, top middle 2/3 etc.
There are no rules on angle except it needs to clear the transom when fully
turned and also the edges of the rails should be cleared. If you make a foam
core version you can remove the foam to save an ounce (Just kidding).
Greg
USA009 --Rose
----- Original Message -----
From: "Christian Rasmussen" <christian@xxxxxxxxxxxxx>
To: <Aikisu@xxxxxxx>
Cc: <swiftsolo@xxxxxxxxxxxx>
Sent: Sunday, August 29, 2004 7:19 PM
Subject: Re: rudder box
> Yes I have.
>
> Based upon my experience. (Not nessesary what I did)
> I would do the following.
>
> - You need the finished rudder blade. (I used a 49er one, but I dont think
there are any more in the US)
> - Wrap the blade in plastic, or use carpet plus plastic. (Similar to Brams
original centerboard box plans in the Manual) You want about 1/16 -1/8
thickness around the blade.
> - Do one layer of S-glass, 3 layers of Carbon I used layers of 94900
(John R Sweet) Its a 10.9 Oz. Then do a final layer of S-glass for
protection. I think 25oz total carbon is enough.
> - Wrap it up and cover it with peel ply or plastic. Depending on the
finish you want. Hang weights in it, similar to Brams instructions on the
spreaders.
> - Buy a yard of small size carbon sleave. Spray the pindle with silicon
and set it up the sleave. After it dries, you should be able to pull it off.
You will glue this onto the rudder box, but make sure that you have enough
clearance, so that when inserting the blade, it does not hit the gudgeons.
Built up the leading edge of the box with enough carbon/s-glass tape to
avoid this problem. Glue it on there, and fill the void with
resing/woodflour. Then overlay with 3 inch. carbon tape. And finally som
s-glass for protection. Not that this step should probably be done in two
parts, since its hard to hold the pindle "pipe" straight while doing all the
other stuff.
>
> - I made the tiller from wrapping "stuff" around a cober pipe. First one
layer of hybrid, which I was not able to get off, so I cut it, and glued it
back together with resin. Then I used a number of carbon sleaves over this
hibrid tube. I finally filled the thing with a 2 part marine foam. If I had
to do this part again, I would try and find a balsa dovel stick, and use
carbon sleaves over it.
> - Cut the box to size.
> - Send the end of the tiller to comply better with the leading edge of the
box. Then glue it on there. When dry fill/fair it. Then use carbon tape on
all sides.
>
> - Let it dry. Put it between to bricks, and step on it. (Quality control)
>
> Sorry for the crude instructions here. I figured I would put something
together quick. Maybe later I will put some detailed instructions together.
>
> Christian
>
> ----- Original Message -----
> From: Aikisu@xxxxxxx
> Date: Sunday, August 29, 2004 1:06 pm
> Subject: rudder box
>
> > To any builder's,
> >
> > Has anyone built their own rudder box or do we have to purchase
> > these from
> > some vendor.
> > Can anyone tell me the lay-up for the our rudder box. How many
> > layers of what
> > glass. Guide pole length, diameter, it's position and angle.
> > Placement of
> > gudgeon holders. any other tidbits.
> > What I have is. id 9 15/16 x?(1 5/16) od 7 3/4 depth x
> > 10 (?/?
> > )lenght
> >
> > Thanks
> > My best to all.
> > ken
> >
>
>
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>
>
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