Ruddy Rudders

[EASLOOP]

I am going to start on the project of building a new rudder for my East Anglian sloop.
I can source two lengths of oak, 12" wide x 2.5" thick by 10' long. Fastened together will produce a single plank of 24" wide from which I will cut out the rudder shape taken from the existing rudder. However, the below water rudder section needs to be tapered toward the trailing edge so as to reduce turbulence and, no doubt, weight.

With only DIY pwer tools including a planer, belt sander etc. how can I be sure to shape this section without going awry and ending up with an unbalanced uneven mess?

I would appreciate comments from anyone with ideas.

rgds
John

 

[Captain Coochie]

I would mark my shape on both ends and run a router or a saw across on a straight edge down to my depth of cut , do this a few times untill you have cuts marking out your shape . Then you can treat each bit a seperate section and plane/sand down to your cut .
Easy innit /forums/images/graemlins/grin.gif

 

[Peterduck]

I would not be using a straightedge as Seaspray advocates, but tracing out the desired hydrofoil shape on a batten which is half the thickness of the rudder. Cut this batten to the profile, and screw it to the rudder [either parallel to the waterline or at right angles to the leading edge] at the appropriate place. Then as Seaspray says, it is easy to cut alongside the batten and achieve the profile that you want. These saw cuts then become 'witness marks' for the shaping by electric plane. This profile will change with the changing chord of the rudder, so the batten will have to be reshaped as you work your way along the rudder. A couple of other thoughts on rudder shape: many rudders can be seen which are widest at the waterline, and taper to the heel. Thus there is the least rudder where the water is densest and most effective. Have a think about having the widest chord at the heel and tapering up to the waterline. A straight trailing edge would allow you to incorporate a trim tab in the rudder, which in turn would make the installation of self-steering a lot easier. L. Francis Herreshoff advocated a groove all the way down the trailing edge to increase sensitivity of the rudder. I don't know how it works, but it seems one of those odd things that don't make sense but do work.
Peter.

 

[EASLOOP]

Thanks for input. I may not have explaied very well bit the rudder 'hydrofoil' is 2.5" thick at the pivot edge sloping down to 1.5" thicj at the trailing edge. So stock has to be removed leaving a smooth wedge shape profile. But sitting here reading your input and thinking it dawned on me that what I am actually doing is planing a very large scarf but from both sides. Problem solved I think.
Thanks for input

John

John Bowden

John B

Sails a sloop

The sloop John B

or does someone already have that handle ???

 

[cliff]

[ QUOTE ]


John

John Bowden

John B

Sails a sloop

The sloop John B

or does someone already have that handle ???

[/ QUOTE ]

JOHN B WCA4916 366518020 USA

JOHN B .... 316001563 CAN

JOHN B FGA9213 F

JOHN B EI7280 250101800 250EI7280 IRL

JOHN B MXUY5 G

5 for the record /forums/images/graemlins/frown.gif
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"Artificial intelligence is no match for natural stupidity"

 

[EASLOOP]

Bummer!

 

[cliff]

You could always call her "John B of Hamble" or John B of Solent" /forums/images/graemlins/grin.gif /forums/images/graemlins/wink.gif
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"Artificial intelligence is no match for natural stupidity"