Dingy design - Basics

[johnneale]

Whats the formula for the ratios between the sail area, daggerboard and rudder for a 8' dingy

e.g if I have a 20sq ft sail area, what is the xxx area for the daggerboard, and yyy for the rudder.

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[Seanick]

a bit less than a Mirror?

 

[lw395]

I don't think there are fixed ratios but 20sqft sounds too small.
The slower the boat, the less efficient the foils, so maybe need to be proportionally bigger than you first think.

 

[Bajansailor]

Here are a few dinghies of similar size which you could use as a guide :

A couple of Phil Bolger designs :
http://www.instantboats.com/nymph.htm
http://www.instantboats.com/epunt.htm

The 8' Catspaw in this link http://www.bandbyachtdesigns.com/cpaw.htm has 36 sq.ft of sail area.


Here is a b-log with a detailed account of building an Oughtred pram dinghy - no dimensions as such, but you could maybe get some ideas re daggerboard etc from the photos (?)
http://bumbleoflochdubh.blogspot.com/

And some dinghies by Dudley Dix :
http://www.dixdesign.com/dinghies.htm