Blue Mistress has a very heavy rudder – “overworked”, the marine surveyor called it.
It might have graced the stern of an early twentieth century vessel.
Compared to similar sized craft, it is also slightly short of the keel . . .
For example, another Folksong 26 . . .
a Folkboat . . .
a Contessa 26** . . .
This may mean that Blue Mistress’ rudder has been repaired sometime in the past, but it may not . . .
So, I’m looking for the answers to three questions:
What is the effect of a heavy rudder on the sailing performance of a long-keeled boat?
What is the effect of a shorter rudder on the sailing performance of a long-keeled boat?
What is the effect of rudder shape on the sailing performance of a long-keeled boat?
A younger me would have searched for a definitive answer.
Now I don’t think there is one answer – but a series of ideas about rudders that, put together, mean we can learn more about small, long-keeled boats.
For example, a Google search showed the Swedish Folkboat Association having a useful note on this – here.
In their submission to the Nordic International Folkboat Association, they state: “We have consulted Lars Larsson, professor in hydrodynamics on Chalmers (Gothenburg’s technical university), folkboat sailor, and earlier three times Swedish Champion in Folkboats. He thinks that the lifting power 10 kg has a moderate effect – the same as if the whole crew (250 kg) moves 0.1 m forwards in the boat. Hydrodynamically it can be a favour to make the rudder a little thicker, so that the water follows a harmonic bend along the keel and rudder on the boats windward side when it tacks with a rudder angel of about 5 degrees ( to prevent the boat from turning up against the wind). The shape of the leeward side is of less importance. To make an even thicker rudder is a disadvantage hydrodynamically.”
The Association then dealt with it in a formal fashion, i.e. there is a revised class rule to be adhered to – here.
Fair enough. But here are no class rules with a Folksong 26, so we have some leeway, which means we can work it out for ourselves . . . with a little help from friends.
If you have answers, part answers – or even more questions, please feel free to comment..
**(I am very grateful to Nick for allowing me to use this picture of Constellation. I enjoy his blog and highly recommend following and supporting his venture back to Australia on Big Oceans/Tiny Boat)