Need help, Sailing side force & heel drag ratio!

[GuestR01312011]

Hi I have an exam in two weeks and need a bit of help regarding Sailing Side Force and heel drag ratios, and would really appreciate some info.

What I though was the heel drag ratio was the ratio of the drag when the model is heeled to that when it is upright, is this correct?
I am given a table of tank test data of, Side Force and Drag at 0 degrees Heel and 0 leeway and then 3 readings at 20 degrees heel on both tacks with different leeways (0,2,3 degrees) and need to get the heel drag ratio, is my method correct?

Also is sailing side force just the side force generated due to the leeway? Or is there one value for all speeds?

Thanks a million!

[Guillermo]

When you say 'sailing side force' you mean the side force generated by the wetted hull+appendages when under way? Is it possible to have side force at all at 0º heel and 0º leeway for simmetrical hull+appendages?

Heel and leeway create two different components of resistance, what are usually known as 'heel resistance' and 'induced resistance' respectively. You're probably looking for what fraction of the total resistance of hull at 0º heel and 0º leeway is the sum of the two. Is it so?

Cheers.

[GuestR01312011]

Thanks for the reply, I figured it out. The sailing side force was the side force generated by heel and leeway at one point of sailing for a certain heel moment. And the ratio is correct I just wasnt sure of the method to extrapolate it off the plot.