Maths model of Laser

[dbharrison1]

I am currently developing a Mathematical Model of a Laser Sailing Dinghy. The model is a 6 Degree of Freedom model , is written in C++ and is currently running in a reasonably representative way. The data used in the model is however, not very reliable. Lift and Drag coefficients for the sail and for the foils come from a book by C.A. Marchaj who was a researcher at Southampton University and these are reasonably representative but could be improved. Lift & Drag coefficients for the hull are not much more than guesses and I would like to improve them.
If anyone knows where any of these data sets are available for use I would be very grateful to hear.

[RThompson]

Hi there,

There is a graduate thesis on a VPP for a Laser I think by Todd Carrico in 2005

17th Chesapeake Sailing Yacht Symposium
I think he may have done some full scale resistance tests towing behind a power boat or something like that.

hope that helps a little

Rob

[dbharrison1]

Thanks Rob, I will check this out.
Dave

[dbharrison1]

Hi again Rob
I dont suppose you have an Email address for Todd Carrico which you could give me?
Regards
David Harrison

[RThompson]

Hi sorry about the delay in reply,

unfortunately i don't have any more info than what would be on the Cheasapeake website.

How did you go about developing lift and drag for the hull?

Did you adapt some planing hull theory or go from first principles?
Rob

[dbharrison1]

Thanks anyway Rob. i'll try the web-site again.
Hull data in the model is currently pretty much guess work based on just a couple of drag force measurements. The hull is not regarded as a foil at all and uses just longitudinal and lateral drag coefficients together with a rotational damping coefficient. Longitudinal drag is taken as a combination of a square law for viscous drag and a cube law for wave drag with transition to a square law with different coefficient when the boat planes.
None of this includes any provision for variation with roll and pitch attiitude and so is not too much use.
Lift and Drag coefficients for the sail and the foils are better and since the model shows roughly the correct speed in a given wind strength maybe the hull data isnt too bad
The object of the model is really to try to predict boat dynamics, including the way the helmsman keeps the boat upright and pulls on the tiller, rather than to predict planing performance.
Regards
Dave