Friday, December 6, 2013

Own IOM design

After the jif, angel dust rg65s.
An IOM is coming:
This is the first model of the IOM project. The plan is to get the boat on the water in spring and learn about the class. The goal is to attend some international events in the second half of 2015.

About the model,
The hull is designed around a Dave Creed keel finn&bulb, for starters a Creed build rudder will be used.
Jelacic 3D moulded sails will provide the power.

The hull is a low wetted surface design, with a beam of 22,5 cm. Designed with the all popular tumblehome, to reduce the hull area(and weight), but complicate building :(.
It is not a copy of a britpop or fraktal but is designed with a philosophy of it's own.

Chines are soft to reduce drag, the tumblehome is the most extreme around the middle of the boat, lenght-wise, because this is theoretically the part of the hull that provides the most "grip" = reducing leeway.
Also this is the part of the hull where the depression of the waves made by the hull is the deepest so wetted surface area will be reduced when the boat is pressed down-wind(where there is no sinkage and the depression is at its deepest)

The waterline is very narrow at stern, to promote light air performance and shape the waterline into an asymetric wing when heeled, combined with round forward sections this shape should make the hull happy to change direcion.

The finn is quite far forward at midship(centre fo the finn), to insure directional stability in caotic conditions downwind and stable upwind(foil wise).

The above combination should give a boat that feels stable directionally but is happy to manouver when needed.

The hull has lots of reserve volume above the static waterlines, to stay above the waves.
The freeboard goes to a  minimum at stern to reduce hull-weight(also potential windage, but due to the wind gradient i think that there is practically none).
The deck will be flat to make the boat simple. For sheeting an arm servo will be used mounted behind the finn, corrector weights will be placed around the finn-but the final placement s a mater of experimentation.