Footy design – Freeship V

Improved, but is far from being acceptable.

We need improve the sections forward to have a better entrance, the side aft need be improved to have better inclined hull symmetry.

But this is another phase. Let’s  see the calculations.

When the hull heel, the draft normally diminish. I tried to see some times the calculation and diminishing the draft in the menu Project –> Project settings I arrived to a 2.9 m inclined draft that give us the 600 tonnes needed, the result is:

  1. Let compare with the same hull upright:

                                                                    inclined            upright

Total length of submerged  body –        29.729 m       34.688 m

Prismatic coefficient –                             0.5864 m        0.5769 m

Wetted Surface Area –                            484.79 m2      351.27 m2

Longitudinal Center of buoyancy –     16.818 m          16.868 m

Waterplane Center of flotation –          16.809 m       16.408 m

The inclined length is very  diminished, this is  caused by the new draft that is more lower.

The prismatic coefficient is a little more hight what is good because if the hull is heeled is because the wind is more strong and the velocity potential is more hight when a more hight Cp is adequate.

The wetted surface area value is some strange, I do not know if it is because we have mirrored the boat, in this case the right value is the half. Is my first time using the software in inclined situation. I will check this latter.

The difference between the two Longitudinal Center of Buoyancy is about 0.050 to aft that will be in our Footy 0.05 cm, that is a very little difference. This signifies that the hull when inclined do not sink the bow or the stern. If LCB goes to forward was better and we would have a stern sink.

Waterplane Center of flotation  changed 0.4 m that in our Footy signifies 0.4 cm, without problem.

The boat design is a spiral that when we pass to this point we need restart again, optimizing the results obtained. The post  objective is popularize the boat design technical aspect  involving the Footy. I hope that peoples like this opportunity not so common and start to look our boats with more technical eyes . I end here, because now it’s just repeating the same steps, which I will do to finish the project. When finished I’ll put the result here.

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About Fred Schmidt

Engenheiro Naval interessado em projeto de veleiros radio-controlados. Naval Architect interested in RC sailboats design
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