Resistance prediction methods/series for catamarans

Hi there,

I am looking for resistance prediction methods/series for catamarans around 10 m lenght, 6 ton displacement and 10 knots of speed (Froude number around 0.52). Any recommendations?

Thanks

 

You can try HERE as this excellent research may give you a good first indication.

 

We use following methods:
- Molland series - see link from AdHoc, for round bilge shapes
- Muller-Graf series - for semi-planing catamarans with chine
- Savitsky planing method with hulls interaction factor - for planing catamarans
- For narrow and light hulls, there is 'slender hull' method, this is originally a graph published by Doubrovsky in his book. However use with care, as comparing with tank tests seems the method underpredicts the resistance.

 

Which is also available HERE.

But with these parameters, the M-G series is generally outside your scope. But may offer you some guidance in addition to the Molland paper.

 

10 knots on a 10m powercat is only just over the hump speed. So it would be best to either aim for displacement speeds of under 8 knots or go for mid teens as a minimum speed.

see here for an example of one of my home built designs in that size range



Richard Woods of Woods Designs

www.sailingcatamarans.com

 

Thanks a lot everyone, will have a fun weekend studying.

Yes the froude number is 0.52. Maybe at around 0.4 (~8kt) would make more sense.

 

I did a similar investigation for a sailing catamaran, see the document attached to the quote#51 and the comments around.
Calculating friction resistance, drag coefficient? https://www.boatdesign.net/threads/calculating-friction-resistance-drag-coefficient.62553/page-4