A New Proa Concept?

[Trevlyns]

Picture this… A conventional Pacific proa (main hull and sail to leeward), now replace the sail in the smaller windward hull, retaining accommodations steering and leeway resistance to the bigger leeward hull.

I’ve seen all manner of layouts – Pacific, Atlantic, Rob Denny’s Harry – but not anything like this. Any thoughts guys?

[grob]

I think this is the concept that won the 2002 Concept boat show



see http://www.bimaran.com/

Gareth

[Trevlyns]

Interesting idea Gareth but that looks like the same principal as Rob Denny’s Harryproa concept with the sail in the leeward hull and accommodations to windward. Also, the hulls are equal length, which I have come across. What I meant was a small windward hull with sail and a larger leeward one.

[grob]

Originally Posted by Trevlyns

Interesting idea Gareth but that looks like the same principal as Rob Denny’s Harryproa concept with the sail in the leeward hull and accommodations to windward. Also, the hulls are equal length, which I have come across. What I meant was a small windward hull with sail and a larger leeward one.

Fair enough , Surely its still the same thing, just depends which way the wind is blowing

These Proas are so confusing.

Gareth

[Freenacin]

Originally Posted by Trevlyns

Interesting idea Gareth but that looks like the same principal as Rob Denny’s Harryproa concept with the sail in the leeward hull and accommodations to windward. Also, the hulls are equal length, which I have come across. What I meant was a small windward hull with sail and a larger leeward one.

So you would have a very light windward hull, and heavier leeward hull? (virtually the opposite of the Harryproa's) That would result in a boat that was much easier to capsize wouldn't it? What would be the advantage?

[rob denney]

Originally Posted by grob

I think this is the concept that won the 2002 Concept boat show



see http://www.bimaran.com/

Gareth

G'day,

The bimaran is a tacking cat, based on W, a boat I designed and built a few years ago. 12m/40' long, weighed 600 kgs when first launched, but has had a whole lot of stuff added as the owner (Gray Treadwell) has been experimenting. W has an unstayed balanced rig and a single telescoping beam, which allows the hulls to pitch independantly and vary the beam from 4 to 7m. It has a rudder on each hull and a single centreboard hung off the beam. Both halves of both hulls were built from a single half mould. It all works pretty well, but not as well as a harryproa.

Re the rig to windward: With the accommodation there as well, this maximises righting moment, but takes up a big lump of accommodation and is very difficult to see. As the unstayed rigs we use are very light, it is not worth the effort. Putting the accommodation to leeward makes no sense at all to me.

regrads,

Rob

[nero]

Rob,

It would be interesting if you could post some of your previous boat designs. You have a wealth of knowledge that seems to be covered up by the harryproa. Have nothing against the harryproa, but think you could help evolve catamarans.

regards

[rob denney]

Originally Posted by nero

Rob,

It would be interesting if you could post some of your previous boat designs. You have a wealth of knowledge that seems to be covered up by the harryproa. Have nothing against the harryproa, but think you could help evolve catamarans.

regards

G'day,

Before harryproas I had only designed two and a half boats that got built, and each was on the back of an envelope, so there is not much to post. Catamaran evolution is going down some strange paths. The all out racers are becoming trimaranish to cope with the loads from their boring (from my design point of view) rules and the cruisers are turning into blocks of flats. I am not sure I want anything to do with either, which I guess is why I am into harryproas, which are faster, roomier and cheaper than either. Still, if you have any cat design questions, I am happy to answer them.

regards,

Rob

[rwatson]

The first time I saw this design was from naval Architect Lloyed Bergeson over 7 years ago - his drawings also included the Flettner Rotor sail as well.
Rob Denney was aware of these designs also, and we have corresponded about the benefits and challenges etc of the design.
Rob is still perfecting the operation, with sails, rudders and other considerations that go with Proas.

[safewalrus]

And the advantages are? if any? and is it any great use? don't see any great rush for them so it would appear to be not unlike redesigning the wheel with hexagonal tires?

A bit pointless!

Still each to his own I guess. Trouble is one of the posters on here has got me interested in these things (proa's) and yeah they do look good but in this case why?