Proa Hulls

[Alex.A]

I see that Harry proa's are rockerless/flat bottomed - and while i get that rocker isn't necessary for tacking - how does this affect sailing/wave action etc? Ease of build is good - and probably the reason but.....
Otherwise have always read that flat hull bottoms are ok for coastal and small cat but not for offshore. Curious as building without rocker would be easier - designing too.

[DrCraze]

well relatively flat bottomed compared to a true micronesian pacific proa. Harryproa's are very seaworthy but are designed for speed and some comfort. How big and what type of sailing did you have in mind?

[Alex.A]

Minimum cruiser minimum cost.
Just curious as to why it might be different to an "normal" cat.
Light wt and long but flat bottomed - pitching?
Easy design / easy construction / easy math....

[DrCraze]

Check out Equilibre, http://www.fwiproa.com/

In my opinion Jeremy fisher hit the nail on the head for proa design. Total minimalist cruiser.

[Alex.A]

Nice.
K-proa's hulls - what i was thinking.........

[terhohalme]

http://wikiproa.pbworks.com/Terho+Halme's+%22Ping-Pong%22

[Alex.A]

Have looked at your proa - like it.
Whats happenning with the EQL12?

[terhohalme]

Never came about.

[Alex.A]

Pity...
Like the look of ping-pong - would've been nice shape in a larger size. 9m?
Could't see under hulls - flat or rocker?

[terhohalme]

More pictures here:
http://picasaweb.google.com/terhohalme

[Alex.A]

TH - Cant open it on my old computer....
I am just wondering if proa and cat of similar displacement will behave similarly....
Or- what would allow a proa to have flat/ter hulls - more length for displacement or that it is much lighter - or...?
For shunting and not tacking - i get that it can be flatter.

[terhohalme]

If the hull lengths of proa are similar it's more or less like a cat.
I used deep-V hulls because I didn't want centerboard. Flatter bottom (dory like) is OK, if using centerboard (or larger rudders like Harry).

All I have to say about proas is somewhere here: http://groups.yahoo.com/group/proa_file/

[Alex.A]

Proa/yahoo is all over the show - should get an organized set-up like this forum!
Dont know about proa yet - still thinking cat......
But want to see what i can learn from proa's and keep in mind for the future.....

[Guest625101138]

Proas have a fundamental advantage as a sailing boat over boats that are symmetrical about the centreline.

On a Harryproa there is a long, light hull selected for it hydrodynamic performance while the other hull is essentially ballast with accommodation and low windage. With a cat both hulls serve a mixture of purposes so cannot be optimised for the one function. Similarly with a tri the centre hull has to serve accommodation, hydrodynamics and windage. The amas on the big ones are designed purely for their hydrodynamics.

With Harryproas the CoG can be close to the windward hull so the heeling moment for its displacement and overall beam is superior to a cat or tri where the CoG is on the centreline apart from any crew or pumped ballast that is moved for each tack.

So the asymmetry about the centrline brings some complications on the proa but there are sailing advantages. Overall the proa offers better bang for buck if you want a fast cruiser with limited accommodation.

I can see a lot of opportunity to develop proas and they seem to be getting some attention. If you have not been through the linked thread it may be worth the effort:
Proa cruising sailboat design, help get this idea out of my head...

Rick W

[Alex.A]

Thanks Rick - have seen thread.
Proa's are getting more attention and bang for buck is definately a +......
but shunting is what most of us cant get our heads around.
Also interested in steering oars.... but little info on web?
Interest=as sweep type and doubling as gaggerboards....