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I thought these Harryproa outriggers were quite interesting. They're made out of glass on plywood and look like something Dom might eventually make.

The wheel pivots, and can be used both inside and outside.
The sheet winch doubles as an anchor capstan - there is no need for a separate windlass.

The twin unstayed masts can be easily handled by one person by hand in the rough. Unthinkable on a traditional cat this size!

18m_melbourne (27).JPG
An earlier single-masted design (looks like 5-10 have been built).

The tender is an integral part of the design, and slots into the hull.


Actual tender


I am aware of the harryproa! I saw one of these moored at Mangonui, and it sailed past me into Whangaroa, but I didn't meet the owner unfortunately. It had a single mast.

I've also sailed aboard a mbuli proa,


there is one in auckland (this is the one I have been on) you can see Rangitoto is the background


Proas look great on paper, and appeal immensly to people who like to be different (such as myself) but the modern ones need quite complicated rudder/daggerboard arrangements, and the traditional ones are quite a hassle to shunt (it's called "shunt" like a train, not tack like an ordinary)... that doesn't really matter in the pacific where you have steady tradewinds and most of your sailing is a beam reach (as is the case in Kiribati)

If you want to cruise in a temparate place, like NZ, and also expect to have to tack up under headlands to get to an anchorage, a tacking outrigger is probably more convienient.

like this one:


(this one crossed the atlantic without instruments or cooking equipment!)

I also prefer this asthetic ;) I'd want hot food though


although, looking at a harry proa again - i notice it uses outboard rudders - this is probably the simplest design (rather than daggerboard rudders, like the mbuli) the unstayed masts means you could probably tack it too?

Also check out the Russel Brown proas,



Yeah! The unstayed masts are my favorite part, they'd be a good candidate for automatic computer control.


On of the difficulties with proas is that generally you want the laterial center of resistance (the view from the side including fins, keel, etc) to be slightly behind the center of effort (center of the sails). On a tacking boat, the rudder and keel/daggerboard is simply mounted aft of the sails, but on a proa, you must swap the rudders/fins and/or sails. The balestron rig (used on the early harryproa) is about the only thing that works like that naturally - because the boom comes forward of the (unstayed) mast and the jib is attached to that. The center of effort still moves back a bit because the main is usually bigger, which makes sense because otherwise the sail would be unstable and you'd need two mainsheets to hold it in place.

Schooner rig (two identical masts) also works because the masts are far apart which makes the CoE not move very much, this lets you get away moving the CoR less.

On a traditional proa, you have a deep V shaped hull, and probably a oceanic lateen sail (different to the mediterranean lateen because it has a boom as well as a yard) you just move the whole sail to the other end, and steer mainly by shifting the CoR with your body weight, back to turn down forward to round up. You'd have a steering oar too, but it's only used sailing downwind.


but if you want a robot sailboat, you may want to consider a design like the planesail


it is steered from inside, with a steering wheel like a car I guess it just feathers the sail instead of reefing? this one has crossed the atlantic, so it must have seen rough weather at various points.

The good thing about this for a robot design, is that you don't directly adjust the trim of the sails (say, with a mainsheet) you instead you adjust the tailplane, which then moves the main wing(s). It uses relatively less power to adjust the tailplane (which can be balanced, for even less effort) and it can be set to keep the wing in the same orientation relative to the wind. If you had a schooner rig, you wouldn't need a rudder!

For a small scale robot sailboat, the hardest thing is making everything not break while it crosses an entire ocean (since there is no crew to fix anything) having as few moving parts is a pretty good idea.

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