BOXY THE PROA
Having considered all the good ideas being promoted on this web-site, I have developed together with my own thoughts for a simple first project. (images produced in Sketchup, not very slick -  I am a definate novice, more can be posted, and I can send the fiel if anyone wishes to play with it)

CONCEPTS
Minimum sized for cruising for 1 person, with space for 2 weekending and a couple more daysailing.  Simple and inexpensive to construct.

SIZE
Length. 7.2m (24’) long, being 3 sheets of plywood.
Width. 600mm wide at waterline, 1200mm wide at lee-bulge.  1 sheet wide and just wide enough to make a single berth.  This gives a 1:12 at waterline. 
Height. 1200mm rising to 1500mm, with a bit more at the hatch.  (Known as full crouching headroom).  This still looks good / right.  (It could be stretched to standing headroom say 1700mm, I had a Hirrondelle which had just about standing headroom on a slightly shorter length).

SECTION
Square: easy to loft and easy to build.
Shallow underwater profile, I guess between 200 and 300mm deep. It may give useful dynamic lift and even planing.

LEE BULGE
To give more internal space and guard against capsize. The lee-pod is extended to form a bulge from end to end. It gives a smoother entry.  To achieve this it does not extend out that far, at 600mm.  It is 600mm high at ends, 900mm at cabin, so about 400mm above water level, so just well clear of wave slapping.  Being long it has a good volume.  It should hold the boat from about 45 deg.

PROFILE
To windward, an even curve end to end.
To leeward, flat in the centre and curved at the ends.  This gives a flat surface for the boards to rest against. It is also asymmetrical (though I am not convinced this adds anything significant).
The lee bulge is an even curve.

ROCKER
Basically flat with a slight lift at the ends.  This will reduce hobby-horsing.

CONSTRUCTION
6mm plywood. Softwood chine logs, 50x50mm right angles triangle.  Stiffened by berths etc, with stringers and or frames as required. Fixed with screws and polyurethane glue.  Below waterline and a bit above, sheathed in grp.  For the really cheapskate & quick version, painted with acrylic house paint.  The deluxe version would be fully sheathed inside and out.

OUTRIGGER
The hull section is a downward pointing ‘wing’, tilted out about 20 deg at the base.  When airborne this should give useful wind induced downforce.
Beams, the cheapskate would be solid timber (it can be argued that weight is no penalty).

HELM STATION
I envisage sitting in the hatch (the companion-way is always the most sought after location).  A Jester style pram hood would complete the picture. A trampoline, could be minimal fish-net, which would reduce capsize reducing windage. A cockpit pod added for day-sailing with friends.

RUDDERS
For simplicity Newick / Jzerro style is hard to beat.  As they sit against a flat straight part of the hull, they could be mounted outside, though they would still have to come through the bulge.  Better would be a simple casing inside the hull, but against the side, so not difficult to form.

RIG
I have to admit to being a ‘junky’ as well as a proa fan. 
The sail is two sided with one piece battens, the front end is about well rounded, about the same diameter as the mast.  The lee side of the sail bellies out to a good curve, this being the side that counts.  The windward side rests against the batten and will pillow between, (not so pretty). 
The great advantage is that the sail can be set well forward on the mast, about 1/3 back.  This will minimize the movement of the centre of pressure between shunts.
Mast, a 6m aluminium tube with a tapered timber top section.  It is free-standing, though braced by a stay or two to the outrigger.

ACCOMMODATION
Keeping your bed dry is to priority.  The central space is small, say 1m wide.  This is deemed a damp space.  It would have the stove and sink and room to sit.  Either side are bulkheads with waterproof doors giving access to the berths.  The doors a good size so that they could be opened / removed in port to allow 2 persons to sit inside.  A good cockpit tent / cheap dome tent completes the picture.

Interesting ideas.

The lee bulge does offer interesting accommodation options. If the berths are in the bulge as opposed to on the floor, you might need to add water ballast to the ama to prevent a capsize at anchor when all the births are occupied and the crew happens to roll to lee in unison.

I wonder how much effect having the mast to lee will have on balance? It would be easier to brace the mast if it was build at the windward side of the hull, but then the rig would interfere with the use of the hatch.

Mark, this looks interesting! I’d try to get the mast on the windward side (for better balance), and that aerodynamic ballast wing ama is simply mad! I mean that in a good way. I remember J.S Taylor proposed something like that with Botje III.

Please post all your images of BOXY into this thread, it gets too confusing to have more than one thread going on the same concept. Thanks!

cpcanoesailor - 07 November 2012 07:58 AM

Interesting ideas.

The lee bulge does offer interesting accommodation options. If the berths are in the bulge as opposed to on the floor, you might need to add water ballast to the ama to prevent a capsize at anchor when all the births are occupied and the crew happens to roll to lee in unison.

I made a mistake on the bulge heights, now corrected.  Yes with 900mm headroom, it would be worthwhile raising the berths (it would still be a bit cosy for two, so no ‘births’’ I suspect!)
I wonder how much effect having the mast to lee will have on balance? It would be easier to brace the mast if it was build at the windward side of the hull, but then the rig would interfere with the use of the hatch.

It is there to not interfere with the hatch.  a larger design could have an offsset hatch, or twin hatches, with mast on windwards side.

Mark, this looks interesting! I’d try to get the mast on the windward side (for better balance), and that aerodynamic ballast wing ama is simply mad! I mean that in a good way. I remember J.S Taylor proposed something like that with Bojte.
I think this is where I first came across the idea. Whilst it would not be something to rely on , if it works at all, it could be worthwhile.  There will be downside,  getting caught aback, the float would push under!  Perhaps not a good idea for a larger boat, that said, not leaning the hull, but retaining an aerofoil would still reduce overturning forces.  Also, it limits storage and you would not wish to slide out along it! 

Please post all your images of BOXY into this thread, it gets too confusing to have more than one thread going on the same concept. Thanks!

I would have, but it only allowed me 3 images.[/quote]

You can post more images in a reply (not fast reply).

I like the very clever simplicity and the way you have added lots of living-area. I would probably not let the lee-pod go all the way forward, as i think it will interfere with the hulls motion going through waves.  Its quite slender, so it might be irrelevant.. Nice idea. It looks like it can become a nice cruising-proa.

Johannes.