CONTENTS                                                                         edited; 10 May 2014
Post #  00.  THE VAKA SKIN                                                  
Post #  02.  SKIN SCANTLINGS , Kauri,Pacific Bee,Jzerro.
Post #  07.  COMPARING BUILD SYSTEMS
Post # 11. #12   51ft “Unama” design   22 May 2012
Post # 13. “Unama”  World Wide Cruising
Post #  31.to 40 Chined hulls and 53ft “Unama” 11 May 2014

Disclaimer;
It is not my intention to claim this specific setup to be the best, or the only possible solution,  but the Russell Brown designs are well proven Blue Water Pacific Proa’s and so a very solid base , to develop the Pacific Proa into a even better performing craft.
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Post #  00.  The Vaka Skin
First the major building difference between;    38’  Pacific Bee   &  36’  Jzerro
Pacific Bee ‘s Vaka is symmetrical   ,  Jzerro is A- symmetrical .
Pacific Bee is Cold Molded 3* red western 1* mahogany ,  Jzerro 2x cold molded Plywood
Pacific Bee has no stringers and frames,  Jzerro has full set of stringers and frames
Pacific Bee has heavier scantlings , Jzerro is build a fair bit lighter.
Both are well travelled with many 10.000 miles under their keels, and suffered no structural damage whatsoever.

“ The Gougeon Brothers on Boat Construction”    is must have wood/epoxy build literature.
“ Understanding Wood “  R.Bruce Hoadley.      Is also advisable.

The two Hull skin’s were made over a temporary half hull chipboard positive mold ,and, consists of 4 layers of 3mm   the first (inside) is Sapelli Mahogany , the other 3 are Red Western Cedar. All at +/- 45 degrees.  Longboarded and epoxy sealed with 6oz. 200gram 0-90 cloth. , this works out to about a thickness of 13-14mm. 

Before Acquiring Cimba, I measured the hull and all other parts with a high quality Swedish moisture meter, Moisture contents 10-12%  above and below the waterline , measured after a full season in the water.  I am very impressed with the build quality after so many miles of rough use. Quality today, still 100% fair.

Although my expertise is in oven baked ,pre-preg carbon fibre corecell structures, I considering building the 55-footer hull the very same way as Cimba. its super strong, not the lightest construction , but it gives a very save feeling , when cruising offshore at night with speed or in bad weather.

While cruising you don’t have to worry about the frequent grounding on beaches, the drying etc., because;  the 2 hull sides are joined with a generous fillet on the inside ,and heavily glassed together.
next the outside was rounded off, this too was heavily glassed over, next there is a thickened carbon powder /epoxy mix applied with a R= 20 fillet mold , so that you end up with a very strong wear resistant keel , Pacific Bee is regularly dragged ashore for wintering on that keel, and its holding its own.

I would suggest a V hull shape is better for the purpose of any sort of grounding, or hitting , as the impact is on that very strong keel, instead of U-shape where you will damaged the skin, and where you have to reinforce a much larger area, a foam-cored boat is a misery when grounded , as the core will eventually disintegrate , over an increasing area, most times without any outside sign , it will be in a heavy seaway that you start to notice the flexing of the inner skin. You may hope you are close to shore .

Except for the sheer strake, there are no frames or stringers , the hull panels taking the full load itself.
Several Bulkheads ,see to it that the hull panels are kept at bay. A strong sheer - deck connection and adequate deck plating prevents further panel bending.
Smart placed interior parts stiffen up the construction further, but are non- essential for supporting the fairly large panels.

Hull bending due to rigging loads.  Because I renewed the sailplan, the way bigger shroud loads have been checked ashore on the trailer, to see if the hull was bending, The windward shroud was pulled by hydraulics to about the maximum SWL of the stays ,  a welding wire was fitted running full length bow to bow.

The hull static deflection at full SWL load was barely measureable , the beams at that load where deflected only about 15mm ,  so that figures gave me confidence that the whole structure was very, very sound and strong, and more important very stiff , proven also by the way in that Med Storm I earlier reported. 
I hope to install several loadcells and strips to registrate the actual sailing loads back into the computer next season.
To sum it up , This strong vaka construction method, leaves you with a very clean, attractive interior in mahogany .  (my environmental opinion on Mahogany today is —cannot use it anymore.—)
I must have forgotten parts, do not hesitate to ask.  So I can add them.

Cheers Sven.

Thanks Sven.

I’d always thought @ 1/2” (12mm) ply was appropriate for a hull of Bee’s size, an lo and behold it’s even a bit heavier than that.  I understand what you’re saying about the mahogany, it’s a tragedy what’s happening to forrests these days.

I actually live in Oregon, and it’s amazing how hard it is to come by actual douglas fir, or “Oregon” as I quite often see it referred to on the forums.  I think it’s all shipped to Japan in raw log form now and they leave us the hemlock for domestic use.

It’s interesting to see that there’s no internal support structure and still that rigid.

Tom

Post #  02.  Skin Scantlings, Kauri, Pacific Bee, Jzerro. 

Hi Tom, 

Consider that Pacific Bee is about 12 mm of wood ,  the other 2 mm is for 200gr glass ,bit of fairing compound and paint, people tend to only calculate the wood and forget the finishing material, which add thickness and weight too.

I would suggest that 9 to 10 mm is enough but you than have to do a frame and stringer construction for this size and displacement Pacific Proa, and used for Blue water cruising.

Now for Jzerro we talk about 2 layers of 4mm marine ply +/-45 degrees again w/ 6oz.200gr cloth. but is a bit smaller than Pacific Bee.

Kauri at 37’ sits in the middle between them, it is a single layer of 3/8 9.5mm tortured marine ply on frames and stringers.

It all depends on how you want to build,  I would build like Jzerro, as the best plywood (Joubert) has better availability anyhow ( again depends where your living)
If you don’t want to bother with a lot of internal volume , you can build like “madness”with has a fairly straight flare.

Cheers Sven

Below Jzerro skin and stringer setup

God that’s a pretty boat inside.

My 1967 36’ Grandbanks is 24,000lbs, has oak fames on 12” centers and singapore mahogany carvel planiking that’s @ 1-1/8” thick.  7/8 teak decks, teak rails, teak parquet floor and cabinetry.  Even the deck house is 1/2” Mahogany ply.  There’s nothing like a wood boat for pure beauty and comfort.

The light weight and strength that can be achieved with modern methods is astounding.

It’s a good thing too, because it would be a crime to cut down that much old growth, hard wood timber to build a boat for a couple to use 10-20 times a year in this day and age.

Tom

Tom, that’s a classic too, if properly maintained its still worth a fortune over here, it is about the only powerboat I like, except for Lobsterboats that is. Haha Cheers Sven

I love it.  I sold my house 6 years ago and bought it with the equity, then moved aboard full time.  It’s hull #60, and one of the oldest grand banks I’ve ever seen personally.  Still trucks along at 8knots burning 3gph with the original 1966 lehmans.

I love to sail though.  the 4.5’ draft also keeps me out of a lot of fun places on the river much of the year.  Lately the marinas haven’t been dredging, so I have to time my commings and goings with the tide.

A 30’ proa with kick up rudders, daggerboard and a 9.9 yamaha would be a great way to cruise around here.

Tom

Hi Sven

Great posting, very positive and informative.
You mentioned your opinion about both modalities of construction, Jzerro’s and PBs expressing your possible intention to build your forthcoming 55 footer in on ocassion in cold mold and the other in ply/ribs/stringers. I probably misread it but ...do you have an specific preference and what are the reasons? advantages and disadvantages from your stand point?
I personally think that the flat ply panel/round single arc system sponsored by South African designer Dudley Dix
has a lot of merit and is fast and straight forward being very adapted to the prao shape. Are you familiar with it and do you have any comments?
Cheers

toni

Post #  07.  Comparing Build systems
Hi Toni,  No you are correct, I mixed it a bit, I will be more clear.

Comparing build systems

For a Pacific Proa’s between say 34 to 55 foot ,

Lets take Jzerro and Pacific Bee for the sake of comparing these different build methods ,its both cold-molded but one with Red-western Cedar the other w/ ply.
Jzerro method
With this method you can order a set of CNC cut frames, stringers , a pile of 4 mm plywood , and you can basically start, Oeps, not true, you also need that keel, made either of solid wood, as I believe Russell did, or as I would do , out of laminated ply , routered to the appropriate width out of plywood strips, laminated over the frames tops , you will end up with the correct V shape ,to staple your planks against. Before you start planking, take a pvc pipe, to see if all stringers are at the right depth, and so fair And of you go with the 45 degrees hull plating. 
See post #2 photo of Jzerro setup , you will notice that the majority of the frames are permanent, between the 2 beam bulkheads you see 2 temperary frames. It’s just a matter of giving the stringers enough support to plank against.
Later when the planking is in place you can add the few extra narrow frames in the middle.
This method gives a minimum of waste material, as such a relative   environmental friendly building method.
After setting up the frames , the keel will form strongback of the construction.  The first skin is glued an tacked against the stringers at 45 degrees, due to the easy hull bend , you can use faily wide planks,  without having to torture them in place. How wide ?,  you will have to try that on your own design, as that differs from shape to shape , but minor spilling between planks due to changing curvature is always necessary. (I use composite nails and staples for fixing, because you can leave them in) ,
Actually this whole method was used by me several times to make throw away 52-footers plugs for Carbon pre-preg IMS racers,  what a waste now that I think of it.  I will scan a few pictures of that environmental crime, so you can see that planking method. Very strong.
Three of us could build that hullplugs in two weeks. so for a less curved 55 Proa I think it’s fair to say I could do that very same . matter of having a proper shop setup,

Pacific Bee Method
The cold-molded method (multiple layers of Red western cedar) again order that CNC machine routered temporary frames, I have one full size 3d CNC machine in the shop ,and a package of chipwood temporary half-hull moulds would take about 2 days to router. another 2 days to setup that frames, and 2 day to stringer and recheck. So about 1 working week for 2 man. That’s is the troughaway costs of a half vaka mould . So this can be saved when using the above Jzerro method.  But you don’t have to make a keel with this method, which saves time too.  And when finished it’s a very clean inner hull surface with differs from the Jzerro method with is cluttered with stringers and extra frames.
However with cold-molding I can make the bend into the cockpit and pod bottom , making the whole construction even stronger against (serious wave impact)

So Its Joubert Okoume Plywood (France) versus Red western Cedar (US NorthWest)  My pick would be ply ,but it’s a bit heavier,

There is much more to this build issue, ......but I realize , I could go on for hours talking about building,  Lets call this part 1 , for now……
Cheers Sven

PACIFIC BEE   Russell Brown build   half hull Buildjig

Hi Sven
Great pictures and description. Going back to the scantlings for both PB and Jzerro, do you have any idea of the weight per square meter of both boats, say in comparative locations? Putting it in another way, for the same length and volume….(estimate) what would you say is the weight difference in between both construction methods?
Another question, referring to an earlier posting. You mentioned that water clearance on BP on the leeward side underneath the pod is 50 and 55 cm ( in an out)  do you feel that that is enough (usually I use for the cats center pod 18% of the hulls center line distance clearance) and for my 12m I’m using 70 and 75cm.What is your experience with pounding, noise etc?
cheers

Hi Toni
Hi Sven
Great pictures and description. Going back to the scantlings for both PB and Jzerro, do you have any idea of the weight per square meter of both boats, say in comparative locations? 
Putting it in another way, for the same length and volume….(estimate) what would you say is the weight difference in between both construction methods?

No, I would have to back engineer that. I always first design and engineer according to my own calculation, before I decide to compair it with other designs, as that way I keep my focus sharp, without being influenced by others or their ideas,  I try to keep a fresh approach on the total concept.

Another question, referring to an earlier posting. You mentioned that water clearance on BP on the leeward side underneath the pod is 50 and 55 cm ( in an out)
do you feel that that is enough (usually I use for the cats center pod 18% of the hulls center line distance clearance) and for my 12m I’m using 70 and 75cm.What is your experience with pounding, noise etc?

I can’t recall or find that figures but they are wrong.  inside 550-outside 650 , but I warn you that that’s a figure that belongs to this design and its total equation, I has no value for other design, it might at best be an indicator figure.
The pod never pounds, mainly because its on the leeward side, besides having enough clearance,  so no noise, barely ever receives any water, except splashes , if you go too high , the pod will be later in the water in case of sudden excessive heel.

cheers Sven

Sven,

I have been following the Proafiles for a while.  Your design for the 15M pacific proa looks good.  Do you plan making a complete set of plans and drawings available?

C. White

Post #11   51ft Uneama design

From Trimaransailor57”
Sven,
I have been following the Proafiles for a while.  Your design for the 15M pacific proa looks good.  Do you plan making a complete set of plans and drawings available?    C. White.

Aloha Chris, welcome in the pacific proa playfield

Before I forget, do you have a internet place to look at your new Arizona Hobbit residence, I happen to be very interested in Earth-ship building, and plan of yours comes very near. thanks.

Before I answer your question on availability of the 51ft plans, an update on the plans of the 51ft Pacific Proa ,
Considerations are as follows;  I have been up and down in pacific proa design size ,    recently I have decided on the size to be.  interestingly I find smaller than 51ft too small to have comfortable live aboard features.
above 60 ft rigging components starts to be too big to handle.

taking the 51fter cruiser apart shows, 
length overall 15,44m   width overall 9,10m
vaka draft 0,51m[rudders up] down 1,40m
3500kg displacement , [fully loaded ][four people cruising]
109m2 mainsail/100%jib,
semi freestanding wingmast [no forestays]
3- double berth
2-single berth
large galley
oven & 3 burner stove
heating
freezer & refrigerator
watermaker
shower & head
hot/cold running water
propulsion diesel inboard
cockpit table 6 chairs
2 large storage compartments for bicycle’s ,sails etc.

Plans availability , I see Pacific Proa design as a fun development area, [ I donot earn any money with it, rather it has costed my design department already huge sums.] so if a very persistent person is really interested to have one ,we could be pursued to help against some reimbursement.

#12

#13 51ft ” Unama ”    World Wide cruising.

Aloha Proa fans.

Many of us dream about sailing under clear blue sky in the Pacific ,  The icebergs of Greenland ,  Cuban Jazz , Lobsters of Maine, Norwegian fjords or whatever nice place to enjoy , however due to our working life ,there is seldom time to reach such places, and the end result is many times ,dreams that remains dreams forever.

How to simplify that logistics problem.

Simply ,put your Proa in a container.  benefit , its way cheaper than crossing any ocean on your own keel, [ without an experienced crew],  besides [ for me at least] its boring, I rather see new coasts. Furthermore, your property does not wear.
and while the container is shipped ,your still working.

Now the challenge is to have a Pacific proa that is very easy to assemble,  and that is precisely what I have designed into this 51ft “Unama”  [see picture] all parts have notches that fit seamless in there sockets,
as I use this system now for 3 years to transport “Pacific Bee” on the roads of Europe, I can tell you that it takes a day with 2 people to assemble this 51 ft “Unama”  ready to sail.

Dream on !!  Cheers Sven

I read everyone of your posts with a lot of interest. Thank you for posting all this very valuable information!
I like your concept in every way. Its a beautiful proa, and it looks like it would be the perfect bluewater-cruiser. Exceedingly fast and weatherly. Probably a dream to sail!

Johannes.

Sven,

Thanks for posting the great drawings of the 51 ft. Proa.  Before I continue, in answer to your question on the Arizona Hobbit hole.  I sold the project before completion and it ended up being built in western New Mexico.  The new owner is a survival fanatic and made me sign a non-dislosure agreement as a condition of sale.  He did keep me updated and is nearly complete.  I will be able to visit next time I am in the area.  Construction was mostly 3 inches of reinforced thin-shell concrete with 8,000 psi shotcrete.  The exterior was then waterproofed with liquid membrane and then 3 - 4 inches of sprayed polyurethane foam before 4 to 8 feet of backfill.  Very secure and safe.

I like the idea of being able to partly disassemble the Proa for shipping in a container but my own plans are to retire aboard.  I imagine that building the same boat without the ability to break down would make construction simpler and cheaper.

What is your method of construction?  I am experienced with cold-molding and that would be my preference for construction methods.  I would guess 5 x 3mm veneer with glass over plus plywood bulkheads.  I think building the Vaka in left and right halves like Pacific Bee over station moulds and stringers would be easier for for me.  I prefer your AMA design to Russells, though his are great looking too.

I am wondering if a “dumbed-down” version would be viable - that is a conventional aluminum mast and rig similar to what Russell has always used along with OB powe on a sledr, and as few exotic materials as possible.  A little carbon fiber on the beams would be fine.  I would prefer to build without all the bells and whistles.  My friends who have cruised all over the Pacific for 20 years did so without A/C, watermaker, Pressure water and refrigeration.  Though solar panels do make having more electrical powered items easier, I would just stick to some basic electronics and lights. 

I tend to be a little bit of a ludditte - though a heretic in other ways.  I love the “perfection” of the proa concept, but not piles of carbon fiber, wing masts, resin infusion, etc.  I like the speed, but am happy with fast, not neccessarily the fastest.  I would consider myself a cruiser only and never a racer.

I like the analogy of computers.  The software people write programs that are more and more complicated, often with features that while interesting are rarely if ever used by the average user.  To run those complicated programs, the hardware people make platforms that are faster with huge memory and an operating system that is very, very complicated in order to run the more complicated programs.  It is all great, but mostly wasted when the home user just needs basic word-processing and the abilty to use the internet. 

I am the guy who never digns web pages, uses spread sheets (though I can) I just send email and write letters.  I don’t even play games.  I do appreciate those that do all that stuff (like my sons) but my needs are pretty simple. 

I would be willing to pay for lines and offsets with location of major bulkheads and the basic scantlings.  I was going to build a big trimaran (40 - 44 feet) but the idea of a large but no-frills proa with accomodations for 4-5 is very compelling.

I am very glad that you have shared your designs and concepts as well as your thoughts, etc. on Pacific Bee and Russell’s other proas.  I know that Russell has always said he would never design a proa for anyone and I have always felt sad about that but I understand and respect his reasons. He is a builder and not a designer(of Proas) so it is what it is.    Thanks.

Chris