Anonymous wrote:

Anonymous wrote:

Since I am getting the hang of including pics, here is just one more pic showing the end of the longer lee hull with an actual sprit included -- such as thoseseenon both ends of the model.

 In the photo in this post:   SO Pahi hull colors.jpg     You have joined the two bows with an extended (false bow?) and left an open space.... do you intend to fill this in?  

                                                           H.W.

Howard, the open space will not be filled in, because the end pieces ( there is one at both hull ends) is a lashed on fitting and can be lifted onto the deck when I wish to fit into a 30ft space such my mooring. These  extended ends are  an attempt to partly replicate those found on models and drawings of 19th century craft ( said to be of 'ancient type').

They increase the length to over 40ft, which improves the headstay and backstay angle, while also helping to take the sheet-point of the mizzen sprit- boom well out and back.

The 'V fitting' you mention, is the bridle for this sheet, and again, is an attempted replication of the traditional craft. I have spent 45 years looking into Polynesian sailing canoes and am learning more about them as I go down the road with this exercise in replicating with some artistic licence thrown in for practical and aesthetic purpose.  

Anonymous wrote:

Howard, your mention of the Burt Rutan 'Boomarang' design seems a good comparison in terms of what I am getting at -- there are both performance and habitation concerns at play here, undoubtably taken care of with flap control and trim by fuel distribution on  the aircraft, while on a double canoe, habitation  can be  less constrained and certainly less technically demanding..... being the reason why the old Pahi shunter provided lightweight and low windage shelter for probably a good many crew persons under a leaf cover dodger, with trim effected by them moving to windward or otherwise, as comfort or performance demanded.

I see that you lean toward an aircraft type cockpit as a habitation unit and guess that having a big hull to leeward is not your priority and that some sort of active foil out to one side might even be on your radar... in which case stepping the mast through  what is called an aka, would be the way to go.

That would be more like a tacking proa though, rather than a catamaran and good for flat water only.

Having akas on both sides makes sense as well then -- no doubt why you are playing with the double outrigger kayak.

Jeremy:

      Intellectual exercises pursuing the different possible solutions to problems have always been a pastime of mine.  Sometimes they result in interesting innovative solutions, sometimes they lead up blind alleys...... but there is no cost to that when nothing is invested.   Unlike most people I do not even own a TV.... In fact I've never lived with one believe it or not.  I read, sketch, work out solutions to the various problems I deal with, and since the advent of the internet, it has been possible to interact with many people, who I would never have had any chance of coming into contact with.

     The reality is that what I might toy with and dream about is a far cry from where I really expect to end up.   A simple catamaran with a biplane rig with free standing masts like Oryx, and quite a few others, is a well proven formula....it works, though leaves some things to be desired.  I do not have the resources or time to pursue something as innovative as you are.  My goal is to be at a point where I can set off so sea in something I am reasonably comfortable with within a couple of years ( really can't leave sooner).   I've toyed with building, but that's a huge commitment, and inevitably ends up costing dear in time and money, and many people who set out on that path, particularly at my age (by no means advanced), imagining a few years, end up spending so many years that their project becomes part of their estate.  Pursuing a dream is what keeps many of us going.  At some point we must exercise some triage, setting priorities....... Pardey's creed "go small, go simple, go now" resonates with me, as does the advice to buy the smallest boat that will do the job, not the largest you can afford.   I think I've already covered why a multihull and a junk rig are high priorities... safety, comfort, reduced fatigue, shallow draft, simple sail handling. minimal components to maintain, low ongoing costs, etc etc etc.   

To say that I'm in awe of your project would be an understatement.... I've built boats in the past, but nothing on that scale or with that level of innovation.   I love outside the box thinking and outside the box thinkers...... men like Buckminster Fuller, when I was a pre-teen, and of course Burt Rutan, whom I recently mentioned fall into that category.  A  number of people.. quite a few actually... in the JRA.  

    Thank you for posting these photos of your model.  Am I right in seeing a crab claw rig, with tackle to move the tack of the sail fore and aft through shunts. The V attached near center of the curved spar is the sheet?   And I'm not sure what happens there during a shunt.   It really is all Greek to me.  Trying to decipher things from pictures and diagrams is far from new to me........ I'll have an "Ah HA" moment and it will all fall into place.

                                                 H.W.

Since I am getting the hang of including pics, here is just one more pic showing the end of the longer lee hull with an actual sprit included -- such as thoseseenon both ends of the model.

To explain the bow shape, it is best to try getting thigs straight on what a Pahi is --

Firstly, a Pahi has historically been either a tacker or catamaran (as in the case of a Tahitian/Raiatea Pahi) or a shunter/proa (in the case of a Tuamotu Pahi), both of which have split rigs.

My Pahi (named Pahi iti) is not the catamaran type ( like a Wharram), but is based on the Tuamotu canoe, having one hull longer than the other , the longer hull being the lee hull, which is the one that  has most influence on directional and diagonal stability.

The shorter hull is always the windward hull, hence the dodger at 90deg to direction of travel.

Then on the bow shape -- since the Pahi type canoe has a built-up hull based on a V section dugout keel rather than a rounded and hollowed tree trunk such as a Va'a or Waka, the end treatment traditionally tends to become pointed.

So what I have done here is create a wave piercer and also flared the topsides, which are  the built-up parts (traditionally called the wash strakes), to throw the bow wave outwards and provide dynamic lift when the bow plunges.

To help explain things better, as a picture usually does, I will try up load a picof a 1:10 scale model of the complete craftshowing both hulls and the traditionally based rig.

Anonymous wrote:

if this pic shows, it is a better one to illustrate cabin

 I guess I'm a bit slow ;-(    A very interesting hull design.   When you said Pahi, I was imagining a  Wharram Pahi, every example of which I can find is a catamaran with the beams located very high.... in the cabin top... to apparently provide duck through access inside.   My initial impression in the picture is of the  windward  hull of a modern Pacific Proa of the conventional type where the cabin projects outboard......... Obviously not the case, so the cutout in the middle is more than a bit confusing..... obviously your "access hole while fitting out".  I'm visualizing your standing rigging and leeward leaned mast.    I'm assuming that you are using a fairly short mast and a crab claw sail.  I've never even seen in proa in real life.   Do you change the mast rake during shunts?

       Rob's HPs with their aerorig or ballestron... whichever name you choose for it.... make shunting a breeze but they are a heavy and complex solution IMHO.   I like the fact that the single mast or masts are central or equidistant from the ends, and unstayed.  It makes shunting a breeze, and like your boat, the half cabin makes a lot of sense for access, and provides shelter from the breeze on most points of sail. 

    That said, proas do not especially interest me other than as a mental exercise.  Asymmetry does not disturb me at all, in fact it appeals to me, in fact Burt Rutan's Boomerang aircraft which is a real study in asymmetry, is almost an exact copy of a design I  had sketched and modeled as a teen when playing with aircraft models. I include a link just for illustration of my comfort level with asymmetry.  

    I've toyed with the idea of a mast in a single hull of a cat.   When the sail is on the leeward side of the boat everything is peachy....   The other way, I'm not so comfortable.  That of course leads right into the proa where the sail is always to  leeward.

      I've come to the conclusion that a full bridge deck cabin, and a biplane rig makes the most sense for me.  I do not like the masts coming down into the narrow hulls, and essentially cutting off access forward from within........  Forward spaces are not as important to me as for some where forward berths are needed.  Just forward of the bulkhead at the forward end of the galley is probably the logical location for a mast step and partner.  A stowage compartment with reach in access (pantry) could be in the upper part of this, and perhaps tankage low and forward of and on top of the step.   An easily removable forward panel (pseudo bulkhead) would provide access to the mast step for service, and everything forward would have to be accessed from the foredeck.  Changing the balance of the sail could allow the mast to move further forward, as on Oryx.  The problem is converting an existing boat.   I always seem to come back to Richard Woods  Sagitta, which in this case has a perfect location for a mast to pass through. Just aft of what is shown as a single berth in one hull and sail stowage in the other.  The forward end of the bridge deck cabin essentially.   

     As someone who has mostly sailed solo, this is not the huge consideration it would be for someone with a crew of four people....The central and aft spaces have far more value to me.  

     I will have to settle on something within the next year or two... my timetable got pushed back for various reasons.  Meanwhile I'm toying with ideas and building my canoe trimaran for sailing and camping on inland lakes.  

                                                                    H.W.