SO Pahi

[Lugalong]

As offered in response to queries about my SO Pahi design and build (Shunting Oceanic Pahi), here is the first posting to show and explain the origin and design of the canoe.

First of all I think I need to explain why this craft is a Pahi, rather than some or other proa variant, even though there is no denying the proa affinity – My early research into Oceanic canoes revealed that originally there were single outrigger and double canoes, with either of the types being tackers, or else shunters.
At about the same time I found the book ‘Project Cheers’ ( documenting Richard Newicks proa Cheers) and latched onto the idea that double ended canoe hulls were a possible solution to a builder with limited facilities and resources; mainly because I had no workshop, but was able to build surfboards in the yard outside my rented room.
This was about 40 years ago, and the craft shown in pics here, is essentially the realization of the ideas that were germinating back then.

Much has been learned during the years up untill until rcently, and I now realize that I should have simply started the build as cold-moulded plywood hull components with identical ends. This would have been within my skill and financial capabilities, albeit, with the know-how that I have only by now accumulated.

As can be seen in the pics, the bottom and wale strake portion of the hull is a laminated resin composite canoe, including the topside stem…..this was achieved by using a shipping container as workspace, to create the basic canoe.

Besides the use of syntetic composites, here is where identification with a Pacific Pahi begins , as the hull section is cordate (like the original), with wash strakes built up off the turned inwards edge of the whale strake.
Description of this type of hull was offered by James Cook, and in fairness, he comes closer than any other, in explaining the structure and form of this hull.
Pity that he was so busy looking for the fabled great southern continent, that he never took the time to study or draw the Tuamotus double ended Pahi shunter.
Also, he might have been able to see the connection between the V bottom hull of the Tongan Tongiaki and the Pahi, both of which are built up on a V section dugout part as a keel member.
Besides hull section, a Pahi has beam wise asymmetry, meaning that shunting suits the configuration and explains how and why the traditional accommodation shelter is closed to windward, giving the canoe a distinct and somewhat ungainly look in comparison to Oceanic tackers.
This feature needs to be assessed on practical rather then aesthetic terms, and it might be helpful to show sketches and diagrams clarifying this design feature….as I plan to do.

Modernization in style of the house goes with materials used, because the intention is for it to suit regular contemporary life afloat.
This is where the cabin layout has advantages; one being the way the cabin width extends between the hulls, as well as outwards(to windward) from the main accommodation hull, creating good usable space for a smallish double hull.
Weight is carried predominantly by the larger lee hull, and admittedly this hull is built with framing that is more sturdy than needs be( as shown by the pics). But then, as a proa type, a Pahi falls into the solid cruiser category, rather than the sporty multihull one.
So, a craft that weighs a few hundred pounds more than it otherwise could, is something I will be able to live with, rather than a fragile or delicate multihull.
Even so,the weight has been manageable by a lone and skinny old guy, throughout the build, Although, it did take two of us to load and move the hulls to the harbourside.
SO Pahi Lee Hull outside Shed.jpgSO Pahi Lee Hull outside Shed.jpgSO Pahi Lee Hull outside Shed.jpg

[timo4352]

So unusual. I'm very interested to see the whole thing come together.
Where about would the water line be on the hull?

[Rumars]

Thank you Lugalong. Is the underwater hull V or U shaped? Some dimensions please? Is the underwater hull cored? I like it a lot, getting inspired here.

[Lugalong]

So unusual. I'm very interested to see the whole thing come together.
Where about would the water line be on the hull?

timo, the waterline will be at least 6" below inwards curved ridge below the flange where the frames and wash strakes meet the underbody of the hull.
The timbers that jut out from the side are there to mount the outboard motor bracket, and the motor will be a short shaft OB, so will be little more than a dinghy's transom height above the waterline.
This is the lee hull and will carry the displacement of the whole craft when heeled under press of sail.SO Pahi lee hull almost launched.jpg
Flare in the topsides provides ample reserve buoyancy when the hull is depressed, but the beak will be wave piercing in chop and small waves.

[Lugalong]

SO Pahi Bow.jpg

Thank you Lugalong. Is the underwater hull V or U shaped? Some dimensions please? Is the underwater hull cored? I like it a lot, getting inspired here.

Rumars, the hull begins as a V where it cuts water and has rounded contours as the sides roll into a parabolic curve where they turn inwards to mimmick the wale strake of the original Pahi. Midships, the section is very close to semi circular, with a shallow V that has a flattened keel ridge for taking to the hard. This keel laminate is thick and solid, progressively thinning out with deadrise, but there is no core.
Dimensions will be made available as I get around to doing some drawings. For now I can tell you the basic dimensions – being 30ft for the lee hull shown with waterline L: B of near 16:1 on a waterline length of at least 27’. Beam on deck of the lee hull is 31/2 ‘.
The other hull (the w/ward hull) has a completely different deck and house plan on a hull about 3’ shorter length.

[Rumars]

You recreated the carved log form very well. I read once that the Sri Lanka fishermen rejected a more V-eed form for their outriggers (also composite underbody) because the boat would not slip sideways when trawling and use the traditional U shaped form.
I asked about the core because of the colour changes, but I suppose this is because of the different thickness.
Do continue the story.

[Lugalong]

You recreated the carved log form very well. I read once that the Sri Lanka fishermen rejected a more V-eed form for their outriggers (also composite underbody) because the boat would not slip sideways when trawling and use the traditional U shaped form.
I asked about the core because of the colour changes, but I suppose this is because of the different thickness.
Do continue the story.

Recreation of the “carved log form” was the result of arriving at the initial shape by carving the underbody in small scale from a prism of foam….. much like the surfboards that I ws shaping.
This form was then cut into sections and copied into a lines drawing., which in turn was scaled up and then made into an 8 ft ½ chined hull in sheet-stock, then covered in foam on the outside.
After again shaping and covering this plug with a laminate of resin/glass cloth, it was filled and faired before making a female mould, from which products were pulled..
Two of these 8 ‘ shells were joined to make a 16 ft hull.
As a development prototype, this canoe was sailed off the beach through the Indian Ocean surf……much like the Sri Lanka Oruwa, compared to which the underwater shape was not too dissimilar.
Being a good shape for running in through the breakers, I can understand from experience how and why the Oru shape evolved.
IN fact, it was through setting out to make asmall Oru copy using this hull, that I developed the flange to attach the plywood topsides.
Quite soon, I think that I should take a pic of this development-- to publish here.

A pic will clearly show how the well rounded and rockered entry runs into a rounded bottom at the midship section…. Like the Sri Lanka Oru fishing outrigger.
Since a round bottom canoe hull has less lateral grip, a board is needed for lateral area, and this is where my steering boards come into play.

[Small boats rock]

Man that boat rocks! Looks like she is mounted on a torpedo. Wouldn't want to get in her way. I wonder, given she will be good in surf like conditions, would that also mean she can handle really rough seas well such as might be expected in the southern ocean? Really interested to follow your progress.

[Lugalong]

Man that boat rocks! Looks like she is mounted on a torpedo. Wouldn't want to get in her way. I wonder, given she will be good in surf like conditions, would that also mean she can handle really rough seas well such as might be expected in the southern ocean? Really interested to follow your progress.

This is probably a good opportunity to explain how the cut-water beak developed on my pahi…..The Oru-like hull that I have mentioned, did not have it, which was fine for surf conditions, but for sailing on the wind into seas, did call for improvement.

The answer seemed to be the bifid bow that you see here.
Sure, as a ramming device it should be effective, and for best effect, a metal tip fitting (like those found on war galleys) would do the trick.
As it is, I think a strong rubber fender would be good for maneuvering in tight spots.
For coping with big seas the flared topsides provide similar reserve buoyancy and lift that has worked well on the Wharram cats that I have sailed on.

[Rumars]

When I see the angle between the cutwater and log I think a knee would look good. Not a full one, just a curved bar. I am sure it's fine structurally as it is but such a bar would be usefull. It provides a handhold for a swimmer, a good place to tie a dinghys painter, things like that. Maybe something to think about.

[wizbang 13]

Gosh that is a cool lookin small craft!!

[Wet Feet]

Gosh that is a cool lookin small craft!!

Indeed it is !

[Lugalong]

Thanks guys, compliments like yourse make the choice to press on worthwhile, because the decision to make the build something of a sculptural exercise was made in the hope of improving the looks of a Pahi shunter……as much as the original configuration made sense as probably the most promising small multihull configuration, the ethnic Pacific original strickes an odd chord in the looks dept.
Building a non original craft, simply has to offer some appeal besides novelty.

[Lugalong]

When I see the angle between the cutwater and log I think a knee would look good. Not a full one, just a curved bar. I am sure it's fine structurally as it is but such a bar would be usefull. It provides a handhold for a swimmer, a good place to tie a dinghys painter, things like that. Maybe something to think about.

You're 'curved bar' idea as a handhold might also serve well as a place to lash a fender for the sharp nose/beak.

Included in this post is a pic of the 16 ft Oru type hull that was a development model preceding the PahiOru replica.jpg

[Rumars]

It is indeed very good looking. I can only say "well done". The Oru looks like you imported it directly from Sri Lanka, absolutley traditional. Did you use the Oru rig on it?

You can lash all matter of things to a bar in that position, even use it as a tie point when on the trailer. It looks better than a eyepad, plus it stiffens the structure. I would just laminate fiberglass over a piece of PVC pipe and spread the ends over the hull, than fair it in. No holes, no worries, just like composite chainplates.

May I ask why the heavy framing for the sides? Are you planing 4mm ply topsides? Or did you plan for a lot of smaller diameter lashed crossbeams and that framing is the foundation for it?

[tdem]

The shape and constructions reminds me of the PNG proas.

[Lugalong]

It is indeed very good looking. I can only say "well done". The Oru looks like you imported it directly from Sri Lanka, absolutley traditional. Did you use the Oru rig on it?

You can lash all matter of things to a bar in that position, even use it as a tie point when on the trailer. It looks better than a eyepad, plus it stiffens the structure. I would just laminate fiberglass over a piece of PVC pipe and spread the ends over the hull, than fair it in. No holes, no worries, just like composite chainplates.



May I ask why the heavy framing for the sides? Are you planing 4mm ply topsides? Or did you plan for a lot of smaller diameter lashed crossbeams and that framing is the foundation for it?

Rumars, no, unfortunately I did not get to trial an Oru type rig.
Following conventional wisdom, I leaned very much toward the crab claw rig for much of my time getting to grips with proas.
I suppose it was because of the so called “cool factor” of the Oceanic Lateen.

Pity this, because the quadrilateral sprit has so much appeal for a small beach launched canoe, if prejudice can be overcome-- I think, and the sprits’l that I had on a tacker( my cruising djong) worked so well. Although, apparently the smaller Oru uses a lug main, and this is essentially the sail I will use on the Pahi.
As you suggest, a curved bar laminated on with splayed-out rovings (or carbon uni) is easy to do and obviously ahandy thing to have.

Frames on the SO Pahi are oversize for an unusual reason and could admittedly be improved.
The other hull is different.
What happened was that I had agents employed to sell the shed and attached home, when I started the frames.
This is no doubt a puzzling reason, so I need to explain that to make progress and have any hope of getting the canoe finished, I had to make compromises.
There were no plans to work from, and the method of attaching the wooden frames and sheeting/planking to the moulded composites underbody was very much in the development stage.
I had 8x2 lengths of Alaskan yellow cedar, and plenty of 3/8” marine ply.
Then in order to keep the shop free of dust and shavings… since there was a constant stream of prospective buyers walking through the place, I economized on the use of the table saw and planer. Also, I was going easy on the epoxy glue application, because, to be honest, This build has helpedAlso, I was going easy on the epoxy glue application, because, to be honest, This build has helped me develop a vaguely efficient system of epoxy application, at the same time as avoiding mess making.
Then by the time I started on the other hull, the place had been sold and I had a couple of months to build the bulkheads and stringers for thinner ply sheeting on that hull.
Still ,Using the 3/8 ply on the lee hull, did make a difference in the time taken getting the job done…. This took only a few days.
As already stated, this lee hull does weigh a couple of hundred lbs more than it needs to, but this hull is the one that bears pretty much all the stress and strain of the structure.
Attachment ( by means of screw fastenings and bolts) of the wooden topsides and frames to the composite’dugout/ underbody’ has been helped by the increased scantlings.

Also, I was going easy on the epoxy glue application, because, to be honest, This build has helped me develop a vaguely efficient system of epoxy application, at the same time as avoiding mess making.
Then by the time I started on the other hull, the place had been sold and I had a couple of months to build the bulkheads and stringers for thinner ply sheeting on that hull.
Still ,Using the 3/8 ply on the lee hull, did make a difference in the time taken getting the job done…. This took only a few days.
As already stated, this lee hull does weigh a couple of hundred lbs more than it needs to, but this hull is the one that bears pretty much all the stress and strain of the structure.
Attachment ( by means of screw fastenings and bolts) of the wooden topsides and frames to the composite’dugout/ underbody’ has been helped by the increased scantlings.

[Rumars]

Well it's stout and very traditional looking. How high are the topsides?

[Woxbox]

Fantastic project. I'll be following every step.

[Lugalong]

Well it's stout and very traditional looking. How high are the topsides?

Yep, stout is a good descriptive word here.

Topside sheeting/planking measures 2ft, up from the lap flange top edge of the underbody/dugout, which is a half sheet of marine plywood.

My previous posting did not include the full word document answer, so I have edited and added the missing text to that last post

[Lugalong]

The shape and constructions reminds me of the PNG proas.

Yep tdem, I see a connect in concept between the Pahi double canoes and this living relic of the Coral sea region..... mainly in the judicious use of timber.
Bearing on the matter is the availability of trees on the western side of the andesite line.
Scarce timber resources on the atolls of the far eastern Pacific must surely have had an influence on design and structure of those craft( especially so in past times). This shows, I think, in the reduction of the dugout to a much smaller keel member, and planking being sewn with more volume added to the bilge. Also, the process of splitting logs into planks and pieces, could have produced another hull out of that log ama.

[Rumars]

I will confess that in your place I would have just epoxy glued the ply on the outside of the flange, made a fillet from the squeezout and run some biaxial tape inside and out. Bolts with taped backers to pull it in. A ply bulkhead under each crossbeam and a gunwale monted beforehand to define the shape. 3/8 ply is plenty strong by itself for a 2 ft span, with 1/4 ply I would have probably run a stringer in the middle.

I'll wait for the continuation of the story.

[Lugalong]

I will confess that in your place I would have just epoxy glued the ply on the outside of the flange, made a fillet from the squeezout and run some biaxial tape inside and out. Bolts with taped backers to pull it in. A ply bulkhead under each crossbeam and a gunwale monted beforehand to define the shape. 3/8 ply is plenty strong by itself for a 2 ft span, with 1/4 ply I would have probably run a stringer in the middle.

I'll wait for the continuation of the story.

Rumars,yes, ¼” plywood and one stringer in the middle is what I have on the other hull (the windward hull), As well, there are bulkheads under the hulls connecting cross beams. In fact, half of each main crossbeam consists of these bulkheads as they extend away from the canoe body, comprising the ends of the double berth compartment too……a pic would explain things more clearly than my word description, but the pic space in this post will rather show things as they are in more detail (inside the lee hull).
There are no doubt various ways to attach the plywood to the flange(one of which is the glue and tabbing you suggest).
However, as I have done, there is no need to disguise any composite laminate…..all that can be seen and felt is the woodwork,

Since I now have to work inside the canoe, I am happy to do only sanding and painting/varnishing, as per regular wooden boat maintenance.
Although the cedar frames are stout, they take up less of the ‘tunnel space’ in this lee hull than bulkheads would.
Pahi Lee Berth.jpg

[Lugalong]

Something that I need to explain in order to clarify my thoughts on design, is the use of the unique Pahi wale strake in tying the craft together.
This relates mainly to the original craft that had only sennit to bind all structural members, but I have also used the wale strake ledge as a lodging place to ‘hook’ the frame upright members under.
With lashing cleats bonded and glued onto the topsides(outside the hull, as additional longitudinal stiffening) the crossbeams are lashed in such a way as to pull the deck and topsides down (in compression) onto the keel log.
The extra thick part of the frame up right (seen in the pic above) is mainly where the step has been created to hook under te wale strake ledge, in conjunction with the lower frame cross member, or else the bulkhead.

[Small boats rock]

Lugalong, do you have any pics of your build which also include a person in/near the boat? If so seeing that would help give a better sense of size. I've been looking at your pics posted so far wondering is this boat something a person can get into, sleep in, or is she purely day sailer? Hmmm, having asked that I am now aware that the pics I've posted of my own build are also devoid of people... must do something about that.

[Lugalong]

Lugalong, do you have any pics of your build which also include a person in/near the boat? If so seeing that would help give a better sense of size. I've been looking at your pics posted so far wondering is this boat something a person can get into, sleep in, or is she purely day sailer? Hmmm, having asked that I am now aware that the pics I've posted of my own build are also devoid of people... must do something about that.

OK, hope this helps…. Pic shows me standing with head out of the companionway hatch in the windward hull, with the the galley area in front of me and seating plus the double berth behind me.
The other pic shows this same hull in the foreground and the lee hull in the background.
Shop is in a bit of a mess, while rushing to get hulls sheeted enough for loading onto a trailer and vacating the place.
Me in Pahi cabin.jpgBoth Pahi hulls.jpg

[aerohydro]

Hi Jeremy,

Fantastic to see your work again! This looks like it's going to be a really interesting boat. I hope we get to see one of your excellent concept sketches for this craft. What sort of overnight accommodation are you planning?

Leon

[Rumars]

Yes lovely, keep it coming.

[wtarzia]

Hi Jeremy,

Fantastic to see your work again! This looks like it's going to be a really interesting boat. I hope we get to see one of your excellent concept sketches for this craft. What sort of overnight accommodation are you planning?

Leon

--- Hey Leon, glad to bump into you again after so long. Did you keep going with proas? The last one of yours I saw was the one posted to Instructables, years ago. -- Wade

[Small boats rock]

Thanks for posting more pics. Definitely have more of a sense of proportion with you in the pic. She is quite substantial. And... your shed looks well organised to me.

[Lugalong]

Hi Jeremy,

Fantastic to see your work again! This looks like it's going to be a really interesting boat. I hope we get to see one of your excellent concept sketches for this craft. What sort of overnight accommodation are you planning?


Leon

Hi Leon, talking of doing sketches/drawing....the plan is to install a heater burner in the cabin, for spending time doing more of that sort of thing when the cold sets in.
Meantime, I need to get cracking and make both hulls weatherproof.
There are a number of berths for sleeping purpose.
cheers.

[Lugalong]

SO Pahi build and design development is still making progress..... lee hull shown here under a tent at the waterside, while there has been sail rig design that I have info and images on.
Posting woes have led me to post this message and pic as a test run to see if I can get more comingPahi ITI under tent.jpgPahi ITI under tent.jpg

[John B]

What you're doing there is what I think the current crop of ultra race boats will evolve into next. Instead of just a ram / reverse bow , I think they will go clipper bow into ram bow/ bulb)
What yard are you at, Lugs?

Ohhhhh, sheet , I see you have Mary Harrigan for company!

[Lugalong]

What you're doing there is what I think the current crop of ultra race boats will evolve into next. Instead of just a ram / reverse bow , I think they will go clipper bow into ram bow/ bulb)
What yard are you at, Lugs?

Ohhhhh, sheet , I see you have Mary Harrigan for company!

John, what I am doing is no doubt a far cry from any ultra race boat, as can be seen if the 1/10 scale model of my Pahi shows in this post.

Maybe though, another designer could come up with a prod and green water shedding deck contours to work on a race boat.

Spot shown is my club yard....all good people and in time I might get to know more about Mary Harrigan.SOPahi rig after Bishop model photo 2.jpg

[Lugalong]

Having re-established my internet connection and files(after the death of a laptop), and having done a picture posting test on the 'outrigger and proa' thread, I am ready to add follow-up info on the build of my SO Pahi (by now having been named Pahi Iti).

Much time has gone into design of a schooner rig, which is based on the original Tuamotuan Pahi rig, which needs some explanation by means of graphic illustration and can now be included in this build narrative...... with the cabin closed in and ready be glassed and painted, the inside will be used as a studio to work on illustrations covering the research into Oceanic sailing craft undertaken over the years whilst working on canoes.
Here first, is a pic or two showing progress on the windward hull.... the hatch aperture allows for finish work to be done without too much space restriction, and the covering is to be a 'cockpit' seating area ( built atop the covering and consisting of hammock or deckchair type seats)
Being a shunter, there is to be another such aperture and structure at the other end of this same hull. SO Pahi ama before glassing4.jpg