Equinox, gale force wind, freezing hail! Spring's here.

Julie and I have moved from Waima.


We swapped our home of five years with people whose roots are in Waima. Their house in the little township of Rawene suited our needs and was similar in value. Now we live within one minute's walking distance to my work at Hokianga Hospital. No more car commuting!

Our new house looks out over the inner Hokianga Harbour so I'm back in touch with the pulse of the tide.

We moved in a convoy of small vehicles the 16 KM (12 miles) in the pouring rain one day in June
with lots of help from our friends.

I hooked up Toroa to the car on his road trailer and said goodbye to the place whare he was rebuilt.

I was alone in the car as we drove the Waima hill and descended into the Omanaia valley. All was going well until we came to the Rawene intersection from State Highway 12. at the turn, the right hand trailer tire burst.

I decided to proceed slowly on the rim, not having a spare to fit. A scene from that great Roger Donaldson film "The World's Fastest Indian" came to mind

The ride was a further 6 KM at 5 KM per hour, I was The World's Slowest Pakeha!

Flump, flump, flump, flump, wobble, wobble, wobble, It was slow noisy progress and to top it all off the car began to overheat. The cooling fans decided to go out in protest. Rovers are very self conscious cars and don't like drawing attention to themselves.

As we rolled past my place of work all my colleagues came to the roadside to jeer at me attracted as they were by my appalling progress. We finally pulled in to our driveway where I disconnected the trailer and left Toroa exactly where he stood.... until yesterday.

Over the three month gap Julie and I have established ourselves in our new environment. Last weekend I finished setting up my workshop with my wood tools on one side and my engineering tools on the other.
My saw bench is in its rightful place outside the workshop with enough undercover space around it to do some real work again.

With my now accessible tools I've unbolted the offending wheel and cut off the mangled tire from the rim. I took the wheel to our nearby garage where I asked the mechanic to fit a recycled tire which I found in the fill behind a retaining wall where my saw bench is now located. So I still don't know what's good and what's bad. Now I'm able to mobilise myself for another assault on the summer sailing opportunities.

My health is still not so good with my right wrist and ankle so swollen that I believe they will never be useful again. Just as well that I have a left hand and a left ankle that are still reasonably OK. (OK?
I think that "OK" must be derived from the Scottish "Och Aye") it has to be.

Toroa still needs a good water blast and also a coat of gloss paint. Who knows when that will happen?

Money's tight everywhere. Where did it all go? Rescuing the US economy?

Meanwhile I'm going to convert our little red Coleman canoe to every form of propulsion known to small boats. A yawl rig, row locks and outboard bracket, that way when I'm sick I can still go boating with minimal stress physically.

Han's Comment on my blog post "Takapu the Proa a Dissertation"

Hi Han

I read about the Gondola in a "Wooden Boat Magazine" article many years ago. Since then I have wanted to study one closely, in action, to see what other benefits there may be from the asymmetry.

From my experience with the Proa I have learned that good design (especially design features with a long successful history) usually solves at least three problems at once.

I believe that this hull shape could simply offset the thrust of the oar but I believe that the answer may not be so simple, it may also have a more fundamental reason. One reason will almost certainly be the need for extra buoyancy over the side that the oarsman stands, on this long slender hull, to keep the boat level for the comfort of passengers.

Another will be the need to counteract a tendency that long slender hulls have to broaching. My experience with long symmetrical canoe hulls is that they have a strong tendency to track off course when a small force acts across the line of least resistance, i.e. wind or wave action. I believe the reason for this broaching action is the result of a pressure differential that gets started when the hull turns through the flow and water speeds up around the outside of the turning circle. This in turn generates lift which exacerbates the turning moment into a logarithmic spiral. The result is almost impossible to correct with any kind of lateral counter force like a long sweep or paddle (a disastrous situation in the congested busy waterways of Venice!).

With an asymmetric hull the pressure differential is constant and therefore more predictable for the oarsman to counteract. Lastly I believe that the oarsman exerts a slight diagonal force in the thrust sweep of his oar which results in lift from the rounded side of the hull. This thrust/lift combination in turn reduces the amount of effort required to move the hull through the water, the same phenomenon that a fish utilises when swimming.

Re rudderless steering.

The Patin Catala of Spain is a great example which has evolved into a very successful sailing class.  http://woodenboat.com/boat/?p=1358

Best

Harmen

2 answers to 2 good questions

Dave ? contacted me with a question asking for me to elaborate on aspects of my sail construction spar materials and tack connection. He also wanted to learn more about the Kiribati Dimple and its effect.

My brown "Novathene" Polytarp sail is laid up with the warp and weft at 45 degrees to an imaginary straight line along the leach between the two spar tips. This orientation allows the fabric to distort freely in both directions, across the sail and down its length, opening up the leech and at the same time accommodating the variable luff curvature induced by the flex in the luff spar and boom without adversely affecting sail shape. The loose bias of this cloth shears and stretches to create a surprisingly fair curve with no induced shape sewn into the panels as we see in a modern sail.

The two spars are made from 4 scavenged windsurfer (sailboard) masts.
The luff spar is constructed with a sleeve joining the bases of two of the fibre glass masts resulting in the tapers running out to the tips top and bottom.
The boom is one mast sleeved into the other with the tapered end to the clew. The angle of intersection at the tack is 60 degrees making the sail roughly an equilateral triangle though to be traditional the Micronesians make their booms slightly longer that the main hull and the luff spar and mast slightly shorter and of roughly equal length.

You will notice that there no empirical rules in any of my commentary only a "rule of thumb" which irritates purists and control types terribly, this rule of thumb also applies to the hull shape.

I have made my connection between luff spar and boom at the tack connect by means of a very small jaw made of marine ply scarfed into the tube section of  the boom which forms an open crutch against the luff spar. The jaw is held in place by the luff and foot tension exerted by the sail when it is bent on with  all its supporting lashings to the boom.

I'll illustrate these details when I have more time.

I'm not to sure how I can expand any further on the Kiribati Dimple idea if it is not made clear from my chapter in my dissertation with comments contributed by some true experts in my later posts on the subject.

There is no science yet to support my hypothesis on the subject of hull asymmetry. I can only speak from experience the publication of which again has left my ideas open to derision and doubt from some surprisingly bright people.

"Hull asymmetry takes various forms throughout the Pacific. In Micronesia, where it was most highly developed, the backbone of the canoe is bent in two directions during construction. In other instances keels are straight but sides are built with parabolic cross sections, one side made rounder than the other and featuring a shallow concave indentation in the lee side of the hull below the waterline. Michael Toy designed the hulls Takapu and Toroa with this feature. He understood that asymmetric hull curvature works as a hydrofoil designed to counteract leeway. My personal experience is that, as the vessel gathers speed, it begins to make ground to windward to the extent that I always have to head below my objective so as not to over shoot the mark."

I drew this illustration showing the sections of the hull of Takapu.
The sections are derived from the plans as drawn in 1977 by Mike Toy. The keel is straight, the volume of the windward side is perhaps twice that of the leeward.

You will see that section 5, the mid bulkhead frame is narrower than the preceding section 4 (and following section six, remembering that the hull is a mirror of itself end to end)

I now also believe that the dimple reduces drag by mitigating the secondary, lee side shock wave and the feature also assists with maintaining directional stability in a following sea.

How much asymmetry? Not too much and not too little!

Takapu the model: fish eye view

Holling Clancy Holling and me

 This post seems a long way off topic, however because of the relevance of Holling C Holling to my early development as an artist and sailor I've also chosen to put this up on my art blog as well.

Holling Clancy Holling and me.

On my 7th Birthday my Grandfather, Henk Oostenrijk from the Netherlands, sent me a book voucher.

My Mother and Father took me to a bookstore in Auckland City where I chose “Seabird,” a beautiful, hard cover book for children written and illustrated by Holling Clancy Holling and published by Collins on the subject of Whaling. My Mother dedicated the book for me by writing my birth date and my Grandfather’s name on the flyleaf.

I no longer have that original copy. It was donated without my knowledge or approval to a local school, fundraising book auction when my children were still attending primary school.

It did solve my Father’s problem of what to give me for my 8th birthday. My obsession that year with “Seabird” gave him the cue. I received from him a copy of “Paddle to the Sea.”

The following year it was “Tree in the Trail”

http://books.google.co.nz/books?id=fjLWevyUu0cC&printsec=frontcover&dq=seabird+Holling+Clancy+Holling&source=gbs_similarbooks_s&cad=1#v=onepage&q&f=false

Those three books changed my life forever. Long before I fully appreciated the literary contents of those books I was gazing in awe at Holling’s illustrations, many of which I copied. Not only that, I began to build my own canoes, models at first and then, on to the real thing.

Like Holling, I had a curiosity about many things and this lead to an interest in the canoes and the people of the Pacific Ocean.

I was compelled to make sailing models of outrigger canoes, whittled out of the dry, woody flowering stems of the flax plant that flourishes in the coastal areas of New Zealand. My friends and I would send them racing across the bay and watch them diminish, longingly, wondering where they might eventually end up, as they dwindled from sight; out to sea.

My first real canoe was designed by New Zealand designer, Frank Pelin and built to his plans by my father and me. That canoe was a 15 foot, plywood, hard chine adaptation of an American Indian birch bark canoe. I named that canoe “Seabird,” the canoe taught me about boat handling from a very young age. I used two types of paddle, the double Eskimo kayak style and the other, the traditional single paddle. My friends and I cruised the sheltered local waterways north of Auckland where we fished and camped all summer long.

Again much influenced by Holling’s realist style and parallel to his path, I chose a career as a commercial graphic artist and mural painter, which eventually lead to sculpture as well. These activities, though not my true passion, helped me to put food on the table for my family.

As I write this I am now in my 50’s and I still cherish and collect copies of Holling’s work. I haunt the children’s section of secondhand bookshops and charity shops always on the lookout for another, yet unseen Holling publication. In this way I have found a 1935 first edition of  “The Book of Indians” a later Collins republication of the same title and a 1948 first edition Houghton Mifflin copy of “Seabird”.

My continuing curiosity about Holling lead me to Walt Giersbach’s blog which seeks to illuminate that which was previously unknown about the life and work of Holling C. Holling and his wife Lucille. Now, thanks to the efforts of people like Joan Hoffman of Michigan and others, details and artifacts from Holling’s life are being collected, displayed, recorded and published so that more may benefit from Holling’s rich legacy, the body of work that he left for our benefit and enjoyment.

Thanks Holling C Holling for daring to follow your dream and so influence the lives of people like me so far away here in New Zealand.

Joan Hoffman, Holling’s biographer wrote me recently:

August 2010

Harmen,

Glad you made contact with Walt.

You and Holling would have had much in common. He had an early interest in canoeing and became very skilled at it. In the Holling Collection is one of his early drawings of a horse drawn at age three.

Holling became a bit better off financially after he wrote and illustrated Paddle-to-the-Sea and the four Houghton Mifflin Co. books that followed (Tree in the Trail, Seabird, Minn of the Mississippi and Pagoo). Before that he did a great deal of advertising and commercial art to put food on the table. He even worked for Walt Disney at times for a pay check. The children's books he wrote before Paddle were done as a sideline. There are about 20+ books Holling either wrote and illustrated or others he illustrated for other authors.

Holling was a talented writer as well as an artist. He wrote some poetry. One of his great assets was a supportive wife. She helped in so many ways. And he had an outgoing personality and could talk with young and old in all walks of life. He had a curiosity about many things.

You won't see any of Holling's work after Pagoo (published in 1957), although he lived until 1973. Unfortunately he developed Parkinson's with dementia. He worked on several other ideas but never completed them.

Joan Hoffman

Winter at Waima

Toroa has come out of the water and is now resting on his trailer at home.

Julie and have not yet resolved our house sale. This problem occupies much of our time and energy. There is also a 4 m3 pile of firewood to split, I've just now come inside from a session with my axe and after a hot bath it's time to relate a little of what's been happening.

Toroa sat at anchor in the tidal stream of the Waima River mouth near the tip of the Rawene peninsula for the better part of 4 months. Without anti fouling paint of any kind he needed regular bottom scrubs. As a result there are now several large oysters that have glued themselves very firmly to the bottom in the few places that missed the regular scrub. Before Toroa goes back in the water some kind of antifouling paint will need to be applied. My new summer mooring location will dry out for part of the tide cycle so a hard type antifouling paint suits that situation best. Then there are the graphics that I have designed which must also be applied before his next outing. The next time Toroa goes in the water it will be his official launch. There will be a proper Maori ceremony attended by a local Kaumatua.

Overall I'm pretty happy with Toroa. I only wish that I did not suffer such a physically disabling disease.
Rheumatoid arthritis is very debilitating when all the major joints swell up. This inflammation makes doing anything strenuous unbelievably painful. The problem is worst in my shoulders, hands, fingers and wrists.

The doctors and specialists are not very positive about my prognosis and are trying to convince me to take strong medication in the form of Predisone and Methotrexate. The contraindications for these drugs on the face of it look worse than my symptoms.

I need to do much more research before I make a choice to go down that path.

When I look inwardly I can't help but feel that the R.A. that I suffer from may be a disease that manifests itself in a mindset of resentment, there are thousands of theories around what causes the disease but no one knows for sure!

This is somewhat off topic I know but I want to share with you just what is going on.

I really appreciate the interest that you are showing in my Canoes of Oceania blog. I'm surprised by the number of people that are following my irregular postings.

It's interesting to read about your various blogs and activities, I want to encourage some of you to share more of yourselves in your profiles.

Just recently Julie and I attended a student showing of short films on the subject of Kaimanakitanga.
Roughly translated this means our treasures of knowledge.

Janine McVeigh a local writer and educator chose my work with Toroa as the subject for her 3 minute film. We felt honoured to be the subject of this kind of documentation and we enjoyed the showing of 9 very different short films at the local campus of Northtech, our Northland Polytechnic. These films covered diverse material such as genealogy, Water, conservation, Native forest, etc. The little film titled "Following my Heart"will be loaded on to Youtube and will be linked here on my blog as well.

Janine wants to dedicate more time to this project and plans to feature Toroa in a documentary in which we hope to include some video footage of Toroa sailing.

It's time to get some more real proa footage out there for more of you to view.

Whilst writing this I received a phone call from Gary Dierking who just got back from a month long canoe sailing trip in Fiji with his wife Rose.  It's good to be in touch with you again Gary, we've missed you.

Well It's time for me to help get an evening meal together. The weather has closed in and the wind has turned to the south which means cold and wet for us.

Bye for now

Harmen

Toroa takes us on a real journey.

Last Sunday the tide and wind were perfect for a trip up harbour to Kohukohu. We had intended on making the trip on Saturday however the wind and rain came in with too much force so we postponed.
I had wanted to attend the opening of the Ukulele Exhibition at the Village Arts Gallery.
The Exhibition was organised by the Kohukohu arts group who regularly put on art exhibitions of a particularly high standard.   http://www.villagearts.co.nz/
The Ukulele Exhibition comprised of a collection of ukuleles which had been given a makeover by well known, established NZ artists. We were blown away ( by the exhibition).

We had a very calm start so we started the outboard and set off with the incoming tide from the Rawene township and were soon navigating the treacherous "Narrows." After 40 minutes at full throttle we made the Kohukohu Wharf where we tied up to the floating pontoon where four young Maori children were diving from the roof of the wharf shelter.

The village of Kohukohu is the second oldest in NZ and is particularly pretty when viewed from the Water. The majority of the houses date back to the 19th Century with most having been carefully restored. The trees, the bird life, the fish all make for a beautiful outing on the harbour on a sunny Autumn day.
We left Toroa tethered to the pontoon after which Julie and I went to the nearby Waterline Cafe and ordered coffee and a chocolate brownie.
After an enjoyable relax on the veranda we walked over to the Gallery where we met Kohukohu residents, John, Marg and Jim,  colleague, curator/gallery owner, and boat enthusiast respectively.

After enjoying and discussing the brilliant show (Julie wanted to buy all the ukuleles on show) we made ready to leave. John, Marg and Jim came out to see us depart as they were particularly interested to see Toroa. With our friends in attendance on the wharf we cast off, raised our sail and set off on starboard tack across the harbour in 10-12 knots of breeze.

All went very smoothly and we sailed, on the wind, up to the Narrows where the decision was taken to drop sail and start the motor.

Under power we finished the trip to Rawene where we picked up our dinghy and paddled Toroa into the stream and anchored him ready for our next outing.

Toroa provided us with everything I have been wanting from him and I am very happy.

Sunday 28th Feb

I decided to take Toroa out to test the newly repaired outboard motor.

After the Chilean Tsunami alert was downgraded to an advisory I thought it would be safe to enter the water to retrieve Toroa from anchor in the tidal stream at Rawene.
I had not counted on the king tide (the highest in 7 years) and the force of the outgoing tidal flow.

I was immediately impressed and mildly fearful that I had not judged my swim trajectory to Toroa across the current.

I just made it.

Once on board I lifted the anchor in a dying south easterly. The breeze was completely gone by the time I raised my mainsail.

Toroa would not respond to any force I could exert without a paddle or out board motor (still on shore) me in my speedos waiting for the wind and heading off toward Australia at a respectable 4-5 knots.

No paddle, no PFD, no clothes, no sun block, no water and no wind.

Poor Julie was dwindling into the distance, a lonely anxious figure on the wharf. Mercifully a light breeze came up and I was able to regain control.

One hour and several shunts later I was fitting the outboard motor at the beach, 20 meters from where I first set out.
Julie took the opportunity to berate me for leaving myself (and her) so vulnerable.

"Just honing my skills mate"was my glib (though somewhat sheepish reply).

The motor started first pull of the starter cord!
We climbed on board with all our gear and provisions  and set off up the Waima River against the tide with the idea in mind that should the motor fail we would still have the current to bear us homeward.

Toroa runs better than expected under power. The Dierking foil works a treat and the new prop, 7 1/4"x 5" is just the right pitch for my set up. I estimate we made around 7 knots of boat speed with 2.5 Hp. with the mast stepped. That will do me.

I received an informal complaint later made by Mrs Fish from the Hokianga Takeaway shop (Mrs Fish and Mr Chip have a commanding view of the area where our little drama was playing itself out) that a man of my age in speedos was pushing the boundaries of respectability.  I remarked later that had I been a buffed, bronzed athlete the speedos could not have been brief enough.

 

Harmen & Julie at Rawene 

Photo by Rose Dierking 

Toroa rides again, again

Today Sunday was much like yesterday with light variable winds to begin with settling in to a sea breeze around 1.00. pm. Julie and I sailed out past the Rawene peninsula on port tack and headed for Motukaraka where there is a beautiful little Catholic Church on the hill.  There we shunted through to starboard tack and sailed past Rawene across the mouth of the Omanaia river. With abuilding breeze of around 12-15 knots we shunted again with the intention of heading back home. Unfortunately I got the shunt sequence wrong by failing to release the mainsheat from the old starboard tack position and got everything caught up. We very nearly got put aback before I figured out what I'd done wrong. Luckily I was able to unclip the sheet and uncross the lines. Once that was done the proa came back under control and we were able to set off again.
Lesson: Despite vast past experience, one over site  on my part and the whole system goes badly wrong.
I'll have to tattoo the instructions on to the inside of my eyelids. either that our set up a tape of subliminal shunting suggestions whilst I'm asleep!

I'll be working on Paul Bowker soon to convince him to come along with his little video camera and GPS for some vital statistics and footage.

Until then

Harmen

Toroa rides again

Today Saturday dawned bright and clear. The cyclone blew itself out and has now become a high pressure cell.
The sea breeze set in at Rawene around 11.00 am. Julie and I loaded our gear in the car and set off to the beach.

We paddled out and returned Toroa to the shore and I set about making the last changes and adjustments to the rig that I planned last night.

Once set up we caught the high tide and we set off up the Waima River on starboard tack in 10 to 12 knots of breeze.

 We put in a shunt which was trouble free and we set off up river. Toroa covers the ground very quickly now so it wasn't long before we were turning back.
Now I have enough confidence to have another go tomorrow.

I added a new endless shunting line which keeps the tack of the sail from moving about whilst I walk the rig from end to end.
I have managed to stay true to my goal of having no rotating parts all the control lines run through dead eyes and thimbles.

The mainsheet is based on the Kiribati style with a single and double purchase rigged to create a 1, 2, or 3 purchase sheet.
This system allows me to run only the one sheet for either tack, unlike Toroa's old twin sheet line set up. I have set up a clip to secure the main sheet dead eye block to either tack position on the lee gunwale with a light retrieving line tied to the centre cockpit scupper hole. That way I don't loose the end of the sheet through the shunt.

Toroa back in his element

Julie and I relaunched Toroa last week.

The outboard motor however would not run. After several hours of mechanical work I was still unable to solve the problem so I finally relented and took Julies advice. We delivered it to the Sail outboard dealer in Kerikeri. Tony diagnosed a blown head gasket! He assures me it will be ready to collect mid next week. The machine came with a bag full of parts which contained all the gaskets needed for the job which was fortunate.

Toroa's re cut sail looks very good and sets well.
I spent some time yesterday sticking non skid strips on to the decks to give me more reliable footing. I've added a tacking line and I'm experimenting with the shunting set up. I'm concerned that my mast, although sturdy is too heavy which makes the shunt a more demanding process than it should be. I may yet have to replace it with something lighter.

In the mean time Toroa patiently sits at anchor in the harbour at Rawene awaiting a day when there is less wind. Friday I took some time off work. Ironically for me, after weeks of hot settled weather the late summer cyclones have started forming. One has been moving south east down the East Coast of the North Island and affecting the pattern over the north. Overnight on Thursday the wind came in from the south at around 25 gusting 35 knots. I'm hoping for better conditions tomorrow Saturday for a trial sail.

I'll post some photos later.

Harmen

Domestic sewing machine does the job!

I got down on the floor today and set up our little "Brother" sewing machine. It handled the coated nylon sail thread and Novathene fabric quite well.
I had to set up the industrial sized spool of thread on a rod supported by two saw horses above the machine but that was the only problem I encountered other than setting up the thread tension correctly.
Once I'd done some practice runs on some scraps of cloth I sewed up the seams. I only broke 3 needles!
Lastly I sat down to hand sew the two joins in the bolt rope with waxed sail makers twine.

The sail now only needs bending back onto the spars and then I can set up for another dry run.
I'm learning patience which does not come naturally to me.
I do love the process of sewing by hand, there's something hypnotic about the activity. The result is so satisfying, so strong. I like to think of the power this inanimate sail is capable of producing, quite magical.

January 2010 progress on Toroa

Work on Toroa's sail and motor has begun again.
Since November 09 I've been distracted by my physical condition which has affected my wrists and hands.
I've also been very busy at the Rawene Hospital solving problems.

My outboard motor now has the Dierking foil fitted and I've ordered a new 7.1/4'x 5'' prop which arrives next week. (It's a Yamaha prop)

A funny thing about the New Zealand importers of Sail Outboards. When I made an enquiry about a replacement prop they tell me the manufacturers never made a long shaft 2,5 Hp 4 stroke outboard!
The outboard motor catalogue published in a recent NZ Boating Magazine lists 2 prop sizes for a Sail brand 2.5 Hp,  7,1/4"x5" and 7,1/4"x8". They tell me they've never stocked a 5" pitch prop either.

I wonder how my long shaft came into existence? Perhaps it's a figment of my imagination. I've posted some pictures of it, can you see it? It measures 19" from the bracket hook to the bottom plate.
Even the Sail brochure/ hand book that it came with says "Long Shaft, Barge Model 4 stroke, 2,5 Hp."!
Has anyone else got one / seen one or am I alone in the world?
Please let me know.

The reason for the foil is to reduce drag and turbulence around the surface piercing shaft. When unchecked the turbulence allows air to make its way down the trailing edge of the leg causing the propeller to cavatate or loose laminar flow over the blade, thereby reducing thrust.
The foil mitigates this problem increasing motor efficiency by a large factor.
Outboard motors are designed to sit behind a transom so the manufacturers only create a foil for the immersed section of the stern leg. The proa presents the unique problem of a surface piercing outboard which this foil answers very well.

I measured, cut and folded a piece of aluminium panel and wrapped it around the stern leg of the motor.
I do not want this structure to be a permanent part of the motor because I need to gain access to the ports  for leg lubrication and water pump. I riveted a v section tab down the trailing edge of the foil and screwed the other side with s/s p.k. screws so that I can unfasten it any time I need to.

I've laid out Toroa's sail on the workshop floor and I've started the modifications I've been planning.

 

 

I've removed the swallow tail tips from Toroa's old red sail (which is featured on youtube) and I've added them as an extension to Takapu's old sail. This procedure results in giving me more sail area down low allowing me to attach the boom much lower on the yard closer to the tack.

I grafted the fabric together using double sided tape which I will then sew with a zig-zag triple stitch. The stitch pattern is critical to the success of this modification as the sail cloth has been laid up diagonal to the angle of the bias to allow for stretch. If the fabric stretches without the equivalent stretch in the stitching the seam will fail or poor set will result. I'm going to try our domestic machine and if it doesn't cope I'll visit our nearest sail maker in Kerikeri next week and ask them to stitch it up for me.