Categories
Habitation

Designing the woodenwidget Plurt

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The Plurt lightweight yurt with the Hoopy.

One day I will try to write a book about design. I find the subject so fascinating and although I never formally studied it I have a good eye and apparently quite an imagination. Plus I love to problem solve, to find solutions to insolvable issues. I believe there is always a way to get something to work. Sometimes the solution is a bit complicated. Other times it is simplicity personified.

There are two ways to design something, either start with a blank sheet or use what is to hand or easily available. The first option will bring the fantastic vision of the designer to reality but it will take a very long time and be very costly. The latter option is more practical and sensible but may end up compromised aesthetically. As someone who designs creations that must be practical and easy to make I cannot take the first option, instead I need to find simple and inexpensive solutions which do not spoil the overall look of the finished product.

Sometimes however common materials come together and get repurposed so well that one can only admire the simplicity of it all. That was my goal with the Plurt. But also I wanted to add another dimension to the design brief which was minimal waste. This means using a material in its entirety or thinking carefully about what to do with any waste left over.

It just makes sense to me to use materials as they come and not have to work on them. It speeds the process and reduces waste to zero. I would make the Plurt using thin ply around a wooden frame with bonded XPS to act as insulation and to add strength to the panel. From working out how much a piece of ply could be bent I reasoned I’d need 6 wall panels which would create a 5 metre diameter circle 1.2m high. The ply would not even need to be cut down.

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The six curved wall panels and door frame.

Of course creating curved shapes is much harder than making straight ones but as a boatbuilder with many decades of experience making things that aren’t flat is as easy as kiss my hand (as Jack Aubrey would say) to me. A jig would be required but as there are 6 panels to make it would be time well spent making one. It would allow the making of 6 identical panels which would ensure a good fit and if they were all the same then they could be interchanged allowing for different configurations with windows and such.

The only downside to a jig is what do you do with it after the panels are made? In the case of the Plurt the wall panel jig is modified and becomes the jig for the roof panels. Once all the panels are made the jig itself becomes a table or a bed for your Plurt and the curved cut out pieces are turned into a free standing shelf unit. No waste.

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The shelves made from the jig. Strong and stable.

Each wall panel has locating pegs which not only hold the panels in the right place ensuring a good fit and seal but they also help to distribute some of the load from the roof. Once the panels are put together clamps pull them tightly together. The clamps act in much the same way as the wire that encircles a traditional yurt but as the entire roof of the Plurt only weighs 150 kilos, the forces on the walls is considerably less.

Designing the roof panels was much more challenging. They are flat but trapezoid in shape and have slightly angled sides so that they sit against each other well. They all fit in to a standard 700c bicycle wheel at the top. Traditional yurts have a large and heavy wooden crown and all of the many roof poles are fitted in to it. It’s one of the reasons why putting up a traditional yurt is not a one man job. I wanted to find a better way.

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See how the tenon sits beautifully in the wheel rim and cannot lift out.

A 700c wheel is about as big a bicycle wheel as you can get and it is a very common size. In designing I find there is a lot of luck. For example when I was doing my experiments to see what I could do with the roof I needed to get the tenon in the end of the roof panel to sit inside the bicycle wheel rim. I had imagined needing to cut a special shaped tenon but as it happens a simple rectangular shape sits beautifully inside the rim when the roof is at its final 26 degree angle. Nice when that happens.

Apart from getting the size and shape of the roof panels right there were many other issues, for example, how would I fill in the inevitable gap between the roof and wall panels created when you place a flat object on a curved one? How would I waterproof the 15 joins? That’s 40 metres of potential leaks! I did some quick experiments and discovered that a simple guttering made from garden hose worked just fine and even held itself in with friction alone. I was very happy to solve this one so easily.

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A worm’s eye view of the roof.

There are many reasons to use garden hose as guttering. It fits in with the low cost and easy to find ethos for a start but it even works on an aesthetic level too as the gutters mimic the poles that you would find on a traditional yurt and helps to break up the large wooden surface. Bottom line? It looks good. It looks right. Other advantages to this system apart from the low cost are that these same gutters can be used to carry cables to the roof should you want a fan or lighting up there. But best of all it allows for a nice margin of error. If the roof panels are not 100% and there are some gaps between them, it really doesn’t matter because the hose just expands slightly to take up the slack.

Calculating the size and shape of the roof panels was not easy but harder than that was trying to minimise waste. For a long time I juggled with different sized panels, more or less panels and different roof angles until I finally found the compromise that would allow a good roof angle but just as importantly the right size that would allow the off cuts from one side of the panel to be used on the inside. A traditional yurt typically has a roof angle of 30 degrees so I was not unhappy about getting to 26 degrees.

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The 15 roof panels leaning against the walls.

Initially I imagined the roof panels would also have some kind of locating device to ensure that they couldn’t move or slip plus they would help to spread the forces but due to the way the panels are fitted when the roof goes up, it just wouldn’t work, so that idea had to be abandoned. It seemed to me that once the whole thing was assembled and sitting right, the tops of the panels would all lock in to the bicycle wheel at the top and the supporting knees would lock in the lower end and once the clamps were added to the lower end it would have sufficient stiffness.

The next issue was how to assemble the roof on top of the wall panels. Traditional yurts often have a central scaffolding which is later removed so I decided to mount the wheel on a post in turn clamped to a simple step ladder. Obviously the wheel has to be mounted centrally to ensure the roof has equal overhangs. There is always a little margin for error of course but not much. Part of the compromise of the minimal waste design meant that there would not be much overhang so it had to be placed pretty accurately. the solution to this was to use a plum bob hanging from the post and pointing at the very centre of the yurt base.

Once the wheel was centred and at the correct height another advantage to this system came to light. Originally I assumed that the panels would be pushed in to the wheel from the outside and as they are triangular the gap would close as they went home but an unseen advantage of the tenon at the end of the roof panels is that they can be dropped in and rest on the inner rim of the bicycle wheel before being pushed home. This means the panel is supported while you adjust the last few millimetres.

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Note the roof panel centrally placed over the door with added rain diverter.

Bear in mind that it’s one thing to make a structure like this but it is quite another to find so simple a way that it can be documented and explained for the builder. Seems that luck was on my side once again. The first roof panel is fitted centrally above the door frame. This was not my decision but arrived at because if there was a join at the door there would be a gutter dripping water on you as you went in when it was raining.

To keep the weight even on the bicycle wheel, the roof panels are assembled one at a time and the next panel is fitted opposite the last one and so on until all the panels are fitted. The roof panel that fits opposite the first one just happened to line up with the end of one of the wall panels so it is an easy thing to describe. The roof panels go in until there are two spaces left. One of the gaps will be too big for a panel and the other too small. A roof panel is fitted to the larger gap and then the rest of the panels are just shuffled across a few millimetres until the last gap is just big enough for the last panel to be dropped in.

At this point the panels are clamped together. There is one clamp at every join nicely hidden at the lower end. Now the roof is pretty solid and yet still not actually fixed to the walls and this is where the knees come in. They have slots in them so they can be adjusted. Once the roof is up, the knees are loosened and a shim is placed behind them so that the next  time the Plurt is disassembled all you have to do is remove the shim, the panel will drop down slightly opening the gap and the tenon will still be resting on the bicycle wheel rim. Now it can be pushed up and lifted out. As the roof panels are only 10 kilos each it’s not a hard thing to do.

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The adjustable plexi dome fitted through the hub of the 700c bike wheel.

The next job is to fit the dome but how can you do this when the bicycle wheel is on a step ladder and has a bolt fitted through it? You can’t. first the scaffolding needs to come down. Once the roof is free standing the mounting bolt fitted to the wheel can be removed making space for the dome which is fitted using a threaded lead bar. But how do you get on the roof to drop it in? You can shimmy up the roof and place it in that way as the roof can easily take the weight but there is a better way.

Simply remove one panel. The roof stays up just fine even with the odd panel removed. Then get the ladder and pass the dome through the big gap and drop in into the hub of the wheel. Now the panel can be refitted and reclamped.

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Fitting the guttering in to the grooves in the roof panels.

Now the Plurt is erected but not fully assembled. The internal guttering needs to be fitted. It’s an easy task but does take a little while as there are 15 x 2.5 metre length gutters to fit.

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Sometimes the best solutions are the simplest. Foam pipe insulation fits perfectly.

The gap between the roof and wall panels was still unsolved at this point. Sometimes when you do not have a solution it’s best to stop thinking about it and often this way a solution will appear and that is exactly what happened. Turns out the perfect material for the job was some foam pipe insulation. It’s a neutral grey colour and can be forced in to the gap making a very respectable seal. It’s perfect and fits the easy build ethos. It’s cheap and readily available and comes in one metre lengths which, believe it or not, is exactly the distance between the roof panel knees so they didn’t even need cutting down to fit. Sometime the design gods are on your side. A perfect solution for what had appeared a really difficult problem to solve. it’s often this way with design. Often what you think will be the hardest problems to solve turn out to be the easiest and vice versa.

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In the Plurt you can fit opening windows anywhere.

Now that the Plurt is fully assembled and weather tight it’s time to fit the windows. This is just much easier to do when the walls are in place and firmly held. Unlike a trad yurt which has an interior lattice the Plurt can have opening windows anywhere in any panel. This is important because a yurt needs good ventilation. As the wall panels are identical you can move the window lay out around if you fancy a change. Not something you can do on most yurts.

The Plurt has many advantages over a traditional yurt and perhaps the biggest is that it does not have a fabric skin. No doubt it’s a good watertight system but it doesn’t allow easily for openings and will eventually rot away in the sun. The Plurt is simply painted plywood so when the paint is getting a bit tired, all it needs is another coat and it’s good for the next few years. replacing a fabric covering for a 5 metre dia yurt is a costly undertaking to have to make every ten years whereas a tin of paint doesn’t cost much in comparison.

The advantages keep coming. If you wanted to make a traditional yurt yourself you’d probably come unstuck at the fabric stage. Unless you have a large clean space and an industrial sewing machine you simply won’t be able to make the covering and having done some heavy duty canvas sewing I can tell you that sliding around a 20 sq metre piece of cloth is very hard, even the professionals struggle. This simple fact alone means that a diy yurt is out of the question for even the most resourceful of people. And consider how hard it is to fit such a cover to a framework standing 3 metres high. Doing away with the fabric is the first step in being able to offer a diy yurt.

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The very cosy and bright Plurt interior.

Another advantage to having no fabric is that it’s easier to have windows that open. Not only that they can be made of glass which is much nicer to look out of than the transparent plastic fitted to most yurts. You can even fit salvaged windows in the Plurt.

None of the panels are long nor heavy so it makes the Plurt much easier to assemble, even alone and it makes it easier to transport and store. Less materials means less cost. The Plurt typically costs about half that of a similarly sized traditional yurt.

Despite the Plurt’s light construction it does not feel flimsy at all. It does not move when the wind blows and the insulation dampens the noise of the rain although you always know it’s raining when you’re in a Plurt.

As I said at the beginning of this post, design is a fascinating subject and it’s amazing how by choosing certain important criteria before you start can have such an effect on a design. There really is very little waste when you build a Plurt and that is a good thing. We all need to be more conscious of how we use the planet’s valuable resources and reducing waste and building in wood is a good place to start.

How many other small dwellings can be built so cheaply and be taken apart in minutes? And on top of all that there’s the element of being in a circle, the calm that it brings compared to straight lines and right angles. All in all I am very pleased with how the Plurt has turned out. It’s a lovely space to spend time in. It could be used to live in, or as an office, a kid’s playroom, a yoga space or even rented out to earn a living from it. Having created the design and spent months perfecting the plans it’s now up to others to decide how they will use their Plurt.

Why Plurt you ask? It’s PLywood yURT but later I discovered that it also stands for P.L.U.R.T. Peace, love, unity, respect and trust. Nice. Plurt it is.

Categories
boats

The Stasha ‘Tweed’ Nesting Dinghy uses Flax

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The Woodenwidget Stasha ‘Tweed’ special edition lightweight nesting dinghy.

The Stasha lightweight nesting dinghy from Woodenwidget has been around now for a few years and I used the prototype for three years as my yacht’s tender. In many ways it’s the perfect dinghy for the Pacific Seacraft Dana, after all it was designed to fit on one! It is easy to stow and launch but more than that it is a fabulous little boat. It is a joy to row and it sails superbly too. When the prototype was showing signs of wear I thought about just putting a new skin on but in the end decided to do something a bit different. And so was born the Stasha ‘Tweed’

The biggest difference between a standard Stasha and the ‘Tweed’ is the fabric. The standard Stasha uses a thin and lightweight heat shrink Dacron covering which is then coated. The ‘Tweed’ uses a Flax fabric woven in the UK. It is specially woven so that it ‘drapes’ well and can conform to a curved surface such as a boat hull. It is normally used with a bio resin that cures with sunlight but I did not try this method deciding to use epoxy resin instead. Not because I think it is better or anything but simply because I had been given a load leftover from another job. If it wasn’t used it would soon be of no use so by using it I avoided buying something and stopped it being wasted.

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Close up of the cloth at the bows. It wasn’t even necessary to overlap the cloth leading to a very tidy look. The fine trim was added to cover the join between the cloth and the panel. This wasn’t entirely necessary as the join was fairly neat but it does lend a pleasant finished look and may even protect the bow panel from damage.

I will be discussing using this material later in this post but if you’re interested here is the link to the site where I bought the Flax fabric. It is the Hi-No twist fabric at £22-50 a metre. The roll is 1.38 m wide so for the Stasha it meant laying it across each section to get enough width to cover in one piece.

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Close up of the raw Flax fabric before epoxy.

One of the problems about using epoxy is that it is brittle and without modification would lead to a fabric covering that could be punctured too easily. In order to make the epoxy a little flexible you can add Benzyl Alcohol. About 2-3% is plenty. It’s a simple and cheap way to do it.

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The test bed for the fabric. This is the finish after the first coat of epoxy. As you can see the finish is very rough so needs sanding and further coats of epoxy.

The fabric is 400 grams a square metre which makes it twice as heavy as the Dacron before the epoxy is even added so using epoxied Flax is not a light option. However the standard Stasha proved to be so easy to stow and use on the boat that it wouldn’t really be a problem if it was a bit heavier. Especially considering that the boat is in two halves so it’s already easy to handle.

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This is how the fabric looks on the inside after epoxy. The finish is much smoother on the inside but far from flat and smooth.

The other difference between the original Stasha and the ‘Tweed’ is that it is made entirely of teak, not ash. Again, this was wood left over from another job and so it would be a shame not to use it. I didn’t know if it would be possible to bend the ribs using teak as it is a much stiffer wood than ash and not known for its flexibility or bending qualities but it wouldn’t hurt to try. If the worst came to the worst, I could always have ash ribs and teak stringers. That would have looked ok.

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Bending the teak ribs in required planning, patience and lots of spare wood. The extra stiffness of teak makes this a very hard job. Ultimately successful however. Wood is an amazing material.

As it happens making the ribs bend was certainly possible but required a lot of patience and spare pieces of wood as the breakage level was high. In a couple of areas I was not able to make ribs in one piece so had to scarf two pieces together. This was no problem but did add time to the build. The orientation of the grain was crucial as well, the slightest run off and the ribs would split. I soaked them before hand for a number of days and kept them wet while I was teasing them into place on the strong back with the hot air gun. It took a very long time to do the ribs and the teak was so much stiffer that the ribs would have a tendency to force the stringers away from the strong back. Ultimately I succeeded but it was not easy.

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One of the wooden rings cut out using two blades in the hole cutting saw. This was then cut into 4 and used to trim the plywood end grain.

Another difference is that every piece of plywood on the ‘Tweed’ has been capped with solid wood so that there is no end grain showing. This is a surprising amount of work, especially where the two sections join as the cutaway has rounded corners. The quickest way I have found to do this is to use two blades in a hole saw and cut out a ring of wood. This is then carefully split into 4 with the grain orientated and then it is glued to the plywood. One of the things that takes so long with adding trim to plywood is the care that you need when trimming it down level.

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Here the plywood end grain trim is being glued on. They will be planed down flush later.

The best approach here is to simply glue on a piece of trim that is slightly wider than the plywood. When it has set, use a hot air gun on the lowest setting, warm up the excess epoxy so it becomes soft and scrape it off using a sharp scraper. This is a very gentle operation. The epoxy will come off very easily with a little heat and a little patience. Once the epoxy is removed it is time to plane down the trim flush with the plywood. Remember that most plywoods have a top veneer of a half a mm or less. You cannot afford to cut into it at all. So a very sharp block plane is needed and also lots of care. Gradually plane down the trim until it is flush. Then use a block and some 180 sandpaper to clean it up.

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Gluing on the inner trim. This is something the standard Stasha in its never ending quest for weight loss never had. It adds a little weight but gives a very sleek look on the finished dinghy.

The last great difference is the addition of inner trim pieces to cover up where the stringers are glued into the end panels. It adds a ‘finished’ look to the boat and also strengthens the glue join. These take a long time to make and fit too as they need to be very neatly made. The quickest way I found was to make a cardboard template for each piece.

The seat used to scratch the varnish on the Stasha so now there are pieces of wood that will remain unvarnished instead. The seat is now made from slats of unvarnished teak rather than a single piece of plywood.

If you were thinking of building a Stasha ‘Tweed’ then I must warn you it’s a lot of work and it demands more skill than for a standard version which is very easy and fast to build. It will weigh about 50% more. With floors and seat it weighs about 17 kilos which is about 5 more than the standard boat but as I said, because it’s in two pieces not one section weighs more than ten kilos.

Asides from weighing a lot more it takes about three times longer to build and uses about five litres of epoxy and two litres of varnish!

The end result is a lightweight but virtually indestructible hard nesting dinghy. It is also extremely nice looking.

The finished fabric is almost two mm thick  so a rebate needs to be cut out of the exterior edges of the panels so that the fabric fits flush in the end.

Also, because of the extra thickness of the fabric it is necessary to remove a couple of mm from the sides of the joining panel on the rear section or it will be too wide to nest without scraping the varnish.

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The varnished front section with panels rebated a little to allow for the thickness of the fabric. The standard Stasha uses much thinner Dacron that doesn’t need to be rebated.

Here’s how the fabric is fitted: The fabric is not wide enough on the roll to fit from one gunwale to the other but it is wide enough to cover from front to back. I bought 4 metres of fabric and didn’t have much left over.

One of the great advantages of this system is that you do not have to rush or panic. You will epoxy only when you are happy with the fitted fabric. It is worth taking your time to get the fitting of the fabric correct because when it is epoxied and varnished it is translucent and any kinks or jumps in the weft or weave of the fabric will be very noticeable.

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The fabric draped over the framework, tensioned and stapled in place.

The fabric needs to be stretched tight before epoxying or it will sag with the weight of the resin. The problem is, how to get the fabric tight when it is such a loose weave. If you pull on one part, it pulls the weave out of line. I used staples to hold the fabric tight. It took a long time to pull it all tight while still keeping the weave straight along the keel. It took a lot of putting staples in and then pulling them out again as I tightened first one side, then the other all the time keeping tension fore and aft as well. This is quite tricky to do as you need as much tension as you can get but without pulling the weave apart or distorting or pulling the weave out of line.

However there is no rush so you can take as long as you like to get the fabric laying right. I found that the fabric lay well over the entire front section if I pulled the aft corners aft first. Then by the time I got to the front, the fabric was able to cover the whole shape in one piece without kinks or pleats. I was particularly impressed that I managed to get the fabric to follow the bow section without having to cut any fabric out.

To make working on the dinghy easier, I varnished the entire framework (except the outer surfaces) with three coats before fitting the cloth. Varnishing the framework is a complete pain in the arse, as is sanding between coats. The plan was to do three coats on the framework and then two entire coats inside making 5 coats for the woodwork and 2 coats for the fabric.

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This is what the front section of the dinghy looks like after its first coat of epoxy. The colour is good but the finish is very rough, far too rough for a boat. It will need sanding smooth and more epoxy then two coats of varnish before it is finished.

The epoxy is brushed on liberally. It is amazing how much epoxy the thick fabric will soak up. I did a test piece first to judge how to apply the epoxy. In the event it was very forgiving and I had no drops of epoxy come through the cloth despite a heavy application. The ideal is to have enough epoxy to wet out the fabric but not so much you are adding weight for no reason. The trick to getting the folded corners to stick down is to apply epoxy to the wood underneath it first, then dab the fabric down with more epoxy.

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The finish on the outside after three coats of sanded epoxy.

Once the epoxy is set it needs to be sanded smooth. If you have applied enough epoxy you will find that even with some quite violent sanding (I used 60 grit on a random orbital) you won’t go through to the cloth. In a couple of places the cloth was visible but that was OK as it needs another couple of coats, each one sanded down smooth. Then the whole surface was sanded down with 120, then 180 and finally 240 grit. Then it received a further two coats of varnish. The varnish is needed as otherwise the epoxy has no UV protection.

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Almost finished varnishing. Four coats on the wood and one on the cloth. It will receive one more coat all over. Note the trim around the stringers where they fit into the front panel. A small touch but makes a large difference to the looks. The epoxy used to glue in the ribs had teak dust blended into it to darken it making it very hard to see it.

The end result is a thick yet slightly flexible and extremely tough skin for the boat. It looks fantastic with the light coming through it. I am happy that I took so long laying the cloth so that the weave was even.

Conclusion:

Not for the faint hearted. Sanding epoxy is a thankless task and varnishing to that level is also soul destroying. If you have 120 plus hours spare then all you need is a set of Stasha plans from Woodenwidget.com and this article and you too can have a splendid looking lightweight nesting dinghy like the Stasha ‘Tweed’.

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View from the inside with the light coming through.

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Categories
Bicycles boats

Folding boat towed by folding bicycle

The Fliptail 7 towed behind a Brompton folding bike

Maybe it’s because I live on a boat that the idea of things that reduce in size for easy storage appeal. After all, if I didn’t have a Brompton, I wouldn’t be able to have a bicycle aboard. For that matter, if I didn’t have a folding dinghy, I wouldn’t have space for a tender either.

It seems amazing to me now that I have waited so long to get this idea together as it’s so obvious I wonder that I didn’t think of it before. The marriage of a human powered bicycle and a human (or wind) powered boat is just great.

The Fliptail 7 from Woodenwidget.com weighs about 18 kilos which is no problem at all for the Brompton. On the stem of the Fliptail there is an eye bolt and on the aft end of the Brompton rack is a pin which the eye is simply dropped onto. The weight of the boat keeps it in place. There is plenty of ground clearance and the turning circle isn’t bad for a vehicle which is over 10 feet long either.

The pin on the rack doesn’t make the Brompton’s folded size any bigger but it does interfere with the bike when the swing arm is swung around. The bike still stands on its own but is not as stable as when all 4 rack wheels are on the ground. The answer I suppose is some sort of easily removed bracket.

The trailer attachment is made of alloy tube and is light and also folds away for easy stowage. It can be used equally for the road or even for launching and retrieving the boat. The Fliptail can be folded or unfolded with the trailer in place. It simply attaches to the boat’s transom where the outboard motor would normally go and could be fitted to any boat so long as it has a flat transom whatever its thickness.

This combination is perfect and I see no reason why you couldn’t go quite a long distance with the boat behind the bike. You can feel the weight when you first start to pedal but you soon forget the bike is there, at least on a level surface. The oars rest naturally in the boat and you could just as easily also add the mast and sails etc to the boat as well making the Fliptail 7 amazingly versatile.

When you get to the camp site you can even use the erected dinghy as shelter to sleep below. The folded Brompton takes up little space inside the boat so you could peddle up stream, put the boat and bike in the water and paddle or sail downstream. When you get where you are going you simply haul the boat out of the water, fold it and hitch it to the Brompton and off you go again. This is camping luxury!

The best bit is that there is no pollution! A bicycle and a row boat. Wow. Talk about setting a good example. Everywhere I go, people look and stare. And I’m not surprised really, it’s not something that you see everyday. More’s the pity.

The trailer attachment is not yet available, though Woodenwidget will soon be offering plans to enable a DIYer to make their own. If you are interested, please drop them a line, maybe if there is a lot of interest, they can be persuaded to speed things up a bit?

If you want to know more about the Woodenwidget range of dinghies for the spatially challenged, please visit Woodenwidget.com and check out their range of clever little boats.

Here’s a link to an article I wrote about the Brompton that you might enjoy too.

Categories
boats Videos

Sailing the world’s lightest nesting dinghy

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Leica M9, 21mm f2.8 Asph ISO 160 250 sec @f 16

Click here to watch a one minute video of the Stasha sailing in a nice breeze. Filmed with the HD Hero Video camera at the island of Porquerolles nr Toulon, France.

Categories
boats

Designing the lightest nesting dinghy in the world

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Panasonic Lumix. The Stasha, the world’s lightest nesting dinghy. Weighs as much as a baby bird (wandering albatross chick)

There’s a saying that I like. ‘If you get in a car and don’t know where you’re going, you’ll never get there’. Designing a boat is a bit like this as you need to know a few things before you can begin. Knowing where to start is easier said than done. So many things can influence the design. I have found that a good place to start is to first think about what you don’t want. For example, I didn’t want a heavy dinghy. Nothing spoils the dinghy experience more than a weighty tender that is hard to move about and stow. This was my starting point. No matter what shape or size of dinghy I came up with it wouldn’t be a heavy one!

For years, I’d been intrigued by boats I’d seen in America that were made using materials from light aircraft. Constructed from a framework of wood and covered in cloth, they looked fragile but were obviously quite tough and since I was determined to keep the weight down I would also have to employ a similar system. So deciding what I didn’t want from my dinghy led me to the construction technique I was going to use.

However, there’s no point having a light dinghy if you have no where to put it. My yacht is just 24 feet long and the only place I could think of to stow a dinghy where it wouldn’t be in the way, look ugly or be unseaworthy was on the tiny foredeck. I got my tape measure out and discovered that it was about 4 feet wide at the aft end where the cabin begins and was a bit more than 4 feet from there to the bows. So it would have to be a nesting dinghy. In theory it could be about 7 feet long when assembled and that was a good size for a small yacht. And so was born the idea of making a super lightweight nesting dinghy.

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Leica M9, 21mm f2.8 Asph. Stasha dinghy, nested and stowed on the deck of a Pacific Seacraft Dana 24.

There’s not much point worrying about aesthetics when you are designing a dinghy, the most important thing in my opinion is stability. There is nothing worse than a tippy dinghy, except perhaps a heavy tippy dinghy. Light boats are less stable than heavy boats so I would be relying mainly on the shape of the boat to provide stability. This meant that it had to be as square as possible. I now had enough information to design the boat’s shape.

The rest of it would be guesswork based on experience. What would happen if I cut a boat in half to make it nest? Would it be strong enough? What kind of forces would the join be under? How would the stringers attach to the end panels? These and many more questions filled my brain. As far as I could tell, no one had ever built a dinghy like this and I wondered why. Have people tried it but drowned during testing or has no one ever tried? Maybe it was a stupid idea that would never work but one of the great beauties of a lightweight boat is that they are cheap to build. Less materials means less cost. I could afford to simply make a boat and see if it worked.

Normally nesting dinghies are made so that the front section comes off and fits inside the rear section but this does not seem logical to me for many reasons. The shape of the front section always needs to be quite pointed but this reduces stability too much. It also means that the interior volume of the dinghy is much reduced so you might have an eight foot nesting dinghy but it will feel much smaller. Then there’s the rowing position. It’s perfectly logical to put a thwart on or above the join but it leads to a bows down attitude when rowing which makes the dinghy hard to row and just looks wrong. Rowing is easier when the bows are slightly up.

The whole concept seemed flawed to me so I tried a bit of lateral thinking and did some sketches with the rear section fitting into the front section and suddenly everything started to make more sense. The most obvious problem with doing it this way around was that the rear section would be slightly narrower than the front which would mean a step where they join. In fact this is not a problem as the bottom of the dinghy remains flush, it’s just the sides that have a small step. I doubted if it would make an appreciable difference to the finished boat’s performance.

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Leica M9, 21mm f2.8 Asph. Sunlight glows through the translucent skin of the Stasha. Note the small step at the join.

This one compromise seemed a small price to pay for the host of advantages that it brought the design. I could have a fairly fine bow, a good interior volume, great stability and a perfect rowing position. Another bonus with this set up is that the rowing position doesn’t have to change when you take a passenger. Not only this but if the passenger sits in the front section back to back with the rower, the combined weight is centred in the boat increasing stability still further and each occupant has a clear, unobstructed view of their surroundings. This is much more pleasant for everyone. Yet another advantage was the fact that the pintles for the rudder are stowed inside the nested boat so ropes can’t get caught on them.

To simplify the building process, I decided to do away with any hint of sheer and make the top of the boat completely straight. Simplifying the wood requirements would also make the boat easier and cheaper to build. Now I had all the information I needed to start to design the boat. I made a few sketches just to see how it would look. Although it was boxy it still had a nice boat like shape which was pleasing.

Next I made a 1 -10 scale cardboard model 220mm long. I wanted a near flat bottom for maximum stability and ease of build but I suspected that the fine framework allied with the pressure of the water on the hull would flex inwards so I incorporated a slight V into the bottom. This would also add more strength to the structure. The sides are almost upright, with only a slight angle outwards. Again, this increases interior volume and stability.

The simplest way to build a boat like this is to make a jig. Panels are cut out and screwed to the jig and then the stringers and ribs are attached to it to create the framework. Happy with my cardboard model I divided it up into 5 sections and used these measurements to make the stations that would dictate it’s shape. I scaled up the measurements by simply adding a zero. Then these measurements were converted into instructions using the simple ‘join the dots’ principal that all Woodenwidget dinghies are built with.

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Leica M9, 21m f2.8 Asph. This photo shows the jig for the front section with all panels, stringers and ribs in place.

Deciding how many stringers and ribs to use was decided by guesswork based on experience and finally what ‘looks right’ while trying to minimise weight and keep the build simple. Obviously the more ribs you have the more work there is to make and fit them. Since lack of weight was everything I did err on the light side.

The end panels on the jig stay as part of the boat while the inner stations are only temporary. The end panels have slots cut in them to accommodate the stringers which are then glued in with epoxy resin. The stringers are held in place on the inner stations with cable ties. The following day the ribs are made and glued in place. The ribs are glued everywhere they touch a stringer. This gives over 60 glue joins which makes for a surprisingly strong structure.

The making of the ribs caused me some concern. On the one hand I wanted the dinghy to be easy to build but it had to be light too. I considered a system that had no bent ribs but it meant making nearly 40 mortices which would take a long time and require a certain skill. It would also add weight and complication. So I decided to take a fresh look at bending ribs with heat.

At some point most boat builders will have a go at steaming wood. It’s a lot of fun and it’s amazing what you can put a piece of wood through before it breaks. If you want to really understand wood this is a great way to do it. You will walk away with a new respect for it as a material.

Some woods bend easier than others so I chose ash because it is strong and light as well as easy to bend. The straightness and orientation of the grain plays a big part in how far you can bend wood as does the amount of moisture content. Thin wood bends easier than thick wood but in any case you’ll need heat. Most boat builders will construct a steam box to do this but since there are only 9 ribs to be bent in the Stasha I needed to find a simpler way.

Pre soaking the wood for a couple of days is essential. Once the wood is completely saturated, they are fitted to the jig. The centre is clamped to the keel and each side of the rib is pushed down while applying heat from a hot air gun. The ribs are pushed down in gradual stages until they touch at all the stringers. This is a little time consuming and it helps to have patience but still easier than any other system I could devise. It’s also the lightest way and gives the dinghy a nice rounded boat shape. This also makes it easier to fit the cloth later.

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Leica M9, 21mm f2.8 Asph. This shot shows one of the ribs being gradually persuaded into place with heat from a hot air gun.

The ribs are then glued where they touch at all the stringers. A day later the structure can be removed from the jig. It’s still quite floppy but gets much stronger at every stage. (To save wood, the stations are cut down to make the jig for the rear section of the dinghy). Inner gunwales and reinforcing knees are added for strength and that’s basically all there is to the wooden structure. Not one screw in it. It’s thanks to the amazing bonding strength of epoxy that a construction so light is even possible.

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Leica M9, 21mm f2.8 Asph. Here’s the framework for the front section complete, just awaiting the kevlar twine and the cloth.

Now all the hard and messy work is done. All that remains is to cover the framework with a special heat shrink Dacron cloth. It’s attached with a product called Heat’n’Bond which is glue on a roll. It is melted with a humble domestic iron. This is cheap, light and very easy to use. It also sticks very well to the cloth and has excellent sheer force qualities. This Heat’n’Bond tape is applied to the keel, gunwales and end panels.

Now Kevlar twine is laid diagonally across the boat and glued to the gunwales. This helps to reduce twist in the structure and also to give more for the cloth to lay against than just the stringers. The cloth is laid on the structure and glued to the gunwales and end panels, then the iron is run over the cloth and all the wrinkles and baggy bits simply disappear leaving a drum tight smooth finish. This is very satisfying to do. The edges of the cloth are protected by small battens of wood and finally coated with a water based varnish but this is just one way to waterproof the fabric.

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Leica M9, 21mm f2.8 Asph. Here the Dacron cloth has been glued in place. The remaining creases magically disappear when the iron is run over it.

Having made the two halves it was time to work out a way to join them. There’s no point having a nesting dinghy if it can’t be easily assembled either on land or on the water. Initially I thought about a very minimal bulkhead for the join along with some kind of waterproofing but that hardly seemed easy. Far better to sacrifice a little weight and have fuller, higher bulkheads. This means that each section is a boat in it’s own right so there is no need to waterproof the join at all. Two simple keyhole slots are all that is needed at the bottom of the join and two bolts at the top. Assembly takes less than a minute.

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Leica M9, 21mm f2.8 Asph. Here the keyhole slot for joining the two sections can be seen.

What we have here is a basic 7 foot nesting rowing boat which is probably fine for most people especially as it rows so well but I also wanted it to sail. Because the rear section nests in the front section, centreboards and the like are out of the question and in any case fitting something like that would add weight and the potential for leaks. It would also be demanding to do and this doesn’t fit in with the easy build ethos.

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The keel is bolted to the side of the boat and can swing up if you run aground. Here the slab sides are a bonus as it gives somewhere to attach the keel lower down. The mast support is made from two thwarts, the upper one bolts to the top of the gunwales and the lower one rests between the ribs below it. Diagonals of string must be added to help spread the load from the mast. Simple, effective and light. The mast and rudder from an Optimist is used with a slightly cut down sail.

If you want an outboard then you’ll have to reinforce and thicken the transom. This adds about half a kilo to the weight of the boat. This option has also been designed to be retro fitted at any time.

I am delighted with how well the boat has turned out. It is pretty, very light, easy to assemble, stows beautifully and fairly unobtrusively on the foredeck. The rowing position is excellent and very comfy. It goes fine with up to a 3.3hp outboard and sails surprisingly well with it’s modified Optimist rig.

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Panasonic Lumix. The Stasha under sail using it’s cut down Optimist rig.

To be honest, I have been surprised at how well this boat works. I had no idea if it could take the stresses from a mast and keel or an engine but it has passed all these tests with flying colours and I’m still here to talk about it. Someone said it seems to ‘Dance on the water’ and it really does. It also slips along and carries it’s way amazingly well for such a light dinghy. Any doubts I might have had about the step in the hull are long forgotten, it seems to make no difference whatsoever. This can be confirmed by watching the water through the translucent hull as it passes the step. The boat hardly leaves a mark of it’s passing as it cuts through the water.

So this proves that if you follow sound basic small boat principals and keep faith with your original wants and don’t wants, you end up with a splendid little boat that is easy and fun to build in the smallest of places. It’s cheap to make and surprisingly tough. It stows away in a minute almost anywhere, including the back of an estate car. It rows well, sails well, takes an engine, two people with shopping and it does all this while weighing the same as a Wandering Albatross chick! (about 10 kilos! Very heavy for a baby bird perhaps but extremely light for a 7 foot dinghy)

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Panasonic Lumix. The Stasha nested. It can be stowed upright if needed. Note the kevlar twine reinforcements.

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To learn more and see some videos of the Stasha in action, please visit Woodenwidget.com