Amateur Yacht Research Society

Following a query during November's meeting, I will report here on my (very slow) progress on my main project, "Insert Hull Here", a frame with hinged Bruce foil. It is intended to contain all the forces generated by the rig and the underwater appendages within the frame, so that the hull only has to provide buoyancy. In theory, it should be possible to attach any hull that has not too much drag in the intended speed range, and has gunwales that are strong enough.

On the lee tack (the foil is to lee), the Bruce foil pushes up. On the weather tack, it acts like the hinged foil first proposed by Hagedoorn, and also advocated by Giles Whittaker. That is, when the foil goes over a wave on the weather tack, a rigidly connected Bruce foiler to has to overcome the roll inertia of the whole boat in order to stay in the water. The hinged foil only has to overcome the roll inertia of itself and the beam up to the hinge, and the rest of the boat can follow later. That generally gives away some righting moment, which has to be made up some other way, for the sake of the foil staying hooked in.

Note that when the boat is on the lee tack, what matters is how high the intersection between weight and foil force is relative to sail force. In the figure below, that distance is 0, meaning the boat does not heel on the lee tack.

When the boat is on the weather tack, what matters is how high the intersection between hull buoyancy and foil force is relative to the sail. Here, there is some lever arm left, though only about 40% of what it would be when using only conventional underwater appendages, But because the foil does not fully balance sail force, some righting moment has to be generated the conventional way.


The forward beam of the frame is laminated. It has some time-consuming fiddly bits, like the mast partner, and the hinge that has to fit the rear beam fairly precisely:
https://www.flickr.com/photos/78112151@ ... ed-public/

Rear beam is partly lashed up with basalt fibre, but not yet epoxied:
https://www.flickr.com/photos/78112151@ ... ed-public/

I have barely started on the foil. I have made some ribs out of 18mm plywood. The plan is to lay up biaxial carbon, and some unidirectional, on the inside of 2mm plywood, epoxy, screw ribs on the ends of the foil, and a nose piece. Insert a foam and biaxial carbon shear web, insert foam ribs, let the epoxy set enough that it sticks to the plywood. Then epoxy the remaining carbon to the second sheet of ply, turn over, and attach the second sheet to the rest. The ply is intended to serve only as a mold that I don't bother to remove. That is why I plan to use very thin ply.

I currently plan to use a 3 metre ladder for the beam from hinge to foil. If anyone has reason to believe that is a bad idea, please tell me. And building the hinge will involve some time-consuming fiddly bits, and I have not quite worked out how they should look. If the hinge were parallel to the longitudinal axis, and horizontal, I could just extend the ladder a bit. But I want the hinge axis to toe in a bit and be lower forward. That makes the foil toe out and pitch down when the boat heels on the weather tack. Giles Whittaker explained in Catalyst. But that means when I extend the foot of the ladder with the bits that form the hinge, those bits have to bend so that they are perpendicular to the hinge axis.

The boat is finished. All that remains to be done is set up the running rigging, and wait for the beginning of the sailing season, in about half a year

Here you can see the boat with the frame tied to the hull, and the foil and beam upside down besides it. I can probably cut off the last two rungs of the ladder, but before I decide, I want to try different foil positions.


I know the foil is rather large. The intention is that even when stalled, the foil should grip the water enough to keep the boat upright with the foil to weather.

Robert - I have just noticed your thread here - it looks to be very intersting experiment. I am surprised that no-one else (to my knowledge, such as that is) has tried to develop the Giles Whittaker hinged foil. I would say that from the films Giles produced a good few years ago now, the idea did work amazingly well, at least in model form. It really did look like an uncapsizeable multihull!

Its not completely clear to me, but my interpretation of your diagrams is that on the 'Lee tack' the arm supporting the hinge for the 'foil arm' is locked, so the system operates much like Gerald Holtom's foiling boats. Then you unlock the hinge as your tack?

From my mental picture of Giles models, I think he had the ratio of the length of the pivoting assembly to the overal beam rather smaller than you have it, in other words, he placed the hinge nearer the foil and further from the hull. Doing that would improve the righting moment and it did look as though the righting moment from the foil fully balanced the sail heeling moment in Giles's models, although this did require a large overal beam.

Best wishes for this project!

John Perry wrote: ↑

Thu Dec 08, 2022 9:35 pm

my interpretation of your diagrams is that on the 'Lee tack' the arm supporting the hinge for the 'foil arm' is locked, so the system operates much like Gerald Holtom's foiling boats. Then you unlock the hinge as your tack?

Yes. The figure in the first post is inconsistent. On the left, I drew, in orange, a waterstay. I forgot to include that in the middle and on the right. That takes care of limiting rotation on the lee tack, but does let the foil swing down on the weather tack. The waterstay could be made adjustable. Then if the foil's lever arm becomes too long after reefing, pushing the foil out until leeway becomes excessive, slacking off the waterstay would angle the foil closer to vertical, and bring it back into the water.

John Perry wrote: ↑

Thu Dec 08, 2022 9:35 pm

From my mental picture of Giles models, I think he had the ratio of the length of the pivoting assembly to the overal beam rather smaller than you have it, in other words, he placed the hinge nearer the foil and further from the hull. Doing that would improve the righting moment and it did look as though the righting moment from the foil fully balanced the sail heeling moment in Giles's models

I am considering that, but there are two additional factors. One is that the more I move the hinge towards the foil, the more the foil heels as the boat heels. The foil would soon end up horizontal, and eventually heeled to the point where leeway pushes it up. In both the boat I built and in the drawing below, the hinge is far enough from the foil that the reversal will not happen. And even when the foil heels to near horizontal, the inclined hinge axis could still angle the foil so that it pulls down despite leeway no longer providing an angle of attack. However, with my present, simple foil, heeling the foil too far puts both struts in the water, and likely will cause lots of drag. A foil built of stronger and stiffer materials might be a simple hook, with only one part breaking the surface. Then moving the hinge further outboard towards the foil might be more practical. I have drawn that, and the drawing suggests a second relevant factor.



With the hinge position I have drawn, I get maximum righting moment at 32 degrees heel. The label in the drawing is wrong: the maximum righting moment comes from the longest lever arm, not steepest angle. I think (at least for hinge positions closer to the hull than the foil) the lever arm gets longest when the force from the foil is at a right angle to a line between hinge and centre of buoyancy. Beyond that, righting moment from the foil diminishes. The shorter the foil's beam, the smaller the heeling angle of maximum stability, and the easier it is to go beyond that when sailing upwind over a wave with the water dropping out from under the foil. But make it too short, as I did on my radio-controlled model, and the foil never gains enough leverage to balance the sail on its own. Gusts did heel the model to the point where the foil's lever arm decreased again.

(I took that picture before I had glued on to the hull and foil the attachment points for a waterstay.)



Also, if I ever scale up to a boat large enough to need a berth, I will need to reduce the in-harbour footprint to that of a monohull. I have an idea for that, but the folded beam will be from hinge to opposite gunwale, and that also limits how far out the hinge can be. So I want to see how this kind of design handles before I make any further decisions.

Finally, in building the frame that holds canoe hull, rig, rudder and foil together, I was also constrained by the lengths of the aluminium tubes that I had left over. I am re-using bits that were cluttering up my attic, reducing the impact on both the environment and my bank account.

John Perry wrote: ↑

Thu Dec 08, 2022 9:35 pm

although this did require a large overal beam.

Looked to be about five times as wide as long. He did not mention whether the models could be made to tack, and I never saw his videos. He mentioned having videos, but I didn't notice a link. And Youtube didn't even exist in 2003.

The boat has been on the water in winds around 4 knots, gusting to 10, suitable for a gentle first test.


The foil stabilises the boat nicely when to lee, in so far as I could test in the gentle wind I had. When to weather, the foil hooks in nicely, but I will need more wind to see how well it stabilises the boat, given the short lever arm of the hinge point.

The wave pattern at the foil suggests more drag at the junction than I had hoped. The hook-shaped foil in one of my previous posts is likely to be better, but I would have found it more difficult to build, so I chose not to.

Here is the foil on the lee tack:
https://youtu.be/et8-YiAHnfo

I mounted the foil so that, at rest, it is pitched up and toed in a little. There was not enough wind to find out how precisely the foil balances the sail's heeling moment. The foil is lashed to the ladder cross beam, so I can move it in or out. The current position is an initial guess at what is enough. The waterline at rest was also a guess, but still ended up where intended.

Here is the foil on the weather tack:
https://youtu.be/Si_zXo5UOqE

Note that the cross beam is no longer horizontal, the waterstay is slack, and foil is deeper in the water than on the lee tack, which is what should happen (compare to the picture in the first post). The foil riding deeper does increase drag, but should ensure that the foil hooks in nicely, and drops down quickly when sailing over a wave. When the boat heels, the toed in and pitched down hinge axis makes the foil noticeably swing back, toe out, and pitch down, possibly even too much, seeing that at one point, the foil seemed to pull the hull to weather. That is not efficient. But I need more testing to be sure what is happening there.

I will test further once exams are graded and I have reinforced the mast. I thought a standard windsurfer mast would be strong enough, but was advised otherwise. I will also try setting the sail lower, to see how sensitive the boat is to the balance of heeling and righting moment.

At 5 square metres, the sail is rather undersized. I bought two lug sails when I was still planning on a different configuration, before I decided this one is more interesting. I may make a new sail during the winter.

In the light winds of the first two tests, the boat tacked reliably from the weather tack to the lee tack, but not from the lee tack to the weather tack. I interpret that as a sign of excessive drag from the foil.

The rudder blade is the extra long one from Dotan, so even though the rudder head is about 25 cm above the waterline, there is still enough blade in the water to give good control, at least so far.

For paddling, the ergonomics are bad. When paddling on port, I have to stick the paddle through the frame, and a brace in the frame gets in the way of steering with the paddle. On starboard, the thrust of the paddle is so far offset from where the drag is that compensating by steering adds a fair bit of drag of its own. I will try fitting an oar to the frame. Thrust should be not far offset from the lateral centre of drag, and I could free one hand for the tiller. A sculling oar might also be an option.

When I bought the hull, I was not paying attention to freeboard, which is quite low, and may limit the sea state the boat can handle to something rather more moderate than I intended.

Exams are done, and I could sail a bit more. The mast is not yet reinforced. Epoxy resin with both a good mix ratio and a slow hardener turns out to be rather more difficult to get hold of than I expected. I had a Norwegian supplier for Aeropoxy, but they stopped stocking the slow hardener, and the only online source I can find is an aeronautical supplier, at three times the price per kilogram and larger minimum quantity.

I experienced something that I thought I had designed out. The foil is pitched up and toed in by a few degrees so that when the boat is level, the foil lifts. The intention was to prevent the foil from sucking itself into the water when close to straight downwind. It happened anyway. Wind was light, so all that happened is that the foil’s buoyancy made it pop up again. I have two plausible explanations for why it happened at all. One is that I designed the frame for a folding canoe with flat sheer. The second-hand aluminium canoe was a chance find. I will have to check whether its sheer lifts the aft part of the frame and pitches the foil down further than I intended. The second is that my weight may have heeled the boat away from the foil, which makes the foil pitch down and toe out. I will have to see whether I can reproduce the effect. I didn’t want to try last time I was sailing, because there was some wind at last, and the foil sucking itself down during a gybe might have been a bit more dramatic. I gybed in the wind shadow of a tied up cruise ship.

Wind speed was initially around 10 knots sustained, gusting to perhaps up to 15, but had weakened by the time I took some video. Early on, I was too busy observing to bother with video. I reefed, both to limit loads on the not yet reinforced mast, and because I calculated new stability curves, not being able to find the spreadsheet that I used for my article in Catalyst 23. It seems I missed something then. The new curves look a bit less benign, unless the centre of effort is very low. So I tied the boom about 30 cm lower, and put in a reef. The cumulative effect should be a centre of effort about 50 cm lower than it was the first time I sailed this boat. Picture here:


That had the desired effect in that the boat barely heeled with the foil to weather. Once more, the foil hooked in nicely, though with more wake, and therefore likely more drag than when it is too lee. That results in more weather helm with the foil to weather than with the foil to lee. As far as helm balance is concerned, the mast could do with being offset a bit more. If I had a better foil, there would be less of a problem.

Foil to weather:
https://youtu.be/MMsDnoFDtxI

Foil to lee:
https://youtu.be/rSiSfLmgSdI

I inflated a small kayak under the thwarts, both for buoyancy and for comfortable seating. It works very nicely for comfort. I hope not to test its other purpose. Also just visible is a small oar that is lashed to the frame. I can now row with one hand while I steer with the other.

The foil being large had the desired effect that it still hooks in at very low speed. At one point, I was so focused on observing the foil that I luffed up to far, and the boat nearly stopped. The foil still gripped the water. When I had a Raptor 17, the small area and high aspect ratio foil completely lost its grip on the water when the boat stopped.

Have just been catching up on the AYRS forum - I should look here more often.

Robert - Great to hear that your boat is sailing nicely and presumably much as it was designed to sail! Hope you can make the best of your rather short summer sailing.

I can see from your last photograph that the foil is pitched up (positive angle of attack even when no leeway) with the boat floating level. I would imagine that is good and I am surprised that despite this you say that the foil was sucked down when sailing dead downwind. By toed-in I am guessing you mean that when looking down on the boat the hinge axis of the foil arm is not parralel with the hull centreline but rather is pointing inwards towards the bow. I can see would cause the angle of attack of the foil to reduce as the foil arm tilts downwards relative to the hull structure and to increase as it tilts upwards, but for only a few degrees of 'toe in' and reasonable heel angles for the hull I would have thought this effect would be very small indeed. So I wonder what causes the sucking down.

You said in an earlier post that if you positioned the foil arm hinge further outboard (as for the Whitacker models) then heel of the main hull would soon make the the working part of the foil horizontal at which point leeway would not generate the requred downforce component from the foil. From seeing Giles Whitaker's films, many years ago now, the fact was that the heel stabilisation provided by the hinged foil was so effective that the main hull never heeled much even in waves which if scaled up to full size would be a pretty rough sea. With the model boat level and considering forces acting in a transverse plane the foil force must have been pretty much intersecting the wind force vector and the weght vector on the centre plane, so no heeling moment. Then if even a small angle of heel occurs that would mean several times larger change to the angle of the foil arm and hence, because the hinge axis is a long way off the centreline, there would be a significant change to the height of the point at which the foil force vector intersects the centre plane, and hence a large righting moment correction, much larger (could be an order of magnitude) than with your geometry. Yes, if the main hull were to heel a lot then the situation would be different but in the short films I remember Giles showing at an AYRS meeting in London the main hull simply did not heel! Or if it did perhaps he did not show that on film. I am a bit surprised that since Giles arrangement seemed to work so well at model scale no one to my knowledge has ever treid it on a full size boat. The wide beam is perhaps discouraging but the arms holding the foils could be made to fold in for berthing.

The first of your two referenced U-Tube videos shows your boat sailing very nicely with the foil on the lee side but the second video does not seem to display, presumably a broken link?

John Perry wrote: ↑

Sun Jul 23, 2023 4:15 pm

I can see from your last photograph that the foil is pitched up (positive angle of attack even when no leeway) with the boat floating level.

That picture is a little misleading because the boat is on the dock, which is not quite level. And this is pretty much the pitch angle the foil was supposed to have when the boat is level, and what I think I saw on my first outing. I will have to check the pitch angle again. The two places where that could change is either the ladder twisting or the hinges bending. Either would mean I seriously underestimated torsion.

John Perry wrote: ↑

Sun Jul 23, 2023 4:15 pm

I would imagine that is good and I am surprised that despite this you say that the foil was sucked down when sailing dead downwind.

I was quite surprised myself.

John Perry wrote: ↑

Sun Jul 23, 2023 4:15 pm

By toed-in I am guessing you mean that when looking down on the boat the hinge axis of the foil arm is not parralel with the hull centreline

No, I was still referring to the foil. Think of the junction of the foil to the strut. Pitching up lifts that line. Toeing in keeps the line at the same pitch, but the forward and comes towards the boat. With the foil slanted about 45 degrees at rest, pitching up 5 degrees should have much the same effect on angle of attack as toeing in 5 degrees, but it has different effects on the strut. Only pitching up will make the strut lift when running dead downwind. My hinge axis is also angled, so that it makes the foil swing back and toe out as well as pitch down. I hoped that, at a moderate heel angle with the foil to weather, that line at the junction would be level and the foil pitched down. So for the at-rest position, I reversed the effects of heel on both pitch and yaw.

John Perry wrote: ↑

Sun Jul 23, 2023 4:15 pm

You said in an earlier post that if you positioned the foil arm hinge further outboard (as for the Whitacker models) then heel of the main hull would soon make the the working part of the foil horizontal at which point leeway would not generate the requred downforce component from the foil. From seeing Giles Whitaker's films, many years ago now, the fact was that the heel stabilisation provided by the hinged foil was so effective that the main hull never heeled much even in waves which if scaled up to full size would be a pretty rough sea.

From the drawings, his boat was about three times as wide as the rig was high. That gave him a foil that started off much closer to vertical, so even though his hinge was far outboard, his foil had more reserve before it went flat.

John Perry wrote: ↑

Sun Jul 23, 2023 4:15 pm

The wide beam is perhaps discouraging but the arms holding the foils could be made to fold in for berthing.

I have worked out a hinge with two degrees of freedom that could be used both to control foil angles better and to fold up the foil in harbour, but if I exploited that foldability to make the boat much wider, I am not confident the boat would tack.

The alternatives are:
2) raise the hinge point. I can't do that on a boat that tacks because the hinge point would then get in the way of the boom and sail.
3) Change the proportions, but I expect that this boat here, with the hull to hinge distance much greater than the hinge to foil distance, and much narrower in proportion to rig height than Giles' models, does suffer from the problem of the foil going flat or reversing its angle to the horizontal (dihedral angle?):


I have never seen a description of how this boat sails, and when I did an image search to find the source and look for an update, I could no longer even find the picture.

John Perry wrote: ↑

Sun Jul 23, 2023 4:15 pm

in the short films I remember Giles showing at an AYRS meeting in London the main hull simply did not heel!

Do you remember whether those films showed the models tacking or gybing, or even changing course from on the wind to a broad reach? Giles used foils on both sides, so he could not put the rig between hull and foil to get the lateral sail balance right. Giles wrote that the foils "must be adjustable fore and aft while sailing in order to balance the helm". None of Giles' models has anything that I recognise as a mechanism for doing so while sailing. And I would be surprised if they could tack.

The lightest and mechanically simplest way of getting both the lever arm for non-heeling and the necessary fore and aft adjustment would be a two-way paravane on a proa. I have tried that before:


Back then, the steering by paravane didn't work, I assume because of the deep V hull. There was not enough wind to test how much the paravane added to stability, but I expect that would have worked fine.

I did consider returning to that configuration with a canoe hull, and I have worked out a simple frame that I could insert into a canoe to hold everything together. What concerns me is that the whole point of foil stabilisation is to carry more sail than you could without, and if the foil is attached only by string, it can't provide any stability when the boat gets caught aback, and then that extra sail is likely to capsize the boat. An unballasted boat dumps the crew in the water, and comes up only if the crew swims, trying not to get tangled in the string, and turns the boat around and pulls it up again. I just checked the water temperature on trondheimhavn.no, and it is 11.3 degrees, in late July. I want a boat that doesn't make me swim. Maybe a proa, but with rounder hulls, would do.

John Perry wrote: ↑

Sun Jul 23, 2023 4:15 pm

The first of your two referenced U-Tube videos shows your boat sailing very nicely with the foil on the lee side but the second video does not seem to display, presumably a broken link?

Fixed.

I had opportunity to sail in 15 knots average wind (confirmed by checking the average wind speed recorded at Trondheim harbour weather station at the time) and a wind direction that gave about 10 nm fetch, resulting in 20 - 30 cm (8 - 12") waves. I reefed again. The water stay was a little loose, and the boat heeled a little to windward when the foil was on the windward side. That reduced freeboard to about 15 cm on the weather side and resulted in a fair bit of water coming in. My crew and I dedicated ourselves to studying the ancient Polynesian art of constant bailing because 5 cm water in a boat only 25 cm deep from bottom to gunwales just does not spark joy.

We started off on the weather tack, and the foil hooked in solidly, and followed the waves nicely. That wave height is far from being a thorough test, but I have not yet seen anything to indicate that the foil would lose its grip. I intended to take video, but the camera was set on picture mode, and because I thought I had video, I did not take multiple pictures. So the only shot I have is very badly framed, but should still be informative.



I did not experience again the foil being sucked down when going downwind, but I did that only when returning to the harbour when the wind had dropped to perhaps 8 knots. I was still going faster than when the foil had been sucked down previously.

I don't know when I will have opportunity to test in more wind and wave. Here is a record of average wind speeds for a year. Of the 10 occasions when average wind speed exceeded 16 knots (8 m/s on the scale to the left) for long enough to show up with that temporal resolution, the one in late October was just barely within the sailing season, the next six were not, and the remaining three were in what is sailing season for others, but exam grading for me. Thursday's 15 knots don't show up with that temporal resolution, so there may be the occasional two hour stretch of more wind not visible on this graph. The point is, I can't promise testing in more trying conditions in less than a year or two, as I may not be able to take time off work when there happens to be wind.



In 15 knots, I could not get the boat to tack without paddling. My crude foil has enough drag that the boat could not get enough speed to sail through a tack, and I think the wide beam does not help, either. It is easier to turn towards than away from the foil, indicating that the centre of drag is offset towards the foil from the centre of gravity. Judging by the wake, I think the foil has more drag than hull and rudder. At one point, I had to do a draw stroke with a paddle from the bow to get the boat around. On the other hand, that confirmed again that the boat is stable when the foil is stalled, which I attribute partly to the foil's volume providing about 60 litres buoyancy when to lee, and partly to the foil's large area. The boat is also stable with the foil to weather and stalled, and thanks to the hinge, the weight of the foil and crossbeam can't do much then.

My crew had not expected the ride to be quite so wet and had not brought a drysuit, so decided to call it a day after one tack out and one back. To avoid a lengthy sail to the upwind harbour entrance, I went in through an entrance that required about 30 m paddling upwind. We could not do it, partly because the offset drag of the foil and mast would have required us both to apply power on the port side, and from the forward seat that is hardly possible because the frame gets in the way. For the aft seat, I have rigged an oar, but I still could not get enough power. I consider being able to get upwind under human power in 15 knots most definitely part of design requirements, and I should be able to do so on my own, never mind with crew.

Preliminary assessment

Stability under full sail with the foil to lee: 10 out of 10.

Stability with a reefed sail and centre of effort low enough for non-heeling with the foil to weather: 10 out of 10. I am now confident enough that I am willing to cleat the sheet in future, freeing a hand for taking better video.

Stability under full sail with the foil to weather: uncertain, having been tested only in light wind. I want to add some more different cases to my stability calculations before I do test that. The low lever arm afforded by the current hinge position (I will discuss the trade-offs when I write an article for Catalyst) might be compensated for by a spring. I will have to calculate that, and there may be an implementation that I can test cheaply.

Speed: 2 out of 10. The foil's drag is too large. I don't know how much of that is due to junction drag and not at all optimised profile, and how much to the large size which contributes to the foil's good manners.

Tacking: 1 out of 10. I attribute this first to low speed due to foil drag, and also to the very wide beam.

Moving under human power: 2 out of 10. The reason is bad ergonomics for paddling. A good oar and an oar lock attached to the frame would be a partial cure. However, with a single oar, I would need the rudder to steer, and would have to think of a way to control the rudder while having two hands on the oar. Also, the foil is always in the water. Given the prevailing light winds, cruising would involve some days under human power, and overcoming the drag of the foil would then be annoying.

Sailing without constant bailing: 1 out of 10. A spray deck should be a partial cure. I have finally worked out how to fit a partial spray deck around this hull and frame, but this really needs a self-bailing or enclosed hull.

Fun to friction ratio: 4 out of 10. The boat is fairly enjoyable to sail, though it does not offer the thrills of a fast beach cat or (I presume, in the absence of experience) a boat that flies on its foils. Nor does it offer the fast tacking of a dinghy. And the bailing distracts from the sailing. The experimentation, the opportunity to find out how a new concept works, is quite enjoyable. That is the fun part. The friction is the ancillary time and work it takes to go sailing. I takes about 20 minutes to get trike and bike trailer out of the basement, retrieve all the gear, and get it securely tied down. 20 minutes down the hill to the harbour. Once there, an hour and 15 minutes until I am ready to sail, consisting of carting boat and foil to the ramp, getting my gear there, setting up foil, rig, rudder, oar and paddles. The same for getting the boat back to its spot and the gear on the bike trailer. 30 minutes up the hill, then 20 minutes putting stuff away, an extra 10 minutes if I have to rinse off salt water and hang up stuff to dry. So 3 hours 10 minutes organising stuff, plus 50 minutes commute for a total of 4 hours friction every time I go sailing. That makes sailing after work impractical, leaving only weekends. For comparison, when I had a Paradox (the Matt Layden microcruiser design), it took about 15 minutes to get the sail rigged (I kept it inside the boat to protect it from its greatest enemy, sunlight) and the boat untied, and about the same to put everything away. Everything I needed for sailing I could keep in the boat. So 30 minutes organising stuff plus 50 minutes commute added up to an hour and 20 minutes, which made sailing after work practical.

Where the current iteration has poor scores they mostly seem to be fixable, primarily by designing and building a better foil, combined with either a self-bailing or an enclosed hull, i. e. an entirely new boat. Reducing friction enough really requires entirely doing away with the need to transport gear and assembling and taking apart the boat and so is not specific to the concept of the hinged Bruce foiler. I would need a boat large and enclosed enough to keep the necessary gear inside. Given the time and cost needed to build or have built such a boat, further iterations are likely to be radio-controlled models.