Foilsculler

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BrianP BrianP
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Foilsculler

Chris Waite Chris Waite
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Re: Foilsculler

This post was updated on .
And I thought the pedyuloh was a tad Heath Robinson

It does seem to demonstrate that like the Mirage drive, a foil driving fore-and-aft like this can achieve a better speed than athwartships like a yuloh or scull over the stern.  It occurs to me that you get more power from the latter, but this is more effective for speed with a long light hull.

And as I speak, my mind has started considering a single fore and aft blade (with the same limited pivot along its length) through a case and driven by a horizontal 'T' shaped crank with foot rest/pedals on the ends of the (top) bar of the 'T'.

Hmmm....

In fact if you wanted double blades like the Mirage, which would reduce any yawing, you could substitute the 'T' with a '+'.  This would not enable the blades to fold flat under the hull, but it probably wouldn't cost anything like as much either and would be considerably neater than the Foilsculler.

Continuing to dream, it could be operated manually by introducing a vertical shaft to bring the 'hand grips' up to chest level.  And/or you could put it (back onto) strings with a pivoted horizontal bar in front of you at hand or foot height driving a vertical blade with whipstaff extension over the stern.  The blade could then be set up to fold like an ordinary rudder to clear weed.

Next project then

CW  
Paul (admin) Paul (admin)
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Re: Foilsculler

It doesn't appear to compete with Timmo and his pedal drive. Ones fore arms would soon tire with that action...but the human body is built to walk for miles and miles.

The pedal concept seems to build on that physiological efficiency.
In fact a man cycling is remarkably efficient. In the same league as birds who can migrate thousands of miles.

Paul
Say NO to Brexit. Kick it into the long grass
Jeremy Jeremy
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Re: Foilsculler

I looked at something similar a few years ago, but using twin vertical foils over the stern with floor pedal operation.  They were designed to pivot up, like a rudder, when not in use.  Operation was by thin wire cables to pedals.  I drew the whole thing up years ago, but can't seem to find the drawings right now.  I did include steering by a tiller that altered the degree of "sweep" of each foil, so it should have worked OK without the dipping rhino rudders that the boat in the video has (and dipping rudders are a good idea, rhino rudders are not (I tried one once - never again).
Timmo Timmo
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Re: Foilsculler

I like the ingenuity and can see ways in which it can evolve.

Immediate drawbacks: 

* those big outriggers will make coming alongside and getting in or out very difficult. It's noticeable that the video was shot at a location where a beach launch was possible.

* how do you make sandwiches, take photos, read a book, etc. while your hands are occupied. Apart from the eficiency of using legs rather than arms (as Paul says) having the hands free is a real bonus. Though if someone does have a phusical problem with using their legs this is a grand solution. 

However, it wouldn't be impossible to adapt the design for leg operation. Just leaves the issue of the outriggers. Could they have amas incorporated... normally out of the water but sufficient to support weight of human entering or leaving boat? Or can the whole design be adapted to bring the blades inboard or back to the stern?

Tim.



On 21 Nov 2016, at 21:46, Jeremy [via UK HBBR Forum] <[hidden email]> wrote:

I looked at something similar a few years ago, but using twin vertical foils over the stern with floor pedal operation.  They were designed to pivot up, like a rudder, when not in use.  Operation was by thin wire cables to pedals.  I drew the whole thing up years ago, but can't seem to find the drawings right now.  I did include steering by a tiller than altered the degree of "sweep" of each foil, so it should have worked OK without the dipping rhino rudders that the boat in the video has (and dipping rudders are a good idea, rhino rudders are not (I tried one once - never again).


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Jeremy Jeremy
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Re: Foilsculler

If it were me then I'd definitely use pedals and a pair of vertical, lifting, foils at the stern, if intent on using oscillating foils like this.  Lots of advantages, from being hands-free through to being able to come alongside easily.  Using twin vertical foils in opposition removes the yawing moment from a single rear foil and making the pair hinge up makes
launching and shallow water operation easier.

The downside is the mechanical complexity.  I think it would be less work to make a pedal driven prop drive, using cables and a pair of sprag clutches on the shaft.   It's been done before, works OK and can be arranged rather like an outboard, so that it tips up around a hinge on the transom.
Chris Partridge Chris Partridge
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Re: Foilsculler

In reply to this post by Timmo
How about a catamaran with a Hobie Mirage drive mounted between the hulls? No problem getting onto the bank, and when weed clags up the flippers you could free them from your seat, by prodding them with the boathook.
Also lots of flat space to camp on.
Timmo Timmo
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That has real potential! Nice stable platform... you could just pitch a tent for accomodation! And, as you say, easier to keep the drive clear of weed.

Just a bit more exposed to weather when aboard, but that's solvable in many ways. May also be more subject to headwinds, but also potentially a price worth paying.

Couple of K1 hulls would probably be sufficient. Nice and slippery, certainly adequate bouyancy at the mid point (specially with a hatch sealing the cockpit.) Just have to check there's sufficient support at the fore and aft ends of the platform. Should be lots of 'older' design hulls that could be obtained economically. Would just need a matched pair. 

Would also create the possibility of a more social 'side by side' twin drive arrangement. Two pedallers sitting on a (carefully designed) sofa, drinks in hand, proceeding down the Thames. Tent could easily be big enough for two. Though do not for one moment think that final part would appeal to my wife... no en-suite hot shower! Though I'm sure someone will suggest how that can be done.

Tim.





On 23 Nov 2016, at 08:57, Chris Partridge [via UK HBBR Forum] <[hidden email]> wrote:

How about a catamaran with a Hobie Mirage drive mounted between the hulls? No problem getting onto the bank, and when weed clags up the flippers you could free them from your seat, by prodding them with the boathook.
Also lots of flat space to camp on.



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Paul (admin) Paul (admin)
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Re: Foilsculler

Cats are very good for electric drive also. Low drag hulls, but also a huge space for solar panels.

Using Timmo's quick-release mechanism for the pedal-flippers, we could reconfigure for the number of crew assuming enough rectangular boxes are built into the hulls.

I'm sure I have some study plans for Paul Fishers smallest cat, or somebody else's. Simple V hulls do the job, but thought is needed to squeeze the flippers into the tiny 13in beam.

http://www.selway-fisher.com/Smallcat.htm 

There's no reason we can't gracefully widen the hulls near the "flipper station" - it's not a race is it?

-Paul
Say NO to Brexit. Kick it into the long grass
Paul (admin) Paul (admin)
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Re: Foilsculler

And here is a simple V-Hull made with Hulls. Roughly the right size as a Hobie, 200in in the water, 177in on deck.
Notice the planks fit efficiently in 16ft:



They probably need fattening up. At 80lbs loading the water was 50% up the hull; but the hulls would be sealed, with access lids for stowage.

-Paul
Say NO to Brexit. Kick it into the long grass
Timmo Timmo
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Re: Foilsculler

In reply to this post by Paul (admin)
The Mirage drives ( or alternative systems) could be fitted into the deck part, saves work on the hulls and helps keep weight inboard/centred. The suspension system for the drives would then not need to be watertight. 

It would mean the dedal part of the Mirage drive(s) would be low down in relation to the seating position but with skinny hulls the deck would probably only be a few inches above the water, so the drive shouldn't be too low. If an alternative to the Mirage drive was developed that extra height may even be a benefit.

Tim.


On 23 Nov 2016, at 13:51, Paul (admin) [via UK HBBR Forum] <[hidden email]> wrote:

Cats are very good for electric drive also. Low drag hulls, but also a huge space for solar panels.

Using Timmo's quick-release mechanism for the pedal-flippers, we could reconfigure for the number of crew assuming enough rectangular boxes are built into the hulls.

I'm sure I have some study plans for Paul Fishers smallest cat, or somebody else's. Simple V hulls do the job, but thought is needed to squeeze the flippers into the tiny 13in beam.

http://www.selway-fisher.com/Smallcat.htm 

There's no reason we can't gracefully widen the hulls near the "flipper station" - it's not a race is it?

-Paul
Sail when you can, motor when you can't http://www.millibee.co.uk



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Jeremy Jeremy
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Re: Foilsculler

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Cats have a lot more drag than mono hulls at low speed, sadly.  I looked at the drag difference and it really is very marked, due to the greater wetted area and because of hull interference increasing wave-making drag, unless the hulls are very widely spaced.

There are other advantages, like stability and being able to be converted into a camping platform, but these come with a pretty big drag penalty.

It's the reason I went for the Winsome hull.  It has a relatively long waterline length (close to the LOA), a relatively low wetted area (compromised only by the need for stability, so has a flat bottom) and around 60% of the hull drag at low speed of a catamaran of the same LOA.
Chris Partridge Chris Partridge
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Re: Foilsculler

Very interesting - I always assumed that a cat with two long narrow hulls would be as slippy as a very slippy thing but clearly not. The increased wetted area I can sort of see (I imagine that some simple maths would prove that but it's too late in the evening and I have a crossword to complete) but the interaction between the hulls is more complex. I can see that a Venturi effect would be created between the two, but how far apart do they have to be for the effect to become ignorable?
The boat I sort of had in mind would have hulls about 16ft long (the default length for plywood boatbuilding) and have enough space between them to sleep on - say 3ft.
Jeremy Jeremy
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The reputation for cats being fast comes from sailing, where the enhanced stability allows more sail to be carried, giving more power.  Coupled with the way a sailing cat can be trimmed to have the windward hull almost out of the water, and they soon got a reputation for high speed for a given waterline length.

At low speeds, though, a cat is really like taking a long sculling shell, cutting it in half and joining the two halves with beams.  he waterline length has been halved (reducing the max "hull speed") and the bow waves between the two hulls hit each other, causing more drag.

There's been a lot of work done on measuring low speed catamaran performance, mainly by the human powered  boat fanatics, as catamaran hulls look like a good option initially.  The optimum hull for speed with a low power input is a very slender, long, monohull, perhaps with skimming outrigger floats for added stability.
Paul (admin) Paul (admin)
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Re: Foilsculler

Long and slender it is then, with a bulge in the middle for sleeping/cooking.

I still think Zeldah ticks the boxes.

Paul
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Chris Partridge Chris Partridge
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Re: Foilsculler

Despite the increased drag, I still think being able to clear weed off the fins easily and the big, stable camping platform are clear advantages for a river cruising boat. Once again, all boats are bundles of compromises.
Timmo Timmo
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Re: Foilsculler

I'd be thinking of pushing the hulls wider apart than 3 feet. Possibly 5 or more. Not sure how much difference that will make to the extent that bow waves interact (has to help a bit), but you might as well have the space on board if you are going multihull. Just had a vision of pitching a tent of some sort over the seating position so you can sit in the dry in the event of rain. Not thinking too hard about the windage of that though.

Tim.


On 24 Nov 2016, at 08:14, Chris Partridge [via UK HBBR Forum] <[hidden email]> wrote:

Despite the increased drag, I still think being able to clear weed off the fins easily and the big, stable camping platform are clear advantages for a river cruising boat. Once again, all boats are bundles of compromises.


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Chris Waite Chris Waite
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Re: Foilsculler

In reply to this post by Paul (admin)
This subject has been drifting

Enough to have Greg spinning in his electron shell; from the Perfect River Raid Boat a long way back, to Rowing/electric cruising boat, to Foilsculler.  This beast is what we imagine ourselves footling down the Thames in, at the beginning of every June….

For the sake of basic boats for bodgers, let’s set aside lapstrake for the moment.  If you look at the last few entries from the point where ChristoPart suggests a catamaran, they go round in a thought-circle that has more ramifications than might at first be apparent; starting on the 23rd of November:

1.  ChristoPart – A catamaran

2.  TimmO – A pair of K1 hulls linked by a sofa

3.  Paulie – Simple V hulls….    With a bulge to take the Mirage drive – presumably one in each hull requiring a permanent crew of two to prevent aimless circling.  This already misses the point that the drive would be air-mounted on the bridge deck for clearing purposes.

Air mounting any drive, rudder (or other foil), increases turbulence and thus reduces efficiency.

4.  Paulie – A plan of a V hull which sinks 50% of its height and would need decking over and needs “fattening up”.

Now I agree about the fattening up a V hull to reduce the two ‘d’s (draught and drag) and here is my version of this on a double ended hull that was built to have an outrigger –

       

5.  TimmO – Moves the drive back to the bridgedeck

6.  Jeremy – Points out that (presumably particularly) a V hull catamaran, aggravated by hull interference, can almost double the drag.

7.  ChristoPart – Is sadly taken aback (well we are sailors), by this news.

8.  Jeremy – Explains that catamaran speed comes from the ability to sustain a larger sailing rig.  He points out that trials have already shown a single long slender hull is the best option for low powered boats.

9.  The discussion - Goes on to dissect the options and possible other advantages of a catamaran.

But, I have already offered up a two-ply-board-length, sixteen foot hull, just wide enough to sleep in, formed from a V hull with a flat bottom cut in  \_/

And it has rounded watery ends to improve flow

This is where, I rest my case

I Premise you

CW

Incidentally, if you want to make the Mirage Drive easier to clear, then extend the box/case with the drive set on the after end of a blanking piece, hinged at its front (like a centreboard - hinged vertically but lying horizontally) and with a surreptitious handle at the back end.  When the weed strikes, simply take your feet away, reach between your legs and pull the handle up, (you can, because you’ve designed it so that as it hinges up the fins still clear the back of the case).  The weed (?mostly) falls off as you raise it; drop it back down and get those little leggies back pedalling again.  
Chris Waite Chris Waite
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Re: Foilsculler

Actually

Thinking a little more clearly; you would not need to extend the whole box/case.  You could put it on an  arm extending forward above the top of the box and hinged at its forward end.

Same effect, smaller box

CW
Timmo Timmo
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Re: Foilsculler

Good thinking. Important (in the case of Zelva) not to extend the box rearwards much because that's where my head is at night. But there's a brain cell or two twitching as a result of the suggestion.

Had also simply considered a quicker clamping method that the turnscrew currently used. Lever clamps look attractive, just need to arrange it so they don't foul my heels when pedalling nor obstruct the area used as kitchen when in overnight mode.

But an arm system that could be operated from the seat... that does merit thought.

Tim.



On 25 Nov 2016, at 11:57, Chris Waite [via UK HBBR Forum] <[hidden email]> wrote:

Actually

Thinking a little more clearly; you would not need to extend the whole box/case.  You could put it on an  arm extending forward above the top of the box and hinged at its forward end.

Same effect, smaller box

CW


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