Design plans for Illusion

Illusion was designed with the simple to use Careene 2008 software written by Robert Lainé, 
Robert has kindly made the software available for download at the bottom of this page.

The program works in metric (mm) only - I would advise Americans to have a go at metric because the maths is much easier. Like most British people in their 50s I have used inches and mm since junior school. My feeling is that mm are more accurate for boat building. With care you can measure and cut to 1 mm, but measuring 1/32nd inch is hard and 1/16th is too crude - 1 mm fits nicely in between at about 1/25th inch.

So if you want the plans/offsets for Illusion download Carene, create a hull and enter these (metric) values for the bottom plank. She will be just over 3m or 10 feet, maximum beam is 39in as per Elusion:

Height forward and aft define the rocker, half width afterward is for the transom.

When you have pressed Validation, move onto these settings for the side planks:

You can now fine tune the design to suit your needs and the Hydrostatic page is great for seeing how she lies with additional ballast. Quickly you will realise that most of the weight should go forward, which is the biggest challenge I think.

File | Save | Development XYZ  will print out the curve offsets for each panel. 

Making the bottom panels from one piece of 9mm ply is tricky. She is mostly flat bottomed so it makes sense to keep one piece. But it is essential to make a saw-cut along the centreline about 2ft back from the bow to bend the V angle at the bow - without that saw-cut bending 9mm ply is impossible. 

So you have to bodge/adjust the design as you build it, which is part of the fun. If bending the bow V is hard, make the saw cut a few inches longer.

I was unable to fold the full V angle of 35 degrees so the bottom panel over hang the side panels by about 15mm. No worries I simply planed the overhang after the internal fillets hardened.

I trimmed the freeboard by 2-3in when the panels were stitched so the above dimensions are not 100% correct for Illusion. You have to make a choice between windage and sea-worthy qualities - there are good arguments for and against freeboard.

Rocker wise Illusion will sit with bow and stern on the waterline with a total displacement of 250kg. In hindsight I won't be getting near that displacement in sheltered waters, but from the videos on this site you will see she sails very well with 100kg displacement.  (100kg = 220lbs)

Jim Michalak on Leeboards

An interesting short article on leeboards by Jim Michalak is here:

http://members.fortunecity.com/duckworks/2004/0715/index.htm#Leeboard Issues

Comparing pictures of Illusion I think my temporary lee board was about right; mounted parallel to the fore-aft axis and the area looks similar to Jim's Slam Dink design on his site. That might explain why the first sail was so successful.

Copyright Jim Michalak

This picture is my first guess at a suitable leeboard:

Desert Island Discs

Since time began BBC Radio 4 have a weekly show where celebrities chose just 10 tracks they could have if washed up (Lost?) on a deserted island. People often choose tracks that bring back memories and its a lot harder than you think to pick just 10 tracks.

For a musical diversion from boating I'm building my list of 10 tracks here.

1. 
   As a kid aged 6 in 1965 we only had five 45 rpm records to play on our record player. The rumour was that every record player in the UK had a copy of this record. What a cracker it is, the simple lyrics are timeless.
2. 
   My Dad was very handy with electrical and mechanical things and had a job in the late 60s changing the records every 2 weeks on jukeboxes in pubs and cafes. One Saturday he took me for a ride to a cafe and picked this song for me. He said people liked it because it was a bit longer than most songs, so they got more for their money (1s then or 5p in new money)
   
   I vividly remember hearing the song and liked it instantly. Here is a modern live version:
   
   
   
3. 
   I was one of those annoying kids that played a record over and over and over and over again. This one especially because of the hypnotic rhythm - it was a hit single in the UK.
   
   
   
4. 
   Around about 1973 I was at school friend's house. We played a few pop songs on his record player..then he asked if I had heard of this song. I said "No, what is it like?"
   
   He played it and today I can remember just how I felt 37 years ago. I was so amazed and had never heard music like that ever before. It was so different to pop music I had listened to on the radio or TV. At the end of the song I could hardly believe my ears and got him to play it again. I can vividly picture myself in his parents lounge standing over the radiogram near a window overlooking the back garden. Where did this music come from? Who on earth is the band? It was an amazing sound.
   
   
   
   So 18 years later, there I am with some mates in Arizona messing around in an amateur band in the drummer's front room trying to play this song (badly). Me on guitar and along comes the solo...ahh I don't know it. But in true rock and roll style I did the first 3 notes then winged it, playing as fast and wild as possible...in key, out of key..who cares. When we played back the cassette it was surprisingly good, shame we lost the tape.
   Rock and Roll...I love it.
   
5. 
   I went to this actual concert in 1975 with some school mates. Due to the beer consumed my memory of the night is a little fuzzy. Hard core fans will know that Jimmy Page broke a finger in his left hand 2 weeks before this concert but in true Rock God style he worked out a way of playing - you can hear a simpler guitar part compared to the album version.
   
   
   
6. 
   This song just floats along with a haunting memory. Its probably in my top 5.
   
   
   
7. 
   In 1977 I went to Uni, Freshers week was fun and in a disco I won a free T-Shirt because I knew exactly when this song was released (1971). It's a classic and was guaranteed to fill the floor back then.
   
   
   
   
8. 
   A massive one hit wonder in 1977, often played twice at Uni discos that year. Over 8 million hits on You Tube and still popular today.
   
9. 
   "And I was thinking to myself...." what were they smoking when they wrote this?
   
   

A design similar to Illusion

I have been discussing other mini-Paradox designs with Paul Raymond who sent me his design based upon Matt Layden's design for Around In Ten design. There is more rocker than Illusion, obviously Matt designed this model as heavy displacement for rough seas, capable of carrying supplies for an extended voyage.

Paul tried using Carene 2008 but could not get a variable flare angle on the sides. He created this model in Rhino (a CAD modeller) and may transfer it to FreeShip.

If you have visited the Around In Ten site you may be thinking that since Illusion is 10ft long I might go completely nuts and try to sail her around the World. I may have a few crazy ideas, but I'm not a nutter with a death wish. A trip down the river with my HBBR friends is far more enjoyable!

Making a sail for Illusion

Phil OxBorrow cut down a Mirror sail to a lug sail for his 16ft canoe. He lent it to me and it worked very well on Illusion so I decided to make a copy knowing that Mirror sails are easily and cheaply available. Ian Hylton from the DCA kindly sent me a spare Mirror sail in return for a donation to the Lifeboats Charity, that I happily made.

Here is Phil's sail - you can't see the seams but it is cut along the 3rd seam leaving the bottom 3 panels.

And here is my prototype cut with a peak about 1ft higher than the 3rd seam and a steeper angle. This will give slightly more area and a slight benefit on sheltered rivers:

The mast length is limited to a tad over 10ft/3m as I intended it to stow inside the boat. In hindsight a slightly longer length would allow me to use more of the Mirror sail's area; however a standard windsurf mast extension gives me extra length (I may need to reinforce the glassfibre mast at the foot).

The yard is aluminium recycled from a shower enclosure. It is lightweight and should be strong enough. For the boom I will laminate two spare lengths of 26mm x 12mm which is the regular door jam size in the UK. That should have the right balance of strength and light weight - the sail attaches at the clew and tack and the sheet will be at the end of the boom, so there will be very little bending moment and I don't need a heavier boom.

Illusion's First Sail

I attended the HBBR Cotwolds rally on September 11th/12th and I'm very grateful to Phill OxBorrow who lent me the lug sail from his canoe Tonawanda and helped me jury rig Illusion.

I used a windsurf mast cut down to just over 3m (10ft) planning that it could fit inside the hull in the future - it is 37% back from the bow just like the Paradox.

The previous day I drilled a hole at the top and screwed two cleats at the base of the mast, all very temporary and experimental.  So I rummaged around in my box of boat fittings and found a suitable block which I tied to the mast; we tied the lugsail tack to the cleats, I found a length of rope in the car boot and 2 minutes later we hauled the sail up the mast. Phil lent me his boom which we tied at each end of the sail and quickly rigged up a block 2/3rds along the boom for the sheet.

The leeboard was temporarily clamped to the port gunwale with G-clamps; the position was a rough guess. The first 40 seconds of the video are of me messing around clamping the board vertically.

By sheer chance it all fitted very well and as you can see she sailed well. The sensation is very much like a windsurfer, which I have sailed on that lake 25 years ago, picking up speed in the F3/4 gusts which are always as random as the Lottery,

Is she planing?  Reports on the web suggest that lightweight flat-bottomed sharpies can indeed plane and exceed their displacement hull speed and it certainly felt like she was getting close to planing. Next time I'll take a GPS to record the speed.

Tacking was slow because the sheeting was not ideal, also I found it difficult to twist around whilst sitting on the bottom. Improved sheeting and a low seat will improve things.

Prototype Lee Board

A few years ago my late Father picked up the remnants of a old wooden dinghy (I think it was a Solo). The dagger board is just the right size for a lee board or centre board, but the end grain had suffered terrible decay.

I scraped the internal core away that had rotted badly but luckily the outer hard wood veneer was in reasonable condition. Further rubbing with a wire brush got me down to sound wood, I splashed on epoxy and waited 10 minutes for it to soak in. Then thickened the remaining and spread it roughly in the end grain. Today it was sanded flat and another layer of thickened epoxy will bring back the original curve:

I think the picture below is worth a thousand words and saves a lot of typing :). I'll experiment with the board clamped in different places whilst sailing. Chris Waite thinks an offset board will be fine on both tacks - if it is I might as well build an offset centreboard case inside Illusion which will leave the centre free for sleeping.

Heresy I hear you say? Matt pioneered chine runners for their simplicity and reliability; he says he has a mental block about anything that can break or go wrong and experienced sailors will always agree with the keep it simple and reliable rule. Coming 3rd in around Florida races you have to take your hat off to Matt for making the chine runners successful.
But traditional centreboards have been proven to work well on racing dinghies who absolutely must sail as close to the wind as possible. As Illusion will be used on lakes, rivers, estuaries as well as lumpy water the extra lateral resistance will always be useful.

Illusion's Rudder Blade

Having developed 3D software for over 15 years at one of the World's leading CAD/CAM companies I decided to go the high-tech design route:

The curved ply is the offcut from Illusion's deck beam to give a pleasant curved edge to the blade.
The large gold plate is from my Grandmother's rather nice tea set.

The large gold plate was a tad too large, but 7.5 in and 11in plates fitted a scrap offcut nicely.

 Here is the result with a 1m (39in) ruler for reference. The rudder stock has been made smaller; at first I followed the Paradox style and then noticed the Elusion and Enigma rudder stocks are slimmer with a different pivot location.

The pivot position was chosen carefully so that the blade can retract fully when she is on a road trailer. Remember I want to make the rudder captive for quick setup.

Illusion's Rudder Stock

Here is the basic principle. The rudder is permanently attached with a pintle at the top, but a stainless rod at the bottom to fit in a gudgeon on the transom.That leaves the offset rudder free to swing through 180 degrees.

This picture shows 9mm ply cut roughly to shape with 6mm stainless threaded rod clamped in place as a mock up. I'll use a 9mm - 9mm - 9mm ply sandwich to lock a 8mm rod in place, because most larger gudgeons accept 8mm pins. At 27mm thick it will be very strong, but it may need packing to fit the upper pintle.

Notice the forward skeg (it should be longer but I used an offcut). That skeg supports the weight of the boat when she dries out and stops her tipping back.

The skeg also supports her during portage. Matt fits wheels slightly forward of the COG in the Ultimate Florida Challenge to move his boats several miles overland - when he stops for a rest the boat stays level on the road.

How was Illusion designed?

With the free Carene 2008 software:

 The software is easy to use, here is a picture of early designs on a 9ft length. I decided that was too small for comfort, eventually designing her at 10ft.

You enter the length, half beam, rocker, panel heights and press the button. It's that simple.

The only real dimensions I had were that Elusion was 9ft long and 38in wide - all other dimensions were reverse engineered from photos found on the Internet.

What is an Illusion?

No not a mirage, but a 10ft boat which is a clone of Elusion the 9ft boat that Matt Layden built for the Ultimate Florida Challenge - a circumnavigation of Florida

http://www.watertribe.com/

Matt is the talented designer behind Paradox and the chine runner concept. He has designed and built a mini-Paradox only 9ft long and sailed it around the coast of Florida. Also with wheels she was pushed many miles across land (portage) in the Ultimate Florida Challenge.


I was so impressed by Little Jim, a Paradox built by Al. When I sat in her I immediately liked the aircraft cockpit concept and seaworthiness, but decided a Paradox was too big and heavy for me. When Elusion appeared at just over half the size of a Paradox I decided to build a clone.

Illusion is Launched

Illusion was launched with due ceremony into the River Hamble today. Graham Neil did his 'I'm Scottish and I cannae watch good whisky dribble into the water' act.

She rowed better than I expected, but without a rudder she can spin easily when my rowing is unbalanced. This is to be expected for a flat bottomed boat without a rudder.

It was a glorious day, good weather, great company and a very enjoyable lunch at the Jolly Sailor pub.

As you can see there is plenty of work remaining. I wanted to prove she could be rowed and test out the hull as soon as possible.