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.