For years I've dreamt about building my own designed racing dinghy/multihull A couple of years ago I almost started and I hooked up with a Naval Architect from Australia who was a whiz at producing CAD renders and buoyancy calculations. However, when I started to add up the cost of the project I was taking a big risk. At that time another forum friend from Norway reminded me that it was very easy to design and build a boat. But extremely difficult to design and build a FAST boat.
Now that I have settled into IOM racing I'm sure I can afford to have a go at building my own boat. If this design isn't as fast as I hope then it would only cost £12.00 for balsa and approx £6.00 for the fibre glass and resin. The radio gear and servo's which will cost in the region of £60.00 will be put into the mark two version. As for the Rigs and Foils I'm designing the hull to take the Lintel's so I can swap around depending on conditions.
The design itself reflects the Lintel's in that it is hard chined but also encompasses a narrower bow and beam and less rocker. The overall hull is quite flat to give a lot of buoyancy with the deepest part of the rocker forward of the mast and widest part of the beam around the keel area. I'm a firm believer in the KISS (keep it simple stupid) principles of design and construction so there's nothing too complex as I don't have the relevant draughtsmanship or computer skills to produce ubber designs.
So, last Thursday I sharpened my 4H pencil and got underway.
If I'd done a little more research I might have gathered that 20 shadows is more than enough. As my local lake is pretty sheltered I'm
confident there is plenty of buoyancy in the bow.
Below the templates have been glued onto 3mm ply.
I didn't want any flare in the bow as I'm not convinced on it's merits. I have studied quite a few photo's of IOM's charging downwind and when the conditions are choppy the flared bows throw the water out to the front and sides. This has got to be having an adverse effect on the boats speed. I can appreciate that the reserve buoyancy is kicking in to prevent a nose dive but my design turns the wine bottle upside down. There's more buoyancy with the bottle standing upright than upside down. Also, the water should have a clean flow aft and not be further deflected ( I reserve the right to change my mind ;-))
The number of shadows is probably overkill but at least I know that the hull will be well supported during the sanding, fairing stages. It's not that noticeable from this angle but I have kept a minimum amount of rocker from midships to bow. I'm guessing that there should just be enough to give a little dynamic lift but with the high buoyancy ratio in this area of the design I honestly haven't got a clue if this will be to the detriment of pointing ability. The transom is a fairly standard width, nothing to thin so it's stable or wide to produce a nodding dog.
Ahh.......a slight flaw in the design, just goes to show it's being built by a human and not computer. Tonight I will be removing the three shadows above and replacing them. I know what the problem is so it's an easy fix. The balsa arrived on Saturday so the next job is to make a stripper but I have yet to decide on the width of the planks.
