It’s been a busy week, the Sydney DNF regatta, a heat of the moth submarine championships yesterday. In amongst all this I some how managed  to repaint my deck, fix all seven leaks in my hull.

I also have popped out a new horizontal to go onto my old, white foil vertical, the remains of which can be seen here.

Unless this foil is a rocket out of the gate, this will be my backup foil for Belmont, and I will be using my current Ilett / Bladerider combo as my main foil.

Life is a funny thing. I never thought that I would be designing a foil whilst being concerned that it would be compatible with a boat that I have never owned, but that is exactly where I find myself at the moment.

My desire to keep my current foil compatible with my Bladerider foil and making the two interchangeable has me re-designing my 2010 foil yet again to include an accurate rendering of a Bladerider centreboard attachment, something that I thought I would do in a non-virtual space, but checking revealed that my bulb needed to be bigger, so, as I needed to re-do the entire design, I decided to add the plug hole for the vertical.

Now this sounds easy, but when you are trying to be accurate it requires a significant amount of work to try and make things as compatible as possible, including moulding and measuring my current BR foil. Whilst doing this third design iteration the irony was not lost on me that I am trying to make things as compatible as possible with a boat that I have never owned. The second irony is that, if I do this job right, then my new foil should be a bolt on upgrade or replacement that would work on any Bladerider.

Well I sent the Rhino file of my 2010 foil to my mould maker (aka my brother) to start the mould construction process again, this time for the “Belmont” foils. Andrew has decided to embark on a rather small construction job, making Farrier F22 for himself, so the CNC machine has been getting a good workout lately. The cut time for a farrier float frame is about 15 mins, so it is heaps quicker than doing it all manually.

The design for my next foil is 100% mine, and has been heavily influenced by the current top of the pops, the Mach 2, combined with what I have learnt from sailing with my current foil. So what is changing and why ?

I have changed The foil planform to allow a flap that is significantly wider in the middle compared to the tips, which has been a feature of all Amac’s foils. My current foil has a flap that is pretty much rectangular ( i.e. the same width in the middle as the tips). Having it much wider in the middle and smaller in the tips should give better control with lower flap drag as the flap can achieve the same effect moving through a smaller angle.

I am no longer using the NACA 63-412 section, but I am keeping it “in the family” so to speak, by using a lower drag NACA section. In the computer it has 10% less drag for only a 3% lift loss at 15kts, so hopefully that will translate into a real on-the water gain.

I have designed two versions of this foil, a bulbed and non-bulbed version. Whilst I am still a not a true believer in the bulb like Amac, the bulbed version will allow me to swap between my BR horizontal and this foil, for back-to-back testing and vertical re-use. If this foil works really well, I will probably make the bulb-less one above.

Not to be left out in the cold, by current foil is be getting some tweaks for this weekend, so hopefully the wether will behave.