The period since the Nationals has been
very busy, with non-sailing activity acquiring all my spare time, which also included
changing jobs.
Now that things have settled down a bit, I thought that it was time to provide a de-brief
of what has happened since the foil conversion was completed, and share my pain with
the world as my boat still hasn’t foiled.
I must say, even though I am very disappointed that boat didn’t foil at the first
attempt, I am not totally surprised. The goal of building a set of foils and expecting
to get the setup 100% correct the first go is a pretty unrealistic expectation.
So what is wrong? Well there are a number of factors that I think are combining to
prevent the boat from lifting off: weight, foil angle, and rear foil size. What has
become evident from various peoples experiences at the national titles with conversions
is that angle of incidence is critical. As it turned out, the centreboard case filler
that my board slots into has my angle at around -2°, where as the majority of the
fleet had angles from 0° to +1°. To “sail around” this problem, I would consistently
have to sail with a 3° stern down attitude compared to the other foilers. That conveniently
leads onto problem number two … the rudder.
Ok, I’ll be the first to admit that my rudder foil is HUGE. It is around 1m in size,
and I always planned to cut it down in size if I needed to. The reason that I made
it so big is A) I used one mould for the rudder and centreboard and B) With the extra
weight that I am carrying compared to guys like Rohan Veal and Scott Babage, I figured
that larger foils = earlier takeoff, but lower maximum speed. The problem is that
with the large rudder, combined with a non-zero degree angle, equals too much lift
at the stern, so when even hanging off the back of the boat, I was unable to get enough
positive angle of incidence lift to haul the boat out of the water.
The other minor hiccup is that my centreboard snapped clean in half at the
bottom of the hull in the second last race of the series on a reach in 25 knot winds,
and I need to make another one …
Interestingly, Phil Stevenson had an identical failure in the same race.
Original post by Bruce McLeod and software by Elliott Back