Ladies and Gents,

As promised here is the response from Kevin- the owner of the Square top in South Africa. Makes for an interesting read and he certainly is facing some of the challenges discussed.

Regards,
Luke

Hi Luke

I must start by saying that it is still early days, and I have a lot of
experimenting to do before I can say that this is the way to go.
A bit of history - I have a few other yachts - Hobie Tiger, Dragonfly D800
tri, and a Farrier F9R Tri, all with BIG square top mains - and they work
very well! So for me it was a natural upgrade for the Mosquito to change
from pinhead to square top - something I have been toying with for a number
of years.

One of the big problems is to get everyone to agree - so what I did was to
build a new main, but with exactly the same sail area as the old main - I
shortened the luff to 6600cm, the foot to 2350cm and added that to the top,
which ended up at 830cm. This way I could convince the negative guys that I
gained no advantage from additional sail area, and then set about proving
that the square top is faster because of design and better sail control. The
mast remains the same length, the boom can be shortened or replaced. The
only cost is a new sail - same price as the old cut.

The positive things:
The boom is higher for the crew to get under
The boom is now parallel with the deck (looks much better)
The main sheet attaches to the clew - this means we can use a very
light boom (28mm aluminium pipe)
The boat looks updated and fast (I feel important for attracting
young sailors to the class)
The price is the same as the old main

Sailing with the square top:
I have had a mixed bag of results - but mostly good. In very light
conditions I found a definite advantage - I was able to point higher than
anyone upwind and go slightly faster - downwind little or no advantage at
this stage. I managed to win our provincial championships fairly easily in
light winds.
On the other end of the scale I find a big advantage upwind and downwind in
strong conditions. The sail is easy to flatten with the Cunningham - as you
tighten it, the leech opens at the top and the sail flattens - every puff I
accelerated away from the rest and managed to extend my lead through the
race.
At first I battled downwind with the spinnaker - The boat kept nose diving
and bus stopping as the puffs hit - so I decided to sail it more like a
Tiger - sheeted in the main and travelled in on the traveller - thereby
reducing the exposed sail area at the top and the tendency to nose dive - I
found I was the same speed in puffs, but faster in the lulls - no more bus
stops - very happy with those results.

Sailing in medium winds was a problem (8 - 12knts). I found I had no
advantage and at times felt to be at a disadvantage in these conditions.
However, I expected this due to the mast problem!

From the outset I felt that the mast would be too soft and bendy to carry a
square top. After the first sail I knew I would need to address this. I have
fitted a forward facing diamond (parrot perch) between the foot and the
hound. This has worked well, but poses a few problems:

The diamond does interfere with jib when tacking - not badly, but
crew needs to help sheets through.
The mast is stiff enough between foot and hound, but bends a lot
above the hound.

In medium wind, I can't get enough leech tension - I sheet in harder to
close the leech, the mast bends, sail flattens and leech opens again.
Creases start forming - use a bit of Cunningham - mast bends and leech
opens.............
So I found myself soundly beaten into second place at our national champs
over December.

Unfortunately I have not had another opportunity to sail my Mosquito again,
but I will be making a few changes to stiffen the mast and overcome the
problem.

On the whole I am very happy with the square top, and can positively say
that once I have sorted out the mast stiffness, it will be a big improvement
on performance and aesthetics!!

I will also be experimenting with a carbon mast - while I know this will
work and will be the best solution, I have to think of the cost to the fleet
- this is however another fight for another day!!

One last comment - The Mosquito is still my favourite and preferred cat to
sail ............... I'll keep you updated of any progress.

Cheers
Kevin