|
An updated version of this page can be found on our new look site. Click here to access
Following is an assortment of texts published at various times and in various forums.
In October 2001 We ran an educational programme involving a group of boat-crazy high school students.
Here are some of the answers to questions arising from the programme.
For instance we explain what is meant by ‘prismatic coefficient’ and how this vital characteristic of a hull affects its motion through the water.
Here is the reply that turned out to be the first in a series of quite detailed explanations of design
terminology. For those of you familiar with the matters discussed, it is only fair to warn you that,
though long, these articles assume no prior knowledge and are therefore qualitative and perhaps oversimplified
at times to get across the essence of a concept.
Cp: In short, it is a measure of the fullness of the ends of a boats underwater body. As you probably
know, a prism is a shape with a constant cross-section in one direction. For example, a cylinder is a
prism with a circular cross-section that remains constant along its central axis.
When you have the two volumes, you divide the smaller one (always the actual hull volume) by the bigger one
(the
imaginary prism) to get a decimal.
This ratio immediately gives us a feel for what kind of speed the boat is optimised for, and hence what kind of wind
conditions it will like.
A high Cp means a smaller midsection at the expense of more wetted area.
As speed increases, wetted area drag goes up roughly proportionally with speed.
Wavemaking drag goes up at a greater rate and typically starts increasing very steeply at hull speed
(the speed of a wave the same length as the boat). At hull speed there is a big bow wave, a ‘hole’ in the middle
and a wave just behind the transom. At this speed a high Cp and hence a smaller midsection means you are punching a
smaller hole through the water. Fatter ends also give buoyancy and stability when the wavetrain gets longer and the
hull is supported on two crests at the two ends.
...One need not do all the math to make a judgement about a boat. A qualitative feel for ‘prismatic’
is invaluable in assessing hull shape. It is also worth noting that a similar argument on volume distribution can
be made for keel bulbs: a long bulb with full ends is more suited to strong winds whilst a short fat one with tapered
ends offers proportionally less drag in light airs. Once again though, we must remember that this is only one
of many considerations.
Recommended texts:
October 2001. The next question was a bit more vague, enquiring about the merits of overhangs to the
waterline.
Ms are only measured overall, so they tend to have plumb ends to keep max waterline at times.
Interestingly, some Ms optimised for light airs do have a bit of overhang. This reduces wetted surface area.
So why the overhang? Well, length is ALWAYS good. Displacement sailing is all about length. When a 10 heels, it is
designed to sink slightly into the water. There is a bit less volume in the topsides in the middle than there would
be if the ends were plumb, so the hull sits into its full heeled waterlines, stem to transom. There is a bow wave
and a stern wave, so the water level at the ends is higher than in the middle.
Downwind, as the boat goes faster and the wave train gets longer and bigger, the middle of the boat is sailing in a
hole and the ends are in wave peaks, so the faster you go, the longer the boat gets. This is very convenient because in
the light stuff the boat is shorter and has less wetted area, but it gets length when it needs it. You want waterline
length to get the bow and stern waves as far apart as possible because water wave speed is related to wavelength and
because a boat cannot overtake its own wake unless it is planing.
Overhangs are good in waves because they can dampen pitching (great example of this was the ‘92 match between the red
Kiwi boat and Il Moro in the Louis Vuitton Cup).
1999, Comments on our IMOCA 60 reproduced in various print outlets
Liberty was designed at a time when the Open Class typeform was coming under review.
Extreme beam, high aft prismatic, flat decks and forward raked relatively heavy wing masts
were features of highly specialised reaching machines with increasingly dubious safety characteristics.
Stability and safety solutions are addressed in the boats very lines.
A cambered foredeck, a large coachroof and less beam in the ends, tied together with a subtle sheer line,
all contribute to a ‘lower’ the inverted centre of buoyancy. Special care was taken in the design of the coachroof to prevent water ingress when inverted.
The basic dimensions of the boat show some reluctance to sacrifice light air and upwind performance for more extreme top speeds.
Uniquely, some structural components and hull panels made for a third generation Farr Whitbread (now Volvo) 60’
were adapted and incorporated into Liberty's construction.
The opportunity to use some bulkheads and topside laminate presented itself after our hull concept had been thoroughly explored.
This meant a substantial saving and was decided upon only provided that we could work it into our original shape.
As it turned out, the Kevlar-epoxy panels were great, eventually making up the bulk of the hull's primary shell.
The toughness of Kevlar was a welcome bonus, with carbon still present in areas where it is of greatest benefit.
The Volvo60' is an entirely different animal, but making the comparison was an interesting exercise.
Aside from tongue-in-cheek parallels with the fully crewed world, the potential of this boat is awesome, even on paper.
The options available in this class are bewildering.
We watched the keel and rig configuration debates whilst doing our own research and considering the choices...
Interestingly, the project started out taking a canting keel virtually for granted, but it was discarded in favour of water ballast.
The D section carbon mast was engineered by Murray-Burns-Dovell.
The deck-stepped configuration with three sets of full width swept back spreaders is simple and light.
Liberty carries significant rake and moderate pre-bend.
To allow the possibility of flying fractional kites, there is no fixed masthead forestay.
Instead, the hounds and spreaders are slightly higher up the mast. A provision was made for deck compression struts
but they were later discarded in favour of a removable Vectran babystay off the lower spreaders.
Simplicity and structural rationality have allowed us a similar power to carry sail on a platform with a higher ballast ratio,
lower wetted surface area and similar displacement to the current trend.
One year on and the boat is being prepared for AroudAlone by her skipper and co-designer John Biddlecombe.
The boat is entered and we all wish him the best of luck in his globetrotting race!
Living in Sydney and being set up for singlehanded operation, the boat has had little chance to race. Rather,
she has been piling on the sea miles singlehanded, 'Biddles' confident that he is learning all along about what makes
Liberty tick.
Recently the boat was third over the line in a record 90+ fleet for the Stratfield
Pittwater (Sydney) to Coffs Harbour race. She beat some specialist
offshore sprinters and was only 'pipped at the post' by considerably longer fully crewed racing machines.
November 2001. Reproduced below is a letter sent to innumerable members of the yachting community by the
enthusiastic promoters of BRONCO, a box rule for rating ocean racers. Everyone had a say in what seems a
genuinely refreshing initiative that will hopefully spark interested debate. Having sailed with Rob Drury and
been asked personally for a contribution, I was more than happy to speak up.
The original: “…I come from my own initiative, unbiased, and without any authority or agenda other than to widen the interest in
and the wish to advance offshore yacht racing. And the means for this to happen needs to be available-thus the web site
www.broncoyachting.com. This site has been created to facilitate BRONCO. Yacht clubs and/or event organisers offering
BRONCO races will need a certificate to accept entries.
Rob Drury,
Carbonicboats.com reply: Following are some thoughts on how the rule might treat specific aspects of design. Open feedback
and discussion of these points should help form an idea of what owners and sailors want.
Divisions:
Each boat will compete with others of equal overall length. 30’, 40’, 50’ and 60’ are common maximum lengths. Perhaps
an existing conservative 33’ yacht (one built prior to the rules official launch) might reasonably be allowed to compete
in the under 30’ division. Maybe the 50’ and 60’ nominal lengths should refer to waterline length and stipulate a maximum
3’ and 4’ overhang respectively so that, say, an Open50 will be 3’ shorter than a BRONCO50. Any such clauses however
detract from the simplicity of the box rule and should be carefully considered.
The boats should meet ISAF and AYF special regulations for cat1 or cat0. This should take care of equipment carried,
stability (more on that later), hatches etc., but cannot be an effective engineering guideline. Structural rules are
always a thorny issue. Specifying minimum panel weights and minimum reinforcement arrangements should be avoided
because the rule minimum will invariably be taken as a ‘safe’ value and may not be adequate for boats with unconventional
arrangements (unless the minimum is conservative which would add material unnecessarily thereby increasing weight and cost)
. Maximum unsupported panel areas, minimum core density etc. have actually proven counterproductive in the past.
At the risk of inciting cries of ‘arbitrary!’ the rule should simply require certain outcomes that would be up
to the designer to demonstrate. Safety factors in the form of lateral acceleration and grounding speed for the fin
would be relevant examples.
Sails:
The design and content of the sail wardrobe should be unrestricted, with limitations on the number of sails carried
in one race AND a maximum number of sails that may be measured each season. Maybe an allowance for a certain number
of additional old sails (with strict limitations on what constitutes an old sail) would encourage people to trade/keep
using sails for a bit. For every race there shall be one mainsail, one tri-sail and one storm jib, the rest of the
wardrobe may be any combination of beating headsails, code-zeroes, kites, whatever…
Spars:
One mast, conventional mainsail boom (as in swivelling behind the mast as opposed to Aero Rig or wishbone) with
unrestricted gooseneck height, only one carbon conventional spinnaker pole allowed (the other can be alloy), only
one bowsprit.
Should there be a provision for rotating masts? Here are some pros and cons: There is no proven overall performance
advantage to a wing mast on a monohull. They are heavier than a conventional spar made of the same material so they
have to be shorter (unless a stability penalty is accepted). Displacement/stability, pitching and sailplan aspect ratio
all suffer. They are a handful in severe weather. They are arguably more expensive. However, they represent a technology
in its infancy and have already shown significant development. In Australia there is very little experience with the
technology and the marine industry would benefit from playing with it, especially in terms of opening the doors
to overseas orders. If a wingmasted Open Class should turn up and happen to get reaching conditions (an angle where a
wingmast has an edge) they would be unbeatable, but, after all, reaching is what Open boats do best.
I think that a good compromise would be to allow that kind of tinkering on the smaller boats where rectifying an error
would be less costly, the engineering less extreme and conversion more expedient.
...Miscellaneous: Each division will have slightly different biases. The smaller boats should be more open than the larger. The basic
choice to make is weather to premise the rule with “anything not specifically prohibited shall be allowed” or “anything
not specifically allowed shall be prohibited”. The first option appeals to me as the more attractive for development
and simplicity. Administration of the rule in its initial stages should be fairly flexible with discretion allowed for
interpretation of unforeseen quirks and how they may relate to the spirit of the rule.
A minimum displacement may be a good idea to keep the boats sane. A minimum hull weight also seems necessary but it must
be made clear that it is to go into structure and accommodation, NOT bilge lead. Perhaps separate minimum weights for the
hull shell and ‘the rest’. Specify a set number of watertight bulkheads, frames, stringers (water ballast tanks count
as stringers) etc, thus leaving furniture as the only option for the remainder of the weight.
Sail area would be best controlled by defining a rectangle delimiting the sail plan. The Open Classes use a fixed
maximum length of overhang that may be split between bowsprit and boom end. Restricting mainsail luff only may lead to
artificially raised booms. A mast height above the water is necessary and would have to be in conjunction with a minimum
height for the mast heel to encourage decent sized coach roofs.
Interior volume and accommodation is once again very difficult to define reliably. Any specific figure will promptly be
adopted as the standard and possibly not be sufficient for boats with unusual layouts. Perhaps a definition of the tasks
that need standing headroom to be performed should be included in the rules, allowing the designer some latitude on
how to satisfy the requirements.
Finally to the issue of stability:
There should be a choice between water ballast and a canting keel. Canting keel yachts should be allowed a fixed
volume of central water ballast distributed in any way required for trim.
Again, I think that a canting keel on a 30’ is much less threatening than on a 60’. Some sort of tradeoff between the
lateral displacement of the bulb and overall beam should be considered. The fin should only be allowed one degree of
freedom. The remainder of the foil geometry should be unrestricted, thus encouraging mucking about with daggerboards,
different rudder combinations etc.
I hope the matters raised will encourage discussion. Specific numbers for parameters within the rule will follow a
consensus on what the outcome of the rule should be and how it is to be encouraged. Ocean racing needs this rule and
now is the time to have our say.
Following is the last SRCYC Newsletter for 2001.
Saturday 1st September 2001 was our first club meeting at D.R.C. We plunged straight into handicap championship
scoring, the previous scheduled social day having been literally blown away by a monster westerly.
The weather was unsettled, the tail end of a southerly blowing itself out and bringing occasional showers. What
looked like the first afternoon northeaster of the season gradually snuck in to replace it, all resulted in very
fluky conditions. Each cloud front brought a burst of breeze from a seemingly unrelated direction. There were random
glassy patches and local inversions of direction thrown in.
We set a fairly conservative course and did a couple of scratch races to acquaint ourselves with the new waters.
The holes in the breeze made it A rig weather, but the gusts tested the light rig.
The first race was fought at the front end between Phillip Page with his Berloiz, Robert Page also with a Berloiz
and myself sailing Ajax1 with a brand new fin.
We agreed to run the minimum of four scoring handicap races, followed by some ‘social’ scratch sailing.
Now it is only a matter of time for our fleet numbers to grow again. We have a regular venue thanks to the efforts of
Robert and Phillip Page in negotiating with D.R.C.
Race Reports
SRCYC 2001/2002 Pointscore Round1
The first round of our scratch championship took place on Saturday 15th September under a glorious Sydney spring sky.
The first few races were sailed in a consistent westerly, which proceeded to die off giving way to an early season
northeaster.
We initially set the course well into the bay to the right of the clubhouse. There, a trough in the hill profile allows
the breeze to reach the water quite cleanly. The course was intentionally long, allowing us to learn about the breeze
on that entire quadrant of the sailing water.
Race 1 saw an orderly, clean but tight start with the entire pack crossing tacks right up the beat. Phillip Page’s
Berloiz and Ajax1 snuck around the top mark on a slight shift and scooted off on the reach with a bit of a lead.
Maurice Fletcher was next around with Tim Harrold and Robert Page hot on his heels.
With ten races sailed, the emphasis was on consistency. Races 3 through 6 took place in very light and variable
conditions, typical of this time of year when the sea breeze struggles to fill in.
For the last three races we experimented with bodily moving the course out and to the left into the new breeze.
Every course change is another lesson learned in the characteristics of our new home waters.
SRCYC 2001/2002 Championship Round1 Results:
A demonstration sail on the tidal waters of Homebush Bay completed a great weekend of R-C boating. All classes were out
for a full day of friendly sailing under the curious eye of prospective residents and the strolling public.
The racing was predominantly in very light airs and glassy water (as expected at this time of year) on a course without
the slightest pretension of having a true beat/run.
A relaxed day was had, with some skippers taking time out to enjoy the food, drinks (once again, you know who you are)
and the carnival atmosphere.
The event was a success in bringing our sport, in all its forms, to the public.
The racing was enjoyable in the picturesque bay that featured the beautiful overgrown wreck of (presumably) a steel ’90
miler’.
Date: 31/03/2001 Conditions: light N, NE breeze building from glassy before noon to 8-10Kn and puffy. Sunny.
Course: triangle, sausage, anticlockwise. Beat is to the right from the bank. Course bias: right side favoured.
Race1: Ajax Mk1's first race. Go to launch and (how embarrassing) the rudder servo emits an agonized spasm and dies.
Deck patch off, spare servo out of box, pop it in, plug it in… The lesson is learned.
Ok, so race one will be my discard. Take the chance to sail around a bit, avidly observing the feel of the new boat.
With the light air sail settings (leeches very open) the helm is quite neutral. Rudder Mk one is quite big (145 cm2),
we will gradually chop bits off and observe the effects on trim, balance, height and wave making.
Experimenting with timed runs to the line the new boat seems much more forgiving. Turning saps less energy.
Race2: Milled around close to the line, sat near the favoured end staking a spot. Squeezed in on the gun shooting
between Robert Page and the pin with about an inch to spare. No contact so tighten up, get some separation and foot
into the lead. Played conservatively after that, stretched ahead in clean air.
Position: 1st
Race3: Thirty seconds to go and I sail into a bit of semi-submerged rubbish… luff up, ease off and back out of it.
As soon as the boat is free it's a mad dash to the line. The closest end happens to be the windward end. 3 seconds
and the pack seems to be on the edge of being early…they ease off to kill time and open up a gap. I jump through it
about 3 seconds late but with pace. Like last race, sheets on, and wind up. Bit more pressure this time and leech is
still open, so not as tight as Id like to be, but enough to squeeze ahead, pick the tack and stretch in clean air.
Position: 1st
Race4: Breeze might be filling in but I keep the same sail settings. Rig dead straight, tops quite open.
This time there is no gap for me at the top end. Put the breaks on and duck under Robert Hales, Robert Page and Dinah.
Accelerate under her quarter and foot away for pace, foot so hard that I end up almost directly in front of the first
boat in the second pack. Course now heavily biased to the right. There is only a short port tack dig. All marks are to
port so I'm locked out…went too fast to be able to tack and duck, could possibly be clear ahead of Dinah, but the two
Roberts would constitute a wall of starboard tackers. Of course they carry on right to the lay. So it's a fourth around
the first top mark. Dig down low on the first half of the reach and use the first law of marine gravity: what goes up
must come down.
Squeeze up under the Skalpel, just breaking the overlap before four boat lengths and rounding third. Meanwhile the two
Roberts have stretched out considerably so all I can do on the second reach is close the gap. Interestingly they tack
away immediately at the bottom mark, onto the lifting starboard tack. Being fairly close by now and not wanting to
follow in their wake, gamble and carry the port tack into the bank. Tack on a fresh puff off the land. Dinah also took
a dig on port, but not quite to the corner. Now she is some 5m abeam of me. Two leaders tacked across about ¾ of the way
up the beat. Paradox cleared Dinah and lee-bowed me gaining the inside track to the mark. The Berloiz had to duck the
Skalpel and tacked behind me.
Now we had a race. Down the run we both went very deep at first. Max ease on the sheets, yard over-square and boat
rolled to windward, edging ahead of the heavier Paradox. Almost past the bottom mark I was again able to come up,
break the overlap and round ahead. This time I tacked immediately and was just able to shoot the line. Position: 1st
Race5: jotting down notes fresh-minded between races gives little breathing room! With the NE breeze consistently
above 8 knots now it was time to play with sail controls, tightening up the A rig. The notes for this race read: 'Last
second spin to miss leeward end. Don't run the line! …Started late but clean. Tacked early, squeezing. Back on
starboard and only two crossed. Couldn't squeeze them off, footed instead, tacked, cleared…” Commenting about the new
boat at the finish: ‘I think Ill keep this one'. Position 1st
Race6: After the break for lunch swapped boats with Robert Page. Most orderly start of the day with Paradox, Ajax,
Skalpel and Berloiz in that order from windward to leeward all on the line and all with speed. It is always
instructive to sail someone else's boat. The differences in feel were very interesting. Powered off to leeward whilst
Robert Page used Ajax's height to squeeze Robert Hales up. Tacked onto port convinced that I would clear Dinah but had
to slam tack when I realized the misjudgement. Cost me a place. Pretty close stuff! Robert and Robert jostled for the
lead, quite evenly matched until Ajax hit a mark, Robert unfamiliar with the boats turning circle.
Race7: Back to our usual craft, breeze building and course very biased to the right. What looked like a great start
went horribly wrong when I darted through the line in a perfect windward position a split second too early. Around the
end costs heaps. Now fighting through the second pack. Put in a few tacks trying to keep clean wind and using every puff.
6th at the top mark. 5th at the bottom mark. In the lead pack by the last top mark. 3d at the last bottom mark edged into second between the two Roberts by the finish. Position:2nd
Race8: Another mediocre start buried under Robert, Robert and Dinah made for an intense fight all around the course.
Squeezed an overlap at the last possible minute (was that four boatlengths?) before the final bottom mark, gaining the
lead from the Berlioz. Sailed toward what looked like more pressure instead of slamming on the mark. Robert, Robert
and Dinah simply tacked inside me seeing that port tack was a dud call. Lesson (re) learned: Don't go out to the
corners, especially not when in the lead! Position: 4th.
Date: 07/04/2001 Conditions: light N, clocking NW. Wind building from 5-8Kn before noon to 10-12Kn and gusty.
Sunny. Course: triangle, sausage, anticlockwise. Beat is to the right from the bank (same as last week but with top
mark closer to bank and bottom mark deeper into pond). Course bias: right side favored but very shifty. Gusts off the
bank lifting on starboard, alternating to fill from opposite shore and lifting on port tack.
Field (top boats): Robert Hales (Paradox); Dinah Hales (Skalpel). Comments: only three actually sailed, no points kept.
Reason being that the bicentennial Park pond was blooming with vegetation and debris presumably due to heavy runoff
from a very rainy week. Notes are sketchy because with murky water and all sizes and shapes of obstacles any
performance data would have been random.
Date: 16/04/2001 Conditions: overcast, clouds coming through with quite sustained southerly wind at medium
altitude. S, SE 5-8Kn dying out to a glassy calm by 1630. Drizzle bands bringing some pressure, but rain held off
during racing. Course: triangle, sausage, anticlockwise. Beat to the right from the bank, sail up past helming
position and away to top mark, reach to the left, reach around western peninsula.
Course bias: good question! Utterly variable breeze influenced by wide lagoon, pond side reed, trees, currents and
the whim of the Gods.
Field (top three boats): Warwick Crossman (Struen Robinson modified Frank Russel Zero); Robert Hales (Paradox);
Dinah Hales (Skalpel). Comments: fleet of six. Three internationally proven boats and a very strong Australian boat
sailed by a talented helmsman. Warwick's boat is immaculately built by Struen Robinson in carbon/polyester. The hull
has a moderate beam with very sweet, fair semicircular sections, even rocker, medium displacement and volumes
just on the full side of mid-range. It uses a Bantock fin with a skinny bulb (circa10%), a IOM Skiff
style 'pear planform' rudder and swing rigs based on Bantock carbon tubes. In the water the boat looks well
balanced and doesn't make a fuss. I refer to it as a 'mature' design, firmly in the middle of the spectrum of
ratios and proportions.
Race1: Very confused light breeze. Started with Warwick, racing boat for boat. Split on short beat and came into top
mark three lengths behind. Hung on for most of reach, lost a bit when he came up and hooked into a puff, but got some
back when he had to come down again in the lee of the pines. Worked our way through the fleet by the lst mark. Coming
out of the final mark it was Robert hales, Warwick and Myself. Tacked away to the right. Then tacked on a nock
and got carried right to the line. Position: 1st
Race2: Started 5 seconds behind Warwick. Tussle to top mark, luffing match between Robert Hales and Warwick.
Robert Page got through and I followed closely around. Dina Hales edged ahead on reach in clear breeze. Fleet
compressed on reach, classic crowded wing-mark rounding. Fresh puff on second reach sorted us out, Ajax edged
ahead perused viciously by Warwick, Robert Hales and Robert Page's now planing Berlioz. Overlap with Dinah doubtful
so went outside at bottom mark. Robert, Robert and Warwick also playing it safe. Based on last race split
immediately but this time the lift came as I sailed out. Others spread fairly evenly. Was reluctant to hit the
corner so tacked back and ploughed across the course on starboard. Everyone ducked. Tacked back and cleared
everyone but Warwick, so ducked him and went to layline. Back on starboard and got that lift, had to crack off
slightly into mark, the boat loved it. With the centres further forward, a bit more flare and a slightly wider
stern coupled with more generous foils Ajax1 can foot better than Nexus. Maintained lead through run and last beat.
Literally 6 boatlengths from the finish line the boat lurched to a halt, fell away and began to drift helplessly
downwind away from the line. Upon retrieval by rescue boat it was discovered that a (very old) plastic shopping bag
looped over the fin is not conducive to speed!
Position: DNF
Continued: 07/04/2001 Race3: Well, last race's misadventure helped the handicap at least... notes read: ‘Good start, on time, on pin,
passed Warwick by top mark by squeezing steady height. Very close first reach and fleet reeling us in. Lost him on
2nd reach and caught Robert Page. Walked away with lead only to pick up some more debris. Dinah also picked up gunk.
Unlucky.’
Position:DNF Comment: Please note that this run of pollution is very peculiar, mainly due to high water level and
storm water run off from two weeks of rain. Generally this is a very clean place.
Race4: Slightly tighter sail settings, exits just horizontal when boat lying down on grass. Started a bit later than
my handicap, squeezed in at top mark, ghosted clear in light air. Small rudder a help here. Almost dead calm by finish,
scary being ahead in such variable conditions.
Position: 1st
Race5: Ok start, couple of seconds late, have to work on timed runs. In touch on first run. Gained lead by last beat
and sailed off to the right. Coming back on starboard I gave it away by lee-bowing Robert Hales on layline to mark.
Should have forced him to tack or duck. In ghosting conditions tacking under a heavier boat with momentum is suicide.
He covered me to the starboard-tack layline to hold me out, meanwhile Robert Page snuck through to beat us both.
Position: 3d.
Race6: Nailed the start this time. Handicap getting steep. Breeze died. Slowly catching fleet. When we were all
sitting at the bottom mark, probably all in contact gunwale to gunwale and going nowhere we called it a day.
Now to ponder the lessons... Will make some changes for next time. Tim Harrold (owner of second Ajax Mk1 hull)
was sailing after a long wait for parts and a weekend sailing big boats. He only joined the races at a respectful
distance in deference to those who are in the hunt for the pointscore. The two Ajax designs were initially identical
in every detail, later varying rigs as part of our continuing experimentation. Tim is playing with very skinny section,
thick walled tube.
Date: 04/05/2001 Conditions: light S, dying in the middle of race2 and creeping in from NE before snuffing it in
the rain. Lightning storms looming, borderline conditions for racing. Course: triangle, sausage, clockwise
(Anticlockwise from third race). Beat is to the right from the bank when course anticlockwise.
Course bias: Not to sound repetitive, but with about 1 knot of breeze (from directly above) it was anyone's guess.
Field (top boats): Warwick Crossman (Robinson re-worked Frank Russel Zero with Bantock fin and swing-rigs);
Brian Dill (Own design); Phillip Page (Berloiz); Robert Hales (Paradox); Brad Gibson (Robinson re-worked Frank
Russel Zero with Brad Gibson rigs). Comments: Last round of M GP series. Top NSW skippers present. 9 boats racing
including 4 internationally proven boats. Not a good day for us... Amongst other things the experimental bilge lead
we had been playing with proved a really bad idea in the drifting conditions (Tim and I were each carrying 400g of
lead in the aft bilge to note its effects on pitching, turning and trim. The object of the exercise was working out
how the change in moment of inertia influences behaviour). Once again, the testing program took priority over race
results. Few races were contested and the finishing order seemed sometimes random. Phillip Page, Brian Dill, Robert
Hales and Brad Gibson sailed very consistently for a very close resolution on points. The first Ajax came a
disappointing 6th but at least we think we know why…
|
|
