Rig and Foil Optimisation at Modest Cost.

Making the "Orange Boat" GO.

More on sailing the Orange boat including early racing
Another Storer keel design - "The Fallen Keel"

How it ended up - beautiful and fast

Duck Flat Wooden boats had something interesting in the used boat section of their yard.

A long, slender hull 24ft (7.3m) by 5ft (1.5m) with an obvious speed potential, but hampered with an excessive amount of deck gear, a silly keel and a mast and rigging that would have been adequate for a boat 50% longer.

The Ducks were told that the boat was a Northeaster or Nor'Easter which, I suspect, had been highly modified during the building process.  (if anyone knows who designed it, where and when it was designed and whether there are any others please email me)

In the end it proved almost unsaleable - as soon as anyone looked at the cramped two cockpit layout they decided to walk away.

In the end the owner of Duck Flat, Ted Dexter, decided to buy it, with an eye for making it a fun boat for a bit of twilight racing.  He trailed it down to Goolwa (at the bottom end of the Murray River) and entered it in a couple of races.  He is not a bad sailor but finished, as they say, stone cold, motherless last.

Now I work for myself, but I also know where my bread is buttered - the Ducks give me quite a lot of work - so I make sure I go up to visit them at Mt Barker at least once, sometimes twice a week.

On one of my visits Ted started to talk to me about what to do about the Orange Boat.  We decided to organise an afternoon and take the beastie for a sail.  Appointed day was rather blowy with occasional rain showers, so the sail was off, but it gave me a good chance to have a look over the boat in its marina pen.

First, it was sitting well below its lines - the bottom edge of the transom was a good 3 inches (75mm) below the water - very damaging to performance, then second, on jumping aboard there was a clear problem with stability.  If both Ted and I were standing on one side the boat would lean over at a startling angle - giving a strong feeling that she was about to go over.

There were four areas to blame
1/ The hull, particularly the deck was built much heavier than the designer had intended - about 350kg (750lbs) overweight - from the hull's extra depth in the water.
2/ The mast and rigging was way too heavy and complex for the boat - (genoa, runners etc) - with the twin cockpit making it impossible to work the gear or to sit out to help keep the boat flat
3/ There was an extraordinary amount of heavy deck gear including 4 winches - on a boat small enough for all sails to be handled by . . . hand!
 4/ The keel, despite having a lead bulb at the bottom, had quite a high centre of gravity and was a hydrodynamically AWFUL shape - not just middling bad - but truly AWFUL - see section below.

Weight Reduction Program:
In the photo to the right, do you see that post in the foreground?  It is the mast tabernacle for the aluminium mast to sit on.  It extends down to the bottom of the boat.  When we pulled that out we found it was hardwood and weighed in at a hefty 39lbs (18kg) . . . let us say, there was a good deal of opportunity for weight reduction!

On my weekly visit Ted and I would stand beside the boat working out what to remove next.

We removed;  all the deck equipment – 90kg, Cut off the stern including a massive hatch – 40kg, Cut a larger cockpit removing all the hardwood around the two cockpit openings – 90kg, threw away the rigging and mast – 45kg, threw away the rudder and oversized shaft – 15kg, Floorboards – 19kg, the massive mast tabernacle (quite adequate for a 40 footer) – 18kg, external gunwales - 8kg. 

Ted also worked from the back to the front of the boat ripping out the hardwood frames and welded
stainless steel angle floors substituting with 6mm plywood web frames so the boat wouldn't lose its shape and to support the new lightweight cockpit that was to be fitted - see adjacent fig.

The cockpit was fabricated out of 6mm gaboon ply reinforced with a layer of fibreglass.  It made the boat self-draining - so any water that comes aboard can drain out easily.  The mast now sits on the cockpit floor and the compression loads are distributed through the length of the cockpit as are the keel loads.

Each week Ted and I would have a discussion - me wanting to rip more stuff out (or rather get Ted to do it!) and Ted wanting to minimise the amount of work that I was suggesting.

I could certainly see his point of view, but one of the great things about being a designer is that I can put forward all these great ideas, but I don't actually have to follow through with any physical labour!!!

In the end the only areas where I didn't get my way were to replace the foredeck (12mm ply where 6 or 8 would be enough) and the stem knee - a massive grown knee and some stainless steel strapping transferring the forestay load to the stem (overkill - two straps 50mm by 4mm stainless- 40 times stronger than needed - the forestay is only a puny 4mm wire).  I guess we can do something about them later if the local competition becomes tougher!

Also see the EPOXY and Boatbuilding FAQ for more detailed info about the methods a.nd troubleshooting and preventing problems 

Keel Development - Efficiency with Shallow Draft and Easy Building:
As I said, the keel was awful.  There was no attempt at making a hydrodynamically effective wingshape.  The drop down section in the middle, when deployed would improve stability, but was completely unshaped - a square sided square edged brick shaped piece of lead filled stainless steel about 40mm (1 3/4 ins) thick.  Its pivot bolts simply poked out into the waterflow and it had a cable for raising/dropping also in the waterflow.

There had been some attempt to get some weight low by adding a bulb, but instead of a streamlined shape the front and back ends were simply cut off at a 45 degree angle.

No wonder the boat could never get over 4 knots unless heading downwind in a blow.

With a bit of fiddling and the choice of one of the new computer developed Eppler laminar flow sections which is relatively thick we were able to get a significant lowering of the centre of gravity - 229mm as well as providing a section with significantly lower drag and higher lift.

The upper stub of the keel is a simple ply box.  It is a great construction method.  If you build of solid timber it takes forever to shape the stub and get it sufficiently accurate for the keel to work effectively.  However, when building of ply,  if the internal framework is the right shape then the ply will conform producing beautiful fair surfaces that require a minimum of filling and sanding.  The lightness of the box for the stub also makes it highly buoyant allowing for quite a few extra kilos of lead to be added to the bulb.

The keel was attached by the now "old" method of drilling oversized holes in the wooden keel structure for the bolts and pouring thickened epoxy around them which is allowed to set.  We did use conventional nuts to hold the finished structure in the boat - in case we ever need to remove the keel.

The rudder was changed to get rid of an excessively heavy arrangement and to close the gap between the top of the rudder and the hull for greater efficiency.  The boat will now spin in its own length.

Another Storer Keel - The Fallen Keel

Rig Development:
The downsides of the old rig were that the mast was very tall but not carrying a lot of sail.  It also was complicated to operate (uppers, two sets of lowers, 2 runners, 2 jumpers and a backstay) and required several genoas and jibs of different sizes be carried.  The genoas required winches.

We decided to get rid of all the junk and go for a much lighter mast with a simple dinghy style three stay rig, but with a pair of lowers.  We also did away with the backstay which allowed us to carry more sail on a much shorter mast by having a large dinghy style roach.

We are very grateful to Brett Averay at Binks Sailmakers in Adelaide who filled in the details about how the lowers interact with the three stay rig as well making a red-hot set of sails for the boat.

The mast is 1.3m (4ft) shorter than the old one and about half the weight.

Such a set-up can be arranged to have an automatic gust response as wind velocity changes which reduces the workload on the steerer and the mainsail trimmer.

Set up this way it makes sense to have as much of the sail area as possible in the mainsail - as it reacts automatically, and to only have a small jib that can be handled without winches (ie simple 2:1 jib sheets) for fast tacking and quick trimming.

It means you can simply hoist the two sails and go sailing rather than fuss about whether to hoist the #1 or #2 genoa or the working jib for the expected conditions.  Performance can be inexpensive when mixed with simplicity

The mast is a new lightweight section that we are able to get made on a custom basis (for a fraction of the cost of similar masts) and is now is light enough for one person to push it up by hand after trailering.  Duck Flat can now supply these masts for boats up to about 10 metres.

Sailing the Orange boat - first races and some more pictures.
Another Storer Keel - The Fallen Keel
(more to come!  I will be posting some of the deconstruction/reconstruction process pics)

This is a doodle of a new version of the Orange Boat.

The objectives are
  • Easier to build
  • Same performance parameters and principle dimensions - proven performance
  • Lighter hull - the weight removed from the hull to be put into the keel for more stability - even better upwind performance
  • Use of the same keel and rig design as the current boat - proven performance


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