The origin of this design came to me many years ago when playing around with my pencil and sketching IOM boats as I often do.
I drew a round deck shape with no gunwale and I thought this probably would work, but I will be laughed at?
Time went by and my son Nathaniel decided he wanted to build an IOM
OK, I said, you can design it!
Well, where do you start?
We had a TS2 and we remember what the late Geoff Smale said to us while we were sailing at the laser 24hr race at Lake Pupuke, Auckland.
‘If you want a fast IOM just put a smaller stern on the TS2 and bring the rocker and keel forward.’
Nathaniel did this and built the Spitfire design.
We built a plug and a full mold for this boat.
Spitfire was a solid glass boat that did need corrector weights.
That boat has proved to be exceptionally fast by beating the NZ top design V 8 in our club racing.
Well , because Nathaniel was doing it, I couldn’t sit back so I got my old sketch out.
I had recently been sailing a F12 catamaran that had wave piercer bows and was very impressed with how this boat did not slow down when going for a nose dive, in fact it would always pop up again without cart wheeling.
Also it would go through any chop on the wind without slowing, so I was very impressed with the wave piercer or back to front bow boats.
So that is where I started with the D1
I could see it could possibly work as the Britt Pops and likes were going narrower than previous wining designs and a wave piercer boat would have to be a narrow boat
When I saw the chine and tumble home topsides of the Brit Pop I realized this was the way to go as it would help to lift the bow and sink the stern when leaning over.
I copied the TS2 keel rocker line and made the boat 185mm wide and made a hard curve on the bilge before the chine in section view to help with stability, I added a flat area on the stern to promote surfing and tracking in the breeze.
This boat was built using strip plank balsa that was glassed both sides.
The boat was built in female molds.
This construction eliminates any twisting that can happen when adding frames or the deck to the boat while under construction.
The boat is completely finished inside before taking out of the molds and fairing glassing outside.
When building the boat I took a bit of rocker out of the keel forward to help stop nose-diving so in effect the point of the bow was 10mm below the waterline.
I made the boat with a case where I could change the keel position as I was concerned that it may nose dive very badly.
I guess the first thing I noticed was that when the boat nose dived it did not slow down in fact almost sailed faster when bow was going under!
The boat was noticeably slower when the keel was in the back position and also harder to control,
So the forward keel position was best.
The boat proved to be very fast especially in heavy weather with B and C rigs.
However, when training against Spitfire with A rig it became very noticeable that D1 Yellow Submarine could not tack so fast and also was not tracking the wind like Spitfire.
The boat would keep sailing in a straight line when it got a knock or a lift so I constantly had to steer the boat while with Spitfire Nathaniel could let go the controls and the boat would steer to the wind!
What was happening was the bow of my boat was acting like a rudder so while it was going fast I was missing out badly when the wind changed.
The Boat had exceptionally fast speed upwind and down wind at times
So it became obvious to me that I had to change the bow sections.
Rather than build a new boat I saw it was easier to build a new bow,
I studied the super quick V8 and designed a similar bow.
I cut a ‘v’ on both sides of the boat and again, using female molds, I strip planked balsa the new bow section.
I was pleased that the actual change in the bow did not interfere with any of the fittings on the boat.
D1 Yellow Submarine performed like a different boat, so we now call this design D2.
It tacks way better and tracks better now in all conditions.
We have now completed molds and have produced one glass boat
Yellow Submarine II that is also sailing very well against the local Kerikeri fleet
The D2 has proved to be a fast boat
We have been putting more time into sailing skills,rig development and building lighter boats in the last year
Sailing skills has been working on less penalties and more consistent results
With rig development we are starting to see benefits from using a full size adjustable mould .We have made a couple of head sails that perform particularly well
We are now building boats that are down to300 gram corrector weights needed. This development will continue with Gran Prix boats that we hope to get down to 400 gram corrector weights and more but still ensuring boats are strong enough for competition
The D3 has arrived. This development came from testing against the Britpop in Sydney .
It was discovered that the D 2 did well against the Britpop in a cross section of conditions
It lost a little when downwind. When a gust came the Britpop would lift and go ahead while the D2 would at first dive a little and slow before it got on the pace again
So with the D3 we built a chine under the bow that meant a very flat section through the middle of the front of boat
This retained the straight lines fore and aft but gave the boat more buoyancy in the bow
The D3 now lifts more in the gust downwind however when the gust is too strong it will flip sooner compared to the D2 that will sail through and recover
The added benefit of the forward chine is it helps the boat point better upwind in fact the boats points exceptionally well mainly because of the aft chine's on the boat
With the D4 we are looking going back to using the D2 bow and a slightly smaller stern that we hope will help th lift the bow more down wind.
We are also lookind at putting on a flat deck with bowl rather than the skiff type deck.
This development will happen after the Nationals next month
We have the ability to design and build IOM boats using CNC so we could custom design and build your dream boat!
Below is the custom design and build Panic