UK-Cherub Class

Get Your Heart Racing


Banshee

banshee_uk9_b.jpg banshee_uk9_e.jpg banshee_uk9_f.jpg banshee_uk9_g.jpg banshee_uk9_h.jpg

In a nut shell the aim of the Banshee design was to develop an competitive hull shape with easy handling. Speed weighted toward the lower summer championship wind range but with the easy of handling making up to any loss of top end when the dogs were off their chains.

New Zealand designer David Lee was commissioned by Daryl Wilkinson to develop lines based around this concept from his highly successful 12-foot skiff , Nuplex, multiple 12-ft skiff Inter-dominion winning boat. With regular conversations and observational input from Daryl the 'Banshee' was penned.

Daryl designed the rest of Banshee Ambulance to be a multi mode boat, allowing for several different ways of sailing.

original_banshee_plans.jpg Construction plans (actual) banshee_trimaran_.jpg

Hull Mould files

banshee-6mm-frames.zip

These are 'dxf' formated files zipped to avoid corruption. © David Lee. Use is granted for personal use only. Commercial use is prohibited without prior consultation with the © holder.

Banshee's built todate

All hulls have been built by Mike Cooke at Aardvark Technologies Aardvark.

Due to Daryl being the slowest of slow when it comes to finishing his boat the sail registration got out of sequence with the hull build dates.

This is what David Lee has to say about the new design...

This design is an evolution of my Nuplex 12 foot skiff design I did with Alex Vallings. Nuplex, for those who don't know, was a very skinny 12 to start with at around 700mm maximum between the chines and a nice fine bow. Alex found the design to be safe and fast in a straight line, but didn't carry speed through the tacks and it didn't perform as well as the woof design when he wanted/needed to sail deep downwind in marginal planning conditions. This was due to the lack of volume in the aft of the hull. The solution was to widen the design in the aft. So I redesigned the aft of Nuplex in 2004 making the maximum width between the chines around 850mm and Alex rebuilt Nuplex in 2007. I realised and so did Daryl that the modified Nuplex design was very close to meeting the UK Cherub rules. The changes necessary to make the design meet the rules were to make it a little wider and raise the forward chine slightly so the integrated topside/snout was possible. I also made a few changes to the shape to reduce drag at slow speeds as a Cherub is not as powered up as a 12 and hence will spend more time at displacement and transition speeds during a race.

Comparisons of drag prediction estimates of the Banshee design to other 12 foot skiff designs is shown in the graph below with the well proven Woof design used as the benchmark. Please note that these estimates are averages over a number of different drag estimation methods taking into account different speed ranges and other limitations. None of these methods take into account the crews’ ability to optimize the hull trim for the speed and only partially take into account the effect of dynamic lift and the associated reduction in wetted surface area. So taking the limitations into account what does the graph show; The Banshee and the modified Nuplex both have more wetted surface area than either the original Nuplex or Woof, which is shown by higher drag below 5 knots.

The Woof design has more of a hump in drag around hull speed in comparison to the other designs. From real life experience the drag of the original Nuplex at early planing speeds is under estimated in comparison to Woof due to the under estimation of the effects of dynamic lift on drag. Considering the changes required to meet the UK Cherub rules the Banshee performance should be similar to that of the modified Nuplex design.

banshee_relative_resistance.jpg

So, how does the Banshee design compare to other UK Cherub designs as seen from a far? It should have a finer bow and most likely more rocker on the mid-forward keel line. It should be faster upwind in almost all conditions and faster downwind in light conditions and hold its own in planning conditions. The design should be safe (relatively) due to the fine bow and progressive increase in volume in the bow, meaning you don't slow down as quickly when you run into the back of wave giving you more time to react. The design is a compromise aimed at winning races, not winning the blast to/from the race track.


designs/banshee.txt · Last modified: 2013/06/25 15:55 (external edit)