Compare and Contrast: Ellway 5 vs Banshee

[mathew_harris]

Having seen photos of both designs just wondering what the differences in the designs should mean on the water and why each design has gone down the root they have, i know both are based on an existing hull designs (SK4 and 12' Skiff) modified to the UK Cherub rules but what will the relative benefits be based on the designs and looking at the boats that father/mother (not sure which) them.

[Phil Alderson]

There is a bit of chat from both designers and pictures of the designs and hulls on the main part of the site.

• Banshee
• ]Ellway 5

It is difficult to say as the rig, foils and nut on the end of the tiller all have a big part to play in the final speed potential of the boats.

[daryl_wilkinson]

the only thing I would say at this point as Phil is quite right about foils, rigs, nutter's etc...

IS, with a visual comparison of the Ellway and what I know about my boat...

The boats are quite similar in concept and I think both hull shapes are optimised around the same zone with the Banshee possibly performing marginally better than the Ellway when the wind strength is at the lighter end of this zone and the Ellway possibly performing marginally better at the higher end of this zone.

It isn't going to be easy to compare my boat with Will and Lucy's when they are both finished either as mine is going to be doing quite a few different roles so could be considered to be slightly compromised ( all though I have done my up most to avoid this ) it isn't as pure as I could have made it. So boat to boat comparisons will have to be made with the next boat(s)?

[phil_kirk]

I agree with Phil especially when you consider the nut on the tiller and more importantly their crew.  A good helm crew partnership make a greater difference than a few Kilos of hull weight, 1-2m^2 of sail area,  different foil sections etc.  As I am finding in a boat as tricky to sail as a cherub the people mask a lot of the differences between the boats.  it will be interesting to see how they both perform and even more interesting to see how the crews find the other boat. if they had a chance of swapping.

[kevin_ellway]

Hopefully, I can help here...

I have been in email conversation with Dave Lee for the last 2 years. I have also seen the lines and the actual Banshee and E5 hulls.

1) The water planes for the 2 hulls are very similar - ie they both have very fine bows and wedge shaped water planes. They look tiny when viewed from ahead compared with any existing Cherub (even the Bieker).

This should make the boats less prone to deceleration (and the attendant nose dive / cartwheel) when the bows go into a wave. The wave drag will also be reduced improving high speed displacement sailing.

2) Hull sections.
The E5 and Banshee have achieved their waterplane shapes in very different ways. On the E5, the chines are low and narrow. This
produces a hull with comparatively low dead rise and panel curve. The Banshee's chines are wider at mid length and forward, but a lot higher. The hull has higher dead rise and a lot of panel curve at mid length.

Both boats have scoop type rocker lines with most of the curvature forward and flat aft of the case. The E5 has around 35mm rocker (similar to a Slug), whereas the Banshee has 53mm of rocker.

So what should this do?

The Banshee will probably have a lower wetted surface and a lower Cp (prismatic coeff). These factors should give it an advantage at boat speeds of <3kts.

The immersed chines on the E5 theoretically increase displacement drag due to flow separation at the chine at displacement speeds. I think this is a small factor though - the P7 isn't exactly slow in light winds!

Between boat speeds of around 3 - 7 knots, the boats should be fairly similar.

From 7-15 ish knots (if the water is flat) the E5 should have the advantage due to its flatter rocker, sharp release edges and lower panel curve.

Above these sorts of speeds, it's all about control. In really rough conditions, the Banshee should be easier to sail.

So the Banshee is a more all round boat (as David Lee has stated). It is somewhere between the Bieker and the E5. The E5 design brief was to excel in the 6 - 16kt wind range, and that's where the design emphasis has been placed.

I would agree entirely with Daryl's et als comments on the stick wagglers. I would suggest that the things that most affect performance, in rank order, are:

1) The crew

2) The rig

3) The fittings - the boat must work

4) The hull

5) The foils

It will be really interesting to see these two boats on the water and I think it is great for the class that there are now some new designs available from builders.

[daryl_wilkinson]

That about sums it up quite well Kevin. And it will be interesting to see how the boats perform in the mid range conditions. And from my point of view if a slightly easier boat to handle will pay off. I am also sure that if you can put the sailing time into your E5 it may well be quicker in mid range flat conditions.

And I'm also with you in being very pleased that the class has two modern hull shapes to choose from that offer the owner clear design choices.

[phil_kirk]

Having only sailed our Dog for nearly a year and one race in a P7 (tippier) I have nothing to compare with.  It is interesting to note that some say the Dog is a difficult boat to sail.  Our brief race in Shiny beast at Corus last year in light airs showed us that the P7 is much tippier but accelerates much more smoothly.  After an hour we felt a lot more comfortable with the boat.  There are so many different variables to compare that it would be difficult to pick one out that would be the driver.

I think there are Cherub features that give all cherubs the same strengths and weaknesses. There are also variations between the different designs that dictate how nosey or tippy or how maoeuvrable each boat is. When you couple that with different crew weights, different sail shapes, foil design it is amazing that we have close racing (some times).

So with my experience, the DOG the baseline against which I compare all other Cherubs. What i don't know is where the DOG sits in the multi variable matrix of Cherubs.
All i do know is that once you learn't to sail one it takes less time to adapt to another. I'm not sure what Point I wanted to make now!