New marblehead vintage

a totally New Drawing around the Marblehead Vintage concept.


One more file with 2 Sail Plans, see attachment

Very good work :smiley:

looks real nice… sort of like an old 12 meter… is there a reason you went with a partial rudder rather than a full flying rudder???
the lines look real smooth and i can see people working on it
good job

That is one seriously beautiful Marblehead Class boat Claudio!
I like the lines moreso than the Madcap, Which is beautiful on it’s own!

Dont stop now, you are on a roll!

Shadows Please?

Thanks to you all,
shadows are coming soon, but overnight I was thinking to another solution with a dual keel option.
Tomorrow I will propose to your attention a deeper keel version.

Hi cougar,
In this particular ‘hull configuration’, the rudder is not very distant from the keel trailing edge and, if well understood, the skeg in front of the rudder is offering some advantages, one is the increasing rudder efficiency, more or less like a rigid sail with a flap, the skeg reduces the effects of drag and turbulences produced by the keel. This effect is lesser when the rudder is positioned at a larger distance from the keel as when fixed the end of the hull.
The skeg is also an efficient support for the rudder axis that can be lighter. This combination is also increasing the route stability, very useful when close hauled, but also when running and therefore requiring less rudder interventions.
In other words, the main point is that the rudder, without skeg, will suffer from keel turbulences being too close to the keel.


I’d Make it the same draft as the Madcap.
You should have those dimensions, but let me know if you need them again.

I definitely like these lines and rudder configuration better than the Madcap. Awesome stuff.

Hi Breakwater,
I found on the Net a poor quality lateral view of Madcap, but sufficient to be redrawn.
Here in attachment the elaborated view of dual keel option.
The deeper keel +70mm allow higher wind sailing for about +2knots or the use of a taller mast to search for better airs and sail efficiency.
The wet area do also increase by about 350cm².
One could chose the keel configuration as function of the predominant local weather conditions.
The shallow keel surface is about 6% of the Sail Area and thus conforming to the rule of thumb, while the deeper keel will increase the ratio to about 10%. Is spite of the increased wet area, is offering a better directional stability.
Comments and critics will be always appreciated !

PS : Added redrawn lines for Madcap

Hmm, yeah. Keel #1

While it would appear to have less righting moment than the Madcap on paper… The Plan’s don’t account for the fact that may skippers have taken a little lead off of the Madcap keel in reality.

You know what’s really nice to look at on this design in comparison to the Madcap?..

The Deck Rocker & the Rudder arrangement.

Especially the deck though…
The Madcap has such a pitched deck. I’m not sure why. I don’t think Ive ever seen a Madcap even come close to nose-diving. It would seem some of the Madcap’s forward buoyancy could be removed. The Estrel deck pitch just looks right

Hi Breakwater,
While I do agree with the deck appearance, overnight I got some thinking again about the waterlines entrances either horizontally and vertically


While the horizontal 1/2 angle is keep around 18°, I was not happy about the sharp curve variation at the base of keel. I decided thus to introduce a softer sloop as depicted in the revision layout, similarly i also removed the keel exit for the same reasons. To note that this profile is widely used on J Class and 12Meters and probably there is a good reason.
In the drawing above I have superimposed the two profiles of MadCap and Esterel and at the same time traced a smooth curve. The bow is also raised to 100mm and the LWL increased to 900mm
I would appreciate your opinion and the opinions of everybody else !
Thank you

You are the designer, and this is the Marblehead class.
You are handcuffed by very, very few rules. If it pleases you as the designer please, by all means. GO WILD!

That’s the point.

I don’t really have Breakwater knowledge, but on a pure esthetically basis I preferred the original version better.

May bee keeping the old “fin exit” with the new fin exit … and that’s just because construction wise (I’m only waiting for the shadows to start building this boat I was undecided between Endeavour or Columbia but after this … ) the first rendition (similar to Madcap) seems easier to build.

But I maybe wrong too.

With further reasoning about smoothness and fluidity, I shall consider the flux speed differential and drag that may exist if the keel root is too long compared with the base.
It may be that additional turbulence may be generated at the trailing keel edge close to the hull body and inducing more drag.
In this respect the paralleled leading and trailing edges may need to be reconsidered . Easier construction, as Gio says, is a must too, including the wooden construction as recalled by the Rules.
I will come back as soon as reordered the various concept ideas !


I like this latest rendition. It has beautiful lines. And as mentioned before in others posts…waiting for shadows! :slight_smile:

Finally, after various readings about naval architecture and keel forms, I decided for this ESTEREL-VM Design :

The major changes :

  • Entrance and exit waterlines shapes at keel level
  • Draft increase
  • Longer LWL
  • Backward repositioning of rudder and skeg

Shadows drawing undergoing

As promised, please find in attachment the General & Shadows Files for the ESTEREL-VM
After several attempts here the last and hope definitive Rev.5.

1 - Due to the length dimensions of shadows 4,5,6 the drawing is split in left and right view.
In particular the Shadows 5 and 6 do not contain in the drawing the extension to the mounting base. The extension should be manually added to reach 110mm from the LWL.
2 - Special attention to be taken for the mounting feature around shadow 7. A plain wooded bloc shall replace the planking stripes due to the sharp trailing edge of the keel. Hope the drawing is sufficiently self explanatory.
3 - It is expected to make from wood the mast and the two booms using the multiply ply assembly. Because of the Displacement, it is not excluded also the use of a sandwich composed of glass and wood veneer while loosing some percentage of the 70% Ratio.

Please enjoy the outcome !

PS: File Rev.5 updated with Rudder/skeg and keel details

Here below the File for the ESTEREL VM rev.2
This model has, of course, some differences with the Rev.5
The Draft is limited to 198mm instead of 215mm
The overhangs are displaced.
The Keel Form is more squared.

Against the static righting moment these are the calculated acceptable wind speed limits with the two Sail Plans Configurations :

Esterel VM2 with Low Rig = 8.5kt at 30° heel and 11.2kt at 45°
Esterel VM2 with High Rig = 7.7kt at 30° heel and 10.2kt at 45°
Esterel VM5 with Low Rig = 9.2kt at 30° heel and 12.0kt at 45°
Esterel VM5 with High Rig = 8.3kt at 30° heel and 10.9kt at 45°

With that and previous posted files, there are 2 competitive versions with different Drag dept and Keel profile


PS : Updating drawing file