10R & Narrow Deck

I could not resist to think about the legendary 10R Class.
With that in mind, I drawn my first 10R combined with a Narrow Deck.
Here a short vue of the ESTEREL-10R with Low Prismatic Coefficient.
Underway another one with High Prismatic Coefficient.
The Sails Plans are still to be made.
Interesting to observe that shadows shapes of the Narrow Deck produce also a favorable static balance of the hull observing the Centre of Flotation when tilted by 25°.

Another ‘classic’ 10R Hull Plan with 0.60 as Prismatic Coefficient !
It should be good for hard wind conditions although relatively short and lighter with less then 6.0kg.
Sail Plans and Appendages not yet drawn…

This instead is my interpretation of a 10R old style “Vintage"
The peculiarity is related to the possibility to change, within a certain limit, the displacement from about 5200g to 5890g by simple modification of the Bulb weight.
The Displacement could be adapted to the wind strenght.
This model is a little longer in order to permit classic overhangs.
Sail Plans are under way and Appendages are similar to the first Esterel model

In spite of lack of interest for ‘big models’, here the general view of my last “All Round” 10 Rater without Narrow Deck.
PC close to 0.58
Shadows Plans will be published soon

Here some refinements about the last design. Two drawings added to shows the design variations.
The difference stays with the width of the stern all other parameters being unchanged.
This last feature is particularly remarked on the tilted shadows drawing where the stern is in contact with the water level suggesting that the Water Line Length is getting greater as expected at 35° of tilt.
Obviously this is a “static view” with a flat water level.
Added the first Sail Plan, according to Rules, for type A Rig

interesting you said lack of interest of big boats. We just launched the Irish A class Association here.
Was not really interested by them for a long time as I didn’t get the concept of the short keel but having sailed one and bought one for less than an IOM ok it needs a bit of TLC she sails well and it fully functional. It’s a Sweet 9 just under 24Kg and just short of 2m long.

Surprisingly to sails - I actually enjoyed racing it but lifted the foot of the pedal as the wind increased a bit as you can feel their weight and they don’t react like IOM but rather closer to full size one. Yet I got hooked and now it is my next project after I finish building my IOM XP.

Hi Gilbert,

It is true since no many visitors watched the tread, no one single comment, you are the first.

Interesting sailing with an A class! Hope you will continue to enjoy it !

Of course 24kg is out of my range of thinking.

I assume that I should stay inside the half of that weight as I did it with the Enterprise and Tuiga to make the transport easier .

My 10Rater are below 6kg and therefore largely appreciated by me while they should be very nice models to drive.
Probably with 1.5kg more then a Class M shall introduce a different feeling.

At this level of design what count for me is the waterlines shape fairing and hull forms as to render very fluid the progression in the water while reducing drags and wave formation. These models could be used without RC Control for Free Sailing. My design teachers are Priest & Lewis with Model Racing Yachts of 1954.

RC controls make the life easier but often masking the hull design defects.

Actually, other then the Narrow Deck model being part of the ‘family’, I do have drawn a Low Prismatic and an High Prismatic such that as funtion of the local predominant weather, one can be built one or the other.


I received some comments and suggestions where there is interest to have long overhangs to obtain longer LWL when the boat is tilted.
My initial idea of fixing the LOA to less of 1.50mt is something that I’m fixed upon since ever to limit the transportation problems.
This is why my J-Class designs are also limited to 1.50mt.

Now accepting the suggestions I decided to elongate the upper part of the hulls while keeping the same immersed volume.
Two models designs, one as ‘classic’ look and one as more modern ‘Narrow Deck’.
Not escluded to use a reversed nose on ND1.
The LOA is now fixed at 1610mm against the original at 1485mm; the overhangs are of 180mm.
See some images below where the shadows are already at 100% scale that can be directly printed on A4 page.
Both models will use Karman fairing at the top of the Fin. In principle the Karman fairing should be part of the hull (construction under evaluation), similarly at the bottom when intefacing the bulb.


I really like the look of the Esterel 10R - ND2. I think you have just provided me with a Winter project. Thank you!


Thank you Eric,
if you need more about shadows let me knows.
Fortunate you, my Lab is not yet ready !

BTW Eric,
if you like, you can reverse the stern or put it vertical. Is just a balsa bloc to be shaped as desired. See revised drawing
Some one suggest that this option may increase the water length at tilt over 45° when close hauled !!!
Nevertheless, over 35° for more of 10/15 seconds, is beter to start thinking about sail plan change

Thanks Claudio.

I do have a few questions. In looking at the shadows, all the stations are vertical, but the stern representation may not be. Is the indicated shape of the stern its actual shape or a shadow of the canted shape? My guess is that it is not the actual shape.

Also, what are your thoughts on hull construction? I am debating making a left and right plug, then laying up a composite hull in two parts. A faster option is to build a wooden hull in one part, then add fiberglass to seal and strengthen it. A separate deck would be added.

Last though is about rigs. I see you have provided a conventional A rig design, but what do you think about a swing rig? The flat deck would accommodate a swing rig easily enough, though I have no idea where I am going to source an appropriate mast tube. I would move the pivot forward to keep the CE of the sail plan in the same location as you suggest for the conventional rig.


Hi Eric,
you are right is not very clear, therefore here a revised drawing[/COLOR]

The plug for sanding reasons should be a unique assembly, this allow getting a god overall view. Nevertheless, if a mould is required then is better to separate the two halves for better de-moulding since is difficult with the assembled hull due to reverse sides.
In the past I have cut two separated shadows and glued on the edge with a crossing 2 cm ribbon of Bristol paper sheet interface to allow easy cut away.
If instead you like a final wooden hull, then the shadows are cut as per drawing and planked with the wooden stripes except the deck. Once finished the planking, you will start FBG lamination inside to get a sturdy hull before starting external sanding

Swing Rig is working well and easy to be substituted, but there is a limitation on the Jib surface. Certainly the mast step shall be moved forward the bow by “x” amount. Similarly, on Class M and due to the ratio ‘Main/Jib’, this advance could stay around 55/60mm ! Trials are needed.
Personally I would prefer a Classic Rig because of the possibility to use Jib Surface above 30% up to 50% of total SA

I had the same problem as Eric. Also the same problem with the bow station, angled back and no real measurement for the thickness of the bumper. Yes I know I could look up the rules… :slight_smile:

here she is in 3D.

hope this drawing revision will help.
The basic idea is to use balsa blocs at each End and shaped by hand. The bumper if not wrong is 15mm thick.
Once the Bow balsa bloc is shaped as you fill being correct, you cut diagonally along the cut line in the bow, see drawing below.

This delicate operation if well done should offer the form to make a Bumper mould.

With the Balsa blocs, nothing forbids you to make a vertical cut instead of tilted one. This is a matter of personal taste as well for the Stern.

If you need more, let me knows.

The 3D drawing is not showing the stern bottom curve and appears having much immersed and deformed volume in the second half backward, may be a view effect!


Bow and stern were not finished, when I came across getting the last stations placed.
It’s just the view. Hard to get a color combo that is easy to see.

Fine, may be possible to see other view orientations with printscreen ?


Thanks for the clarifications and thoughts. They help a lot.


Eric -
try Larry Ludwig for a mast section. I know he has some of metal (aluminum) and “thought” he also had carbon tubes - but not positive. He’s down your way, so may not have big postage costs, especially if freight cost would exceed the cost of driving.


Speaking of gas prices - sure haven’t seen any reduction in UPS/FedEx freight charges - must be making a mitt-full of profit.

Some rudimentary 3D views of the 10R-ND model also because I’m unable to do it better !!
confirming that 3D is not my cup of tea !