12 Metre Class

Here I am with new projets drawings.

In 1958 the 12 Metre Class started with new boats design.

The idea is to presents here some drawings of the boats of that Class period from 1958 onward.

I choosed this Class because is still keeping the charm of Old Times Sailing. Probably are not so famous as the larger J-Class, but easy to scale down to a reasonable size and cheapers requiring less electronics.

To make relative small boats is appreciated by several modelers since the scale ratio is not too severe to obtain a good design.

I started by choosing the scale 1/25 and 1/20 that produce a model of 850mm and 1062mm overall.

Non complications with severals Jibs commands.

These models can have double function, as “Static at Home” by remowing the fin/bulb or “Dynamic in theWaters” by adding the Fin/bulb assy.

The choice of external ballast hanging is for a good righting moment not achievable with integrated ballast.

The first drawings are for the COLUMBIA 1958

The hulls are not “deformed” in order to insert ballast.

Once ready, it will take some times, I will introduce the VIM, SHEPTRE and GLEAM…


Why not use the International Metre Rule to design a boat (or class of boat) rather than build a replica? As boat design does not scale well it might be interesting to see how the old rule might best be interpreted into something model-sized…

I’m just thinking about it… the added depth (and contemporary design’s chain/skin girth ratios) would make for a very different model at this scale…

Hi Claudio,

I love the way you know we secretly obsess over the classic lines. Just exquisite!..
Thanks, Jim.

Just to recall to those that do not used yet this method of construction. Hot wire often employed as depicted from 3D view below !
Here the principle already developed in other treads concerning the use of polystyrene foam :

Thank you, Jim !


claudio, do you have a copy in cadd or freeship I could play around with… mjs82 at georgetown.edu

also saw this page. I nearly cried…

Hi marc,
this is one of the many reasons that push my idea to recall, in some ways, the old dreams.

I decided to make my Hot Wire Table and Cutter in order to avoid a lot of electrostatic dust when using the Band Saw. Too long cleaning for the tooling to.
This table is not supposed to be big but sufficient to cut precisely the various blocs needed for the hull assembly. It may be that a free hand Cutter I will also made to replace my actual rudimentary tool.

This setup will allow to cut into two directions, horizontal and vertical .
The cheap hot wire can be the multi brain steel cable used for the forestay or scrouds after removal of teflon cover

This is the overall guiding drawing :


PS some usefull indications :


hot wire table saw…nice…i got a coupon for 40% any single item at MIcheals craft store. I know saw a hot knife like this…
for 20 bucks…so if I can get it for 12, all the better…

Hot Wire Table under construction !

The Hot Wire Table is completed , ready and tested : all OK !

Here the pictures :

last pictures :

One picture missing for vertical cut, waiting for camera support !!! She is gone for shopping !!!


The missing pics !

PS :
All papersshadows marked down and ready to be glued !

my last results are good for the bin ! Too many imperfections at the surface.
Recovery still possible with adapted filler or glass lamination first and then polyester filler.
Better to start up again ! probably with slightly larger model.


don’t scrap it claudio, use lightweight spackle as a filler. It dries quickly, is foam safe, and sands alot like the foam.
I am in favor of a bigger boat though, maybe something like 1.2 meters or so?
Are you gonna post the plans at nonsoleve.com? (sp) I think many peopls would appreciate more free plans, I know I would. Although, you’ve got me backlogged!

I already decided to scrap it and to change scale also to 1/17.5 that give a LOA of 121.3 cm and a DSPL of 4889 cm3 : 2933g for the bulb and 1956g for the construction, but before I want to build the vertical hotwire cutter .

The last plans drawn will be posted also in Nonsolovele - Amon


Just for curiosity I have compared two boats , a J-Class Enterprise against a 12 Metre Columbia, both scaled to a LOA of 120cm
From the attached pics it is evident that, from construction point of view, the 12 Metre offer more volume while maintaining similar styling form.


The Vertical Hot Wire Cutter is ready and work very well.

I got nevertheless some troubles to obtain horrizontal stiffness of the Arm. Since the arm was cutout from plywood of 10mm, I was obliged to reinforce the full arm setup. Differences are noted between the drawings and the actual construction.


A couple of thoughts -

many hot-wire instructions suggest chromium wire for the cutting wire. It is sort of expensive and sometimes hard to find in bulk. I tried and now use regular stainless steel wire that I use for rigging. Works OK and can buy many feet/meters at fishing stores at low cost.

Item two - don’t let wire get red-hot. Temp is too high and wire will stretch - also will burn-out faster needing replacement. You just need it hot enough to cut the foam cleanly. Too hot and it will melt the foam leaving a hard melted “blob” and too cold and you will see the cutting wire bend and feel how hard it is to make the cut. Practice on scrap foam. Also if making a long cut - wire will cool down during the cut so cut slow to keep wire temp correct.

After posting, I remembered that I had used a modified hot-wire to cut out the centers of my F-48 main hull (trimaran) to allow for radio gear and electronics. I started with an old Weller soldering gun, and replaced the soldering tip with a modified, copper wire to cut out the portions of the foam hull. My plan was to leave foam inside, cover with glass (1/2 oz.) so needed to make room for my radio gear.

Following photos show the gun, the modified tip/cutting wire, both a cut and un-cut main hull, a closer look at area where foam was removed, and finally, the bits of foam after removal.