RG65 Cobra5 Patterns

Hi all,

Eric asked for plans for Cobra5. Since I had to scan them, I thought I might as well post them for anyone who might be interested. The larger file is the patterns for the hull panels. The smaller file is a printscreen from my Freeship file that should be helpful in understanding how the panels fit together to form the hull.

Print on legal-sized paper and join the ends on the dotted lines. Sorry non-USA builders…you will have to figure it out for A4…if anyone can help me understand how to make a ‘universal’ version, please contact me.

This is not a complete set of building plans. I leave it up to the builder to add a fin, rudder, bulb, electronics, and rig of choice.

The displacement of the boat Jim Linville sailed in Albuquerque was about 850g…but I’d recommend 800g.

Here are some other dimensions we used:

  1. Distance from the transom to the leading edge of the fin 35.0 cm
  2. Distance from the transom to the center of the rudder tube 6.0 cm
  3. Distance from the bow station to the mast step tube 21.7 cm
  4. ID of mast step tube 1/8 “
  5. Length of the rudder 15.0 cm
  6. Distance from the bottom of the hull to the bottom of the keel bulb 37.0cm

We felt our fins were longer than necessary, and will probably shorten them on future boats.


Thanks for the plans Bill.

Dave Gettman-

Thanks Bill.

I was impressed with how well this design moved through the water. It will be fun to experiment with a hull that is fast to build. I will take photos and let you know how it goes.

Hi Bill!!

thanks for the plans!! This is just the kind of build I was waiting for to get into the RG-65 world!! Oh well, i guess all the rest of projects can wait for a couple of hours! Can’t wait till I get home and start building. Ok, so now for some newbee questions (Please forgive me, learning a lot still!)
You mentioned the length of the keel could be reduced, what would be the minimum length recomendable?
I know in some classes you are allowed to use only AA bateries, in the rg -65 is it also mandatory or could you go with lipos and regulators to minimize weight?
What is the max length recomended?
How wide are the keel fin and rudder?
Sorry if I ask too many question, just trying to get an general idea
Again, thank you so much for sharing this design with us!!!


Hi Enrico,

The sites referenced in this forum will help. Read the rules carefully, so that you don’t inadvertantly build a boat that doesn’t measure up.

There are no battery restrictions. Lipos/regulators are fine. I use 3 AAA lithium Energizers…non-rechargeable but light weight and no worries if they get wet.

I’m not sure about fin length…maybe 250-270mm…minimum prabably around 230mm? Others who have more class experience might be able to help.

My fin/rudder are about 50mm at the top, and taper toward the bottom…but you will see lots of variations that work.

Study pictures before you start building, and choose what looks good to you.

Have fun…Bill

Thanks Bill! I will certainly look around and thank you fro responding my question!!! Already printing the patterns, I’ll get the hull built and go from there.

Thanks again


Rules can be downloaded from this page:




About ready to hit the water, my Cobra 5,with a McRig. I still need to fix a few issues, spars section being one of them, but overall I am happy with the result, it’s my first RG65. Made of 3mm depron and expoxy/fiberglass, a tad heavy but a good starter hull to fine tune the rigging and balance. The rudder is OK by the way, but close.

The McRig is a special challenge, at this stage for me it’s more guesswork than science, that’s one reason I chose to try the RG65, plenty of latitude to experiment. My club near Paris has around 10 RG65 sailors, among them the 2010 national champion, and @ntoine, the French RG65 guru. He prepared the champion’s boat but finished second with his. The winning boat was a GT65, made in Germany, based on a British IOM design. So a comparison between the different boats will be interesting, provided our pond is free from ice.
Many thanks to Bill for sharing his design

Stern view of a German GT65 (glass) hull.

and a top view of hull

Yes, the design is a bit complex, hard chines combined with round sections, and the max width ahead of the boat’s middle length, maybe 30% from the bow. Currently we have 4 of them either sailing or being readied at my club. The local lore says the winning boat got its speed from a special skin, sort of sharkskin feel but yet smooth. Color is silver gray. How it was made I don’t know, and other hulls bought from the same source don’t have that feature, just plain fiberglass. I think it’s model sailor lore, and I hope to proove it with my Cobra.

the GT 65 is inspire from the lintel iom design from David Creed


Where do you get stuff like that?

“Where Do You Get Stuff Like That” … ?

May want to be a bit more specific with the question, perhaps – as well as to whom you are asking.

Design - from IOM & German RG65 class
Designer - from IOM Class
“Skin” - 3M made the “skin-stuff” for a CUP or two ago - and maybe someone had some small pieces. Similar technology for swim suits for Olympics if I recall correctly - not the “same” - only “similar”

Where do you get raw hulls like that one?

The GT65 can be bought here http://www.rc-station.de/seiten/rc-station/rc-station.html prices are in euros cost of bare hull is €50 + shipping. Delivery time is long, count a good 6 weeks before it ships, then whatever time it takes to reach your location.

As Patrick notes - Germany is where the builder is located.

It’s surprising that the only places you can order an RG65 hull from are in Europe- no U.S. places. Mr. Heron has a prototype shown on his website, and Mr. Pugwash has no interest in the RG65.

You can try Earl Boebert and see if he still has the molds and would be willing to lay up a boat or two. Several raced in Albuquerque in November. You can also try RCSails.com and see what Siri has to offer from Thailand. He has kits, as well as just major parts/components. If I am correct Ernie Thorpe has one listed in classifieds - ho bought two and is now selling one…unless it is already sold.

With balsa boats being as competitive as glass boats, not much interest in building a mold and glass - especially since this is a development class and subject to the latest whim of designs. Too many forget that the design needs a skipper’s touch to be fast.

I’d like to build up one for when I go to the local camp for MS kids, so I’d go with something (very inexpensive) for that. The Footies are “OK,” but some kids can handle a bigger boat with more speed.

It fits in the car rigged which is an advantage over my 1M to take to the park on Sundays. I’d start with a cheapie pleasure sailor, and consider something competitive if I plan to get more involved.

Other than Cobra 5 and the Jif1, are there any other boats that use the flat panels?