scaling down the 6 metre rule

[Omer Oppenheimer]

hi everyone
i'm a first time poster and hopefully soon builder

i want to build a displacement dinghy on classic lines (6 metre rule tribute). the idea is that the deck will be flush and except for the cockpit leg room, will basically be a big raft, with combing protecting the cockpit. i hope to make something fast and light, that i can cam out on using a mesh tent from the boom. so the length of the boat from the combing back needs at least 2 meters. this can include the overhangs.
ive never heard of this design. is there a reason why not?
how can i scale down something like a 6 metre rule sailboat, to the length of 3.5- 4 meters? thank you all in advance

 

[Doug Lord]

Have you seen this boat-The International 2.4 meter: International 2.4mR Class Association :: Home http://www.inter24metre.org/
Check under the "Sailboats" forum here-there are plans to build this boat out of plywood.

 

[Omer Oppenheimer]

Indeed I have seen them, and they are beautiful. So scaleing up a 2.4 is also possible? It needs to be big enough and stable enough for two adults to sleep on the aft deck (that is an extention of the cockpit benches), and from what I understand this is a solo racer

 

[Dolfiman]

2,4 m ji means Loa of about 4,2 m and displacement ~ 250 kg, but they are oriented to one adult (it is the class adopted for the competition of the disadvantaged).

You have another very active class on Swiss lakes, the 15m2 SNS which are under the 4m ji rule, meaning Loa of about 6,8 to 7 m, displacement ~ 800 kg, for 3 adults , and very in line with beautiful hull lovers :
Class web site : 15m2 SNS – 4mR http://www.15m2-sns-class.ch/
Examples of design :
http://www.15m2-sns-class.ch//wp-content/uploads/05_Sebschmidt_Plans_f.pdf
Ruedi Stadelmann http://www.15m2-sns-class.ch/?page_id=2794
EVINSA http://www.15m2-sns-class.ch/?page_id=11408

May you can envisage an intermediate design between these classes, for your 2 adults objective.

 

[Omer Oppenheimer]

2,4 m ji means Loa of about 4,2 m and displacement ~ 250 kg, but they are oriented to one adult (it is the class adopted for the competition of the disadvantaged).

You have another very active class on Swiss lakes, the 15m2 SNS which are under the 4m ji rule, meaning Loa of about 6,8 to 7 m, displacement ~ 800 kg, for 3 adults , and very in line with beautiful hull lovers :
Class web site : 15m2 SNS – 4mR http://www.15m2-sns-class.ch/
Examples of design :
http://www.15m2-sns-class.ch//wp-content/uploads/05_Sebschmidt_Plans_f.pdf
Ruedi Stadelmann http://www.15m2-sns-class.ch/?page_id=2794
EVINSA http://www.15m2-sns-class.ch/?page_id=11408

May you can envisage an intermediate design between these classes, for your 2 adults objective.

Thanks! Evinsa is the closest design i'v seen yet. Didnt know about this class.

 

[Dolfiman]

As I am also interested by this kind of objective, I did this early stage approach of a mini keel boat for 2 crew, intermediate between the above 2,4 mR et 15m2 SNS/4 mR . In case of interest, you can use it as a starting point for your project. I give you also the Gene-Hull application that I have used and its User Guide.

 

[Doug Lord]

Really nice, Dolfiman!!

 

[Omer Oppenheimer]

wow
first of all thanks. the plan looks awesome!
im still kind of of torn, as i want this to be car roofable, and i'm slowly realizing you cant have everything in life.

 

[Dolfiman]

im still kind of of torn, as i want this to be car roofable, and i'm slowly realizing you cant have everything in life.

Doug, Omer , thanks for your kind words.

Car roofable means a weight of hull (without its removable parts) of about 50 kg max., and a length of about 4,5 m max., to put it easy on a car roof (preferably by two people). Then you fall in the logic of a light dinghy, with no real alternative.

Then you can consider the car trailerable standard option, meaning by an usual car and without driving extra license ( in France, when : trailer weight o.a. < 750 kg, beam o.a. < 2,55 m ; lenght o.a. (of the mast) < 12 m ; height o.a. < 4,5 m). Compatible with a 5,5 m day-boat, with two sub-options :
*** a day-boat with a lifting keel or weighty daggerboard and a removable rudder : most trailers are equipped to allow the launch and the recovery of such boat from a slipway . Some day-boats in the 5,5 m range are designed with both a weighty daggerboard (e.g. ~ 100 kg) + a water ballast (e.g. ~ 200 l ) so to have a sailing displacement boat while a light for the trailing. With also the advantage, by light winds, you are not obliged to fill the water ballast and you have a light boat.
*** a small classic keel-boat (with fixed keel and rudder) with a draft of around 1 m. A crane is necessary a priori for the launch/recovery, but some amateurs have succeeded to avoid this constraint by using a rolling cradle itself mounted on the trailer, as showed in this video.