Suggestions on this design

Hi all,

Im sure some of you will have seen some of my topics before and will know that I have been running through lots of different designs over the past year and a half or so. I finally decided to test my skills by designing a dinghy to a box rule. The class I have chosen is that of the national 12. I have created a basic CAD model using a mix of Free!ship and DELFTship and am displaying the DELFTship results. my intention was to attempt to create a balance between maneuvrability for river and lake courses and power from use with a t foil rudder for more open stretches and coastal areas as these all feature in the national 12 circuit in the UK. The dinghy uses a chine that starts about 1/2 way from the stern rather than full length (i have feeling it might need to be something more like 1/3 of the length however) I did this as I believe that having the more rounded front and middle sections of the hull will promote roll and thus better tacking and the flatter surfaces aft in conjunction with a t foil rudder will promote sufficient power and planing ability. I would like to know your thoughts on this and the design in general as if I deem it a general success I will be building a 3/4 scale prototype for my A-level design course. many thanks for any help.

George T

 

Why do you wish to let the hull roll in order to tack? Unless you put some rocker in the keel line it will be slow to tack in any case. Why have you shown reverse camber in the forward sections? Show us some actual section views so that we can make useful comments.

 

Hi messabout,
this is a quick reply, i will be posting more pictures later. I'm not sure how familiar you are with dinghy racing as the aim especially on inland waterways is to rol the boat over to windward during a tack and slowly bring it up out of the tack (almost like pumping but legal) this is to maintain boat speed, i will attach later a picture illustrating this. the more rounded section i hoped will aid with this rather than a full length hard chine. as for the inverse camber, that is simply stylistic, i was heavily influenced by current national 12 designs which i will again post later when i have the time

 

sorry to say its a long time since I last raced a N12, before you were born in fact. So cannot comment, except to say you haven't given enough information, no idea of rocker or CofB for example. But it looks quite full forwards

This is a good example of roll tacking that I often use



Richard Woods