Posted by FWAL |
Sep 27, 2012 @ 05:38 AM | 3,438 Views
I've spent months thinking about VMG's design. Trying to pluck out the good design elements and ways to best overcome the design flaws. Basically, prior to pilling in the lead ballast to bring her up to the IOM Class minimum of 4kgs she was sailing really well, especially up wind. However, after the introduction of almost 10oz or 700grams of lead her performance was compromised due to what I consider to be her transom sitting to low in the water and also the habit of her sailing with a bows down attitude off the wind.
So now I think I know where the problems occur it should be a pretty quick fix! I have increased the draft slightly (57mm) as I've decreased the overall beam (185) and lengthened the rocker line. The rocker is what I have concluded was the main cause of VMG's sinking bow as the longitudinal hull line was too curved which produced a see saw effect (bows up and transom down or vise versa going down wind). I hope by lengthening the rocker curve it will help promote a more level longitudinal trim off the wind thus producing less hull and specifically bulb drag.
Just to be on the safe side I have made the bow slightly fuller compared to VMG's and also incorporated a bit more reserve buoyancy in the bow in the form of a more diamond shape cross section.
Other than that the mast, fin and rudder postions haven't been changed. I have yet to decide on the type of deck form, be it flush or sunken or the final position of the winch/pot. The winch location is proving to be a real head scratcher as I have yet to decide on either an arm or drum winch. The only thing I do know for certain is that I wont be going down the Eurgle route again (and again and again...)
Other than that I think I'm just about ready to start the task of transposing the design onto the shadow blanks.
Due to one thing or another and despite building 6 new gliders this year I've hardly done any filming. So yesterday although the conditions weren't brilliant I did film my new Blejzyk Mefisto and Homebrew P15.
I hope you like.