Jy 21

A hypothetical boat design that Jerry is 'playing with'.
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Jy 21

#1 Post by 4CE » Wed Jan 02, 2013 7:48 pm

Your designs work to the 'eye'...because they 'work' by design as I have opined before. Given the JY 21(JY for Jerry) maintains the same mantra... then how do you optimize a 'surefooted' posture under way, (mitigate 'hobby-horseing'), raising the comfort of the motion in the ocean(sorry)?

To the fun part of 'slapping mud on the wall- see what sticks'....

Jerry isn't it true when you design sails (jib, main) there is the slot effect between them - enabling more lift based on shape and size of the 'gap'...?

What if one could inovate a similar concept in the fin-bulb(retractable) , meaning a twin bulb-foil gapped on the same single fin one bulb above the other with a designed shape and gap...I am obviously not an NA...just a wild idea to kick around.

Might it work to increase performance? Its ok by me for straight talk, I like learning.


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#2 Post by sal » Tue Jan 08, 2013 8:39 pm

Hi 4CE,

I'm not Jerry, but aerodynamics and hydrodynamics don't often operate on the same principles. It is just my opinion, but I think the additional drag would cost more than any gain in performance. Underwater, I like to study fish, especially fast fish. For above the water, I like to study birds and planes. the Sailboat is an anomoly that works in both worlds.


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#3 Post by GHO » Tue Jan 08, 2013 10:41 pm


You are right about Hydro and Aero operating in different 'ways' - speed and viscosity are different in the settings - For a displacement sailing boat - the range speed over the surfaces is quite dramatic vs the speeds experienced at the hydro (underwater fins and hull) surfaces. Witness a jib headed rig being preferred at lower speeds and a una rig being more effective at higher speeds - MOST of us do not get to experience the dramatic range of speed in the hydro mode (drag being more pronounced) Very much a "fine tuning" exercise making compromises. There are many boats with similar dimensions that do not sail the with same speed potential or exhibit similar behaviors. That is what separates the 'good' from the 'excellent' designs. Ahh late evening ramblings of a 'I-read-a-book-about-it-once' guy - I have not stayed at that Hotel, nor do I play an aerodynamicist or hydrodynamicist on TV......I would hire a "Pro" and listen to his ramblings! ;>)
Montgomery 17 "Ohhh Boy!"
that ain't bad gelcoat....that's patina!

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