Newport 27 Rudder??

[asathor]

The darker material is epoxy with a filler, the white is the original rudder - I kept it so I could see the original profile between the humps since I was eyeballing it. It has since been sealed.

My hump count is not scientifically determined - I would have smaller and more frequent humps on a thin profile - and that is just a hunch until research has been done on more profiles no will know for sure. I knew I needed a bit more bite from my rudder so I was comfortable increasing the wettet surface in trade for some of the improvements. If you boat, like mine did, tends to round up or be a little unruly on a run increase the surface. Rounding up is much more easily controlled and running is now Cool!

If you use bondo remember that it may separate if it gets wet so seal heavily and expect to repair it or use marine grade materials right away. I don't see any reason that you would want to go back unless you want to race with class boats that has to be identical - but doing as I did you can always take a belt sander to it because you can see the the white gellcoat below.

[PAR]

Asathor, vortex generation isn't new, as with most things in yacht design.

The loss of lift is caused by separation of the boundary layer, so it goes to try to delay the occurrence of separation. Friction, resulting from the flow over a foil, is the basic cause and reducing friction or accelerating the boundary layer the goals.

Many ideas have come about over the years, holes on the lee side, slots, conveyor belts, pumping air through nozzles into the boundary layer. In fact, golf balls have a very precise set of dimples to move air from the free stream to re-energize the boundary layer, allowing them to fly much farther. In the 60's a friend, while working at DuPont came up with the idea of bumps rather then dimples on golf balls. They worked great, so well he got some into production (or maybe DuPont did) and they where promptly banned from use in the PGA as they put most courses on the putt-putt list.

I've seen small vanes (foil shaped) fitted at alternating angles on top of wings (about midway on the chord). Each generates small tip vortices which rotate in alternate directions. Air is dragged into the boundary layer from the free stream by the vortices. An increase in drag results, but is offset by the increase in lift.

Bumps seem a logical direction.

[MarioCoccon]

Hi: My name is Mario, I have a Newport 27 1971 that I bought it three years ago. The boat was sit in the same place for 8 years. But taking about the rudder, I bought it for a person that cross the atlantic four times, past Venezuela, all the Caribbean, Texas, New York and a lot of more places. His son grow in the boat, he start in Texas when with all the equipment electric plant, 100gal of combustible, 150 gals of water etc increase 1,800 pounds in extra weight. The boat have the tall rig 37 and cutted to 34 put a 180 genoa and a hobbie cat main. He never have problem with the rudder even with wethear helm. also he have the spade rudder of the newport 27s that he only used for big distances not for helm because he have more balance thats all. I am selling a columbia 30 flush deck for the reason that newport 27 demostrate me that is a solid rock in 27. Iam changing the all gen for a Onan 3.5kw putting the tall rig again of a Kalik 32 modern mast with original angle, and trowing away the all Atomic Bomb for a Volkswagen diesel 1.6 43hp that weight less than the Atomic. He toll me that continue using the big Genoa and I will do it. I think he have more experience with the newport 27 than a lot of us, with not ofense. Dont change the rudder this is my sailboat #10 and Iam only 26 years old. My last boat was a C&C 35 1973 MKI that I bought it without rudder and the only think I do was copy a rudder of the MKII because C&C 35 have problem since then new in down wind or reaching thats all, and he work perfect. I hope so that my information help you Mario-Coccon

[beardentheatre]

in regards to heavy weatherhelm on newport 27, its called p factor. the angle of the prop causes this just as on a single engine airplane climbing. this p factor causes a lot of right rudder to be applied, its unavoidable as the angled prop does not provide equal thrust on either blade it favors one side the decending blade, only a level prop shaft wood cure this inherant design flaw .