there's a terrific picture that illustrates the tip vortex taken by daniel forster I can't find the link
search on these words: sailing cape town fog daniel forster a small thumb nail comes up maybe someone can find a good link.
the picture has been used in several books and articles as well
Search found 265 matches
- August 24th, 2016, 7:55 am
- Forum: Technical Forum
- Topic: Square Top vs Pin Head
- Replies: 25
- Views: 26867
- August 24th, 2016, 7:48 am
- Forum: Technical Forum
- Topic: Square Top vs Pin Head
- Replies: 25
- Views: 26867
Re: Square Top vs Pin Head
Okay Geoff, now you'll have to explain to everyone else. Nearly fell outa my chair. LOLgahamby wrote:If I read Bill correctly, the only cure is (more cowbell)
- August 21st, 2016, 4:02 pm
- Forum: General Discussion
- Topic: More on leeway and sail trim (tom's video)
- Replies: 7
- Views: 8380
Re: More on leeway and sail trim (tom's video)
Please re-read my initial post I never stated that the boat was going to windward. I'm guessing here, but I think your first answer was full of sarcasm and ridicule. Maybe the second answer also.
- August 21st, 2016, 12:04 pm
- Forum: General Discussion
- Topic: More on leeway and sail trim (tom's video)
- Replies: 7
- Views: 8380
Re: More on leeway and sail trim (tom's video)
Without boards going to windward imagine that! What kind of breakthrough we talking here shared lift.
Excellent illustration eh?
Excellent illustration eh?
- August 21st, 2016, 7:17 am
- Forum: General Discussion
- Topic: More on leeway and sail trim (tom's video)
- Replies: 7
- Views: 8380
More on leeway and sail trim (tom's video)
Tom P. forgive me for using your video, but it is the most terrific illustration that one could have. Find Tom's video link in his previous post. Go to 59 sec mark and watch the boat crab, the wake is nearly 30 degrees to the heading. Watch the next 16 secs, OVER AND OVER, at the 1:15 mark Tom turns...
- August 19th, 2016, 2:15 pm
- Forum: General Discussion
- Topic: Dagger boards versus shared lift
- Replies: 35
- Views: 34745
Re: Dagger boards versus shared lift
I'm speaking of the entire system. All of the drag forces combined equals the propulsion forces. If it were not so the boat would continue accelerating until the drag force exactly equalled the propulsion force and we reach equilibrium.
- August 19th, 2016, 7:21 am
- Forum: General Discussion
- Topic: Dagger boards versus shared lift
- Replies: 35
- Views: 34745
Re: Dagger boards versus shared lift
......... bringing this thread full circle ......... let's talk some more about dagger boards and shared lift. As we all know the 15 and the 17 have no dagger boards, the 19 and the 20 both sail perfectly fine with dagger boards in the full up position. So what is going on here? We are talking about...
- August 18th, 2016, 9:21 pm
- Forum: General Discussion
- Topic: Dagger boards versus shared lift
- Replies: 35
- Views: 34745
Re: Dagger boards versus shared lift
and the angle of attack is the leeway angle? If we are talking about 'motionless water' and the boat is moving forward the angle of attack can only be the leeway angle.
- August 18th, 2016, 5:10 pm
- Forum: General Discussion
- Topic: Dagger boards versus shared lift
- Replies: 35
- Views: 34745
Re: Dagger boards versus shared lift
Thanks Bill, as my father used to say, "you are a gentleman, a scholar and a judge of good bourbon." He was a Purdue man and they were "Boilermakers" of course. I am aware that the boards don't know the difference between current and plain old motion. It relative right? Water mov...
- August 18th, 2016, 11:35 am
- Forum: General Discussion
- Topic: Dagger boards versus shared lift
- Replies: 35
- Views: 34745
Re: Dagger boards versus shared lift
current = wind and has a very profound effect on boat speed and dagger board management. Bill did what he always does and reframed my question. If he boards are near or at stall speeds, up or down? That is the question. Can I make it any more succinct? Let's leave the current out, okay. If the board...
- August 16th, 2016, 8:56 pm
- Forum: General Discussion
- Topic: Jib Barber Hauler system SC 20
- Replies: 11
- Views: 11292
Re: Jib Barber Hauler system SC 20
I mean, the system was set up like that to begin with--I have to be doing something wrong! Hmmmmmmmmmm I think it might be like the original cable traveler, not the greatest solution but a necessary one. The spaghetti mess of the barber haulers and the jib sheets was just not palatable to my crew s...
- August 16th, 2016, 12:00 pm
- Forum: General Discussion
- Topic: Jib Barber Hauler system SC 20
- Replies: 11
- Views: 11292
Re: Jib Barber Hauler system SC 20
Dan, my boat had the boom mounted barber haulers with the stainless rings. The system was a giant p.i.t.a. I've noticed that some owners use the 4 way adjusting jib blocks, somewhat akin to the Prindle system. Once I narrowed the boat it became a moot point. You might have to set up some traverseing...
- August 16th, 2016, 9:35 am
- Forum: General Discussion
- Topic: Dagger boards versus shared lift
- Replies: 35
- Views: 34745
Re: Dagger boards versus shared lift
So at stall speeds boards up? But it's not that easy. Bill has given some broad rules of thumb. Let's add in currents and tides. Where I sail you can have 3 knots of boat speed and 9 knots of current flow over the boards. So what rules apply here? With an ebb tide and river flow we can easily see si...
- August 15th, 2016, 6:32 pm
- Forum: General Discussion
- Topic: Dagger boards versus shared lift
- Replies: 35
- Views: 34745
Re: Dagger boards versus shared lift
Hi Rich, Now let's slow down going to windward. The wind has dropped off and we can only go 3 knots to windward. The sail side force is small but the dynamic water pressure on the board is down very dramatically. At 10 knots it was 100. At 3 knots it is 9 or one eleventh of what it was at 10 knots....
- August 15th, 2016, 6:15 am
- Forum: General Discussion
- Topic: Supercat 17 footage from drone
- Replies: 13
- Views: 18373
Re: Supercat 17 footage from drone
Tom,
Nice sails! Who made em? There's another thread on this board asking about who makes colored dacron sails with modern shaping. Looks like you found somebody willing to do just that, high aspect, roachless, fat head!
Nice sails! Who made em? There's another thread on this board asking about who makes colored dacron sails with modern shaping. Looks like you found somebody willing to do just that, high aspect, roachless, fat head!