Laser 28 - Excellent example of this great design Hamble le rice |
![]() |
Laser 140101 Tynemouth |
![]() |
Laser 161752 Tynemouth |
![]() |
List classes of boat for sale |
dinghy design questions |
Post Reply ![]() |
Page <1 23456 7> |
Author | ||||
gbrspratt ![]() Posting king ![]() Joined: 26 Sep 11 Location: Felixstowe Online Status: Offline Posts: 170 |
![]() ![]() ![]() ![]() Posted: 09 Oct 14 at 7:06pm |
|||
You brought the plusplus Jim? What was it like? Does it need the modifications talked about on the website?
So for waterline length is key for upwind does but does hull shape effect pointing? And how? What hull shape is fast down wind? If we say in ten knots of breeze. |
||||
![]() |
||||
getafix ![]() Really should get out more ![]() ![]() Joined: 28 Mar 06 Location: United Kingdom Online Status: Offline Posts: 2143 |
![]() ![]() ![]() ![]() |
|||
Hull shapes are out there already IMO, ok I'm sure refinement with materials and weight distribution could add a few % here and there but the big gains are to be had with the foils above and below the "waterline" as ably demonstrated recently in the AC and with Moths... Can't wait for the "trickle down" as I can't afford one of those foiling cats .... yet!
Edited by getafix - 09 Oct 14 at 7:11pm |
||||
![]() |
||||
Medway Maniac ![]() Really should get out more ![]() ![]() Joined: 13 May 05 Location: United Kingdom Online Status: Offline Posts: 2788 |
![]() ![]() ![]() ![]() |
|||
People like to say it does, but in reality the lift provided by the hull is tiny compared to that generated by the foils, which moreover generate lift with a lot less additional drag than the hull, which when you think about it is a very low aspect-ratio foil! As an example, I'd cite the Fireball - no bow to dig in but goes to windward like stink. Good foils and a very well-developed rig. As getafix says, the 'foils' above and below the waterline are what count.
|
||||
![]() |
||||
Jim Mitch ![]() Newbie ![]() ![]() Joined: 04 Jun 07 Location: United Kingdom Online Status: Offline Posts: 7 |
![]() ![]() ![]() ![]() |
|||
I always thought Blue Arrow looked interesting. The ultimate "long and thin" design? Given the advances in foil and wing technology, would it work better today?
http://www.americas-cup-history.at/english/blue.htm |
||||
![]() |
||||
JimC ![]() Really should get out more ![]() ![]() Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6662 |
![]() ![]() ![]() ![]() |
|||
Well, I would say so [grin]
Not really in the sense of affecting leeway. Foils are so much more powerful and efficient than the hull. But indirectly, well hull shape affects drag, and drag affects pointing ability.
Very hard to make hard or fast rules. But all else being equal a long boat will still be better than a short one unless you can get into a real planing mode with very little wave generation, and there are precious few dinghies that can manage that.
Certainly interesting. The thing about it though was that it was primarily a rule beating boat but most of the rules it had to beat were unwritten. They had to work up a boat that would meet the Deed of Gift rules (not too difficult), be faster than the Yanks catamaran (pretty challenging) but, when the principle dimensions were put on paper, sight unseenm make the Kiwis and Yanks think it couldn't possibly be faster than the big Kiwi monohull so they'd be allowed to play (very difficult and in the event they failed at that). So it wasn't necessarily the boat they'd have built for maximum speed round a track. My understanding was that they were not allowed to play, and so with the last of the money they went sailing faster and faster in more and more wind, and then one day... bang. Edited by JimC - 09 Oct 14 at 8:59pm |
||||
![]() |
||||
Rupert ![]() Really should get out more ![]() Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956 |
![]() ![]() ![]() ![]() |
|||
John Claridge was involved with Blue Arrow, as a sailor of narrow Moths. He had some interesting tales to tell. Surprised the idea hasn't been revisited without the rules.
|
||||
Firefly 2324, Puffin 229, Minisail 3446 Mirror 70686
|
||||
![]() |
||||
andymck ![]() Far too distracted from work ![]() Joined: 15 Dec 06 Location: Stamford Online Status: Offline Posts: 397 |
![]() ![]() ![]() ![]() |
|||
[QUOTE=gbrspratt]
So for waterline length is key for upwind does but does hull shape effect pointing? And how? Scam Hull shape can be changed to affect pointing ability. N12 and Merlin designs have since the 70's had fine deep bows as they improve upwind performance by giving lift off the bow. The DCB was a big move away from this, the winged rudder helps overcome the need along with the trim tab. This of course is used to overcome other constraints, in boats that are designed to plane downwind, and go at displacement speeds upwind. Of course for a displacement boat I would agree with a u shaped cross section with a banana rocker like the americas cup boats, or look at the modern radio controlled hulls like the 1m britpop. These attempt to reduce wetted area in light winds then go to maximum waterline once healed like the old J's and metre class boats. Going downwind designs over the last 15 years have also changed. In the N12 wide flat sterns had already been tucked in with the planing surface sometimes more forward. The winged rudders have changed the trim angle again, with the boats planing less bow up. The stern waves have as a result got smaller. It feels more like the way a motor boat planes. Of course the skiffs are different, so again depends on power to weight ratio. Andy |
||||
Andy Mck
|
||||
![]() |
||||
gbrspratt ![]() Posting king ![]() Joined: 26 Sep 11 Location: Felixstowe Online Status: Offline Posts: 170 |
![]() ![]() ![]() ![]() |
|||
Its not scam. Its Matt. But close! Just trying to get my head around a few things. |
||||
![]() |
||||
JimC ![]() Really should get out more ![]() ![]() Joined: 17 May 04 Location: United Kingdom Online Status: Offline Posts: 6662 |
![]() ![]() ![]() ![]() |
|||
Has to be a myth. There's not a chance that the lift/drag you'd get off the hull could contribute anything useful compared to what the foils are doing. The reduced wave impact of a fine deep bow might be another matter. Just because something works doesn't mean people know *why* it works. |
||||
![]() |
||||
andymck ![]() Far too distracted from work ![]() Joined: 15 Dec 06 Location: Stamford Online Status: Offline Posts: 397 |
![]() ![]() ![]() ![]() |
|||
Sorry matt
|
||||
Andy Mck
|
||||
![]() |
Post Reply ![]() |
Page <1 23456 7> |
Forum Jump | Forum Permissions ![]() You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |