AntarcticPilot
Well-Known Member
Nothing new under the sun - the ancient peruvians used multiple dagger-boards to navigate their rafts! No rudder on them; they just changed the position of the centre of lateral resistance to turn the boat.
I had to look twice at this...
- Thread starter mrming
- Start date
BelleSerene
Well-Known Member
Raced against her in Sydney Harbour. (Think she may have beaten us.) She's fearsome.
Buck Turgidson
Well-Known Member
Something that I don't get with DSS as currently implemented is that the drag would surely be less if the wing were hosted by an above water arm like an outrigger but with the wing rather than a float. Is this a rule thing?
flaming
Well-Known Member
Not toally sure I understand what you're saying - but having an arm above the water supporting something under the water does sort of sound like you're going to struggle to meet the definition of "monohull".
What I like about the DSS compared to a canting keel is the simplicity and the fact that the faster you're going the more stability you have.
Reports from the Infinity boats have said it's a very strange feeling to find the boat getting stiffer as it gets faster.
KellysEye
Well-Known Member
>https://www.youtube.com/watch?v=ksDTRR1HhsI
I've never heard off DSS and was going to ask what it was, so thanks for posting the video, it's amazing.
I've never heard off DSS and was going to ask what it was, so thanks for posting the video, it's amazing.
BruceDanforth
Well-Known Member
They will get a cold beer in the bar at Eden after they break it anyway.
Buck Turgidson
Well-Known Member
That's my question. Does a foil count as a hull? If not then you would be better off hanging it out from above the waterline. You would eliminate the parasite drag from the foil/hull interface and all the area close inboard which has a short arm.
The stiffening will always happen with the square of the speed ;-)
Steersman
Active Member
Just watched the video describing DSS. It looks very good, but I think I'm a bit too much a traditionalist.
When I started sailing, I considered it a sport, but now, with such sophisticated gadgets like DSS, electric steering, and self tacking jibs it seems to me that sailing is becoming just a push button hobby with nice views.
When I started sailing, I considered it a sport, but now, with such sophisticated gadgets like DSS, electric steering, and self tacking jibs it seems to me that sailing is becoming just a push button hobby with nice views.
Woodlouse
Well-Known Member
Strength would be an issue. Also on boats such as that you take aerodynamics into account as well as hydrodynamics so having a large immovable outrigger on both topsides would incur far more of a penalty than a retractable foil under the water that's only deployed as required.
Buck Turgidson
Well-Known Member
Put the same mechanism 2 feet above the waterline? Or on the coachroof and let the heel angle dictate how much foil gets immersed. It becomes self stabilising!
I'm guessing that either the drag at the surface of a cantilevered foil must be higher than the submerged hull/foil interface or it somehow becomes a multihull if the foil isn't all submerged.
I'm not knocking it by the way, I think it's a good innovation. They might want to sweep the next version a tad to get some dihedral effect too ;-)
mrming
Well-Known Member
As far as I understand it, there's nothing inherently push-button about DSS. It's another foil, like a keel or daggerboard but horizontal. In a smaller boat you would probably pull a string to tack it from side to side. You might choose to have it computer controlled on a 100' super maxi, but it could easily be adjusted manually according to the feel of the boat on a smaller yacht.
As for hanging the DSS foil out above the waterline, it wouldn't do anything at the speed Wild Oats is going. It needs to be immersed to generate lift.
Twister_Ken
Well-Known Member
What a great way of picking up the pot bobber that you just missed with the bow.
Also has the makings of an excellent MOB recovery system.
Also has the makings of an excellent MOB recovery system.
flaming
Well-Known Member
Logic says it would as it's designed to support the boat, but a quick scan of the IRC rules and the RRS doesn't provide any definitive answers.
mrming
Well-Known Member
According to the DSS site:
Wonder if effects the max beam measurement? You could end up with a pretty wide boat!
flaming
Well-Known Member
Yes, as it is currently deployed yes as it's just a foil coming out of the hull. Buck was (I think) asking about a system that doesn't deploy the foil from the hull, but suspends it from a beam above the waterline. The idea I think being to get the foil further outboard for less drag.
There was a mini built with DSS (but not raced this time) and I understand it did have to fit into the max hull measurement. Made for a pretty skinny mini!
Woodlouse
Well-Known Member
My understanding of hydrodynamics is not great but I believe, as you say, that the greatest resistance stems from wave creation between the two elements. So an appendage that starts above the water and extends below it will create more drag than one that is fully submerged. Also, since you want it to be working as much as possible it makes sense to have it low in the hull instead of needing the boat pushed over to before it begins to work.
I'd imagine though strength and simplicity would be the greatest deciding factors though.