UK-Cherub Forum
Cherub Chat => Tech Chat => Topic started by: Neil C. on September 25, 2008, 01:26:51 PM
-
Is this the future of Cherub sailing?
http://ib.myimage.ch/main.php?g2_itemId=13725 (http://ib.myimage.ch/main.php?g2_itemId=13725)
-
Is this?
-
It'll never measure ;D
;)
-
I love the spaceframe foiler, it deserves significant respect - do they have a dual wand system at work?
Please remember the Clanger clause, this is the basic rule that discounts speculative cad files or sticking a set of moth foils on and taking a cheap photo....
IT IS B**L S***T UNTIL YOU HAVE IT SAILING
-
Didn't it sail at the 18 Europeans and get annihilated?
-
Is the yellow thing at the back for floatation ,or an airbag for the imminent crash!
-
I wonder. Spend a bit of time and cash on decent lifting foils and 3 or 4 carbon tubes to take the mast, shroud and forestay loads. A few bits of 4mm ply at about a tenner each for the minimalist hull, some plastic guttering tubes from B&Q for the rest of the spaceframe and trapezing racks and Fanny's yer Aunt, job done! Anybody else think it's possible?
-
no but let me know when you try it!
It would cut down the cost of a hull but what nightmare to build all thos tubes.
board in front of the mast is interesting and a bow sprit that they dont use.
-
You would get wipped by the woddies in light airs though.
When everyone has finnished optimising to the 2005 rules we'll get bored and try fully foiling. Less need for kites, wheelie bars and the ability to extend the gantry. It will change all the foil shapes again though.
Some moths use car throttle cables between the wand and the centreboard. Clever!
-
Who's next...
-
I'll do it! I'll make the foils at the sticky weekend. Mind you, it's winter now...
-
Why not buy some from Harken?
http://www.foils.org/Miller_harken_hydrofoils.pdf (http://www.foils.org/Miller_harken_hydrofoils.pdf)
-
where on earth did you find that! Fantastic, must be around 85'?
-
http://www.foils.org/miller.htm
-
ah... should of guessed really shouldn't I, Doh!
-
Those R-Class boys have been busy. New Dan leach design on full foils. See full story on www.rclass.org
(http://z10.invisionfree.com/12ft_skiffs/index.php?act=Attach&type=post&id=2561489)
-
Nice... anyone got a set ordered yet?
-
Hmmm, square section boom....interesting... ;D
-
triangular shorley?
-
The standard L3 (i think its called) hull has got to be the best looking boat I have ever seen. How would it do as a cherub? I think they are a bit longer and you would need a retracting pole but it is a fine looking boat.
-
Mr Tinner knows a bit about this. I think the L3 is too narrow but the new L4 measures.
-
The R-Class skiffs are very simiar to the UK Cherub, but there are one or two detail differences. They are a "restricted skiff" (hence the R-Class title), meaning they're on the whole a 12 Footer, with restricted sail area. A lot of the kiwi 12 Foot Skiff guys sail in R-Class events with the small rig on. The key differences are a longer waterline length at 3.9m, (12's and Cherubs are both 3.7m). There is no minimum weight, and interestingly no maximum beam! That's why if you look closely at the photo of the foiling R above, you'll see that it has a double set of trapezing racks. They stick on the extra-wide racks in R-mode, and remove the extensions for 12 regattas. The opinion seems to be that the L3 (above) is too narrow. Even very experienced 12 guys coudn't keep it going with the big rigs on, and have gone back to Woof hulls. They've recently launched the L4 (below), which is a different design altogether.
http://www.rclass.org/info/construction/l4-hull/L4_Hull_Shell.JPG/image_view_fullscreen (http://www.rclass.org/info/construction/l4-hull/L4_Hull_Shell.JPG/image_view_fullscreen)
-
I'm ready for 'R' Class / UK Cherub unification... ;D
-
(hence the R-Class title),
Don't believe so. Kiwi classes in the days before the Cherub were mostly known by letters. The unrestricted 12 footers were the Qs, the unrestricted 18 footers were M, P is the Kiwi Oppie equivalent, Zs were a 12'6 one design (with spinnaker and no jib!) that was well capable of planing in 1921, X were 14' one design and so on through Is Ts, Ys etc etc. In the book I have at least there is no mention of any particular scheme for the choice of letters. Rs and Qs tend to be from Wellington and Auckland areas respectively.
-
Check out this shizzle! (http://www.3news.co.nz/High-hopes-Innovation-to-help-yachting-crew-to-third-national-title/tabid/317/articleID/88979/cat/187/Default.aspx#video)
In my opinion, when looking downunder to compare their ships with Cherubs we'll get a much better idea looking at the R-Class than the 12's. The 12's are designed to always be sailed totally overpowered, that's why shapes like the Woof work. R-class have very small sail area for the amount of righting moment, just like Cherubs. The L3 has completely wiped the floor at the last couple of Leanders, it works as an R, but as Neil says it's too skinny to work as a skiff. But as a Cherub...
The L4 is a bit wider, I haven't decided if it will measure as a Cherub yet. But it's interesting to note the L4 has a second spray rail, and they've modified the foiling L3 to also have another spray rail. The L4 was designed to be a skiff and an R-class, taking into account the fact the L3 was too skinny because it was designed purely as an R.
-
So who is going to put the foils on first. When I get a bloody job sorted...
-
Daryl, is your boat a Banshee bottom with a Cardinal Sin deck?
-
Nope. The side deck bits are much wider on the Cardinal Sin. A point which I actually really like about my boat. It's wide enough for a whole foot rather than having to tip toe on the edge!
-
Daryl, is your boat a Banshee bottom with a Cardinal Sin deck?
No.
-
For those who like to follow developments but are less geeky than me:
http://www.rclass.org/info/construction/hydrofoils/hydrofoil-notes-january-2009
-
I think the really interesting thing in that report is...
When foiling, the boat is much more stable and easier to sail than a conventional R.
There has been plenty of outside speculation that "the boats will be harder to sail" on foils. It turns out that the R on foils is actually more stable and much easier to control. It didn't take long to acclimate to the decrease in lateral resistance from the much smaller vertical main foil, and stop falling into windward when wiring.
-
It is interesting that the R Class rejected T-foils as they were too draggy downwind. I hear the 14s are starting to question them as well. Is it just because the cherub is so short they are of benefit to us?
-
It may well also be a function of flat. The T-Foil only gives a massive hit when the mast is bolt upright - from looking at the piccies this is not the case downwind with their rigs?
-
I hear the 14s are starting to question them as well.
Can you post a link about this?
-
here's the link to the R's foiling history http://www.rclass.org/info/construction/hydrofoils/hydrofoil-project (http://www.rclass.org/info/construction/hydrofoils/hydrofoil-project)
-
It may well also be a function of flat. The T-Foil only gives a massive hit when the mast is bolt upright - from looking at the piccies this is not the case downwind with their rigs?
I think it is more to do with the fact that they have a clear and unrestricted aim of making the boat as fast as possible. Given that there skill level is high by virtue of sailing in consistently high wind strength and use of larger kites negates the need to damping downwind for extra speed from control. The gain upwind did not benefit them downwind. So it was logical to move to a fully foiling boat, which has significant advantages in speed up and downwind as well as damping for improved control.
-
I hear the 14s are starting to question them as well.
Can you post a link about this?
Haven't read anything as such, just the chat I hear from folks in the uni club. May be rubbish - I don't know.
-
It may well also be a function of flat. The T-Foil only gives a massive hit when the mast is bolt upright - from looking at the piccies this is not the case downwind with their rigs?
I'm not sure how the mast position effects T-foil speed advantage (unless you mean capsized and not capsized). If the R's sail more bow up than normal then they would just change the angle of the foil relative to the water.
-
The 14's are not allowed to trapeze behind the transom so there is limited scope for setting the T to lift down wind.
-
They also have 2 feet more hull in front of the transom so gain all the benifits of controlability from the extra waterline length.
-
I'm not sure how the mast position effects T-foil speed advantage
I'm not completely sure how this works myself. But the foil on Born Slippy certainly only seems to give use a boost when the mast is not leaning too far left/right.
A stab:
The lift from the foil acts along the line of the rudder blade. If the boat is healed then some of that lift then starts working against the back of the hull steering the boat (sin30 ~ 0.5) and needing to be corrected. The loss of lift is only small (cos 30 ~0.87), but there appears to be a whole load of extra drag. I'm sure the theorists out there can reference the reason, although it may have nothing to do with this and simply be a function of the slug hull shape.
-
How would the L3s main spray rail count as a chine with respect to our rules? Im thinking of scaling the L3 for a new boat. Where would the chine beam measurements be taken from if its a spray rail rather than a chine?