UK-Cherub Forum
Cherub Chat => Tech Chat => Topic started by: Phil Alderson on February 12, 2011, 10:09:05 AM
-
What do you think of this new design 14 from Paul Bieker
http://www.biekerboats.com/Bieker_Boats/I-14_B6.html (http://www.biekerboats.com/Bieker_Boats/I-14_B6.html)
The shape of the bow is interesting, and getting rid of the top spreaders would mean a move away from prebent rigs
-
I thought this was an interesting comment. It's a bit different from the current ethos in our class:
"Over the years, I have had a lot of experience watching fuller bows outperform finer bows in boats that have a lot of power for their length, the most obvious example being the IACC yachts. It may be startling, but a 14 has approximately the same displacement to length ratio as an IACC yacht, so I think it is a fair guess to think that they would benefit from a fuller entry."
-
The rig will break. If it doesn't then the mid mast will look horrendous anyway with reversed bend :/
-
The rig will break. If it doesn't then the mid mast will look horrendous anyway with reversed bend
Paul is pretty smart, I wouldn't bet he's wrong even if if its not something I'd try. Halo's original tin stick (which was something of a treetrunk I admit) had the kite hoist equidistant between hounds and mast tip and with forward angled spreaders the rigid prod to the gooseneck was the only thing stopping it inverting, yet it never showed any signs of doing so... He says he's got aft raked spreaders so it should be possible to keep the mast bending the right way. I've just had a quick look through old pics of 18s and Qs and can't spot what the staying arrangements were, but they certainly had masthead kites before prebent topmasts. The key will be not to dump the main too far. I loathe all the knitting round two spreader rigs, but I'm not smart enough to think of an alternative.
-
I was very amused when this appeared on SA... the direction of the bow design fits very closely with some of the thoughts ive been having since seeing the new crop of boats in the flesh at largo for the first time. I don't thing its a huge departure from the current class thinking but its something that makes a lot of sense to me. Think of it a little like a dreadnought bow without compromising on waterline length.
Im more interested in the rig design - I don't agree with the above comment at all though. If its been engineered correctly (and there's no reason to think someone of Biekers stature would get this too far off) theres no reason to think it will fall apart or that the bend characteristic's will be any worse that the many other single spreader rigs on the water. The interesting thing will be whether the tradeoffs required to make it work will be too much of a compromise. Im not convinced but hes not the only new 14 to be taking this route.
-
There are a few interesting things about the rig change.
In tha ali mast days there were a few 14's with masthead kites and no top spreaders.
One of the arguments towards using the prebent rigs is that the topmast is supported sideways keeping the power in the rig, and also when you bend the mast enough with the cunningham, it all flattens off, and you loose the side suport, and dump power.
With the un-supported rig you do not get the side support, and potentially less overall bend in the mast if you have a shorter stronger top section. How is this going to change the sail design and responce over the wind range, how will it affect the fat top rigs.
-
I hadn't thought of using The main as a kind of backstay.
-
It is all very interesting.
The bow thing: People have been round the houses with this before. What happens at the cutwater is unknown to me, but I do know that bows faired in to a point beyond the bow and then rounded off has been common (on and off) in Marblehead and 36 rater models for a long time. Additional drag on pitch down is down to the entry angle, and if the cutwater is really draggy anyway then you could get a finer angle by doing this. Certainly our 26 foot Wharram catamaran would throw water several metres forwards from the cutwater when travelling at speed. More prosaically, it is probably easier to make something really strong and light with the bow rounded off a bit.
The rig thing: I really like it when things change a bit and suddenly the pressures are there to reverse several design cycles. T foils and other things make the boats go faster upwind, high modulus carbon means the staying does not need to be so thorough. This means having no uppers gains you more, and loses you less. Is it below maximum height?
-
Using the main as a backstay is the norm on the F18 cats like the tiger.
At the worlds in Cape Town in 2008, one boat broke his rig buy dumping the main sheet instead of the traveller in a big gust....
bit harder to set up and control on a skiff.
-
I would think that the no uppers developement would leead to a stiffer to section with more weight i the mast tube.
I would expect the load path from the top of the mast would go along the top of the sail and down the leach. All other parts of the sail are curved. Also on a broad reach even with the boom over the quarter the head of the main will be off the centreline. Couple this with the head of the kite pulling forwards and to leeward only the mast tube stifnes is resisting the sideways component of both forces.
-
I understand that the trap wires are going to be attached at the top of the mast downwinf to help support the kite.
-
that's a sensible idea. In the same way that the 505's do I suppose.
It would also reduce the forward pull of the trapeeze wire that trys to use the helm as a swing ball.
-
I wonder if the helm will get a feel for the power in the kite through his trapeze???
-
I wonder if the helm will get a feel for the power in the kite through his trapeze???
Big gust = catapult? Could be fun!
-
more fiddly ropes to changed the Trap position upwind or down wind.
Don't want the mast top trap up wind. as would bend the top the wrong way. I know the 505 had a system that when the kite was up it would release the tweakers so the trap position moved hight up the mast then up wind they are pulled in to the hounds.
Sounds like lots of adjusting of trap hight.. when changing legs.
-
There are so many ways to do this, especially if you are designing a stick from scratch.
A photo of the rig that has gone sailing would be more fun to speculate about?
-
This is the system on the 5oh:
(http://www.yachtsandyachting.com/forum/uploads/11740/CIMG2351.JPG)
-
Yes so more holes in the mast and more string inside it which probably ballances out the cap shrouds removed from the outside.
More fiddly to rig a boat too!
The gains are starting to look smaller.
I think reducing windage is an important aspect when moving faster than say 12-15knots. On saturday when planing down wind, I could hear the sound of the air rushing over the rig and thought that's slowing us down.
-
Very interesting!
There is deffinately something that all good designers do that looks so simple yet is clearly very difficult to acomplish.
They make combining something quite sysmic in its ability to break new ground with the ability to do something that doesn't appear to radical.
Basically they improve everything a little.
I have seen the bow thing done before and will depend on trim and sea state to work effectivly.
But it is gain with little downside.
The rig is more interesting and I think the devil is in the detail.
If you think of a mast as a stick with a taper itprobably wouldn't work but I am sure he will do some clever things with layup and shape.
All very clever.
I am not generally a big beleaver in looking at the badge but it is a very good badge.
p.s.
14's currently cost how much?
1 of those for each member of my family and we are in house buying teritory.
If we could afford to sail one of those Lara wouldn't be too light she'd just need to bring her wallet sailing with her.
-
14's currently cost how much?
I don't suppose a Cherub would be very different if you ordered a ready to sail boat with a full grand piano finish, and all the adjustable everything gear fitout the 14s have...
The adjustable everything was once explained to me by a 14 sailor as "OK you can't adjust all that stuff in the middle of the race, but it does mean you can do a complete resetup between races if the weather changes"... Sooner them than me: all that dosh for once in a blue moon, but then I have the simplest and lowest budget new rules Canoe in the world, so what do I know.
-
so what do I know.
A fair amount of good stuff :-)
(Can't find the back-rub smiley)
-
I think that one of the things that the full adjustability gives you is the ability to find settings quicker you can go for a sail, make some changes and quickly get an idea of what change makes what difference to the feel of the boat.
This should make it to know when to change gears, and what to do for a given behaviour of the boat. Whereas with a non adjustable boat, you go for a sail, it does not feel right, so you make a change for the time out sailing when the weather has changed, and it is more difficult to not know what did what.
Having said that it is a lot extra to spend on a boat, just to get that ability.
For the single spreader rig, as I recall there was at least one, or possibly two at the Europeans, I have seen pictures but can't find them now.
-
Is this what you are looking for ?
http://www.asnquiberon.com/wp-content/gallery/european-i-14-2010/6.jpg
Note how high the hounds are, this one doesnt have trap wires to the masttop, just limits the amount of unsupported top section, well its supported by the leach of the mainsail I guess; all seems ok to me until the gybe where the crew gets it right and the helm gets it wrong. But thats never happenned in my boat so we'd be OK :)
-
That was the boat I was referring to earlier - there are 2 currently on the water of that design (Possibly more in build or on the water since I last looked) but I don't know whether they both went with the single spreader rig.
Interesting that the solid flairs are still considered the way to go by some given our fleets mass exodus towards racks in the last few years.
-
Cheers Graham, that was the one I was thinking about.
I am not sure about the solid wings either, although when you watch a 49er relaxing pre start they do sort of make sence.
-
Aerodynamic drag is another factor: the scaffolding and so on is pretty poor for that. On the othe hand of course there's less wave/spray impact. But the aero drag is a constant, the wave impact isn't. Quite how you work out the best compromise between factors like that is beyond me.
-
As a 3rd rate sailor, moving from the slug to E5 I only miss the flairs when the racks hit the water to windward.
The wings gave a remote second chance of redemption from a prolonged swim. The additional flexibility from having the racks means that if I was doing it over again it'd be racked as well.
-
There is another issue: 14s with racks gain less than cherubs with racks, so it should come as no surprise that the issue is more open for them than for us. That is, the gap is less in a 14, so there is less to gain by having racks (you can't go inside the racks either).
Also racks are easier to build if you are a home builder, but mean more components if you are a production builder. Another pressure to have flares ina 14 and racks in a cherub. Its pretty finely balanced for both though.
-
It's easier getting into a racked boat after a capsize if you can get in between the racks and the hull.
Read: i haven't got the knack of doing a water start yet.
-
they have already popped the hull out of the mould???
-
It was interesting to see the I14 at the show.
The mast tip extends 1.3m above the hounds and has a much stiffer section than ours. The boat's displayed had a 2 spreader rig and the cap shrouds just looked wrong on the short tip.
The hull was very streamlined and yes Aero drag will make a difference but only a small one.
think of the drag caused by two sailors not wearing skin tight leotards and you will see an even bigger area where areo drag savings can be made.
Getting the rig right and especially getting it to work right will make a bigger difference than these areo changes in my opinion.
-
Speaking to the owner on the sunday he said it was partially to have less boat hitting waves and partially to look cool
-
The mast on the b6 snapped at the hounds
-
Yep - blamed on mounting the spreaders away from the backing plates...
-
think of the drag caused by two sailors not wearing skin tight leotards and you will see an even bigger area where areo drag savings can be made.
Adam May did some wetsuit/drysuit/lycra/rashtop etc wind-tunnel testing, and concluded that he was never going to wear a drysuit again!
-
comfort vs performance - If I recall correctly Adam wore a drysuit at last years chilly Moth Inlands
-
And using the assumption that the sailing clothing manufacturers are making money I suspect style is also a consideration.
You may have lower drag sailing in a mankini but would be the laughing stock of the fleet. Especially in those championships based around the centre of a popular seaside town.
-
Now there's an idea for the nationals.
-
And using the assumption that the sailing clothing manufacturers are making money I suspect style is also a consideration.
You may have lower drag sailing in a mankini but would be the laughing stock of the fleet. Especially in those championships based around the centre of a popular seaside town.
Phil, are you speaking from experience? you know far too much about it.
Don't reply, we'll only think, "the lady doth protest too much".
-
I did hear that there was a mankini in use at the RS200 nationals.
-
Now there's an idea for the nationals.
There is no way i will have matching kit then
-
Dean will you go more for the shaved legs and lycra?
-
Might as well be feature a rubber hat and go as a swim team. Lets face it, in a wetsuit you're only slowing yourselves down through the water. OOOOOOoooooOOOOooooo