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#197193 - 11/20/09 05:32 PM Re: Viper Cunningham? ***** [Re: scooby_simon]  
Joined: Mar 2008
Posts: 201
simonp Offline
enthusiast
simonp  Offline
enthusiast

Joined: Mar 2008
Posts: 201
Adelaide, South Australia
I already have an external 8 to 1. I dont think I need more purchase (I grunt a lot) just I like the clean look of the internal system. But Ive never worked out how people attach those top blocks.


Simon
BLADE F16 AUS405
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#197203 - 11/20/09 06:04 PM Re: Viper Cunningham? [Re: simonp]  
Joined: Jun 2001
Posts: 9,582
Wouter Offline
Carpal Tunnel
Wouter  Offline
Carpal Tunnel

Joined: Jun 2001
Posts: 9,582
North-West Europe

Pre drill holes in the plate

Lay the mast flat

Drill holes in the mast using the plate as a template (remember carefully which side goes where)

Tape the plate to a long stiff rod or beam. Broomstick worked well for me. Don't go overboard with tape it, you are not forcing up the mast.

Fiddle about with the broom stick while your helper looks through the whole in the mast to see whether one hole is about to aling itself.

If so, use a iceprick of screwdriver to "stabilize" the plate.

Increase screwdriver size as to align the plate better and better.

Keep the screwdriver in and try to aling an opposing hole. Use again some screwdriver to properly align the plate.

The plate should be aligned pretty well know, try to put blind rivets in the remaining two holes. With a bit of fiddle this works. If confident you can pull the broom free before doing this.

From then onwards replace screw drivers with rivets.

Doubt check whether everthing is at it should be. (testing operation of downhaul over full swing, no lines crossed ?)

Certain everything is alright ?

Rivet all fasteners into place.

I think it took me 5 minutes do do, but I had the whole system neatly lined up next to the mast.

It is really not as difficult as it sounds.

8:1 will do but 12:1 is better with respect to finetuning the luff tension.

Wouter

Last edited by Wouter; 11/20/09 06:05 PM.

Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
#197213 - 11/20/09 10:49 PM Re: Viper Cunningham? [Re: mikeborden]  
Joined: Sep 2006
Posts: 586
Dazz Offline
addict
Dazz  Offline
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Joined: Sep 2006
Posts: 586
Hobart, Tasmania, Oz.
Originally Posted by mikeborden


I do like the system on the Vipers pretty well, but sometimes the lines or blocks get "snagged" on something when you are trying to downhaul really hard. You just have to pull a little harder and it comes undone. Whatever that is...I do know it's not the blocks bottoming out...I make sure I do that correctly before going out on the water...


We employ the same system on the cap, the snag is the two floating blocks running along the main beam hitting each other as they pass by, only happens at a certain point and not all the time.

I have spent many sleepless nights trying to work out something better.. there must be a better way.


C2 AUS 222 by Goodall design
"Darph Bobo"
#197232 - 11/21/09 11:23 AM Re: Viper Cunningham? [Re: scooby_simon]  
Joined: Apr 2004
Posts: 713
davefarmer Offline
old hand
davefarmer  Offline
old hand

Joined: Apr 2004
Posts: 713
WA, ID, MT
[quote=scooby_simon]If you do not want to go internal to the mast; you can have a cascade 16:1 externally

[Linked Image]

Scooby,
It looks like you've replaced the micro cheek blk at the very base of the mast aft, with something larger, what prompted that? What is that blk, I don't recognize it? A wire blk? How about the red twing ball in the blue line, is that your way of terminating the blue line after it's been fed thru the blk(s) at the mainsail tack? Nice! Is the red line 3/16"? Which line(Mfgr)? Thanks for the pic and post!

Dave

#197237 - 11/21/09 03:22 PM Re: Viper Cunningham? [Re: davefarmer]  
Joined: Feb 2004
Posts: 3,528
scooby_simon Offline
Hull Flying, Snow Sliding....
scooby_simon  Offline
Hull Flying, Snow Sliding....
Carpal Tunnel

Joined: Feb 2004
Posts: 3,528
Looking for a Job, I got credi...
Originally Posted by davefarmer
[quote=scooby_simon]If you do not want to go internal to the mast; you can have a cascade 16:1 externally

[Linked Image]

Scooby,
It looks like you've replaced the micro cheek blk at the very base of the mast aft, with something larger, what prompted that? What is that blk, I don't recognize it? A wire blk? How about the red twing ball in the blue line, is that your way of terminating the blue line after it's been fed thru the blk(s) at the mainsail tack? Nice! Is the red line 3/16"? Which line(Mfgr)? Thanks for the pic and post!

Dave


Micro cheek block is still there; the wire block (as you guess) is just tied to it; I wanted a larger dia block as at times the rope was rubbing on the gooseneck when I had lots of DH on.

Not sure who made the red rope; it's just what the chandler had at the time; I THINK it's 5mm; this setup is very efficient, I never really need to pull it hard; it just comes in when needed and because it's a cascade with fairly big blocks it runs out very well too.

The red ball, is, as you guess the termination of the line that goes thru the block on the sail.

I have a bit of D12 with the ball on spliced onto the forward block; the D12 that goes thru the block on the sail has a spliced loop just big enough to get the ball thru once pulled snug thru the block on the sail.


Last edited by scooby_simon; 11/21/09 03:33 PM.

F16 - GBR 553 - SOLD

I also talk sport here
#197248 - 11/21/09 10:43 PM Re: Viper Cunningham? [Re: scooby_simon]  
Joined: Apr 2004
Posts: 713
davefarmer Offline
old hand
davefarmer  Offline
old hand

Joined: Apr 2004
Posts: 713
WA, ID, MT
What blks are you using at the mainsail tack, and how are they attached? Thanks!

Dave

#197253 - 11/22/09 02:51 AM Re: Viper Cunningham? [Re: davefarmer]  
Joined: Feb 2004
Posts: 3,528
scooby_simon Offline
Hull Flying, Snow Sliding....
scooby_simon  Offline
Hull Flying, Snow Sliding....
Carpal Tunnel

Joined: Feb 2004
Posts: 3,528
Looking for a Job, I got credi...
I think it's a 28mm Harken carbo, not sure....

[Linked Image]

Bit of Spectra line goes thru the sail and back a few times and another block on the other side; not very high tec but it works!

Shed loads of downhaul on in that pic, all with one hand and not working very hard!

Last edited by scooby_simon; 11/22/09 02:52 AM.

F16 - GBR 553 - SOLD

I also talk sport here
#197911 - 12/01/09 09:22 AM Re: Viper Cunningham? [Re: Wouter]  
Joined: Sep 2003
Posts: 34
patrik Offline
newbie
patrik  Offline
newbie

Joined: Sep 2003
Posts: 34
Sweden, Gothenburg
Originally Posted by Wouter

Quote

Matt or someone else would be able to answer the above question better than me..



Okay I'll bite !

The Viper has a 4:1 purchase system betweent the sail and the bottom of the mast; you can see it in the 4th picture.

The total system is a 16:1 and that means that the (single) blue line that goes up from the beam to the sail will only see 4 times the load that you pull on your downhaul line. Typically a human being does pull more then 50 kg; Therefor the force in the blue line is typically 200 kg or less while the total downhaul force on the sail may be around 800 kg's.

A normal boat of F16 dimensions will quite easily see up to 1500 kg in mast step loads. Afterall the mainsheet tackle alone will already induce close to 400 kg of compression on the mast foot. The forestay and sidestay add similar amounts to the total.

Going up from say 1500 kg to 1700 kg (13%) is not a big deal at all.

Wouter



Hi Wouter, All,

Is around 50Kg a value that could be expected as mainsheet force, is this a typical value for a "normal" adult man? or would it tend to be high? or low? (I am asking as I had a question from my sailmaker on how much forestay tension I would expect). I am putting a tornado rig on a monohull, boom 2,4m, 1:10 purchase, forestay same distance away from mastbase. question is what the contribution from the mainsheet would be on the forestay? Input greatly appreciated as I ordered a sail yesterday and need to give some input in order for the sailmaker to possibly adjust for forestay sag compared to a non-rotating mast setup wich could have higher sidestay tension.

Kind regards
Patrik

#197912 - 12/01/09 09:26 AM Re: Viper Cunningham? [Re: patrik]  
Joined: May 2003
Posts: 4,451
Rolf_Nilsen Offline
Rolf_Nilsen  Offline


Carpal Tunnel

Joined: May 2003
Posts: 4,451
West coast of Norway
What is your stability like compared to a Tornado? It is not only how hard you crank on the mainsheet but also the stability curve of the boat. Less stability = less mainsheet tension. smile
You probably want to look at similar boats to see what purchase they go with. 50kgs is a load you could pull from the trapeze with good footing. I never measured though.

#197914 - 12/01/09 09:44 AM Re: Viper Cunningham? [Re: Rolf_Nilsen]  
Joined: Sep 2003
Posts: 34
patrik Offline
newbie
patrik  Offline
newbie

Joined: Sep 2003
Posts: 34
Sweden, Gothenburg
Hello Rolf,
Thanks for the input.
The stability factor from the boat will be limited, the righting moment will mainly come from 2 crew in trapeze. Racks extending ca 2,5 from the boats centerline. The boat is intended to be sailed "completely" flat. The keel weight will be to balance the mast but not much more. This together with sail area means it will be fully powered up earlier than a T, but later than an A-cat.(if my calcs are correct).

Kind regards

Patrik

#197926 - 12/01/09 11:30 AM Re: Viper Cunningham? [Re: patrik]  
Joined: Sep 2005
Posts: 893
waynemarlow Offline
old hand
waynemarlow  Offline
old hand

Joined: Sep 2005
Posts: 893
From actual land based experiments 50kgs is really a bit of a struggle one handed and needs leg drive as well. A straight pull one handed of 45 kgs took the skin off my hands so unless you are super athletic and can lock your feet into to something then 50kgs is going to be your upper max.

#280448 - 09/06/15 05:08 AM Re: Viper Cunningham? [Re: Timbo]  
Joined: Apr 2009
Posts: 88
Matthew Dawson Offline
journeyman
Matthew Dawson  Offline
journeyman

Joined: Apr 2009
Posts: 88
An old thread but a good one. I like looking through these old setup threads. I am keen to try Wouter's 1:12 internal system on my Cobra. I miss Wouter.

One thing I wonder about internal downhaul systems is how to prevent problems that could come up if the system loses tension in a capsize, whilst on the road, etc. What are the tips for avoiding any problems?


Cobra 570
Cobra 581
Mosquito 126
Arafura Cadet 738
#280580 - 09/22/15 01:57 PM Re: Viper Cunningham? [Re: Timbo]  
Joined: Jul 2006
Posts: 549
Gilo Offline
addict
Gilo  Offline
addict

Joined: Jul 2006
Posts: 549
Knokke-Heist - Belgium
Matthew,

Never had any issues with the internal system on my Blade or Falcon and I travel a lot (I try to minimize the capzised though :-) ).

Since 2 years we are using the nicest system from a usage point of view on the Falcon I find.
There is an external 1/16 downhaul as you can find on many F18's, but it comes with spinlocks and is easy to remove from the mast (meaning you can splice it in the front beam).
Compared to most other cunningsystems this one is always easy to cleat or uncleat (even with high tension on it) and does not undo itself when taking it out on your trapeze!

I can post some pics if you like.

Gill


Falcon F16 - BEL666
Boats: TheBoatShop.be
Stories: bladef16.blogspot.com
#280582 - 09/23/15 02:47 AM Re: Viper Cunningham? [Re: Timbo]  
Joined: Apr 2009
Posts: 88
Matthew Dawson Offline
journeyman
Matthew Dawson  Offline
journeyman

Joined: Apr 2009
Posts: 88
Thanks Gill

I would love to see some pics.


Cobra 570
Cobra 581
Mosquito 126
Arafura Cadet 738
#280655 - 09/29/15 11:41 AM Re: Viper Cunningham? [Re: Timbo]  
Joined: Jul 2006
Posts: 549
Gilo Offline
addict
Gilo  Offline
addict

Joined: Jul 2006
Posts: 549
Knokke-Heist - Belgium
Hi Matthew,

You can find how it looks in the beam.

[Linked Image]

This is a picture showing the setup.
[Linked Image]

The blue line is the cunningham. You just have to remove the spinlocks and 2 shackles and the system is fully loose.

The spinlocks prevent the line from uncleating when getting in the trapeze.

The orange line is the mast rotation quick release.

Gill

Attached Files
Last edited by Gilo; 09/29/15 11:42 AM.

Falcon F16 - BEL666
Boats: TheBoatShop.be
Stories: bladef16.blogspot.com
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