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New boat four hulls #52159
06/30/05 01:33 PM
06/30/05 01:33 PM
Joined: Aug 2002
Posts: 545
Brighton, UK
grob Offline OP
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grob  Offline OP
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Brighton, UK
John Alani suggested I start a new thread about the boat, at the moment it is tagged on the end of
http://www.catsailor.com/forums/sho...sed&sb=5&o=&fpart=3&vc=1
[Linked Image]

To answer the questions:-


Quote
When sailing off the wind, do you put the sails to the outside like a wing and wing fashion? I know that would be slow. How does the sails affect the tramp area? It almost looks like on either tack the sails would be in your way.

Yes you can put the sails to the outside, makes it look like an insect, Not sure how you judge the tack though, am I on starboard or Port? The sails are cut quite high, the back of the boom is around 1m high so they don't get in the way to badly, plus the tramp is huge 2.2x3.8m and because it is so stable it is not sensitive to where you choose to sit. Also the sails are almost entirely see through so visibility is excelent.
Quote
Where do you sit? How do you hike out/trapeze

You can trapese off the boom like a normal windsurfer.
Quote
Do windsurfing type adjusters really add that much more weight

No, and the windsurfing rigs are really nice, high tech and cheap, Our rig has camber inducers and an allan key to adjust the batten tension. The masts weigh 2.5kg!
Quote
How much does the whole piece of kit weigh, Gareth? How have your trials gone?


The boat weighs 105kg all up, the traials are going well, It is so different to sail that we are learning all the time. Its very stable, with a low centre of effort and bouyancy in the corners, gusts seem to have no effect other than to make it go faster. As a gust comes the top of the sail twists and exhausts off.

Capsize testing was interesting, because the rig is so short it turtles pretty quick. It easy to right because it is so light. Do people think the turtling is a problem, we can add floats to the top of the mast to stop this, it is then very easy to right bacause the rig is so short and light.

I have got some sailing photos but they are even worse quality than the others
[Linked Image]

I will try to get some better shots soon. And I will update the website this weekend.

Gareth
www.fourhulls.com

-- Have You Seen This? --
Re: New boat four hulls [Re: grob] #52160
06/30/05 02:26 PM
06/30/05 02:26 PM
Joined: Aug 2002
Posts: 545
Brighton, UK
grob Offline OP
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grob  Offline OP
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Brighton, UK
Dermots question from the other thread, Why don't we use camber inducers on cat sails?

I guess for a couple of reasons,

1. They are more more complicated and costly, windsurfing sails are sold in such vast numbers that costs are significantly lower.

2. They work best on sleeve sails and circular masts.

3. In light winds you have to pop them round so they might not be as practicle on tall rigs.

I am no expert so there may be another reason! I would like to hear it as I am still trying to decide wether to go camless with my next bigger rig.

Gareth
www.fourhulls.com


Re: New boat four hulls [Re: grob] #52161
06/30/05 02:30 PM
06/30/05 02:30 PM
Joined: Jun 2001
Posts: 12,310
South Carolina
Jake Offline
Carpal Tunnel
Jake  Offline
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South Carolina
At the risk of sounding stupid...what's a "camber inducer"?


Jake Kohl
Re: New boat four hulls [Re: Jake] #52162
06/30/05 03:22 PM
06/30/05 03:22 PM
Joined: Aug 2002
Posts: 545
Brighton, UK
grob Offline OP
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grob  Offline OP
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Brighton, UK
Its a plastic, yoke shaped device that connects a batten and the mast, and provides aerodynamic shape to the sail of a sailboard.

[Linked Image]

Gareth


Cats don't use camber inducers ... [Re: grob] #52163
06/30/05 03:42 PM
06/30/05 03:42 PM
Joined: Jun 2001
Posts: 9,582
North-West Europe
Wouter Offline
Carpal Tunnel
Wouter  Offline
Carpal Tunnel

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

Cats don't use camber inducers because they have rotating wingmasts !


Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
Re: Cats don't use camber inducers ... [Re: Wouter] #52164
06/30/05 05:23 PM
06/30/05 05:23 PM
Joined: Oct 2001
Posts: 915
Dublin, Ireland
Dermot Offline
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Dermot  Offline
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Dublin, Ireland
I had to ask - now I know - BUT, can we not use anything more efficient, and quicker to adjust, than string Only asking !


Dermot
Catapult 265
Re: New boat four hulls [Re: grob] #52165
06/30/05 05:31 PM
06/30/05 05:31 PM
Joined: Feb 2005
Posts: 1,382
Essex, UK
Jalani Offline
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Jalani  Offline
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Posts: 1,382
Essex, UK
I'm curious Gareth, if you sit between the rigs - on the tramp - to sail the boat without hiking/trapping, isn't it a bit like sitting in a windtunnel with the accelerated flow round the sails?

There don't appear to be any boards, so what is the hull shape that ensures the boat doesn't make excessive leeway?

What is the strongest breeze you've been out in so far? Do you think your design is as fast/faster than a similar sized 'standard' catamaran design?

Looks like an A1 job though, Gareth.


John Alani
___________
Stealth F16s GBR527 and GBR538
Re: New boat four hulls [Re: Jalani] #52166
06/30/05 05:54 PM
06/30/05 05:54 PM
Joined: Aug 2002
Posts: 545
Brighton, UK
grob Offline OP
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grob  Offline OP
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Posts: 545
Brighton, UK
Quote
Looks like an A1 job though


Thanks John,

No you don't notice a "wind tunnel effect" sitting between the sails.

There are no boards, or skeg, the hulls themselves are pure aerofoil shapes and they seem to work very well, no excessive leeway.
I will take a picture of them this weekend. We store the boat upside down on Brighton beach as the local scumbags like to use the trampoline as a trampoline and other nocturnal activities

We haven't been out in big winds yet so its too early to say how well it performs, its been up to 10knots in 10 knots of wind with 170kg crew and 14sq metres of sail. Next step is 20 sq metres of sail.

Gareth

Re: Cats don't use camber inducers ... [Re: Wouter] #52167
06/30/05 06:02 PM
06/30/05 06:02 PM
Joined: Aug 2002
Posts: 545
Brighton, UK
grob Offline OP
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grob  Offline OP
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Joined: Aug 2002
Posts: 545
Brighton, UK
Quote

Cats don't use camber inducers because they have rotating wingmasts !


I think a wingmast is quite a heavy way of getting the optimum sail shape compared to camber inducers. However I don't think you would want a sleeved sail on a cat. As taking the whole rig off after a sail would be a pain.

Gareth

Re: Cats don't use camber inducers ... [Re: Dermot] #52168
06/30/05 07:12 PM
06/30/05 07:12 PM
Joined: Nov 2002
Posts: 606
League City, TX
flumpmaster Offline
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flumpmaster  Offline
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League City, TX
I think Macca has already done this on his super Taipan. I agree with you Dermot - those windsurf batten tension adjusters give a really clean finish to the back of a sail. Given that on sails with low strech material (vs. Dacron) you do not need much batten tension (other than the top couple of battens) then I would think that velcro pockets would work on OK. That string is a pain in the butt when you have cold hands.

Chris.


Dave Ingram is my president. tcdyc rules

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