Thinking of moving jib blocks to trampoline - problem? :: Catamaran Sailboats at TheBeachcats.com

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Thinking of moving jib blocks to trampoline - problem?

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MN3

Rank: Master Chief

Registered: Jun 20, 2006

Last visit: Apr 06, 2024

Posts: 7088
Posted: Apr 19, 2022 - 08:20 AM

shortyfoxHere's another idea you've may not have considered: Put the jib blocks on traveler tracks on the main beam. The caveat to this is that the foot of the jib would have to altered to get the proper sheeting angle. Hobie 16 is done this way and so is the Nacra 500 / 570. Look at a diagram of one of those Nacras and you'll see what I mean about the jib cut. Sailors totally performance orientated may scoff at this, but it certainly would enable you to change the slot and free up your tramp at the same time.

Smaller jib means less sail area for downwind
not an issue with a spin boat but on a non spin boat, ... you will feel it
charlescarlis

Rank: Mate

Registered: Jun 30, 2018

Last visit: Mar 20, 2024

Posts: 583
Posted: Apr 19, 2022 - 08:57 AM

Got no spin, though it's meant to have one, so... And, I like not having the complexity for now.

But, that's a good point on anything I do that recuts the jib to a smaller size; downwind performance to suffer. Looks like looking around for some stainless triangle brackets and try my hand at making the Tornado-style jib block arrangement. After looking at the tramp-mounted blocks in action and the stress they put on the fabric, I think I'll give that a pass.

--
Chuck C.
H21SE 408
--
texastuma

Rank: Mate

Registered: Nov 22, 2012

Last visit: Apr 11, 2024

Posts: 397
Posted: Apr 19, 2022 - 04:49 PM

charlescarlisHobie 21se - we sail it as intended, so not gentle, but not abused either. Point is, we put the designed forces on the boat, sail and rig.

I've never much liked how the jib cars are only adjustable fore and aft, and going upwind, I believe I'm loosing a bit of ability to point because I can't close the slot enough. Soooo..., since I'm about to start making a new trampoline, I was going to sew some heavy reinforcements in it to accommodate a few extra grommets on each side, allowing me to run a few loops of line to be able to mount the blocks ala F18 style. same average position fore and aft, but with 3 loops, giving me some adjust-ability with closing the slot more. I guess I'd have to find an average fore-aft position with the loop length to adjust leech/foot tension, though not adjustable while sailing...

Can a trampoline hold the loads without ripping out? Seems like it'd be a lot on this boat.
Is this just trading one problem for another? I suppose I could add a clew board to the jib if need-be...

The "classic" Tornadoes have done this years (decades) ago, while still an olympic class boat. I haven't dug through the responses yet, but I'm sure someone (or I) can find a pic. Brining the jib lead inboard will really help your point in medium air. But, simply and with out big modifications to the trampoline, you can add the 4-way system. Unfortunately, it does separate the trampoline, but that helps keep the crew up forward where they belong... I can take a picture, or you can come by and look how Franken is set-up.

--
Scott

Prindle Fleet 2
TCDYC

Prindle 18-2 Mod "FrankenKitty"
Tornado Classic "Fast Furniture"
Prindle 19 "Mr. Wiggly"
Nacra 5.8 "De ja vu"
Nacra 5.0
Nacra 5.8
Tornadoes (Reg White)
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texastuma

Rank: Mate

Registered: Nov 22, 2012

Last visit: Apr 11, 2024

Posts: 397
Posted: Apr 19, 2022 - 04:54 PM

charlescarlisThe track is standard Ronstan, 5/8", I believe. Looks like I'll need to likely need to fabricate something to bolt onto the slides, which I can still get. Not terribly difficult, just a pain. Thanks!

Let me check. I think I have an extra set of cars and triangles from the Prindle 19. They may be the same track. I think they are Ronstan cars.

charlescarlisThought about that, but I THINK my jib overlaps a bit, so a traveler and track on the beam might not work, but will have to check that out. I'd have to re-cut the jib, if not get an entirely new one made, I think. Real estate on the trampoline is not an issue. I'm merely trying to improve sheeting so that I can get it to point higher. I think that before I do anything really permanent like drilling new holes into the beam, I'll play with replacing the jib cars with some custom built jobs I can run a cable between and experiment with configurations. That can be un-done easily with no harm/foul.

Otherwise, a track on the front beam makes a lot of sense. At that point, tough it's a self tacking jib setup and be done with it. Which, ACTUALLY...

I think you would lose 1/2 the size on your jib. I thought about that with Franken to keep the tramp simple, but I have gotten to where I like the jib power and can handle it easily.

--
Scott

Prindle Fleet 2
TCDYC

Prindle 18-2 Mod "FrankenKitty"
Tornado Classic "Fast Furniture"
Prindle 19 "Mr. Wiggly"
Nacra 5.8 "De ja vu"
Nacra 5.0
Nacra 5.8
Tornadoes (Reg White)
--
cholley12

Rank: Mate

Registered: Feb 28, 2018

Last visit: Feb 13, 2023

Posts: 145
Posted: Apr 20, 2022 - 02:17 AM

Chuck,

Chris here,

I would just string a dyneema strap across like my prindle is done, and like the classic tornado. Use a bullet block on both sides and set a clam cleat facing it to adjust in and out

--
Captain Chris Holley
Fulshear, TX
'87 Prindle 19 "¡Hijole!"
'74 sunfish "1fish"
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revintage

Rank: Mate

Registered: Aug 13, 2017

Last visit: Nov 29, 2023

Posts: 280
Posted: Apr 20, 2022 - 04:56 AM

I second to using Dyneema. Easy to splice by yourself, anyone can do it. Use something like 5mm DM20, even if it oversize visavi strength. Note: There must be slack in the strap, otherwise you risk to rip out the traveler track. The way Chris has done with a Bullet and a metal Clamcleat is std procedure, simple and straight forward.

--
Brgds
Lars

Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler

https://www.facebook.com/groups/1192604934176635
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shortyfox

Rank: Mate

Registered: Apr 07, 2017

Last visit: Apr 11, 2024

Posts: 340
Posted: Apr 20, 2022 - 07:18 AM

[q
Quoteuote]I think you would lose 1/2 the size on your jib. I thought about that with Franken to keep the tramp simple, but I have gotten to where I like the jib power and can handle it easily.

[/quote]

I found a pretty good line drawing of a 21 on line and the jib foot looks pretty high up. If you put your jib blocks on the main beam (like a N570) it appears to me you would actually have to add material to the foot of that jib to get the jib sheets to pull towards the center of effort. Imagine drawing a line from the tack angling down towards the front beam. Your clew would be much lower, close to the jib block when sheeted in tight. I know you're committed to doing it another way but I'm just curious. Someone let me know if I'm wrong and why.

--
Bill Townsend
G-Cat 5.0
Sarasota
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charlescarlis

Rank: Mate

Registered: Jun 30, 2018

Last visit: Mar 20, 2024

Posts: 583
Posted: Apr 20, 2022 - 10:52 AM

I think you may be right, just been a long time since I set her up to recall correctly. That should change this weekend. I've actually got 3 different jobs, with one being 110%, which may be coloring my memory. Best to set it up this weekend and start playing with it to see what's possible. I've got to bend a new main I'm picking up anyhow. I already have the dyneema and fids, so that's easy enough to try Chris' idea.

Still, the idea of a self tacking jib, though expensive has merit in the end. But setting up the 4-way or just adding tweakers may be all it needs...

Man I appreciate the advice, guys!

--
Chuck C.
H21SE 408
--
rodgers

Rank: Lubber

Registered: May 10, 2007

Last visit: Aug 13, 2023

Posts: 22
Posted: Apr 20, 2022 - 02:36 PM

Hello,
Back when Tornado came out, i sailed them. Same with the supercat 20.
The Panther Craft T had the jib strop running fore and aft with a rubber tube around it, making them into hiking straps as well. The jib could be pulled outboard by the barber hauler.
As you mentioned, the Super Cat had the jib blocks mounted to the hulls with a simple system that pulled the jib inboard from the boom. As you ease the main the jib moves outboard.
Later on the Tornado i raceed on had a bare wire running across the tramp across wise(i think under the tramp) with loops that the jib blocks attached to above the tramp. We could move the jib block on the lazy sheet side easily using a snap hook attachment. We also used the barber hauler off the wind. No spi in those days.
hope this helps.