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Thinking of moving jib blocks to trampoline - problem?  Bottom

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  • Hobie 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...

    --
    Chuck C.
    H21SE 408
    --
  • It’s been done. You’re fine. H20 style you could run a cable between the jib cars and let the block pull on that and just have a line to resist the car moving out
  • The Hobie 18 sailors in Australia are doing something similar to what you describe.

    http://m.facebook.com/Hob…631736/?type=3&source=54

    I suspect that the trampoline needs to be well reinforced to take the loads and so that the jib tension isn’t “springy.” The 21 would need be even more heavily reinforced.

    Another option could be to run a stainless cable or Dynema cord between the jib cars, across the top of the tramp to act as a “traveler” system. This would be similar to the H20 jib system. It is a little intrusive on the trampoline area though.

    sm



    Edited by Dogboy on Apr 13, 2022 - 05:17 PM.
  • You can certainly reinforce the area of the tramp around the jib blocks to take the load. The problem is the tramp is flexible and no matter how tight you can get it; it will lift up some during a puff and come back down when it slacks a little. You will have to constantly be sheeting in and out to sail efficiently. Does the 21 have rails? If it does, you can have a cable or line running underneath the tramp, secured to each hull with a backup bar. Make it super tight because this will be taking the load. On your tramp, directly over this wire or line, have big stainless grommets installed with reinforcing material. Attach your jib blocks through the grommet with a long d-shackle. You'll probably want to be inboard at least a foot from your current ideal fore and aft position of your jib blocks. This set up works best with a barberhauler because you will want to move the jib sheets outboard from time to time when you're off the wind. We'll get into that later because this is all moot if you don't have a way secure that line under the tramp that will take the load.

    What Dogboy suggested could be a good option. Take it a step further, and in about the middle 3 feet of that line or wire have a piece of line with a 2 or 3 purchase using a fiddle block. You can open and close the slot. Once again, you'll have to really secure a pad-eye mounted where your jib blocks would normally be fore and aft.

    --
    Bill Townsend
    G-Cat 5.7
    Sarasota
    --
  • it's got rails, exactly like a H18. I haven't looked at a H20 system yet, only what the Ausies are doing, the Prindle system and Supercat 20 system. Setting up the loops and reinforcement on the trampoline would be about the easiest for me, but the least secure feeling. Yeah, the cables on top of the tramp is a lot of extra hardware... Thinking about it. Doing a cable system below, for a place to attach is novel, but I can't think of how to attach since the jib track is above. Wondering if something like just installing inhauls with rings might get me close to the same place with less stuff on top???

    --
    Chuck C.
    H21SE 408
    --
  • Some kind of inhaul/reverse barberhaul system will clutter up your tramp. The nice thing about a barberhaul system that pulls the sheets outboard is it can be made part of the main beam and what makes that work well is because when, say, the wind is blowing on your aft quarter, your jib has a tendency to twist off and lose some power. Redirecting the sheet angle outboard and forward at the same time allows you to get the most efficient sail shape.

    Here's how you might be able to do the cable system below: Since your boat has rails, drill a quarter inch hole through the top of the rail. Stick a carriage bolt through the rail and underneath have the bolt pass through a backup bar. Next, put a pad eye on the end of the bolt followed by the lock nut and now you've got your attachment points. My 5.7 was rigged this way and it worked well. Not being familiar with the 21 there may be obstacles to this I'm not familiar with. I'm going sailing today and there's a 21 where I keep my boat. If it's still there, I'll take a look.

    --
    Bill Townsend
    G-Cat 5.7
    Sarasota
    --
  • Don´t try to reinvent the wheel! Just do it the way it has always been done on numerous beachcats. A stainless wire between the existing rails will solve all your problems in a simple way. The wire needs the slack as seen in the image, though.

    This is the way it was done back in the days I was racing in the Tornado class:
    http://www.pbase.com/d30/image/26755452.jpg

    Also check the downwind barberhaul system(blue ropes) :
    http://www.pbase.com/d30/image/26755453.jpg



    Edited by revintage on Apr 14, 2022 - 01:20 PM.

    --
    Brgds
    Lars

    Present multihulls:
    Frankencat 5.8/F20
    Frankentri 5.5/Tornado/F18
    Aerow trimaran foiler

    https://www.facebook.com/groups/1192604934176635
    --
  • Man, I appreciate it Bill - I'm open to any ideas. Simpler is better, but if the solution is good, I'm OK with a little more complexity. The rails, though are bedded on the hulls, so there's no real way to get a bolt through there, underneath. It may be that this is an effort in futility. However, I'll go ahead and build the reinforcements into the tramp while I build it.

    --
    Chuck C.
    H21SE 408
    --
  • Hey Lars - that looks like the ticket, especially since I can use the track I have. Any more pics of the cable across the tramp? I guess I can go to the Tornado pages and do some research - great tip!

    --
    Chuck C.
    H21SE 408
    --
  • These are the best I found on TornadoCat:

    https://soderquist.se/pict025.jpg

    https://soderquist.se/pict095.jpg



    Edited by revintage on Apr 14, 2022 - 03:07 PM.

    --
    Brgds
    Lars

    Present multihulls:
    Frankencat 5.8/F20
    Frankentri 5.5/Tornado/F18
    Aerow trimaran foiler

    https://www.facebook.com/groups/1192604934176635
    --
  • Perfect!

    TornadoCat - will have to look that one up. I like this system, so far; looks do-able. This arrangement allows you to then travel the blocks in and out, but not really change the sheeting angle; which I guess once you get it where you want it (generally), you can mange the compromise with the sheet tension.
    Edit-NM, I figured the sheet angle out on the way home from work. The tracks slide. Perfect.



    Edited by charlescarlis on Apr 14, 2022 - 06:53 PM.

    --
    Chuck C.
    H21SE 408
    --
  • Here is what I did, with two Laser boom vang blocks
    https://www.thebeachcats.…ictures?g2_itemId=136436
    It’s a continuous dyneema loop, with loops to hook the jib blocks, those go at different sides of the loop, the adjustment lines go at the same side of the loop. To make sure that both sides are at the same position, adjust them at the outmost position, both touching the block. On the picture the adjustment line starts at the same point than the attachment loop, on the other side it starts separate, on the other side of the dyneema loop.

    Sorry i can’t insert the picture from my cell phone.
    The only drawback of this system is that you need to adjust on both sides, to me it’s perfectly ok, I adjust it very rarely just for the conditions of the day, not much more. The barberhauler is used for specific sailing angles, that’s different, I personally haven’t really needed it so I don’t have one on my boat.



    Edited by Andinista on Apr 15, 2022 - 01:59 PM.
  • Where did you get the track blocks and triangle plate to mount the blocks to? I haven't found them yet. Even the Ronstan slide travelers (in stainless steel) are being discontinued, but I can still get a couple now.

    --
    Chuck C.
    H21SE 408
    --
  • I got the triangle plate from Murrays, long ago, I don’t see it now. The track slide is available there. The vang blocks, I had one from an old Laser and got a second one at a local store (far from you I’m sure), I see they are still available, here for instance
    https://westcoastsailing.…-lower-vang-block-allen/
    For the triangle plate, if I had to replace one I’d try cutting a stay adjuster or a chain plate on two segments and make a triangle with them, from the bolts of the slide to the pin on the block.



    Edited by Andinista on Apr 17, 2022 - 06:29 AM.
  • Hey Chuck,
    Take a picture of your existing travelers. Probably you can modify them. I have a pair of Nacra travelers, question is if you have the same track?



    Edited by revintage on Apr 17, 2022 - 12:20 PM.

    --
    Brgds
    Lars

    Present multihulls:
    Frankencat 5.8/F20
    Frankentri 5.5/Tornado/F18
    Aerow trimaran foiler

    https://www.facebook.com/groups/1192604934176635
    --
  • The 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!

    --
    Chuck C.
    H21SE 408
    --
  • No pain, no gain icon_cool .

    --
    Brgds
    Lars

    Present multihulls:
    Frankencat 5.8/F20
    Frankentri 5.5/Tornado/F18
    Aerow trimaran foiler

    https://www.facebook.com/groups/1192604934176635
    --
  • Here'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.

    --
    Bill Townsend
    G-Cat 5.7
    Sarasota
    --
  • Thought 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. icon_smile 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...

    --
    Chuck C.
    H21SE 408
    --
  • Appears to be pretty common around here, at least on the Nacras. Was at the local Nacra states over the weekend, and at least 5 of the 17 boats had the jib blocks on the tramps.

    Unfortunately i didn't take many photos of the setup, but I'll see what gets posted in the next few days

    https://www.thebeachcats.com/gallery2/main.php?g2_view=core.DownloadItem&g2_itemId=136547&g2_serialNumber=3



    Edited by johnoau on Apr 19, 2022 - 12:37 PM.

    --
    1335 XTSea Nacra 5.8 NA
    Cleveland Yacht Club
    Brisbane, AU
    --

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