Sailing Nacra 5.7 all weekend. I have become aware how fast the boat is in heavy and lights winds and how smooth the boat cuts through the waves. It is kind of funny to fly pass motor boats on the thing watching people bounce around on their big motor boats. One thing I have an occasional problem with it the jib blocks sometimes get caught on the mast by the diamond wires during the jibe and tack.
What is the best to prevent this?

The best way to prevent it is to use a preventer. A bungi cord stretched across the front crossbar is lifted for form an A-frame. The jib sheet is run over the top of the preventer avoiding snags.



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Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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+1 on the preventer.

You can also make a very simple short "V" shaped bridle from spare line about a foot long on either leg to move the jib blocks away from the jib clew. This lowers them down to below the shrouds and allows the preventer (as shown in Tom's picture) to do its job.

Tom - Your mast stepping pin is in, presuming you took this picture right after stepping or just before de-stepping correct?

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One thing I have an occasional problem with it the jib blocks sometimes get caught on the mast by the diamond wires during the jibe and tack.
What is the best to prevent this?

Are you here only to troll?
You have had the answers in front of you for two months, both the remedy & Carbonc’s response are clearly shown in the manual. Item 55 & 61
https://www.nacrasailing.…tage-assembly-manual.pdf

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Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
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i use a jib preventor but it runs around the diamond wires
i do not think this is high enough. the way tominpa has his rigged seems better
how do you attach the eye to the mast?

also looks adjustable

edchris you ever zoom into manal photos?
the other color manual is outstanding format but
imagine making those delrin screwes throgh a photographic descrption of steps using photos of the quality in
the old manual.

There is no issue running your preventer through the bottom of the shrouds. Works fine for me. Have you done item 51 from the manual as I suggested?

It can be made to easily attach/detach from the jib using a carabiner

61 Yes I had done that. I think the issue is because my jib sheet is attached directly to the jib at the block like tominpa. The jam preventer is higher on his setup. I had been running the jam preventer through the diamond wires. In the picture in 55 it shows the jib attached with an extra rope from the jib sheet block to the jib. Ill try this next time I go out.

carbonc

+1 on the preventer.

Tom - Your mast stepping pin is in, presuming you took this picture right after stepping or just before de-stepping correct?

That is correct. The pin only has one ring in it in that picture, and it was pulled before launch. This was taken on the day I re-launched the boat after fixing a hole in the hull from storm damage.

--
Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
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Rungi, my preventer is held up by a bungi that runs from the eye on the front of the mast, under the preventer and back up to either the eye for a lower set, or to the main halyard for a higher set.

--
Tom
NACRA 5.7 (1984 Sail 181)
Pennsylvania
--

Rungi, I must ask why you had not already done item 55 from the manual. Multiple people here have advised you that most of your troubles are related to you not following the manual.

Rungi, I must ask why you had not already done item 55 from the manual. Multiple people here have advised you that most of your troubles are related to you not following the manual.

carbonc

Rungi, I must ask why you had not already done item 55 from the manual. Multiple people here have advised you that most of your troubles are related to you not following the manual.

a short bridal on your jib clew is the solution to avoid jib clew block hang up on the forestay as mentioned originally.

the preventer line "helps" but in my experience that preventer line is to prevent the jib sheet from snagging on /under the mast base and not the solution for forestay hangup - ymmv

I looked at Step 55 and have to say correct in theory but the "luggage tag" method shown is not optimal. some lines will slip with that non-knot. it can be fatal (capsize) if it comes loose at the wrong time (when uncleating is needed to prevent a swim)

This is the PREFECT location for a quick release knot and loop. It doesn't have to be a splice.
this way you can leave the jib sheets always on the boat (no need to untie/remove the jibsheet for jib removal)



Edited by MN3 on Nov 02, 2021 - 02:12 PM.

Thanks

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Rungi, I must ask why you had not already done item 55 from the manual. Multiple people here have advised you that most of your troubles are related to you not following the manual.

I had not noticed it. It appeared straight forward to me. I had mine set up exactly like tominpa using the photo he posted before. It may be the height of his preventer that allows him not to use the extra rope. I am assuming it does not get caught on the diamond wires but I do not know. tominpa you have any problems with the block catching the diamond wires? Your jib looks like it is a little higher than mine.

Believe it or not the first think I ordered from Murray sports was the manual thinking they would send me one with clear photos. It was just a copy they printed out form the free download and stapled together. The pictures are very difficult to see in detail. Clear pictures make the boat set up easy to copy. Even if you can not speak English. Sorry to cause you so many problems.

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The pictures are very difficult to see in detail. Clear pictures make the boat set up easy to copy.

The pdf of the manual posted multiple places on this site, and in this thread, has very clear pictures. I’ve seen other users post links to the same pdf in your other posts. There is no confusion what is needed when looking at the step 55 pictures, perhaps only refinement on how to execute it as MN3 has identified.

I actually have the exact same issue on mine. Maybe a few years are slightly different? The preventer works great most of the time sometimes the clew of the jib rides up above it and the blocks hang up on the diamond wires themselves. This always happens when you use the jib to back wind on a tack. You can try to lengthen the pigtail that connects the blocks to the jib or you can make sure you let both jib lines slack so the clew passes the mast by a bit before tightening up the jib line on the new point of sale (what i end up doing). It i wasnt so lazy i'd put a pad eye higher on the mast and just extend the jib preventer up a few more feet. That would likely solve the problem completely.

--
Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
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Sorry i meant shorten the pigtails.

--
Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
--

Quote

i'd put a pad eye higher on the mast and just extend the jib preventer up a few more feet. That would likely solve the problem completely.

I like this idea!
Then the pigtail may not even be needed

Try not to overthink it too much. You have one of the most forgiving fast cats you can get. I normally run mine completely solo. Keep it simple as you can and have fun!

--
Dave Bonin
1981 Nacra 5.2 "Lucile"
1986 Nacra 5.7 "Belle"
Winnipeg, Manitoba, Canada
--

Quote

I like this idea!
Then the pigtail may not even be needed

I highly recommend doing what the manual says, and then only decide what isn’t needed based on success, and what needs to be improved based on failure. Continuously refusing to follow the manual and trying to iterate a better solution amidst constant failure and struggles is a fools errand.



Edited by carbonc on Nov 03, 2021 - 11:28 PM.

.



Edited by carbonc on Nov 03, 2021 - 11:27 PM.

Quote

Continuously refusing to follow the manual and trying to iterate a better solution amidst constant failure and struggles is a fools errand.

You nailed it !



Edited by revintage on Nov 04, 2021 - 07:20 AM.

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Brgds
Lars

Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler

https://www.facebook.com/groups/1192604934176635
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its not over thinking it works perfectly. i tested it today
you can tie an alpine butterfly on main halyard rope at a height above the diamond wires mast attchment
run preventor throgh the buterfly loop. the pigtail is not needed.
the jib sheets cross smoothly every time!

The pigtail also serves to shorten the jib sheets significantly and keep the trampoline clear. You’re fixing one issue instead of accepting a solution that fixes both.

rungi

its not over thinking it works perfectly. i tested it today
you can tie an alpine butterfly on main halyard rope at a height above the diamond wires mast attchment
run preventor throgh the buterfly loop. the pigtail is not needed.
the jib sheets cross smoothly every time!

So before lowering your main, you first remove the preventor and then loosen the butterfly knot?

Give up those crazy "reinventing the wheel" ideas and follow the sensible suggestions you have got here and go by the book!

Tried to find an image on how it should be done and the only one was this vintage photo from the early 80´s, with one of my first Tornado´s. No problem to tie the bungi chord with a clove hitch on each diamond wire a fair bit up.
Click to enlarge!



Edited by revintage on Nov 07, 2021 - 07:23 AM.

--
Brgds
Lars

Frankentri 5.8/5.5/Inter20
Aerow trimaran foiler

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

I have to step the mast often so I have been optimizing rigging time, what I did with the preventer is adding a small hook to attach it to the eyestrap on the mast. To unmount it I just unhook it and leave it on the boat, horizontal along the beam.

That is even a better idea. I just don't have the eye strap. I also step the mast often

Add a thin line between the diamond wires at the desired height. Clove hitches should remain in place, probably better with shock cord.