Hi,
I recently upgraded from a Hobie Wave to a Nacra 460 Sport. The Nacra comes with a single trapeze and I would like to add a second trapeze for the skipper (me). The tramp only has a grommet for one trap bungee.
My questions:
1. Do I need to worry about stressing the mast by adding the second trap?
2. Is it necessary to add a second grommet to the tramp for the second trap, or can i use the same grommet for both?
3. I may consider making my own trap wire either out of cable or cord. Any disadvantages to using cord and if not, what is the common cord to use? 3mm dyneema?
-Rob
Adding a second trapeze to Nacra 460
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Posted: Jun 14, 2017 - 04:29 PM
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Posted: Jun 14, 2017 - 06:07 PM
What is the reason you feel like you need a second trapeze? It was designed and built with only 1 for a reason. Where do you usually sail and what is your total crew weight?
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Pete
2001 NACRA 450 SOLD
2000 NACRA 500 TOTAL LOSS
2004 NACRA INTER 20 SOLD
2016 NACRA 500 Sport
DeLand, FL
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Posted: Jun 14, 2017 - 06:40 PM
4.6m = 15.09' boat
2.35m =- 7.7' beam
no spreaders?
probably too small of a mast extrusion to hold 2 adults -
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Posted: Jun 14, 2017 - 10:09 PM
I agree with MN3. I had a 4.5, there's just not enough power in that boat to double trap. It's really only big enough for two medium to small people or an adult and a kid.
Edited by tnell on Jun 14, 2017 - 10:10 PM.
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Tim
Collierville (Memphis), TN
Supercat 15--sold :(
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Posted: Jun 14, 2017 - 11:02 PM
I sail in the SF Bay Area, winds in to the 20mph range on a regular basis. Crew weight ~300 lbs or less when 2 up. The mast is pretty substantial, looks like a 500 mast without the diamond wires.
I've seen smaller boats like the topaz 14 with double traps which made me wonder why not double on my new to me nacra. -
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Posted: Jun 15, 2017 - 07:09 AM
I cannot comment on that mast taking that or not, seems your weight is reasonable. Is that mast a wing section?
I believe I have 1.8mm soft trap lines. The disadvantage is that it will wear out, give it 3 years and replace. Several of my friends have used the soft line ejection seat over the years, sometimes it can lead to bad bad situations.
SS is easier to just have made at west marine though. Lasts WAY longer
You do want the trap lines separated from one another, otherwise they will twist around each other and make a mess of themselves.
Edited by bacho on Jun 15, 2017 - 07:10 AM.
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Offering sails and other go fast parts for A-class catamarans
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Posted: Jun 15, 2017 - 08:57 AM
looking at pics of the boat, i see you have no dolphin striker - this MUST reduce the amount of stress the boat can handle (although neither does that topaz)
They have a bow foil on their boat - that must help distribute the loads of the spinnaker and double trap
As per your dyneema trap wire: one major issue with it is the amount of chafe at the hound - -
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Posted: Jun 15, 2017 - 09:04 AM
Ha HA, been der done dat. (though not in a bad bad situation)
Went back to wire, although my buddy ejected once using that. The little plastic biscuit for adjusting length broke while double trapped. That allowed him to fall until it hit the end of the adjusting line. The shock load broke the line, he did a back flop, I ejected as the 5.7 went over
Edited by Edchris177 on Jun 15, 2017 - 09:05 AM.
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Posted: Jun 15, 2017 - 09:22 AM
I sail the previous model to the 460. A 2001 Nacra 450 off the east coast of FL in the Atlantic ocean regularly 1 Up at 220 lbs solo and single Trap is perfect. By the time I had some crew weight we barely fly a hull and nobody is on the Trap. The 450/460 is really an ideal solo cat in my opinion I would stick with 1 Trap and if you have crew with ya just let them enjoy it. When solo you will enjoy it LOL.
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Pete
2001 NACRA 450 SOLD
2000 NACRA 500 TOTAL LOSS
2004 NACRA INTER 20 SOLD
2016 NACRA 500 Sport
DeLand, FL
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Posted: Jun 15, 2017 - 09:33 AM
We sell the double trapeze as an option on the Nacra 460 so it's not a problem.
I'd recommend buying from Murrays or another Nacra dealer.
Stainless steel wires are best for most people as they have a longer and more predictable lifespan. You really should replace all wires on the boat every 5 years. However, most people will chose to go much longer, even 20 years plus. But it's hard to inspect to determine when it will break at which point when it breaks it's time to replace. The problem with this is that you never what day it's going to snap and could put you in a dangerous situation.
Dyneema trapeze lines are great, pretty much the only thing that limits their life is chafe. There is no definite time on when you should cycle them. On some lower grades (really cheap knock off stuff) UV might be an issue but not on any decent dyneema designed for sailing. You need to inspect them regularly for chafe or pulls in the rope, if you're not dropping your rig often to do this then I would steer clear. If you can find a way to eliminate chafe they could last 20 years plus. Most boats that use them (F18s, A Cats, various Skiffs) are only putting their rig up on weekends of regattas and have time to inspect the dyneema each time they put up the rig.
Edited by nacrasailing on Jun 15, 2017 - 09:34 AM. -
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Posted: Jun 15, 2017 - 12:32 PM
Thanks Nacrasailing! Of course that is what I wanted to hear.
Any tips on adding grommets to the tramp for the bungee? Do I need to melt the frayed ends of the tramp material after I punch the hole for the grommet? How far back from the installed trap wire should I put the new grommet; 6" a foot?
MN3, what is the bow foil you write of. I not sure I see it in the pictures online. -
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Posted: Jun 15, 2017 - 01:43 PM
A bow foil is a horizontal foil (similar to a beam but not mounted to the hulls). Helps distribute the load and greatly reduces the beams from wanting to implode due to the forces of the bridal
you can see it on both these images
and
does not appear to be on all versions -
Edited by MN3 on Jun 15, 2017 - 01:45 PM. -
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Posted: Jun 15, 2017 - 02:55 PM
Got it. Thanks
My Wave has the bow spreader bar that it attaches to the bows and is part of the jib kit. Looks like it's the same idea.
The 460 also has a spinnaker; I guess nacra does not think the bow foil is needed. -
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Posted: Jun 15, 2017 - 04:43 PM
The bridle foil makes it so that the bridle wires are pulling up on the hulls vs pulling in. By using the bridle foil you are able to lower the tack of the jib on a boat that had a smaller jib and use a larger jib ie. nacra 5.8 vs nacra 5.8 NA. Other boats that were designed with the foil like the Nacra 6.0 NA and Nacra 5.5 SL. Without the foil on these two boats, to have the jib tack as low as it is with the foil, the bridle wires would be pulling in on the hull thus pulling the bows together. If the bridle wires came together at an angle not pulling the bows together, you could not carry the large jib because the tack of the jib would have to be raised. Boats like the Hobie Wave, hobie 17 and Nacra 5.5 uni use the foil in the same way. It's about the stresses on the hull.
Instead of modifying your tramp on the 460, run your front trap bungee thru the main beam like the rest of the nacras.
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Jun 15, 2017 - 07:28 PM
So MN3, your bridle foil in the pictures acts as a spreader to change the angle of the bridal wires, but does not take 100% of the load and transfer it to the hulls, correct?
The other foils I have seen, on a NACRA 6.0 and the like, had the jib mounted to the top center of the foil, and the ends of the foil extrusion were connected to the hulls by 6" double thimble-ended SS cable. The extrusion had a vertical pole in the middle, in front of the jib mount, that at the top held the center of a taut, beefy SS cable mounted to either end to keep the foil flat under load.
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Sheet In!
Bob
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Posted: Jun 15, 2017 - 08:20 PM
nacra55, there is already a bungee running through my front beam and I could not figure out what it was for. Now I know. After your suggestion I watched a Nacra 500 video and saw the front trap bungee in the front beam. Easy. Thanks.
I've got unknown blocks on my front beam. The guy who sold me the boat said it was for the spinnaker sheet, but I dont think it is. I thought maybe for mast rotation, but there is nothing on the mast to attach it to besides a pad eye on each side (in slightly different locations). Perhaps someone knows what the blocks are for, there is one on each side. Hopefully my pic is clear enough!
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Posted: Jun 15, 2017 - 11:20 PM
My guess is spin tack line. But that's an odd place for a flip flop block. No flip flop block on the mast? Anything under the back side of the main beam? Cleat or block? Do you know if the tack line is separate from the spin halyard?
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Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
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Posted: Jun 16, 2017 - 08:07 AM
correct - there is still load on the hulls - but as Nacra55 stated (very well) it helps prevent the pull of the bridal (wanting to pull the bows inward) and on many models allows for a lower and bigger jib -
It seems pretty likely the addition of the foil on this particular boat is for the addition of the spinnaker. The spin pole bridal mounts on the tips of most cats and would add lots of inward pressure when heated up. -
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Posted: Jun 16, 2017 - 09:57 AM
There is a flip flop block on both the starboard and port side of the front beam. None on the mast.
There is a cleat on the spinnaker pole that may be used for the tack line. I've not used the spinnaker yet, so I'm not 100% on the set up and information on the internet is vague at best.
I cant imagine the flip flop blocks are for the spinnaker sheet like the previous owners said as there are ratcheting blocks (removed in my picture above) on the front beam for that. And I dont think the spinnaker cleats off.
Maybe they have been put there to assist in solo mast raising? perhaps a pigtail off of the trap lines to stop mast swing while winching the mast up... -
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Posted: Jun 16, 2017 - 12:31 PM
There are many ways to rig a spin but blocks on the front beam (not on the outer most area) are typically turning blocks - may or may not be ratchet (a blocks on the beam in the image) \
blocks work optimally at 180' turns so adding a turning block allows for much better overall angle of purchase and much more effective use.
this is a pretty typical beach cat setup
Edited by MN3 on Jun 16, 2017 - 12:34 PM.
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