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convert 430 or 400 rdm to a 370?
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gronquist



Joined: 12 May 2000
Posts: 33

PostPosted: Thu Dec 27, 2012 1:30 pm    Post subject: convert 430 or 400 rdm to a 370? Reply with quote

I've got a spare 430, but no 370. Any possibility of cutting off 60 cm from the base? Or would the taper not fit the mast base if I did that. Or would a 400 work? (taking off 30 cm).
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paulf.



Joined: 21 Mar 1996
Posts: 317

PostPosted: Thu Dec 27, 2012 2:14 pm    Post subject: Reply with quote

there are a million threads on this topic here if you search. there is no part you can cut off to give an acceptable flex or bend curve for proper sail performance. you will get a 370cm carbon flag pole, which then might have some usefulness.
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swchandler



Joined: 08 Nov 1993
Posts: 5771

PostPosted: Thu Dec 27, 2012 2:17 pm    Post subject: Reply with quote

Tem,

I don't think that cutting either a 430 or a 400 is the right path. The important thing to remember about different sized masts is the stiffness built into them. A 430 is far too stiff. Also, cutting off a portion at the top or the bottom changes the intended bend curve, and it most likely changes the position of the reinforcement built into the mast around the intended boom area if you cut off the bottom portion.

You didn't mention the sail(s) you want to rig on a 370 and their respective luff length(s). My 4.2 calls for a 370 mast, but I find that it works very well on a 400 mast. Sure, I have a little mast sticking out of the top of the sail, but it's under 5cms. Now if you have 30cms sticking out the top, it's not going to be ideal, but you'll still would be flexing the mast from the top. The only downside would be the stiffness of the 400 and the tighter leech that would most likely result.
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thombiz



Joined: 25 Jun 2007
Posts: 553
Location: Corpus Christi

PostPosted: Thu Dec 27, 2012 2:38 pm    Post subject: Reply with quote

One possibility is to buy a 370 top to fit your 400 bottom.
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U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Fri Dec 28, 2012 10:30 pm    Post subject: Reply with quote

he has a 430 spare . NO 400

I would consider a 370 section to make a 400.

Ezzy would recommend a 370 bottom and 430 top, others recommend the opposite, 430 bottom and 370 top, or depending on what brand mast it is NOT at all

I would not cut the 430, period

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swchandler



Joined: 08 Nov 1993
Posts: 5771

PostPosted: Fri Dec 28, 2012 11:17 pm    Post subject: Reply with quote

U2U2U2,

I broke my 400 and entertained a match between a 430 bottom and a 370 top, and I actually tried to sail it with my 5.0. The combo was an SDM match, with a Fiberspar 75% carbon Reflex Wave 430 bottom and a Fiberspar 30% carbon Tidal Wave 370 top. I can't emphasize enough how wrong things were. Way too stiff below and way too soft above. Totally nuts.

That said, I'm not trying to cast a shadow on some of the latest discussion trying to find a solution matching different mast lengths and stiffnesses for certain brand sails. However, much of that discussion recently is matching a 370 bottom with a 430 top, particularly using No Limitz Original and Sumo components with Gaastra Sails. As I've noted more recently regarding my No Limitz 400 RDM, just replacing the Original top with a Sumo top provided an improved result with my Windwing sail. It's my take that No Limitz is providing some interesting leadership in this arena, especially since the ferrule interface is standard between the size ranges. Given the fact that Ezzy masts are made by No Limitz, similar advantages can be gained.
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U2U2U2



Joined: 06 Jul 2001
Posts: 3056
Location: Shipsterns Bluff, Tasmania. Colorado

PostPosted: Sat Dec 29, 2012 1:48 am    Post subject: Reply with quote

My initial feeling is that your 370/430 combo has too much difference in carbon percentage.

I have a 5.0 Ezzy Panther, it wants a 400 mast,I did not want a 400 for a single sail, so I had 2 options.

A 370 with a 40cm North RDM extendo or the 370 Bottom and 430 top.

I tried both , the 370 worked, it did not look so good, too loose in the leech, made sense as the mast was too soft , the range was much less than the 4.5 or 5.5 Panthers, worked but did not have the performance intended.

Using the 370bottom and 430 top, was much better, cant say their were any disadvantage.

The 370/430 combo I would have thought not a likely match, being more than 1 size apart. David had recommended to try this.

For Hot Sails masts they advise using the opposite sides, 400 bottom 370top. From memory they don't advise going more than 1 size difference. Softer on top for them, makes sense as they are more flex top

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keycocker



Joined: 10 Jul 2005
Posts: 3334

PostPosted: Sat Dec 29, 2012 3:30 am    Post subject: Reply with quote

Sail design is hard and these guys are not working in a NASA lab.
Sometimes the wrong mast works better than the right mast on a particular sail. The sail designer ,over time, will figure out why that would be.
Meanwhile they got to keep selling sails, with a yearly upgrade at a certain time of year. The really great version with right mast combo and perfect rig settings may wind up only ever getting sailed by one guy who happened to have it when they moved on to the 2008 lineup of models.
Everyone else is still using the wrong mast combo because it is printed on the sail way back in the beginning before they could sail them a while and sort them out.
Try everything. Change settings while you are sailing. Put those odd mast setups on different sails and get a happy surprise once or twice.
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keycocker



Joined: 10 Jul 2005
Posts: 3334

PostPosted: Sat Dec 29, 2012 3:30 am    Post subject: Reply with quote

Oops
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dennis_c



Joined: 05 May 1998
Posts: 649
Location: Rio

PostPosted: Sat Dec 29, 2012 9:20 am    Post subject: Reply with quote

keycocker wrote:
Sail design is hard and these guys are not working in a NASA lab.

And NASA managed to miss Mars.
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