FMJ Navigators

Desert Archer

New member
Warning about Spine

I bought a dozen of the 400 Navigator FMJs from Lancaster Archery Supply in the US. I have been shooting the 430 Navigator but wanted to go up in bow weight for NFAA/IFAA Field (specifically for the 70 and 80 yard shots). Also wanted a heavier arrow to help my point of aim (barebow recurve) on the close shots.

Turns out the 400 FMJ tune almost exactly like the 430s in the original configuration. Easton (a factory rep) says it is because of the heavier weight. 430 Nav is 8.4 gpi while the FMJ is 9.5 gpi.

Anyway, I now have about $210 in shafts and points that aren't working as intended. Just wanted to let anyone looking for a stiffer Navigator like I was to be warned. You would probably need to order the FMJs at least two steps heavier in spine than the old Navs (which they don't offer for me).

Dave
 

greydog

New member
That's interesting, I would have though all things being equal the extra weight would have made the FMJ Nav's spine stiffer........have they made any changes to the density or weave of the carbon layer in the FMJ's ?
 

JohnK

Well-known member
Oh, very interesting.

I'm getting excellent flight shooting 32" 480s with 120gr points, but when I'm shooting properly the tip of the point isn't far from the arrow rest (or so I'm told). I was thinking of either a set of 430 Navs or 460 FMJs for field; but from what you say I'd need the 400 FMJs.

Thanks for the info Dave, very useful. I'm just sorry you had to find out the hard way.
 

Desert Archer

New member
John,

I was (and still am) shooting full length 430 Nav (the original) from a 41# Spigarelli/WinEx bow. With the 120g point they bare shaft fine and fly better than I can shoot. (smiley face goes here)

I wanted to try a new bow which is about at it's lowest poundage at 44#. That was the one the 400s were supposed to be for. I tried cutting the 33" shaft down to 32.5" (my minimum) to stiffen them, then broke off the points until they were only 100g, and finally added cresting wraps to the Flex-Fletch vanes to add weight at the back, again to stiffen them. They still bare shaft weak at 20 yards. I even fooled around with tiller and got the bow down to 43#. Still the Nav FMJ show weak.

After giving up on the new bow, just for grins and giggles I shot the Navigator FMJ in my 41# Spig. Bare shaft landed right in the middle of the fletched ones. FMJs are a solution to a problem I didn't have. (forced laughter, but not funny)

Dave
 

jerryRTD

Well-known member
That's interesting, I would have though all things being equal the extra weight would have made the FMJ Nav's spine stiffer........have they made any changes to the density or weave of the carbon layer in the FMJ's ?
Any arrow that is heavier will have a dynamic spine softer than an arrow that is lighter with the same static spine. The heavier arrow will require more energy to accelerate it this greater amount of energy will be applied at the rear of the arrow and will bend the arrow more. Think of the arrow as a spring and the mass of that arrow at the end of the spring.
 
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JohnK

Well-known member
Well, on the bright side at least you can shoot them with your current set up, so they're not a total loss. :)
 

greydog

New member
Any arrow that is heavier will have a dynamic spine softer than an arrow that is lighter with the same static spine. The heavier arrow will require more energy to accelerate it this greater amount of energy will be applied at the rear of the arrow and will bend the arrow more. Think of the arrow as a spring and the mass of that arrow at the end of the spring.
I see what you mean, I'm not sure I agree though. I think there is more to it as the shaft is slightly wider and ther materials, though the same are used the other way round, changing their diameters relative to a normal Navigator, and therefore how they react dynamically, though in this case it seems the evidence says they react softer, I just don't think the extra mass is the whole answer.
 

jerryRTD

Well-known member
I see what you mean, I'm not sure I agree though. I think there is more to it as the shaft is slightly wider and ther materials, though the same are used the other way round, changing their diameters relative to a normal Navigator, and therefore how they react dynamically, though in this case it seems the evidence says they react softer, I just don't think the extra mass is the whole answer.
Materials and diameters will effect the static spine as well as dymamic spine. Mass will only effect dynamic spine. Be it point mass or the mass of the shaft.
 

DavePotter

Member
saw them today at local archery shop... very pretty, want some now and they do a spine in my size. Apparently. Im T2 group on the easton charts.

Dave.
 
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