Hi all,

In the enclosed diagram, drawing (1) shows my current setup. I don't know if this is original or just plain wrong, but I don't trust 'em!

There is no way to adjust the length of any of the rods that make up the spreader assembly.
There is also no spreader rake (negative rake, actually!) I don't think this is dangerous, because the rigid spreader bars should prevent mast inversion, but it seems kind of weird! Is this dangerous and should it be replaced asap? That's my main question.

It is my understanding that with this setup, all I can do is adjust the lateral stiffness of the mast (below the hounds). There is no way I can induce forward-aft bend to flatten the sail. Down haul would be working against the negative rake, and pointless IMHO. The only way I can flatten the sail is by loosening the diamond wires. Am I right, or am I just paranoid?

In the attached diagram I have drawn (2) the situation as I think it should be. Do you agree with this or have I got it wrong somewhere. Note I did omit some detail from the diagram, because I don't have all night ;-)
I think this setup would be safer for the mast because it would allow the mast to bend (fore-aft) with tight diamond wires and some down haul on. I think this is what Rick recommends in his book, but I may have got ot wrong somehow.

Thanks in advance,
Dennis

PS: I can live with sub-optimal, my main concern is safety!

Dennis,

Never had a 5.2. Seen lots of them.

If the sail was not cut for a 'pre-bend' mast, you don't need pre-bend.

If it's the stock set up appropriately set up, it should not be any danger, to you, or the mast.

Some 5.2 buff will post I'm sure.

The 91 Performance Catamaran manual confirms your proposal.

My 5.2 has a single straight spreader bar through the mast. No rake is possible.

Hmm I guess this means there were all sorts of different configurations possible.
Bok, how old is your 5.2?
Todd, do you know how I can tell whether the sail was cut for pre-bend or not?
Kris, I saw that too, Its one of the things that got me thinking on this.

The 5.2 is sailed with a soft rig. the diamond wires are set up slightly slack. to depower - allow the mast to rotate, this allows fore/aft bend of mast. to power up - reduce rotation [as far as pointing at shrouds]

The loosest that you would want the wires is so that you can clamp both to the mast with one hand [around front of mast] about 400mm above attachment point on mast.

The two front rods should be adjustable, it should be easy to make new ones in a workshop, the manual shows the suggested geometry http://nacra.us/nacra/nacra.pdf?bcsi_scan_4B3822EAEF26C5CF=0&bcsi_scan_filename=nacra.pdf.
Older model had just a straight spreader through the the mast, I'd say yours is the new one withouth the adjustable rods. I don't see a clear need to replace them anyway, I think you don't get negative rake by tensioning, per your drawing it would tension backwards, as the dotted line on your drawing is behing the center of the mast, right? So I'd just care if you feel the sail is not shaped right.

Your front rods have two perforations in one end, I bet you actually have 4 rear rods. Maybe the guy that assembled the mast was a bit distracted..
By the way, shouldn't you be drinking beer at night rather than taking pics of your mast?

I correct my statement above: actually it's not the dotted line against the center of the mast, but the dotted line against the attachment point of the diamond wires, that are in the front of the mast. Those would tend to approach the dotted line when tensioning, bending the mast.

<quote>By the way, shouldn't you be drinking beer at night rather than taking pics of your mast?</quote>
Don't worry, I caught up on the beer afterwards! After a whole day of working on the boat it was badly needed.

I think I'll just leave it as it is for now. Just glad it doesn't appear to be a dangerous situation.
Dennis

Mine is a 1978.
The original spreader bar went through a hole in the mast. There were (outside to inside) keeper pins, fender washers then rubber washers to "seal" the hole. Never worked too well for sealing. I had a spreader bar welded into the holes and sealed up with metal. Seemed to hold the water out better.

Sounds like the original setup was a problem waiting to happen! I just checked, my mast is 100% air-tight! Hooray, that's one thing on this boat that is up to spec!

That's what I have on mine. Wiggling straight bar through the mast hold in place by pins and washers.