Double spreader, swept vs straight?

[rpack]

Good Morning All,
I'm a new member of this forum, new to sailing, new to rigging boats. I have been an aircraft rigger for many years and currently teach apprentices how to take care of industrial equipment. I have a Lancer 27 that I just bought a new mast for after an accident raising the old one. The mast came off a Jackett 27 and is keel stepped, double spreader rig. My old mast was a Kenyon single swept spreader. I see my choices as building a keel step and deck partners and keel stepping the new mast, or shortening and deck stepping it. Either way I have to reconcile the new spreader and shroud configuration to my boat. Would I be better off to retain the straight spreaders and move my chainplates or install swept spreaders on the new mast and leave the chainplates where they are? Any advice you have would be greatly appreciated
Thanks

Rich

[Robbie.g]

Moving chainplates on any boat, can create more problems, and be much more time and money consuming than first thought..... Easier i feel, to match the mast to the boat, and as by the sounds of it you have lots of experience working with alloy machines, fabricating new spreader sockets, stay points etc should be a doddle.
Worth looking at the construction of the spreaders, if they are just a piece of round tube, then it my be worth changing to a foil section if the spreaders are well swept, as this is more suitable for the higher loads etc, and more straightforward to get a strong attachment to the mast
Rob

[rpack]

Thanks Rob,
That leads to the next question: Single or double spreader? I can move my old spreaders and brackets over to the new mast, and move stays, hounds etc, but wouldn't double spreaders result in a stronger rig? And how to figure spreader length and sweep? I can draw the deck and rig in cad and figure out how to connect the dots from the stay attach points to the existing chainplates but that may not give me the optimum angles for the wires at the mast.

[Brion Toss]

Happy New Year,
The good news is that you appear to have the technical and tool reserves that would make many riggers drool with envy. The bad news is that you appear to be attempting, as Disraeli put it, to cross a chasm in two leaps.
The question of swept spreaders involves much besides chainplates, or should; are your Genoa tracks, for instance, positioned to take advantage of the new rig? It would seem unlikely, and there wouldn't be much point in going with this rig if they weren't. So I'm inclined to agree with Robbie that the chainplate switch is more bother than it's worth.
But we've also gone right by the suitability of the new mast in terms of moments of inertia. Have you run the numbers on what the boat needs? For all we know the original mast was the wrong size, and even if it were perfect, a double-spreader mast, even deck-stepped, will want to be much lighter.
Fair leads,
Brion Toss

[Robbie.g]

As brion points out there are lots of things going on here..
I've just got this to go on http://sailboatdata.com/VIEWRECORD.ASP?CLASS_ID=444 & http://sailboatdata.com/VIEWRECORD.ASP?CLASS_ID=826
A double spreader is the way to go if the 'new' mast is a lighter section, but the ramifications in terms of complication are high. i.e. The bottom spreaders may finish up being quite low, therefore the lowers would be low and cause obstruction to the foredeck; not to mention the attachment for the intermediate stay to the deck, or make it discontinuous!?
brion has it, check the numbers (Distp. RM etc), find how close the moments of the 'ideal' and your 'new' rig are, and go from there. I guess it could be close, just on eyeball..
I would tend to think that single spreader rig would be the best, given the type of craft.
Cheers

[rpack]

All Right Fellas!.
Now we're cookin' Something to get my melon wrapped around. Learning for me is much better done with a "problem" in front of me. The mast section of the new mast is slightly slimmer than the old, I don't have the numbers on tap right away but the moments really can't be more than the old, the mast came off of Mr Jacketts personal boat and has all the bells and whistles according to the marine surveyor who sold it to me (yes I know about salesmanship). I'd post pictures but I'm not a grownup yet on this forum. I won the bid on Ebay for $300, having the mast shipped now. My best estimate for a new replacement came from Buzz Ballenger and was several orders of magnitude more. I don't have a problem with less weight aloft but I'm afraid the slimmer section really needs double spreaders. Thanks to both of you for the input, the best information comes from those who do the work.

[rpack]

I'll get as much of the specs as are available and post them if you have time to help me with this
Happy New Year

Rich