Rig design

[Ricardo]

Hi!
I'm looking for information about rigs( main dimensions, etc...) but it's being very difficult to find it on the inernet. Could you please tell me some websites of rig/mast builders? Thank you very much
Kind regards
Ricardo

 

[SailDesign]

www.hallspars.com
www.rigrite.com

Those should get you started.

Steve

 

[Ricardo]

Hi!
I'm having some problems to get information about spreaders, it location on mast, the angles the support cables do, and I can't find it. Do you know any site where I can get it?
Thank you very much.
Kind regards
Ricardo

 

[SailDesign]

Now you are basically saying you need a designer
Seriously, though, if you talk to either of the companies I gave links for, they can and will help you with this.
Failing that, find a library or bookstore with some marine books. Most design books will have this kind of information. There are no exact "standards" for spreader placement and shroud angles - all of us designers have our own likes and dislikes.
Sparkman and Stephens had a set of tables showing theirs, and any designer who worked there (lots and lots of them) should have a copy of this. I never did, but it is in the second edition of "Skene's Elements of yacht Design" revised by Francis Kinney.
Good luck with the search.

Steve

 

[stew fl]

Spreader placement

Normally the spreaders would be about half way
on a smaller rig ( uppers & lowers), but how about
mast pumping, I put my spreaders at exactly half
way which is fine for strength (static loads) but what about harmonics under way.
Now I am thinking that they should be at some
distance close to half way but not a multiple of the mast length.
As far as spreader length is concerned look at some
boats & you can make up you're own formula,
spreader length divided by beam.

 

[SailDesign]

Stew,
The locations will differ from deck-stepped to keel-stepped masts, and from masthead to fractional rigs. "About half-way" just doesn't cut it when you are looking at designing a rig. A great deal of rig design is also influenced by the sail inventory - are you taking the shrouds out to the gumwale, or do they need to come inboard because you want to use an overlapping headsail?
This is why I said he was really saying he needed a designer, or a spar-builder (links supplied)
Steve

 

[stew fl]

Spreader placement

Sail design,
I really wasn't trying to answer a question I was kind of asking one.
Before I rerigged my boat,( different mast, moved the chain plates in and up to the cabin top from the gunwales as well as forward some, head stay from 3/4 to 13/14, and fabricated my own spreaders on a swept back spreader rig with single lowers) I looked at a lot of books and a lot of rigs at my local marina and guess what?
On single spreader rigs the spreaders are about half way up.
All other things aside you are absolutely right.
If you don't know what you're doing leave it to the experts, after all the experts designed my McGregor 25. Nuff Said!
My question was really about mast pumping and whether or not the experts take into account the resonant frequency of the stick and, I would suppose the hull or the part of the hull that matters, and do they make any sort of attempt to make shure that they are out of sync so as to limit
mast pumping or should I just not care because it only happens going downwind and the rig will be blown forward when it breaks and I probably won't be hurt much.
Thanx for listening,
STEW

 

[Stephen Ditmore]

A couple of articles:
http://www.classicmarine.co.uk/Articles/Reference start.htm
http://boatbuilding.com/content/AES.html

 

[SailDesign]

I would tend not to worry about resonant frequencies in a rig. if properly tensioned, the shrouds should damo it, and the number of welds and attachements should make it a pretty high frequency to boot.

Steve "never worried in the past..."