Mast Splice below the partners???

[Brion Toss]

Hello,
I'd need to see the numbers on the sections' stiffness, but a keel-stepped mast is typically around 40% stiffer than a deck-stepped one of the same moments, so if you are correct that the two are close to the same stiffness, then the new one will be much more buckle-prone than the old. Have you run the numbers on the ideal moments of inertia for this boat? Again, I don't have access to the data here, but if things are the way they sound, deck-stepping the new mast could be disastrous.
Fair leads,
Brion Toss

[HappySailor]

Originally Posted by Brion Toss

Hello,
I'd need to see the numbers on the sections' stiffness, but a keel-stepped mast is typically around 40% stiffer than a deck-stepped one of the same moments, so if you are correct that the two are close to the same stiffness, then the new one will be much more buckle-prone than the old. Have you run the numbers on the ideal moments of inertia for this boat? Again, I don't have access to the data here, but if things are the way they sound, deck-stepping the new mast could be disastrous.
Fair leads,
Brion Toss

Thanks for the great info Brion!

So what I'm taking away here is... that say two identical profiles, one keel and one deck stepped, the keel stepped rig will be 40%ish stiffer just by configuration?

In the latest iteration of possible take-off rigs, I've found the same exact profile except 11 ft shorter, going from a triple aft to double aft... Butt splicing this 7 ft brings the kicker and goose in the right height, and leaves the splice just below the deck...

Impossible idea?

I have not run moment numbers, only going by what was on the boat prior. Dubois and Wauquiez have been completely unresponsive for the better part of 3 years of attempts for all other inquiries as well as this... Any recommended reading???

Thanks Again!

[Brion Toss]

Hi again,
If your sleeve has generous overlap, properly secured, then you will have a mast that is at least as stiff as one of the same dimensions that ran full length. All you need do now is to find or form the sleeve. This still leaves the question of whether or not the section is correct, so it might be nice to run those numbers, see what you have.
Fair leads,
Brion Toss

[HappySailor]

Originally Posted by Brion Toss

Hi again,
If your sleeve has generous overlap, properly secured, then you will have a mast that is at least as stiff as one of the same dimensions that ran full length. All you need do now is to find or form the sleeve. This still leaves the question of whether or not the section is correct, so it might be nice to run those numbers, see what you have.
Fair leads,
Brion Toss

Hi Brion,

Sounds reasonable if done right... I don't have any RM numbers for the boat... But will run with the published table... I'll run the calculations found in the apprentice to what I had before, and the proposed changes... See if the section still holds up...

Any major SF or constant changes for triple 20 degree aft swept, cutter stays, and 4 baby stays in addition to D1/V1's?

Maybe I just need to cut you a check instead... )P

Thanks Again!

[Brion Toss]

Hi again,
Yeah, you were already well over the "questions too short to charge for" standard that I try to use here.
Fair leads,
Brion Toss

[HappySailor]

Originally Posted by Brion Toss

Hi again,
Yeah, you were already well over the "questions too short to charge for" standard that I try to use here.
Fair leads,
Brion Toss

And for that I'm truly grateful !
Spartalk is a fantastic resource to be sure...

Actually the major questions were answered....
1. It is entirely possible to have a splice just below the partners if done correctly
2. it is NOT POSSIBLE for an extrusion to be configured as a decked stepped rig, when the boat was previously designed with the identical extrusion as a keel stepped rig... The profile isn't stiff enough...

I'll send an email to your consultation address, rigging@

Thanks so much for your help!