MacGregorSailors.com

Neo wrote:

grady wrote:

Neo wrote:Yes depower is reducing power.
...if the mast is straighter and you haul your cunningham, outhaul and vang down hard, this makes the sail flatter and it with deflect the wind and thus depower the boat.

Sorry I'm a novice in this sailing game .... Seems like a lot of "work and wires" just reduce the efficiency of the main .... Am I missing something?
Would I need a Backstay (should be called "AftStay" ) if I went for a Tapered Mast?

Do later Macs have a BackStay?

No worries about the hijack, I'll Hijack the thread back when I have an update on my replacement mast .... Just for everyone's information BWY are moving this week so no quotes for me

All the best.
Neo

In high winds you may want less vang to let the top of the sail twist off and produce less lift. You do want more halyard/cunningham tension and out haul. The back stay tension will flatten the center of the sail, reduce the belly. Back stay adjustment is more for racing, when you are just out cruzing you will generally just reef the sail since you are not worried about staying 100% powered up 100% of the time. Not sure how much the tapered mast would help? Doubt it would hurt anything. If yo are rigged for no back stay and do not want one I would not add one.

grady wrote:Not sure how much the tapered mast would help? Doubt it would hurt anything. If yo are rigged for no back stay and do not want one I would not add one.

So it's Ok to have a tapered mast without a backstay ... as I'm not a racer

Yep IX I always like to shed a few pounds .... But looking classy is even better

Can't say I'm definitely gona do this guys ... just playing with the idea for now

Still not convinced with bending the mast and decreasing vang tension depowers, especially in a fractional rig.

The sailmakers guilds I have read say everything on hard and mast straight

The pivot point for any bending of the mast would be where the forestay connection point, as this is the point at which the mast is supported, so the top of the mast bends a lot and the around the pivot point very little this would cause the leech to belly, so then you have to try and take out the belly of the leach and the only way to do that is to tighten the vang, but the vang is inefficient at this as its pulling the boom down from less than 1/3 of the way out from the mast.

If you loosen the vang you are allowing the boom to lift and thus induce belly into the sail, it may allow the head to twist, but the majority of the power is generated well below the head, so you you need to try and hold the boom down with the main sheet and to get mechanical advantage you need to have your mainsheet attached to the end of the boom. Seems a convoluted way of doing things.

This whole argument is made more complex if you dont have a traveller like most X and M models

A theory simple to prove as explained in my reading is just get a sheet of ply and offset it to the wind at 20 degrees, the wind deflects off it, now get a sheet and do the same, the sheet will fill with wind and will get harder to hold

I do love a good theory of sailing discussion, as even the experts cant agree on many of the details

PS I think the backstay on the X is mostly to help tension the rig because of the weight of the furler, I think mine is just about factory standard and to get anything but modest tension is close on impossible as there isnt any mechanical advantage, just the one block, I would think a minimum of 4 to 1 would be required to any decent tension of such a large mast

It seem like the "Worst Nightmare" is if and how to bend a mast rather than breaking it

Nice write-up Mike

All the best.
Neo

sailboatmike wrote:Still not convinced with bending the mast and decreasing vang tension depowers, especially in a fractional rig.

The sailmakers guilds I have read say everything on hard and mast straight

The pivot point for any bending of the mast would be where the forestay connection point, as this is the point at which the mast is supported, so the top of the mast bends a lot and the around the pivot point very little this would cause the leech to belly, so then you have to try and take out the belly of the leach and the only way to do that is to tighten the vang, but the vang is inefficient at this as its pulling the boom down from less than 1/3 of the way out from the mast.

If you loosen the vang you are allowing the boom to lift and thus induce belly into the sail, it may allow the head to twist, but the majority of the power is generated well below the head, so you you need to try and hold the boom down with the main sheet and to get mechanical advantage you need to have your mainsheet attached to the end of the boom. Seems a convoluted way of doing things.

This whole argument is made more complex if you dont have a traveller like most X and M models

A theory simple to prove as explained in my reading is just get a sheet of ply and offset it to the wind at 20 degrees, the wind deflects off it, now get a sheet and do the same, the sheet will fill with wind and will get harder to hold

I do love a good theory of sailing discussion, as even the experts cant agree on many of the details

PS I think the backstay on the X is mostly to help tension the rig because of the weight of the furler, I think mine is just about factory standard and to get anything but modest tension is close on impossible as there isnt any mechanical advantage, just the one block, I would think a minimum of 4 to 1 would be required to any decent tension of such a large mast

Please post links to those sailmakers that state no back stay tension in high winds.

Your mast pre bend is measured and then the sail luff is cut to match.

The entire rig is tensioned differently for different wind speeds, Uppers lowers and head stay.

Found this it is kinda cool.

http://www.nauticed.org/sailing-blog/sa ... igh-winds/

Yes that was cool ...I lernt quite a bit from that... Thanks for sharing Grady

So thinking about this there's no way you could have a back stay (it would effect the swing) or tighten a backstay with and swinging mast (it would bend the mast sideways'ish)

Nope I resolved that issue !



http://vid844.photobucket.com/albums/ab ... 0011-1.mp4

http://i844.photobucket.com/albums/ab1/ ... 010021.jpg

these r some old vid during the fabricating process
masthead swivel mount
http://i844.photobucket.com/albums/ab1/ ... 010014.jpg

J

Highlander wrote:Nope I resolved that issue !

Well done for solving that .... I guess you need it with all those furlers too.

You're very brave with all your project .... But the complexity of your setup at the back makes my head spin
All the bars must weigh a fair amount. Have you noticed any difference in the way she handles?

All the best.
Neo

81venture wrote:What about buying a whole donor boat for a new mast?

Might be an option if the insurance company doesn't pay up ... Although scrapped boats are few and far between in Australia.


BTW does anyone have a diagram showing all the fitting on the Mast and how high each one is from the base?

All the best.
Neo

So I'm trying to follow this..and i have a 96

How necessary is the backstay since they removed them on the M... I don't "race" and never will...

Would love to get rid of it, if that is possible

Might be an option if the insurance company doesn't pay up ... Although scrapped boats are few and far between in Australia.

I am 99.9% sure the M mast section is the same as a Nacra 5.2 beach cat mast section. If you look for a used mast look at beach cats and not traditional mono sailboats, their masts are way too heavy.

81venture wrote:So I'm trying to follow this..and i have a 96

How necessary is the backstay since they removed them on the M... I don't "race" and never will...

Would love to get rid of it, if that is possible

Short answer - no.

Long answer - still no. The problem is the position of the side stays on the X - they are not in the right place to support the mast without a backstay. Can you move them?

Short answer - no.

Long answer - no. Ask any marine surveyor about moving jack plates - you will always get the same answer: "Not in my survey!" I won't sign off on it!"

sorry just to answer: Is a backstay mormally to trim the mast/sail and not to hold the mast?? !!!

You can move the chainplates. The hull will need to be beefed up. The hull is slightly thicker where the chainplates are located from the factory.
It's not a job undertaken lightly though.
Ix