Buying A New Bottom Section HELP!!!

Glen

New Member
I am purchasing a new radial lower section, and have a few questions. I was wondering if:
1) All lower sections are made the same and have absolutely no difference
2) Can you find better lower sections if you look hard enough at the details?
3) Are there any tips for buying a new lower section?


Thanks for all of your help.
 

sailor327

New Member
1) What exactly do you mean. are you talking all radial lowers or all lowers (4.7,radial,full) in general. But overall i am pretty sure all radial lowers are manufactured the same.
2) it would take a very trained eye to find minute details but they are generaly all the same
3) nothin that i can think of
 
Glen said:
I am purchasing a new radial lower section, and have a few questions. I was wondering if:
1) All lower sections are made the same and have absolutely no difference
2) Can you find better lower sections if you look hard enough at the details?
3) Are there any tips for buying a new lower section?
1. In theory: yes, all radial lower sections are made in the same way; in practice: probably not, but most likely the ones made wherever you live are all the same.
2. Unless you have fancy equipment that can measure the stiffness, only the wall thickness can tell you something.
3. Pray to whatever deity you have some faith in before buying the section.
Good luck!

GWF
 

Glen

New Member
I am asking if there are any differences between 2 radial lower sections that are noticable to the human eye. How can you tell the thinkness of the walls acuratly? is the wall the same thickness all the way down the spar?
 

Rob B

Well-Known Member
The mfg tolorances are very small. You can not tell the diff w/the naked eye. Best thing to do is to break it in properly.
 

WestCoast

New Member
Glen-

I don't think my electornic scall will weight a lower section.

We had a couple customers go to worlds and they bought new boats to train in. We weighed top sections and bottom sections, and not one fell out of what we would consider our margin of error.

I have 3 radial bottom sections, so you are free to weigh each one and we'll get the one you want, but they do fit a very very tight tolerance.
 

gouvernail

Super Opinionated and Always Correct
GENERALLY and not always becuase there are other factors but if they were made in the same batch of metal and you ae looking for the stiffer piece of extrusion???
also...If the pieces ae the same length..

you can tap in the sections and the one with the higher pitch is usually the stiffer section.
I tested about 30 top sections a few years ago and the higher pitch trick worked 100% of the time . I
My test..I mounted a lower section on a keelboat trailer with the tp end somewhat higher than the base...maybe 30 degrees from level. I stuck stuck various top sections into the mounted lower and hung an object on the tip of the top section. My weight was an empty galon can with ten pounds of lead tied to the handle. I stuck the top of the top section against the inside bottom of the paint can.

I measured the difference to the ground from at reat and loaded. Each mast was measured a few times. I measured the height, turned the mast, mneasured again and did it enough times with each mast to convince myself I had a decent mean number for the individual mast.

I labeled all the masts with their deflection numbers and then tried tapping the masts with a small hammer. I lined the masts up according to pitch.The bendier masts were the lower notes. No exceptions.

coolhuh??
 

gouvernail

Super Opinionated and Always Correct
Edited version of the above.... I ran out of time...

Maybe the test below does not pertain to bottom sections or booms. Each has an inner tube that may throw the entire test off.

Also. I only tested 30 top sections. There are over 200000 top sections out there. My sample results may have been coincidence.
I think I found out the following: You can tap in the sections and the one with the higher pitch is usually the stiffer section.

I tested about 30 top sections a few years ago and the higher pitch trick worked 100% of the time .
My test..I mounted a lower section on a keelboat trailer with the top end somewhat higher than the base...maybe 30 degrees from level. I stuck various top sections into the mounted lower and hung an object on the tip of the top section. My weight was an empty gallon can with ten pounds of lead tied to the handle. I stuck the top of the top section against the inside bottom of that paint can.

I measured the difference to the ground from at rest and loaded. Each mast was measured a few times. I measured the height, turned the mast, measured again and did it enough times with each mast to convince myself I had a decent mean number for the individual mast.

I labeled all the masts with their deflection numbers and then tried tapping the masts with a small hammer. I lined the masts up according to pitch.The bendier masts were the lower notes. No exceptions.

cool huh??]
 

LooserLu

LooserLu
Ludwig, the civil-engineer, would measure in this way:

He knows a simple physical term for a spring: "Force (F) is linear equivalent (with a constant (c)) to the static swing (call it length (l)) of the spring"

"F"="c"x"l".

The spars of a Laser, in small limits of course, have the same behavior like a spring.

"c" is a measure for the stiffness of a spring, also for the tube of a spar.

If you put a low but constant load "F1" to one end the spar, that is fixed at the other end (f.e. in the mast step) and measure the static swing "l(F1)". You can do some simple mathematics with your pocket-computer to find out the "spring-constant" "c" for that spar.

The term for the pocket-computer is: "c" = "F1" / "l(F1)"

If you have the chance to choose between several pieces of the same sort of spar that you want to have, do this measurement with all that pieces (Take always the same load F1). The piece with the biggest "c" should be the stiffest one.

To be sure one everytime put the same load onto the spar, you can take a simple spring-balance (f.e. a store for fishing articles or a "1$-Store" for household articles) that you fix with a small line (and tape) to the end of the mast (everytime: perpendicular to the length-axle).

For real, the engineers do not measure the "c". They want to find out the "Modulus of Elasticity" (E). This will be not as simple for the lower section of the mast section of the Radial than for the upper section of the mast, because the mast diameter differs (in reason of its inner sleeve and some other variables). Over the lenght of the the mast section of the Radial, there are in minimum two "E"s...
Also, the ratio of the alloy of the material (I know 46 different sorts), that is mixed with the aluminum for the tube of a spar, has a big influence to the elasticity. Only the person, that produce the tube for a spar, knows (but not scientific exact) the ratio for the alloy.

For the upper mast section I did some "simple" mathematics at this thread:

http://www.laserforum.org/showpost.php?p=7258&postcount=18

But, "the LooserLu" thinks: More elegance of course has the way, the 'gouv' already above has found out: one only need a sensible and clean ear - great idea!


Finally I have to say, that there is some truth in ..
49208 said:
IMHO, Bring an accurate scale, weigh them and pick the heaviest one.
.. words. Here, a former pro-Laserite told me the same: heavier tubes are stiffer than the lighter ones. But I havn't tested this in the moment.

Ciao
LooserLu
 

TheBoathouse

New Member
Glen said:
I am purchasing a new radial lower section, and have a few questions. I was wondering if:
1) All lower sections are made the same and have absolutely no difference
2) Can you find better lower sections if you look hard enough at the details?
3) Are there any tips for buying a new lower section?

Thanks for all of your help.
1) a) all lower sections are made the same BUT b) every single one of them is different. By the nature of extruded aluminum each and everyone is different some minor some major...Some have thin walls in the right places some have thick walls....unfortunately its not an exact science..Only true way to tell difference is to slice them into many pieces and measure wall thickness with calipers...but then all you have is a bunch of small pieces :eek:

2) Not with the naked eye but try gouvernail and LaserLu suggestions

3) Close your eyes and pick one off the rack.....;)
 

Merrily

Administrator
gouvernail said:
With my luck I would choose a #*&+##$ing Sun%^$*fish spar
I guess all those symbols must mean "goshed darned" Sunfish spar. Now you've really done it, Goub--Bradley hosts The Sunfish Forum too. If you've hurt his feelings, I'LL have to load some vittles into the cockpit of my Laser, add some sled runners to it, and sail down there and give you some OHIO whupass. It won't be pretty. I fight like a girl.

Merrily

P.S. Merry Christmas, and Happy all them there other holidays too!
 

gouvernail

Super Opinionated and Always Correct
Merrily said:
I guess Sunfish hurt his feelings, I'LL have to add some sled runners to it. It won't be pretty. I fight like a girl.

Almost 20 years ago, I started the Austin Sunfish fleet becuase there are people in this world who are more suited to having fun on a Sunfish than having fun on a Laser.
I started the fleet as a second group who would compliment our Wednesday Night Laser races. Our Laser fleet was united in its distain for my actions and I had to run the race committee for the entire last month of the season because nobody else in our fleet was willing to have any part of my experiment.
The Sunfish fleet took off and by the end of the second summer it was larger than our Laser fleet. It took fifteen years for the Laser fleet to finally catch back up to the Sunfish and this year we had about as many Lasers as Sunfish.
I absolutely believe each fleet is exactly what the other fleet needs. Before the Sunfish fleet was started we averaged about 15 sailors per night and one race committee guy ran the show.

Now we have about 55 sailboat boats per night and there are three sailors on the committee boat too.

I still think Sunfish exist to torture people who would like to go sailing but only can find a Sunfish.

Last...The 2006 Sunfish NA Champs are in Dallas at the same time as the US laser nationals in COrpus. THAT is STOOOOOPID scheduling.

Who do I blame??

USSailing. THEY are supposed to be the US managers of the great sport of sailing. They don't maintain the following simple database covering the top fifty one design associations :
US and Canadian national championships for 2006 through 2008
NA Champs for 2006 through 2010
Regional champs through 2007
All scheduled regattas for 2006
All USSailing championships through 2010
All Olympic regattas and USteam quailfiers through 2012
All Collegiate and High School Championships through 2010


How the hell can any national sports authority run without such basic information??

Oh wait...USSailing is too busy running a really expensive and stooooopid regatta in the middle of our off season in a place as far to the lower right hand corner of the map as they can shove it, where there is consistently NO wind for at least half the days of the scheduled event.
They spend Millions of dollars of their money and the sailors money and invite people from all over the world to participate in an event that is doomed to failure by lack of proper weather and they have no funds left to do their job...manage the sport of sailing in the US...

But I digress..
Sunfish still suck......
 

Rob B

Well-Known Member
49208 said:
IMHO, Bring an accurate scale, weigh them and pick the heaviest one.
Where can you go and just sort through a large selection of mast sections?
 

glasky

Member
Probably the most annoying thing with various top masts and bases is the variable 'fit' you get when interchanging different bits to rig as a Radial or standard Rig. In a club situation, with a number of club boats and rigs this can become particularly annoying if members ignore spar 'pair' markings and start rigging using any combination of spar pieces from the boatshed. Last one to rig may not be able to force the top section into the last available base and everyone has to de-rig and sort spar pairs out so all fit.

This may not be a problem for the individual owner if you have only one rig - but if you alternate a single top section between Radial and Standard bottom sections, one is invariably too loose (the other just right or impossible to remove after sailing without resorting to leverage on the goosneck, which in turn loosens it over time).

Mucking about using tape on one set up and removing it (and all the residual adhesive build-up and grit it attracts) detracts from what is otherwise an easy and simple rigging job. Getting a one-size-fits-all setup and maintaining this is quite a chore.

Have yet to find two bottom sections (of same or different rig types) that fit well with any given topmast.

Is this manufacturing variance or deformation caused to spars in use?
 

halibut

New Member
Same here. We have four Laser rigs (2 full / 2 radial) with spare sections, and some uppers fit snug with the lower section, while others are quite loose and require taping.

Kind of amazing that there is so much tolerance slop between sections. You could also make an argument that to pick out a "stiff" lower section take along a upper mast fitting and find a lower that fits snug = thicker section profile?

I wonder what the acceptable tolerances are? Or are they part of the not to be revealed "secret" manufacturer's specs?
 
I am wondering: is this a difference in mast-thickness (the diameter I should say) or a difference in the plastic fittings? I assume it is the latter.
GWF
 

49208

Tentmaker
Georg W.F. said:
I am wondering: is this a difference in mast-thickness (the diameter I should say) or a difference in the plastic fittings? I assume it is the latter.
GWF
Not nec. If the upper is snug in one lower and loose in another, it's the lower section inside dia that is changing.
 
Well, if that is indeed the case, then one can simply measure the (inside) diameter of a new lower mast section (instead of playing music on it :) ). I assumed the manufacturer would do that, but you suggest that there is a lot of of tolerance here. It would be interesting to know whether these are perhaps older vs newer sections, or that these are made at the same time. And is it also the case that a section with a larger inner diameter, also has a larger outer diameter (so that the thickness is the same). That would seem to result in a heavier section.
GWF
 

Laserite

New Member
NOt all bottom sections are "equal" as not all bottom sections are made in the same manner. I am in Australia and have recently manged ot gaet my hands on an English bottom section. This English bottom section is completely different (well to look at anyway) It look as if it has been spun rather than extruded, however I have no idea about the truth to this. I can vouch for is their longevity (well so far). I come form a windy place and normnmally afetr two - three outing in 20-25 knots the bottom section develops a permanent bend, not so with the English bottom section. I have sailed with this mast in plenty of windy days with high vang tension with no permanent bend at all. Apparenty this was the same result in Brasil at he masters werervthere was not one permanent bend to a radial (English) bottom section.

Can anyone explain why the English masts differ to the Australian masts in the manner in whihc they are made.

PS so far their does not ot be any differnec overall in performace between the Aust mast and the English mast.
 

gouvernail

Super Opinionated and Always Correct
Laserite said:
normally after two - three outings in 20-25 knots the bottom section develops a permanent bend, not so with the English bottom section. I have sailed with this mast on plenty of windy days with high vang tension with no permanent bend at all. ......
PS so far their does not ot be any difference overall in performance between the Aust mast and the English mast.
Huh?
Isn't a bent mast slower??

Are you sailing Radial or Laser?

I have only ever bent one North American Laser bottom section and that was in an outrageous breeze. How outrageous? see below...

Anyway, radial sections seem to bend a lot. Top sections only seem to bend when a bad batch of metal sneaks by the inspectors and in North America Vanguard has generally been willing to replace recently purchased bent lower sections.

The wind description>>>
How outrageous? The event was a Laser Midwinters in Sarasota. The wind was blowing hard enough to make the officials wonder whether to sail. Just as the race started the wind really picked up. Then half way up the weather leg it picked up again. Sometime after that as we were going down a run it seemed to double again.
Most of the 106 boat Laser fleet was blown to the leeward shore. The race was eventually cancelled after only seven of us crossed the line before the pin blew away and two more before the committee boat abandoned its position and began rescue work.
Fifty miles to the north a NOOD regatta was turned into a disaster by the same storm as keelboats were strewn all over Tampa Bay. A few hours later four tornadoes ripped communities just east of the regatta site.

I completely submarined my boat on a run and the mast bent about ten degrees sideways. A few secoonds later Lars Hanson flipped backwards end over end. As his bow went up on a wave, his sail took his boat straight up in the air and the transom blew to leeward until the boat was entirely upside down and the tip of the mast was clear of the water. The sail blew to leeward and the bow came straight down a few feew to leeward of Lars. When I asked him about the experience he told me his only concern was that the boat not fall on top of him.

back to the wind...A few seconds later Bill Hardesty gybed inside me at the leeward mark and when his boom shattered it ripped through the pads of my lifejacket, tore my spray jacket and the shirt inside and left a bruise on the center of my upper back that was black and blue for a few days. I am convinced the padding on my jacket saved me from an extremely serious injury.

The only reason I bent my lower section that day was the submarine experience. The top section and boom were unharmed. My sail was garbage.
 

Laserite

New Member
I sail a radial and yes it is a generally accepted concept that bent sections are slower. Hence the reason to buy one that does not develop a permanent bend. I have never sailed in conditions you have described, however I can state that all radial bottom sections at the club I sail at have developed permanent bends, in some cases only after a couiple of races. These bends are relatively minor (especially compared to the top sections that require "reshaping" after every day of sailing). On another point it is not uncommon to see snapped radial bottom sections. I broke one last season as did another person in the same race.

So far the English bottom sections are the only ones to stand up, however I have only had this mast since November, although it did hold up through the Aust titles.
 

gouvernail

Super Opinionated and Always Correct
Cool. Perhaps the builders all over the world should test for themselves and if they find the same result should either purchase their extrusion from whoever is supplying the English or at least have their extrusion suppliers preform to the successful English extruder's specs.

I just hope the real reason for your mast's durability is NOT that it happens to be built outside the official specifications.

But

if it is outside the specs and durable...I believe the world council and builders should and probably would re-examine the specs.

Instituting production under those specs after the 2008 Olympics..of course
 

LooserLu

LooserLu
Hi.
Me was told, that at one of your youth-championship-events of the last year here, the rate of (new) Radial-lowermast-sections, that had minor cracks at the tube, was un-common high. All of this masts came from Performance Sailcraft Europe. The reason for this failurs is unknown.
One secret for a good working mast is the conector plug that fits the mast parts most tight together. The best, me was told, are the white-ones that come, guess from where....: Down under...
G'Day
LooserLu
 
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