Aluminum mast worries
Steve Madere
Two friends of mine each bought two aluminum Weichert masts.
These masts come with a one year warranty but the distributor
has assured me that you can only get one replacement if it
fails (two failures and you're out of luck).
Anyway....
Each of these guys had the top half of one mast split when
the masts were less than two months old. The split appeared
at the joint between the bottom and top half sections.
Is this typical? Are they doing something wrong that is
causing the split? We have looked them over and guessed that
the problem lies in placing the seam along the same line
as the boom. For now, they are trying to line up the seam
perpendicular to the boom every time they rig and hoping
that will solve the problem.
I just broke my own mast (it was a lousy one anyway) and need
to replace it right away. I had planned on getting one of
these Weichert masts until the seam splitting problem appeared.
I would like to know what is a good, inexpensive mast that
will stand up in relatively light conditions ( < 30 knots).
I'm looking for something with 80% of the perfomance of the
best for 50% of the price. This is usually the way
pricing schemes work out. (that last 20% is often quite
expensive).
Oh, yeah. All I do is slalom. I have a Hi Tech 9.0 and
various lousy sails (5.5, 5.9, 6.5). (I'm upgrading incrementally).
Steve Madere.
Rolland Waters
>
>Two friends of mine each bought two aluminum Weichert masts.
>the masts were less than two months old. The split appeared
>at the joint between the bottom and top half sections.
>
>Is this typical? Are they doing something wrong that is
>causing the split?
One problem with two piece masts is that the top piece tends to break
if the two pieces slide apart even a little bit. A wrap of duct tape
or a few wraps of electrical tape keeps the two pieces together.
(This also solves the sand intrusion inseperability problem.)
Aluminum masts should break on the weld if they slide apart.
(When they slide apart the bottom piece causes point loading in
the top piece.
All that aside, the Weichert is supposed to be fairly solid for
an alumninum mast.
>I just broke my own mast (it was a lousy one anyway) and need
>to replace it right away. I had planned on getting one of
>these Weichert masts until the seam splitting problem appeared.
>I would like to know what is a good, inexpensive mast that
>will stand up in relatively light conditions ( < 30 knots).
I'd consider a used mast, particularly if you know it's history,
or you live in an area where people don't abuse masts. If you
want a new one, consider the Fiberspar Performance series,
about 70% of the cost of their World Cup series, same bend and
performance - the finish is a little rougher and the weight a
little more (higher glass/carbon ratio than the World Cups).
A new Fiberspar Performance Wave mast (absolutely bullet proof)
at Dill was $220...
Rolland
Tom Albertz
four years. This year I added a 220 cm epoxy top and a 245 cm carbon top
to my quiver. I don't use the aluminum top any more (which is 245 cm).
Had no problems with it, but the carbon top is lighter. And weight
reduction on top is more effective. I use the yellow top (220 cm epoxy)
for 4.3 and 5.0 sails and the carbon top for larger sails.
Dynamic Speed AL75 (2-piece aluminum) about $200
Carbon/Alum Combi about $300
carbon top about $200
yellow top about $90
These prices are list prices. You can probably do better today.
A pure-bred carbon mast is probably $350-$400.
Mark Bishop
>I've had good luck with the North 2-piece aluminum mast. I used one for
>four years. This year I added a 220 cm epoxy top and a 245 cm carbon top
>to my quiver. I don't use the aluminum top any more (which is 245 cm).
>Had no problems with it, but the carbon top is lighter. And weight
>reduction on top is more effective. I use the yellow top (220 cm epoxy)
>for 4.3 and 5.0 sails and the carbon top for larger sails.
I also own a North 2-piece aluminum mast (AL-75) and have had good luck
with it for the past year and a half. I paid around $160 for the (new) two
piece during a sail in Hood River..
A QUESTION: I use the north mast with a 4.0 and 4.5 Ezzy Wave and a 5.0
Gaastra with adjustable tops. I have been looking to buy a 6.0 North Prisma
which would fit the North AL-75 great, right?? Wrong- this past weekend I
rigged up a used Prisma in hopes of buying it. When I had it fully rigged the
foot of the sail was about 3" off the ground. (ie. didn't come close to closing
the gap) I was very surprised that is didn't rig up properly and pointed it
out the guy at Windance. He said that since I was using a Chinook downhall
instead of the North system which evidentally clips into the mast, the sail
will not close the gap.
POSSIBLE ANSWER: The guy went on to say that in order to correct the
problem, you could chop 3" off the NORTH mast!! OR you could make the 6.0 an
adjustible top but hardly worth 3".
What should I do?? I am a little unsure of cutting into the mast. ==> do
you cut from the bottom or the top??? The guy said that by cutting the top
you could still use the north system of downhall later but then you would
reduce the amount of 'curve top'. Should I look into a 220 yellow top?? I'm
not too excided about shelling out extra $......
Tell me what you know..
Mark
==========================> WindSurf the Gorge!! <===========================
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Mark Bishop \ \
markb%robin.wv...@relay.cs.net \ 777 \
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al...@zack.wv.tek.com
>In article <1260...@hpfcso.HP.COM> to...@hpfcso.HP.COM (Tom Albertz) writes:
>reduce the amount of 'curve top'. Should I look into a 220 yellow top?? I'm
>not too excided about shelling out extra $......
>
> Tell me what you know..
>
I've had a North aluminum mast for about 3 years and it has worked well
for me. My mast is an older model and the bottom section is about 6 inches
shorter than the newer model. I bought a North purple top (about 6 inches
taller than a yellow top) and I really like it. I'm not sure if it performs
as well as the aluminum top, but I like the feel better. I use it with
everything from a 3.5 to a 5.5. The only sail I use the aluminum top with
is my 6.8. I also like having less mast sticking out of the top of my
3.5, 4.0 and 4.5 sails.
Alan Zimmerman
al...@orca.WV.TEK.COM
Tom von Alten
I'd cut the sail before I'd cut the mast. If I were going to cut the mast,
I'd start at the top, rather than shop for a custom mast base...
Jon Outta my way - I'm going windsurfing Hue
>
> What should I do?? I am a little unsure of cutting into the mast. ==> do
> you cut from the bottom or the top??? The guy said that by cutting the top
Always cut from the bottom, unless you will end up attaching the booms on
the non-reinforced part of the mast. If this happens, you probably need to
buy a special short mast.
Wouldn't it just be easier to buy a different mast base? I use Windsurfing
Hawaii, and when I stick it in a 15'-3" mast, it works perfectly with sails
claiming to have a 15'-3" luff.
-Jonathan
Tom Albertz
>rigged up a used Prisma in hopes of buying it. When I had it fully rigged the
>foot of the sail was about 3" off the ground. (ie. didn't come close to closing
>the gap)
>
>problem, you could chop 3" off the NORTH mast!! OR you could make the 6.0 an
>adjustible top but hardly worth 3".
I wouldn't cut the mast - unless you'll never need a 15'-3" mast. You can
get 220 cm tops in carbon or epoxy. You top haul tight and extend at the
bottom. The extra weight is better at the bottom than the top anyway. If
you cut the mast, the top would be the better call.
I'm surprised North would make a sail shorter than 15-3 without an adj. top.
Doesn't it sound like it's been a bad summer everywhere.
Tom "ready for Corpus in October" Albertz.
Ken Berger
Eeeeegadddds. dont cut the sail, you'll probably ruin it. The
common procedure if you're going to chop off a mast is to cut from
the bottom. This could present lot's of other problems though. If
you cut too much off, your will have to rig your boom above the
re-enforced area on the mast. It will also destroy the flex pattern
of the mast. Don't cut from the top.
If you sail in high wind conditons, get the proper length mast and
sleep better at night.
Mark Bishop
>In article <159...@hpdmd48.boi.hp.com> al...@hpdmd48.boi.hp.com (Tom von Alten) writes:
>>> What should I do?? I am a little unsure of cutting into the mast. ==> do
>Eeeeegadddds. dont cut the sail, you'll probably ruin it. The
>common procedure if you're going to chop off a mast is to cut from
>the bottom. This could present lot's of other problems though. If
>you cut too much off, your will have to rig your boom above the
>re-enforced area on the mast. It will also destroy the flex pattern
>of the mast. Don't cut from the top.
Why shouldn't you cut from the top?? If you cut the mast at the top, you
would not have to worry about rigging out of the re-enforced area ==> Right??
Mark Bishop
Rolland Waters
>would not have to worry about rigging out of the re-enforced area ==> Right??
The mast tip has a significantly smaller diameter than the base and so
is less rigid. To a small delta, making a mast softer is generally
less harmful than making a mast stiffer. Cutting the base makes it
softer, cutting the tip makes it stiffer.
For the case where you have a mast of the proper length for some sails
and a little too long for others you generally want to cut the mast from
the bottom. The reason is that when you rig your longer luff length
sails you'll use a base extension that will have approximately the same
bend characteristics of the bottom of the mast that you cut off, and
so the mast bend won't change.
If you're cutting more than two or three inches then you need to worry
about reinforced areas and changing mast bends and then you need to talk
to both the mast and the sail manufacturers. Generally you'll then want
to cut some from both the base and the tip.
One last thing - several masts, including the new Fiberspar Waves and
the last Ampro Greys, have extra base reinforcement that goes up 4-6".
You don't want to cut more than about 2" of this off, since it keeps
the mast base from splitting. I don't know of any aluminum masts
that have base reinforcements, but look for a thickening of the metal
or a separate collar.
Rolland
Jon Outta my way - I'm going windsurfing Hue
Huh? I hope you mean "shorten the adjustable top", and not recut the sail.
In any case, the original poster had a 6.0 Prisma, which probably doesn't
have an adjustable top, but appears to have a luff length < 15'-3". Maybe you
can have a little 3" stub added to the top of the luff sleeve?
It looks like everyone agrees that if you *have* to cut the mast, cut from
the bottom.
-Jonathan
Robert Poortinga
>problem, you could chop 3" off the NORTH mast!! OR you could make the 6.0 an
>adjustible top but hardly worth 3".
>
> What should I do??
Cut the mast ??? Cut the sail ????? Big mistakes!!! Don't be a cheapskate,
and buy the North base ($40-$50). It is an excellent system, and saves the
weight of a conventional base. I have an '88 North Speed Slalom 5.5 with the
same problem. With the North base, it rigs perfectly.
You could get the yellow top (about $80) which works well with North sails 5.0
and smaller, but it might have too much top flex for the 6.0. I believe there
is a carbon 220cm top, but it is a bit more pricey ($180).
Bob Poortinga There's a hard wind that's gonna blow...
poor...@silver.ucs.indiana.edu ... R. Zimmerman
Steve Madere
(Robert Poortinga) writes:
| You could get the yellow top (about $80) which works well with North
sails 5.0
| and smaller, but it might have too much top flex for the 6.0. I
believe there
| is a carbon 220cm top, but it is a bit more pricey ($180).
Where can I get info on these masts? Are they available from a mail
order
outlet at the prices listed above?
On a related note....
I am replacing my entire rig and I need some advice on sails.
Over the past few weeks I have seen an incredible amout of equipment
failure. First I put my knee through a monofilm mylar sail (at
extremely
low speed). Then I broke my mast while uphauling in very light wind
(I had not sailed it at all that day, this was my first uphaul that
day and the wind was too light to waterstart). Finally, I have a new
board that I bought about five weeks ago. I have not sailed it yet as
the wind has been too light ever since it arrived. However I have
dinged
it 3 times!!. This board is so incredibly fragile, I can't believe it.
If I just look at it sideways it gets another ding clear through to the
fiberglass. (It's a Hi-Tec 9.0 XTC for anybod who's interested).
Anyway, this has made me something of a fanatic when it comes to
equipment reliability. For this reason I will not even consider a
monofilm sail. I want a sail that I can fall on top of without having
it explode. I also don't want my mast or booms to bend if I get
launched.
So anyway, I'm looking for an aluminum mast, good, strong booms and a
mylar
laminate sail.
The Sailboard Warehouse is running this special where you can get a
Weichert framework for half price if you also buy one of their sails.
This makes the cost of a two-piece aluminum race mast only $125!!!
Because of this, I am seriously considering any sail in their catalog
as a possibility but I know almost nothing about most of the
manufacturers
that they carry.
Which of the following sails is a good deal considering my priorities?
(robust, reasonably fast, easy handling)
Energy RAF Slalom (Mylar) 5.2m $234
Energy RAF Fun (Dacron) 4.9m $169
TopSails Custom Wing Race (Mylar) 5.0m $374 2 Cams
TopSails Cup Wing Slalom (Mylar) 5.0m $334 R/C ?
TopSails Free Wing Fun (LDS RipStop) 4.6m $209 RAF
Neil Pryde RAF-CAM Dynamic 5.0m $375
Neil Pryde RAF-CAM Slalom ST 5.0m $445
Neil Pryde RAF-CAM Speed/Slalom 5.0 $420
If you know of any other sails which are a significantly better deal
or if you have any advice on masts please let me know. I am interested
in the idea of a two peice mast with interchangeable tops for different
conditions. But once again, reliability is the main issue for now.
Thanks in advance
Steve Madere
Robert Poortinga
>In article <58...@iuvax.cs.indiana.edu>, poor...@silver.ucs.indiana.edu
>(Robert Poortinga) writes:
>| ... is a carbon 220cm top, but it is a bit more pricey ($180).
>Where can I get info on these masts? Are they available from a mail order
>outlet at the prices listed above?
Hmmm. Checking my catalogs, I find the yellow 220cm fiberglass top for
$89.00 (off by $9 from my previous post) and the carbon 220cm top for $179.
There are available from Sailways (800) 544-9463. You might be able to find
them on sale somewhere since it is the end of the season. Remember, these
are tops for North AL75 aluminum or North EPX fiberglass masts only!
>I am replacing my entire rig and I need some advice on sails....
>So anyway, I'm looking for an aluminum mast, good, strong booms and a
>mylar laminate sail.
>
>Steve Madere
I wholeheartedly recommend North sails and masts. There are built to last.
They may weigh a little more and cost a little more, but they are
definitely worth it. I had two Pryde sails at one time and they both ended
up stretching out of shape. I have an '87 North that I have used (and abused)
quite a lot and it is still in good shape. I have heard some not so nice
things about Energy sails and Weichart masts (check previous posts to this
group). Just remember, you get what you pay for!
Bob Poortinga It's a hard wind that's gonna blow...
poor...@silver.ucs.indiana.edu ... R. Zimmerman
Tom Albertz
You would love this sail. Lots of sailors in Northern Colorado have
purchased these this year and nobody can say enough about them. They
are powerful, well balanced, have a wide wind range...
I have sailed my 6.5 when other sailors were powered on 5.0's. And I was
comfortable. You would not regret buying this sail.
I am one of those sailors who can't say enough ............. obviously.
Tom.
Tom von Alten
> >It looks like everyone agrees that if you *have* to cut the mast, cut from
> >the bottom.
> >
> >-Jonathan
>
> I don't agree in all cases. Each situation should be analyzed individually.
Yeah, I don't remember agreeing to that, either, Jon. As for the
stiffer/softer argument, I'd replace it with a weaker/stronger argument:
cut the structure where you will reduce the strength the least (which
is - you guessed it - the TOP. (Was the "make it softer" plan an attempt
to avoid the weakness of being stiffer??)
I still see the SAIL as the problem, however.
No, I didn't mean start hacking away at the sail indiscriminately, or
to recut it completely. I meant make the top adjustable; a relatively
simple, painless and low risk modification. (I had this done to one
of my sails when I faced this problem.)
Tom "still waiting for my 4 year old Ampro 1-pc (uncut)
fiberglass mast to cause me the first problem" von Alten
Tom von Alten
my work. I made a couple of inversions, and now think the result was
backwards. Although I stand by my advice in the last posting, I now make
the assertion that
$ASSERTION MODE ON
For a tube of constant cross-sectional area (i.e. constant amount of
material per unit length), BOTH STIFFNESS AND STRENGTH INCREASE WITH
INCREASING DIAMETER.
$ASSERTION MODE OFF
Let's see if I can keep from screwing up this time...
STIFFNESS - Analyze a cantilever beam with a point load at the end. Define
the "stiffness" as the spring rate for linear deflections.
F * L^3 F 3EI
y = --------- -> --- = --- = k
3EI y L^3
Assume the length (L) and elastic modulus (E) are constant. For a tube, the
area moment of inertia (I) is
pi 4 4
---- * (d - d )
64 o i
If the cross-sectional area of the tube is constant, the inner diameter can
be expressed in terms of the outer diameter:
pi 2 2 2 2 4A
A = ---- (d - d ) -> d = d - ----
4 o i i o pi
Substitute for d[i] in "I" and drop the subscript on d[o]:
2
A 2 A
k ~ I -> k ~ --- d - ---- (Note: "is proportional to")
8 4*pi
This could be rearranged some, but it's clear enough that it increases with
the diameter, as everyone expects.
-------------
STRENGTH - Again, consider beam analysis and consider that for a given load,
if all but cross-sectional configuration is equal, the "stronger" beam will
have a lower maximum stress. The maximum stress (will all the appropriate
simplifying and linearizing assumptions for beam analysis) is given by:
M c
s = -----
I
where the maximum moment (M) is a function of the load, the maximum distance
from the neutral axis (c) is d/2 for our tube, and I is the same as above.
Strength, if you will is _inversely_ proportional to this maximum stress, so
strength ~ I/c (also known as the section modulus, Z.)
Hence, 2
A A
strength ~ --- d - ------
4 2*pi*d
The derivative of this term with respect to d is everywhere positive. Q.E.D.
--------------
For extreme cases - such as very large diameter, very thin tubes - the
assumptions do not hold. We have to worry about wall buckling, material
defects, the nonlinearity of fiberglass/epoxy, &tc.
Tom "engineering a better way of life" von Alten
Tom Albertz
>
>Tom "engineering a better way of life" von Alten
Isn't "wall buckling" always the main factor in mast breakdowns ?
..which is why the boom area is reinforced ?
Did I miss the whole boat ?
...Not all of us are the same kind of engineer.
I always hated math............
Rolland Waters
> [sophisticated analysis that proves that both strength and stiffness
> go up with increasing diameter, holding amount of material constant]
Rolland is seen to stumble away, mumbling something that sounds like
"The difference between theory and practice is far greater in practice
than in theory", but we can't quite be sure...
> For extreme cases - such as very large diameter, very thin tubes - the
> assumptions do not hold. We have to worry about wall buckling, material
> defects, the nonlinearity of fiberglass/epoxy, &tc.
Yeah, that's the ticket! Most masts fail under point loading, and the
resistance to point loading is going to be greater where the wall
thickness is greater, closer to the tip! Hah! I've retreated to the
boundaries of statistics, and we have no data!! :-)
Oh well, live and learn...
Rolland
Tom von Alten
> Isn't "wall buckling" always the main factor in mast breakdowns ?
> ..which is why the boom area is reinforced ?
Well, the boom area is the primary damage zone... but just because it fails
there doesn't mean it's due to wall buckling. I may be misusing someone
else's terminology, but by buckling, I'm talking about a _compressive_
failure due to instability of a (relatively) thin wall. The expected
failure mode for bending would be tensile, which could still be related to
the concentrated load from the boom attachment.
The two design features that should be of primary interest to someone who
doesn't want broken masts are
1) boom area reinforcement of the mast
2) a boom end that distributes the stress as uniformly as possible
to the mast
> Did I miss the whole boat ?
^^^^
Are you sure you're in the right notesfile, Tom? :-)
> ...Not all of us are the same kind of engineer.
Amen.
> I always hated math............
Bummer.
vil...@hummin.enet.dec.com
Hi
Ive got a 16' ampro grey wave that I've been using for big sails, until
I discovered carbon. So I decided to use the mast for what it does
best: smaller wave and slalom sails. I'd like to cut a foot off it
and turn it into a 15 footer. I figured on cutting it at the bottom,
and reinforcing the bottom and boom area with a few layers of glass.
Then I though it would be a lot easier to chop off the top, but I would
loose the ability to use the extensions that fit inside the top of the
mast.
I'm also considering to just buy a 15' wave mast, the easiest of all,
but an expense.
Any opinions? Am I cutting off too much. How would the bend character-
istics change. I don't know the specs, but I think its a 7.0 din.
My guess is its a hard top, and seems to flex most just above the boom.
/Dan