[Alberg30] A30 mast support beam
Mike Lehman
sail_505 at hotmail.com
Sat Feb 23 12:54:36 PST 2002
Dan,
Just a couple of things to add...
1. I was mistaken on the thinkness it is 3/8" not 1/2" aluminum.
2. When choosing the bolts, buy ones that are not threaded all the way to
the head.
3. As a final step I made some wood braces that attached to the bulkhead
stiffeners on either side of the door. I made these from oak and stained
them to match teak in the boat. It seemed important to fit tight to the
underside of the beam, so I trimmed them with a belt sander until I was
happy with the fit. See the last picuture at
http://alberg30.org/collaborate/moin.cgi/DeckBeamRepair
It's hard to see in the picture, but I accomplished the goal of making look
like an original part of the boat.
4. It is important to note, for everyone, that the mast does not sit
directly on the beam, only the after edge. As the back stay is tightened the
mast twists by putting more pressure aft which is why you always see the
deck deflected behind the mast. To minimize this affect make sure the mast
base is pushed as far forward as possible on the step.
That's all folks - Dan, if you need help you can always call me. Good luck.
----Original Message Follows----
From: Dan Morley <dan.morley at sympatico.ca>
Reply-To: public-list at alberg30.org
To: public-list at alberg30.org
Subject: Re: [Alberg30] A30 mast support beam
Date: Fri, 22 Feb 2002 23:58:25 -0500
Wow!, Mike,
I intend to undertake this repair within 5 weeks, and the information
you
have provided will be extremely helpful. Many thanks for taking the time to
pass it on.
Dan Morley (#322)
Mike Lehman wrote:
> OK, I am caught up now and can spend some time talking about the beam
repair
> to the A30.
>
> First let me reinforce what George has already stated: this repair was
> designed by Bruce Rankin who was a professor of engineering at the US
Naval
> Academy. Bruce, more than anyone I have ever met, could tell you the
sheer
> strength of just about any material just by looking at it. Bob Marshall,
> original owner of #215, also deserves a lot of credit, since he started
this
> with some early reinforcement plates over 25 years ago. To the best of my
> knowledge, over 100 Albergs have had this repair and it has withstood the
> test of time on boats that are raced hard (i.e. 28 knots on the deck,
gusts
> to 35, full main and #1 genoa).
>
> Having said that, I am not saying there isn't a better way...but I know
this
> one works and is permanent. The job is about a 10 hour project.
>
> The mast does not have to be removed. The shrouds need to be loosened
> considerably. As you use a house jack to crank the beam back into place,
you
> will need to check the shrouds because it is surprising how much they
> tighten as the beam is raised. It is not uncommon to find a beam that is
> 2"-2-1/2" deflected on boats that have been raced hard. Care should be
taken
> to make sure you spread the load both top and bottom with several layers
of
> 2x6's, otherwise you will crush the cabin sole (with or without the mast
in
> place). It is advisable, although not necessary, to crank the beam back
in
> stages...a couple of turns today, a couple of turns next weekend, etc.
> (depends on how strong you are).
>
> Once you are satisfied that the beam is positioned to the original spot
> (check it with the curve/spacing of the door), you can make a template
from
> cardboard. This was not difficult. The after plate is 54"[?] (doing this
> from memory)and the forward plate was 51"[?]. The important part, of
course,
> is the top curve and the angle on the ends. Trim the cardboard until you
are
> pleased with the fit, then tape into place and simply trace the bottom
> curve. I made the templates about 1/8" narrower than the beam itself. The
> aluminum plates themselves will need 'touch up' with a belt sander,
because
> nothing ever fits exactly the way it is supposed to, plus you will want
to
> 'knock off' the sharp edges. From the reports I have gotten the plates
> provided from my template by Washington Aluminum seems to fit pretty
well.
>
> Now that you have a template, it's time to find the aluminum for the job.
I
> used 0.50" 6061 grade aluminum and found that it was nearly as expensive
to
> buy the raw aluminum and cut it myself as it was to have it
professionally
> cut using a water jet process by Washington Aluminum. I spend a whole
> afternoon on the phone looking for local sources and advice from machine
> shops and finally decided on Washington Aluminum, becuase they were local
> and had the experience and the price was reasonable.
>
> Using the belt sander, you can trim the plates until you are satisfied
with
> the fit and you are now ready for permanent installation.
>
> All of the existing bolts can be removed from the beam (actually, you can
do
> this early because it being supported by the jack). I decided that I did
not
> want any additional holes in the beam, so planned to use the exisiting
> holes. Using several "C" clamps, clamp the first plate into place, and
using
> a 1/4" x 6-1/2" drill bit, drill from the opposite side just enough to
mark
> the plate. Remove the plate once all of the holes are marked, and drill
the
> aluminum with 5/16" holes (I increased the bolt diameter because the
> original bolts were all bent). Drill the holes in the wood beam out to
> 5/16". Put the plate back in place using the bolts to hold it in
position.
> Now clamp the opposite plate in place, and drill enough to mark it just
like
> you did the first one. Once everything is drilled put it all together
*dry*
> to make sure everything is going to fit.
>
> I used West System aluminum etch to wash the plates so I would have a
good
> bond with the epoxy. Mix up thickened epoxy, paint the wood beam
liberally,
> getting it into the cracks as much as possible, work rapidly to bolt
> everything together. Clean up your mess and go have a beer.
>
> In a week or so you can remove the jack. Using a marine caulking, caulk
all
> the edges, and when dry you are ready for paint. Walla - a permanent
repair
> - now pay attention to where the forward lowers attach, because the loads
> are still there you have just transferred them to another part of the
boat.
>
> Hope this helps, good luck.
>
> ----Original Message Follows----
> From: "Furey, Bill (CORP)" <bill.furey at corporate.ge.com>
> Reply-To: public-list at alberg30.org
> To: "'public-list at alberg30.org'" <public-list at alberg30.org>
> Subject: RE: [Alberg30] A30 mast support beam
> Date: Thu, 21 Feb 2002 12:34:34 -0500
>
> George: couple of dumb(or maybe not) questions- 1. Can you jack the beam
> up(carefully)
> with the mast in place-if so-some tips,pls.
> 2. Assuming one uses the Washington Inc aluminum plates(they have them
for
> my boat,
> A-35($285 a pair)- when you jack up the beam & fasten on the plates, to
the
> beam-
> why won't the beam sag again(this from a non-engineer with a slight
dislexic
> problem-
> maybe they're one & the same)I understand you glass or seal the
extremities
> & the overhead,
> but is this enough??-thks.
>
> -----Original Message-----
> From: George Dinwiddie [mailto:gdinwiddie at min.net]
> Sent: Thursday, February 21, 2002 11:52 AM
> To: public-list at alberg30.org
> Subject: Re: [Alberg30] A30 mast support beam
>
> Dan,
>
> Jan Grodzinski posted (on the member list) a company that digitized
> and cut the plates for him. I've copied the company address to
> http://www.alberg30.org/maintenance/disorganized/deckbeam/repair.html
>
> - George
>
> > Dan Morley said:
> >
> > I have been speaking with Kirk from Washington Aluminum, regarding
> > aluminum plates to reinforce the mast support beam of my 1968 A30.
The
> > shipping / customs procedures for shipping to Canada are expensive and
> > awkward - not to mention the very unfavourable $ exchange! My beam
does
> > not appear to have sagged at all, but is just starting to delaminate.
> > Thus, I think I could use my exisitng beam as a template, and have the
> > plates manufactured locally (but might this be a bad idea?). I am
> > wondering, however, if there is a chance someone out there already has
> > templates for the repair plates?
> > Thanks
> > Dan Morley (#322)
>
> --
> ----------------------------------------------------------------------
> George Dinwiddie gdinwiddie at alberg30.org
> The gods do not deduct from man's allotted span those hours spent in
> sailing. http://www.Alberg30.org/
> ----------------------------------------------------------------------
>
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Mike Lehman
"Gilleleje" #505
(410) 544-9067
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