[Public-List] Mast beam

Fri May 31 04:49:43 PDT 2013

Mike,

So all boats came stock from Whitby with the beam through bolted to the
bulkhead?

-jeff

Jeff Fongemie
#116 Seagrass

http://picasaweb.google.com/fongemie

On Fri, May 31, 2013 at 7:40 AM, Mike Lehman <sail_505 at hotmail.com> wrote:

> Glenn
>
> You may not like the appearance of the aluminum sister plates...but they
> have never failed. We have had boats racing in 50 knot winds with large
> waves and driving hard without a beam failure once the beams have been
> properly reinforced.
>
> On all of the boats the bulkheads support the beam and the deck, the
> vertical oak pieces along the bulkheads are stiffeners that prevent the
> bulkheads from buckling under high loads. The main problem is the beam is
> not well supported under the aft end and the mast sits on the aft side of
> the beam which causes the beam to twist back. The solution to this is to
> add knees to the existing oak supports to prevent the twisting.
>
> On the liner boats the problem is a bit different. I you carefully inspect
> the bottom of the bulkhead you will see that is rests on the floor liner
> and there is not adequate support under the floor. This is the problem that
> George mentioned in an earlier post on this subject. Adding extra support
> under the floor to transfer the load to the hull solves this.
>
> One main problem with ALL the boats is the bolts that Whitby used are 1/4"
> threaded all the way to the head of the bolt. These bolts were used on the
> chainplates and the main beam. When these old bolts are removed they are
> often bent, especially the main beam bolts. They should ALL be replaced
> with 5/16" shoulder bolts. The increase in strength is almost 3x because of
> the increase in diameter and especially because of the shoulder.
>
> I don't think push the sag out of a beam in the liner boats, but you can
> stop its progress.
>
>
>
> ~~~_/)_/)~~ Mike Lehman ~~_/)~~~
>
>
> -----Original Message----- From: Glennb
> Sent: Thursday, May 30, 2013 11:18 PM
> To: fongemie at gmail.com ; Alberg 30 Public List -- open to all
>
> Subject: Re: [Public-List] Mast beam
>
> Jeff,
>
> My boat, Dolce is a pre-liner boat, built in 1968.  when I bought the boat
> the mast support beam was partially delaminated on one side - several
> laminates, varing lengths up to 1/3 length of the beam were separated.    I
> sailed the boat for two seasons this way then replaced the beam spring time
> of my third year when the delamination became worse.  I mention this
> because the beam was serviceable even when partially delaminated.
>
> Rather than put in the aluminum plates described on the alberg30 site, I
> opted to saw a bigger one piece  4x6 beam out of purple heart.  This
> required a 4 x 12 beam to start with, as the crown of the beam extends the
> height of the beam vertically something over 9" top to bottom.  I
> reinstalled the sawn and shaped beam by glassing in the ends and thru
> bolting to the  plywood bulkhead.  Same method as the original.  I went
> oversize on the beam because I wanted a stout, permanent ocean service fix.
> Probably overkill now, but I never need worry about mast compression!!
> purple heart varnishes up nicely and is good structural-load bearing
> material.
>
> The biggest problem I found is that the forward edge of the cabin top
> curves downward and forward at the upper forward corner of the beam, hence
> I found I had to round and shape the forward corners of the beam and
> forward edge to get a tight fit up against the cabin top.
>
> Where it did not fit snugly, I injected a bunch of 5200 to fill the gap
> and act as a load bearing surface between the beam and the roof top.  This
> seems to have worked well as I have no compression on the door frame etc.
>
> Had I to do it over now, I wouldnt hesitate to cut laminate strips out of
> oak or some other nice hardwood and epoxy a beam together as you are
> thinking about doing.  sawing a whole one piece beam also works well but
> uses more material.  (I never have liked the idea of bolting up aluminim
> plates over damaged/delaminated structural beams. The damaged beams will
> only continue to delaminate and fail behind the aluminum- eventually
> becoming nothing but a loose pile of laminate material wedged together by
> some metal.  Just doesnt seem like a seamanlike fix + wood compression
> beams look great when varnished.)
>
> If you really wanted to reinforce the load bearing beams, you could put in
> beefier vertical posts, maybe knees up against the  beam, bolted and glued
> to the bulkhead.  this would certainly carry the load better. You wold
> probably need to install loading pads on the hull, to receive the bigger
> beams, as you wouldn't want small hard spots on the hull to receive the
> additional  downward compression loads larger beams would deliver.  However
> I've found the alberg cabin top and bulkhead is extremely robust and strong
> to begin with, so perhaps the extra vertical supports are overkill.  On the
> other hand Yves Galinas, of Jean du Sud fame recommends making up a
> removable vertical mast support beam to wedge in place under the mast when
> sailing in heavy weather.  So your call depending on what kind of sailing
> you might eventually decide to do.
>
> The most work went into picking away at the original fiberglass beam ends
> and shaping the beam to fit back into the space.  The project is definitely
> doable.  But worth the extra effort when done right!
>
> Good luck,
>
> Glenn
> Dolce 318
>
> Sent from my iPad
>
> On May 30, 2013, at 2:24 PM, Jeffrey <fongemie at gmail.com> wrote:
>
>  Hi everyone,
>>
>> I'm diverting the conversation here talking about a pre-liner boat (sorry)
>> but I also need to do something with my boat's mast beam.
>>
>> https://plus.google.com/**photos/115571802364472829939/**
>> albums/5182769471833731569<https://plus.google.com/photos/115571802364472829939/albums/5182769471833731569>
>>
>> I keep thinking that I want to rip it out and laminate a new one to the
>> same curve. One thing I'm a little unclear on is exactly how the beam
>> transfers the load onto the hull. If you look at the my images in the
>> link,
>> the fiberglass tabbing to the cabin side can't do much, or the bulkhead
>> that it is bolted to. Seems the support posts must be doing all the work,
>> but they don't even sit squarely under the beam. What the heck holds up my
>> mast?
>>
>> Jeff Fongemie
>> #116 Seagrass
>>
>> http://picasaweb.google.com/**fongemie<http://picasaweb.google.com/fongemie>
>>
>>
>>
>>
>>
>>
>>
>>
>> On Thu, May 30, 2013 at 4:57 PM, Kris Coward <kris at melon.org> wrote:
>>
>>
>>> I also get a bit of a dip on 583, but it's enough to cause slight
>>> problems with the doors. I've been tempted to address mine by either
>>> re-hanging the hanging locker/vee berth door a smidge lower, or sanding
>>> off the top 1/8" or so, but I already confound that door with the filler
>>> cushions always in place in the vee, so that fix is quite far down my
>>> to-do list.
>>>
>>> -Kris
>>>
>>> On Thu, May 30, 2013 at 04:44:54PM -0400, David Gilbert wrote:
>>>
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-- 
______________

Jeffrey Fongemie

<http://instagram.com/jfongemie>

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