[Public-List] Cutlass Bearing Flange Alberg 30

Thu Jul 22 10:09:43 PDT 2010

Hi Roger,

Seems a waste of effort to me, suggest you read my 9:52 AM post today if you 
have missed it.

Hey, the lag bolts method has worked for 40 or more years ....

Best

John

----- Original Message ----- 
From: "Roger L. Kingsland" <r.kingsland at ksba.com>
To: "'Alberg 30 Public List -- open to all'" 
<public-list at lists.alberg30.org>
Sent: Thursday, July 22, 2010 12:52 PM
Subject: Re: [Public-List] Cutlass Bearing Flange Alberg 30

> Albergers,
>
> I am trying to wrap my head around the idea of tapping fiberglass thru 
> which
> machine screw (or bolt threads) go.  I assume the "grip" on the screw
> exerted by the FG threads would be less than the nut, say, for yucks, half
> as much.  So first one must torque the screw head, say to 50 lbs, into the
> threaded FG then put the washers and nut on the end and torque the head
> and/or nut to 100 lbs.  I suppose it would be possible to 1st torque the 
> nut
> to 50 lbs then tighten the head to 100 lbs.  This way, at least in theory,
> the FG threads would be snug w/ the nut and the nut threads would take the
> additional load that the FG couldn't.  If the head were restrained while 
> the
> nut was tightened (more likely w/ a slot or Phillips head) then even a few
> turns of the nut would likely strip the FG threads.
>
> If the justification for tapping the FG is added strength, I would argue
> that fasteners alone must be more than strong enough to handle the load,
> making the FG threads unnecessary.  Plus another critical component of the
> connection is properly distributing the load via a washer and/or backer
> plate.  The tapped FG won't help in this regard.
>
> I suppose better waterproofing could be a justification but this would 
> only
> occur if the weaker FG threads are not damaged during the installation.
> Plus I would not like to rely on simply a tight fit between screw and FG
> that might degrade if rigging forces cause them to loosen.  I would be 
> more
> comfortable with some kind of "squishy" stuff between the two materials w/
> enough room to flex just a little; what about a slight bevel at the top of
> the fiberglass hole with an appropriately sized "O" ring around the bolt
> shaft that could seat inside the bevel when squished down by a washer or 
> the
> base of a piece of hardware?  This might work for highly loaded hardware,
> like cleats, that should bedded in epoxy to prevent any movement.  I found
> some adhesive, double faced, squishy tape that I put under hatch hinges 
> and
> stanchion bases in the hope that, when I tighten the fasteners, the 
> material
> will expand and seal around the fastener shafts (keeping my fingers
> crossed).
>
> Food for thought for those like me who agonize over this kind of stuff. 
> Any
> opinions?
>
> Roger 148#
>
>
>
> -----Original Message-----
> From: public-list-bounces at lists.alberg30.org
> [mailto:public-list-bounces at lists.alberg30.org] On Behalf Of Gordon Laco
> Sent: Thursday, July 22, 2010 10:18 AM
> To: Alberg 30 Public List -- open to all
> Subject: Re: [Public-List] Cutlass Bearing Flange Alberg 30
> Importance: High
>
> Good points John - you are correct about SS underwater... Bronze can be 
> iffy
> too if the alloy is not correct.
>
> When my cutlass bearing came off I found that one of the bolts had 
> corroded
> to the consistency of a biscuit.  It was just crumbly powder under a head
> that look fine.  I was able to get the stump out by clipping vice grips on
> it and gently turning it out.
>
>
> Gord #426 Surprise
>
>
> On 22/07/10 9:52 AM, "John Birch" <Sunstone at cogeco.ca> wrote:
>
>> Hi Peter,
>>
>> They are lag bolts, tapped into the glass. There are no inserts.
>>
>> Periodically, all bronze bolts underwater should be removed and
>> inspected - perhaps once a decade or so. You should never use SS Bolts
>> (deprived of oxygen, they become active and move the wrong way on the
> periodic table.
>>
>> Buying silicon or manganese bronze marine bolts is hard to do, go to a
>> reputable supplier - in the Toronto area go to Pacific Fasteners on
>> Chauncey Drive off Islington to make sure you are getting the right
>> bronze or monell fastners.
>>
>> There are some instances where drilling and tapping machine screws
>> into fiberglass is helpful to ensure a stronger attachment. One
>> example I've done is the traveler track, another are the winches, all
>> followed with as wide a washer or plate as can be fitted below and
>> then lock washers, thread Locktight and then a nut. It makes for a
>> particularly strong attachment that means the whole glassed area would
>> have to break off - and I cant imagine the load necessary to cause such a
> failure.
>>
>> The cutlass bearing attachment is threaded on to the bronze shaft
>> tube, which is bedded throughout its internal length in the hull with
>> Dolfinite from the factory, or some other adhesive caulk if
>> retrofitted, then the bearing housing turned onto the threads on the
>> tube and then the housing is bolted into place. I suspect the cutlass
>> housing would do just fine without the bolts, but why test the theory.
>> Ensure the lag bolts are going into solid glass and not into resin
>> starved glass and insert them with lots of caulking on the threads.
>>
>> Water migration into the glass will over time degrade the glass. If
>> your holes are degraded, suggest adding a fresh low viscosity epoxy
>> resin to re-wet the glass fibers after ensuring is all dried out.
>>
>> Those lag bolts were cut with a tap to create the threads into the glass.
>> You cant just drill a hole and use self tapping lag bolts or you'll
>> crack the glass. The holes have to be threaded with a tap set first.
>>
>> Caulking is critical to prevent water seepage into the holes, which
>> will eventually break down the resin/glass bond in the area if allowed
>> to seep in.
>>
>> Hope this is a help
>>
>> Best
>>
>> John
>>
>> ----- Original Message -----
>> From: "Jeffrey" <fongemie at gmail.com>
>> To: "Alberg 30 Public List -- open to all"
>> <public-list at lists.alberg30.org>
>> Sent: Thursday, July 22, 2010 8:53 AM
>> Subject: Re: [Public-List] Cutlass Bearing Flange Alberg 30
>>
>>
>>> They screw into the fiberglass. Not sure if there are any inserts or
>>> nuts imbedded in the fiberglass or not. I couldn't tell for sure when
>>> I had mine off this spring. it looked to be just fiberglass.
>>>
>>> -jeff
>>>
>>> Jeff Fongemie
>>> #116 Seagrass
>>>
>>> http://picasaweb.google.com/fongemie
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Thu, Jul 22, 2010 at 8:30 AM, Peter Milley <milleype at kingston.net>
>>> wrote:
>>>>
>>>>
>>>> Do the two bolts behind the propeller on the Al 30, holding the
>>>> cutlass bearing flange to the hull just screw into the fiberglass or
>>>> are there nuts behind them on the inside of the hull?
>>>>
>>>> Peter Milley
>>>>
>>>> _______________________________________________
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>>>
>>>
>>>
>>> --
>>> Jeffrey Fongemie
>>> _______________________________________________
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>>
>>
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>
>
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