[Public-List] Fwd: Wood to glass article

[Glenn]

More interesting detail about  glass construction...

Gpb

Sent from my iPad

Begin forwarded message:

> From: "dan at proboat.com" <daniel.spurr at gmail.com>
> Date: September 5, 2013 3:41:46 AM GMT+04:00
> To: Glenn <brooks.glenn at comcast.net>
> Subject: Re: Wood to glass article
> Reply-To: dan at proboat.com
> 
> Glenn
> 
> Sure, pass along my remarks...for whatever they're worth. 
> 
> Another thing to consider when comparing 1960s-era boats to more modern boats...those older boats were laminated mainly with woven roving and chopped strand mat, hand laid with lots of polyester resin. The WR especially added thickness quickly, and weight was not much of a concern. The fabrics have steadily improved as have the processes, such as vacuum bagging that consolidates the laminate. Resin-to-glass ratios improved (less resin, more glass), so that you can get a thinner, lighter laminate that's just as strong or stronger than the old, thicker laminate that also had much more air entrapped. It's not just thickness that matters.
> 
> The big racing multihulls may have 2" cores with 1/8" carbon skins. And they are stiff and strong enough to surf the Southern Ocean at 35 knots. 
> 
> Dan
> 
> 
> On Wed, Sep 4, 2013 at 12:47 PM, Glenn <brooks.glenn at comcast.net> wrote:
> Hi Dan,
> 
> Thank you very much for your reply.  Great perspective on hull thickness. I am a member of the Alberg 30 clan and  am myself guilty of thinking only about the thickest part of the hull - which Is an inch or thereabouts below the waterline, Hence my original interest.  
> 
> If you don't mind I would like to pass on this information to our A 30 list serve as I am sure there are others who are interested In your comments also.
> 
> Best regards
> Glenn Brooks
> SV Dolce #318
> 
> 
> Sent from my iPhone
> 
> On Sep 4, 2013, at 6:53 PM, "dan at proboat.com" <daniel.spurr at gmail.com> wrote:
> 
>> Hi Glenn
>> 
>> Sorry to have taken so long responding.
>> 
>> You raise an interesting question, one many others have asked. There are several answers.
>> 
>> First, many of those early glass hulls were/are not as thick as some people claim. And some owners were misled by where they observed their hull's thickness. For example, if you drilled a hole for a transducer in the turn of the bilge area of a Pearson Triton, it might be an inch thick. But on the side of the keel and in the topsides it's maybe a 1/4" or 5/16" thick (I'm guessing...even though I owned a Triton years ago). So the guy who says, "My hull is a inch thick--wow!" may not be seeing the whole picture.
>> 
>> Years ago, I asked Everett Pearson the same question you asked, about early glass builders building to wood scantlings, and he said, "Nonsense. We had lab tests performed and we knew exactly what we were doing...and our laminates were no where near as thick as wood planks." You can read more about this interchange in my book Heart of Glass. Now out of print but you can find used copies cheap on Amazon.com.
>> 
>> Lastly, Owens Corning Fiberglas commissioned naval architects Gibbs & Cox in the late '50s to write a manual for boatbuilders. Titled Marine Design Manual and published in 1960, it's the first really authoritative and comprehensive treatment of how to engineer fiberglass boats, and while not all builders read it, there was competent, scientific information available. I don't know how many builders approached their work with a serious engineering view, as opposed to a couple of guys in a garage slapping together boats, but certainly many in the industry were well informed. 
>> 
>> Hope this helps.
>> 
>> Regards,
>> 
>> Dan
>> 
>> 
>> On Sun, Sep 1, 2013 at 11:18 AM, Glenn <brooks.glenn at comcast.net> wrote:
>> Hello Dan,
>> 
>>  I have just read your article on line concerning early day fiberglass boat building pioneers, and am fascinated by the historical narrative you report in the article.
>> 
>> So much  so I hope you might be able to shed some light on the big mystery of today regarding early fiberglass boat building: namely, why did early sailboat builders make such heavily laid up hulls?  All the early boats such as Aeromarine and Palmer Johnson Rhodes Bounty, Whidby boat company Alberg 30 and others build stout 1" thick hulls, even though US Navy research and experience in WWII seems to indicate naval architects of the day knew quite a lot about fiberglass structural properties.   I own a 1968 Alberg 30 as well as previous wood sailboats since 1970 have never bought the 1960's naval legend that boat builders coming out of WWII simply did not know the strength properties of Fiberglass, hence built hulls to match the scantlings of comparable size wooden hulls.
>> 
>> Have you ever researched this topic, and if so could you comment on the real historical story behind early day FG construction?  I think it would make a great article.
>> 
>> Thanks very much for any information you could provide.
>> 
>> Best regards
>> Glenn Brooks
>> 
>> Sent from my iPad
>> 
>> 
>> 
>> -- 
>> Dan Spurr
>> Editor-at-Large
>> Professional BoatBuilder
>> www.proboat.com
>> www.woodenboat.com
> 
> 
> 
> -- 
> Dan Spurr
> Editor-at-Large
> Professional BoatBuilder
> www.proboat.com
> www.woodenboat.com