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Old 01-01-2017, 09:26   #31
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Re: glassing plywood prior to hull installation

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Originally Posted by Scout 30 View Post
You might want to post this question on the WoodenBoat Forum. It's a specialized boat building forum. I can guarantee that you won't get any ridiculous recommendations to build with polyester resin there. Cold molded & stitch n' glue boats are always built with epoxy for a reason. When you get a boat kit from Chesapeake Light Craft they send you epoxy for a reason. Sam Devlin builds stich n' glue boats worth hundreds of thousands of dollars with epoxy for a reason. Call up Sam Devlin & ask him why he's not using polyester resin. I'm sure he could use a good laugh although what ramblinrod is proposing is not very funny. I've seen the disastrous results of taking the cheap route with polyester resin firsthand & it's not pretty. And good luck ever selling a wooden boat built with polyester resin. In fact, good luck giving it away.
Let's not get ridiculous here.

Almost every production fibreglass boat built in the last 50 years has been with polyester FRP over wood.

Millions and millions of boats.

Many still going strong.

Polyester resin FRP over wood boats commonly outlive their original purchasers/builders IF it is done correctly.
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Old 01-01-2017, 09:29   #32
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Re: glassing plywood prior to hull installation

I do appreciate all the reply's and I want to touch on a few points because it seems like my intent in posting the question here was somewhat misunderstood.

My intent was simply to have a discussion on the pros and cons and a general philosophical debate on this particular construction method. However some seem to have taken my question as I was asking like a deer caught in the headlights attempting to build a boat based on the musings of various posters from the web. Quite the contrary, I'm a data and research nerd when it comes to my projects.

I'm certainly a nautical and boat building rookie and some of the advice here was outstanding, and is exactly the reason I read this forum. It's hard to interpret tone and inflection with online posts, additionally is is very difficult to know how your point was taken or received. With that said, a couple of statements made my brow arch. If I misunderstood the writers intent I sincerely apologize.

I'm new to boats, but not to construction. I've built, plumbed and wired homes. I have built nearly every piece of furniture in my home so I am no stranger to plywood and its properties.

I've worked with epoxy and fiberglass with good results, but I'm aware of it's limitations to an extent. I have read Larry Pardey's book (among many others on boat building and construction) and his suspicions on epoxy. I have also read things from the Gougeon brothers extolling it's limitless virtues. I'm sure the truth lies somewhere in the middle. All my structural joints will be done with resorcinol adhesive. I recognize this can be difficult to work with but I have the equipment and facilities to, I hope, facilitate a good result. I am completely unfamiliar with polyester resin and even after the spirited for/against debate here I will not be using it at all, regardless.

So to clarify I came here, to this forum, as part of my learning process, not my only process. I believe it is part of my due diligence, beyond just reading books and talking to professionals, to speak with regular experienced boaters. I would hope that simply posing a question on a forum would not imply that the poster does not have the ability to complete his project.

I have talked with Mr. Buehler at length (actually is health has not been great but he says he is doing better now) and asked him enough questions that he probably dreads my emails. However his availability and response time has been excellent, all part of the deal when you buy your plans from him.

I should have described my situation better to begin with, as I said it can be difficult to get your true message out on an online forum. This method was described by Mr. Buehler but he has never done it, as I believe his boat building days are behind him. So Having never done it myself I posted the question here. Simply to see if anyone had any experience with it, or having extensive personal boat building knowledge, get their opinion of the idea.

That's all, I'm not headed out to the shop to do it all today. I will determine my best course of action when the time comes based on my research, of which, this forum is just a part. So again, thanks for all who posted so much great info. Your points were received......I think.
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Old 01-01-2017, 09:41   #33
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Re: glassing plywood prior to hull installation

Kinda seemed like you mighta had a little 'construction experience' from the pictures of your boat shed...good luck with the project.
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Old 01-01-2017, 09:48   #34
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Re: glassing plywood prior to hull installation

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Kinda seemed like you mighta had a little 'construction experience' from the pictures of your boat shed...good luck with the project.
That was a fun one though. Love when you can be off by an 1/8th here or there. After all, it's just a temporary structure.
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Old 01-01-2017, 10:59   #35
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Re: glassing plywood prior to hull installation

The Ducks are awesome go anywhere boats. Good luck with the project!
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Old 01-01-2017, 14:43   #36
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Re: glassing plywood prior to hull installation

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All my structural joints will be done with resorcinol adhesive. I recognize this can be difficult to work with but I have the equipment and facilities to, I hope, facilitate a good result.
As the hull will be multiple layers of plywood does this mean that you will be gluing the layers together with resorcinol?
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Old 01-01-2017, 15:13   #37
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Re: glassing plywood prior to hull installation

Resorcinol is a great glue but it has no gap filling properties. The joints must be really well fitting & well clamped. Epoxy is more forgiving in this regard.











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Old 01-01-2017, 15:35   #38
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Re: glassing plywood prior to hull installation

Re: poly adhesive qualities.
I had a marine business and before that was a shipwright and spent many years on the water. I fiberglassed a lot of commercial decks and repaired many poly decks. Usually when stripping a poly glass deck, all one has to do is get under an edge, pull up and the whole covering come up. I'm not an engineer, but experience has shown, poly has a adhesive value very close to zero. Epoxy on the other hand is a bitch to remove.
Epoxy with Wests' high density filler has an even higher gluing ability. I have machined it, drilled and threaded it and use it to set all my screws in it to stop water entry. I have to use an impact tool to get the screws out.
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Old 01-01-2017, 16:31   #39
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Re: glassing plywood prior to hull installation

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Originally Posted by Lepke View Post
Re: poly adhesive qualities.
I had a marine business and before that was a shipwright and spent many years on the water. I fiberglassed a lot of commercial decks and repaired many poly decks. Usually when stripping a poly glass deck, all one has to do is get under an edge, pull up and the whole covering come up. I'm not an engineer, but experience has shown, poly has a adhesive value very close to zero. Epoxy on the other hand is a bitch to remove.
Epoxy with Wests' high density filler has an even higher gluing ability. I have machined it, drilled and threaded it and use it to set all my screws in it to stop water entry. I have to use an impact tool to get the screws out.
What can I say, I have been working with polyester and epoxy resins for
40 years and currently own a marine service business, where approximately 25% of our business is working with fibreglass and gelcoat.

I repair several boat decks per year. All are polyester resin FRP over wood. Where deck penetrations have permitted moisture ingress, delamination may occur. This can be peeled off easily. (So can epoxy based FRP, just as easily.) Where delamination has not occurred due to moisture ingress, if one attempts
peel polyester based FRP it will pull the surface of the wood off with it. (In other words the bond has not failed and is stronger than the wood it is adhered to.
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Old 01-01-2017, 16:56   #40
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Re: glassing plywood prior to hull installation

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Originally Posted by ramblinrod View Post
What can I say, I have been working with polyester and epoxy resins for
40 years and currently own a marine service business, where approximately 25% of our business is working with fibreglass and gelcoat.

I repair several boat decks per year. All are polyester resin FRP over wood. Where deck penetrations have permitted moisture ingress, delamination may occur. This can be peeled off easily. (So can epoxy based FRP, just as easily.) Where delamination has not occurred due to moisture ingress, if one attempts
peel polyester based FRP it will pull the surface of the wood off with it. (In other words the bond has not failed and is stronger than the wood it is adhered to.
Enough of this BS. Polyester resin is not a glue. Period. Epoxy is a glue. Period. Polyester resin's strength in boat building is that subsequent layers, if applied before the previous layer has cured, create a molecular bond and so a thick strong layup can be achieved. However, if polyester resin is applied after the previous layer has cured it becomes a secondary bond & has little strength. It is not appropriate for use in repairs where secondary bonds are always required.

You can continue to take advantage of your customers by using a substandard product and there's nothing we can do about it but if you're going to come on this forum & try to pretend that what you're doing makes sense you're gonna get called on it.
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Old 01-01-2017, 17:20   #41
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Re: glassing plywood prior to hull installation

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Originally Posted by ramblinrod View Post
What can I say, I have been working with polyester and epoxy resins for
40 years and currently own a marine service business, where approximately 25% of our business is working with fibreglass and gelcoat.

I repair several boat decks per year. All are polyester resin FRP over wood.
I doubt any builder would describe a fiberglass boat as "polyester resin FRP over wood."

Properly called cored fiberglass by the industry worldwide.

A lot different than cold moulding with polyester and then covering with polyester.
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Old 01-01-2017, 18:37   #42
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Re: glassing plywood prior to hull installation

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Originally Posted by mitiempo View Post
I doubt any builder would describe a fiberglass boat as "polyester resin FRP over wood."

Properly called cored fiberglass by the industry worldwide.

A lot different than cold moulding with polyester and then covering with polyester.
The wood and fibreglass doesn't know who calls the process what.

I don't know what more I can say other than properly performed polyester FRP layups and repairs are as strong as they need to be.

Every wood cored polyester FRP boat, every boat with polyester FRP tabbed bulkhead, is a testament to this fact.

To not accept this is to ignore reality.
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Old 01-01-2017, 20:55   #43
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Re: glassing plywood prior to hull installation

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Originally Posted by Scout 30 View Post
Enough of this BS. Polyester resin is not a glue. Period. Epoxy is a glue. Period. Polyester resin's strength in boat building is that subsequent layers, if applied before the previous layer has cured, create a molecular bond and so a thick strong layup can be achieved. However, if polyester resin is applied after the previous layer has cured it becomes a secondary bond & has little strength. It is not appropriate for use in repairs where secondary bonds are always required.

You can continue to take advantage of your customers by using a substandard product and there's nothing we can do about it but if you're going to come on this forum & try to pretend that what you're doing makes sense you're gonna get called on it.
BS indeed...

glue
ɡlo͞o/
noun
noun: glue; plural noun: glues
  1. 1.
    an adhesive substance used for sticking objects or materials together.

    verb
    fasten or join with or as if with glue.


    The word 'Adhesive' may be used interchangeably with glue, cement, mucilage, or paste,[1] and is any substance applied to one surface, or both surfaces, of two separate items that binds them together and resists their separation.
And polyester resin certainly seems to fall under that definition...

The failures associated with polyester mostly come from their application,
not from the formulation of the resin itself; to pretend otherwise borders on fantasy.

With apologies to Scott for the hijack, some pictures from various repairs and refitments, all on boats made from polyester resin and wood, and all repairs done with polyester resin.

First picture. The blue chisel is stuck between the glass and the plywood.
When I finally got the inner skin off, I had to cut the 1 1/2 plywood transom laminate into 6" wide sections with a skilsaw and chisel if off in pieces to remove it from the outer skin. That is what I would call a successful lamination of wood and polyester resin.

Second picture. A wheelbarrow full of completely saturated and about half rotted transom material from a Wellcraft skiboat. Note the fiberglass mat still sticking to some of the larger pieces of not-yet-rotted plywood. This was caused by the still tenacious bond of the wet wood to the outer fiberglass skin.

Picture three. The red circled areas show where the transom plywood, though water saturated, delaminated the fiberglass skin when it was removed. The brown areas are where the wood had just completely rotted away; kinda hard to expect polyester resin to stick to humus...

Picture four. Shows the beginning of a re-repair on a little 33' Egg Harbor sportfisher rear deck. As will be seen, even though there is only about 30 percent contact between the wood and the fiberglass, the bond is quite substantial.

Picture five. The area circled in yellow on the wood had no contact at all with the fiberglass (as seen by the mirrored, glossy areas) of the deck itself.

Picture six. Just another view, better showing the tenaciousness of the polyester/wood bond, where it contacted the fiberglass. As Rod stated, the bond between the two ripped the wood apart before the bond failed.

Picture seven. Showing the beginning of a bit more proper repair; grinding down to solid glass.

Picture eight. A heavily saturated layer of mat to even things out and provide a better bond with what's to come...

Picture nine. Which is, for a variety of reasons, not wood, but 1" scored, (if I remember correctly) 6 lb density, PVC foam. The foam is set in fairly wet isophthalic polyester resin/glass bead paste, and covered with a 2 layers of 18 oz roving and a layer of ounce and a half mat. The rib components are 3"x3", and glassed with the same schedule. The result is very stiff; there are no center supports. A 1" crown is also now built into the deck, to prevent pooling.

Picture ten. Prior to gelcoating/nonskidding. The slight crown is noticeable.

Picture eleven. The finished product. Lighter, stiffer and rotproof.
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Old 01-01-2017, 22:52   #44
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Re: glassing plywood prior to hull installation

Quote:
Originally Posted by Scout 30 View Post
Enough of this BS. Polyester resin is not a glue. Period. Epoxy is a glue. Period. Polyester resin's strength in boat building is that subsequent layers, if applied before the previous layer has cured, create a molecular bond and so a thick strong layup can be achieved. However, if polyester resin is applied after the previous layer has cured it becomes a secondary bond & has little strength. It is not appropriate for use in repairs where secondary bonds are always required.

You can continue to take advantage of your customers by using a substandard product and there's nothing we can do about it but if you're going to come on this forum & try to pretend that what you're doing makes sense you're gonna get called on it.
Thank you for your input.

In total, I perform about 200 to 500 secondary mechanical polyester bond adhesions on various boats per year.

I teach FRP repair. I demonstrate how similar techniques can be used with polyester resin and epoxy, the differences in using hardener for epoxy resin vs MEKP catalyst for polyester resin, and the pros and cons of each.

It is my understanding that secondary mechanical bond polyester resin adhesions have been successfully performed since the invention of fibreglass boats.

Here is a photo of one of the many polyester resin FRP fractures that were in the hull of my current personal boat.



Here is a photo of the polyester resin FRP repairs I performed in fall of 2012.

Note that the boat was built in 1975, so these repairs were definitely secondary mechanical bonds and not primary cross-linked chemical bonds.



Here is a photo of the finished product in spring of 2013 after Awlgrip.



Here is a photo of my boat in spring of 2016, after about 3000 nm of sailing since the 2012 polyester resin FRP repairs, in all conditions Lake Ontario could throw at us.



So far, I have had no secondary mechanical bond failures since I started using polyester resin 40 years ago. Just beginner's luck I guess. ;-)
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Old 02-01-2017, 01:47   #45
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Re: glassing plywood prior to hull installation

Guys, you can start a polyester vs. epoxy thread 24/7. The forum's always open, & starting a thread is free.


To the OP, what's the plan to provide clamping power when gluing on the layers. As 10mm plywood (in sheets) will have a lot of spring back. Probably more than staples can contend with, especially well enough to prevent any gaps or voids in between each layer. Which is critical when using resourcinal.

Also, using epoxy has the advantage that it'll encapsulate each piece of wood. So that it becomes fairly impervious to water, & thus, rot. Plus this will also prevent water from setting up shop somewhere in your laminate & being frozen during colder weather. Something which would probably wreak havoc with the structure, & it's structural properties.

Yep, it'll cost more... well, in the short run anyway.
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