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Old 24-02-2020, 05:42   #1
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Structural Reinforcement WITHOUT Using Epoxy?

I have acres of roof on my deck house.

I had initially designed in a forward cockpit like Gunboats use, buy have found a more elegant solution to managing the rig. The forward cockpit previously took a lot of the roof load. With it gone, the roof is going to be pretty floppy.

I need to either add verical columns (not as good), or... Add structural reinforcement in the form of beams across the span of the roof.

I can add these inside to make things look nicer as I'm going to have a drop ceiling anyway for looks.

Ideally, I'd be glassing on some beams running the length of the ceiling (as pictured here).

How can I permanently and structurally attach these WITHOUT epoxy? Specifically looking for structural adhesives that will work to continuously hold the load of the roof. I do have polyester but the roof is already epoxy.
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Old 24-02-2020, 06:27   #2
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Re: Structural Reinforcement WITHOUT Using Epoxy?

Note:. The beam will be pre built from foam/polyester/glass or possibly just be a lightweight wood. Then it needs bonding to the surface of the ceiling which is roughed up epoxy/glass.
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Old 24-02-2020, 06:33   #3
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Re: Structural Reinforcement WITHOUT Using Epoxy?

What's the reason for wanting to avoid epoxy to install the beam? Personally, I'd think epoxying it on or glassing it on with epoxy would be the best way to do it.
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Old 24-02-2020, 06:47   #4
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Re: Structural Reinforcement WITHOUT Using Epoxy?

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What's the reason for wanting to avoid epoxy to install the beam? Personally, I'd think epoxying it on or glassing it on with epoxy would be the best way to do it.

The reason:

Sunday, we decided to epoxy up a pair of 6' x 1" strips on land, 300' away from the boat. Used about 12oz of epoxy.

Everything used on these strips 300' away was immediately thrown into the trash after use and the strips were left there, 300' away overnight.

I did not touch any of the epoxy work or go near it other than for a 30 second inspection where I stayed upwind of it. My girlfriend did all the work and pretty much bathed in vinegar at every opportunity. We were meticulous about not getting any near me.

Later that evening, all my joints started hurting, my lungs got phlegmy and stiff and hurt (I couldn't breathe), my airways, sinuses were on fire, my eyes were developing a film over them making vision blurry and I broke out with a couple dozen hives from ankles to elbows to head.

All while on antihistamines. Came very close to starting Prednisone to help treat it before realizing it would have no effect until after the reaction subsided.

And this was with the work 300' away from me.

I absolutely can't use epoxy without possibly dying. Things are getting worse in that department.
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Old 24-02-2020, 06:49   #5
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Re: Structural Reinforcement WITHOUT Using Epoxy?

I don't know why epoxy is out, but maybe 5200? That's what a lot of boats have connecting the deck to hull joint, with some fasteners.
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Old 24-02-2020, 06:53   #6
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Re: Structural Reinforcement WITHOUT Using Epoxy?

That's not good. Other than mechanically fastening the beams, I can't think of a good solution. I'm not sure a non-marine construction adhesive would do well in that application. Being that the roof is epoxy, polyester resin won't stick, so that option is out.

What does the construction of the roof look like? Cored or solid and how thick?
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Old 24-02-2020, 06:54   #7
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Re: Structural Reinforcement WITHOUT Using Epoxy?

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I don't know why epoxy is out, but maybe 5200? That's what a lot of boats have connecting the deck to hull joint, with some fasteners.
Was definitely considering 5200. Does it do well in tension?

That's what I'm seeing as the forces here. The beam will want to pop off the ceiling from weight and wave action. Can 5200 hold up to constant tension?
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Old 24-02-2020, 06:56   #8
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Re: Structural Reinforcement WITHOUT Using Epoxy?

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Originally Posted by rslifkin View Post
That's not good. Other than mechanically fastening the beams, I can't think of a good solution. I'm not sure a non-marine construction adhesive would do well in that application. Being that the roof is epoxy, polyester resin won't stick, so that option is out.

What does the construction of the roof look like? Cored or solid and how thick?
Roof is 1" thick foam core with 64oz of glass top and bottom. The entire boat is very light weight and I'm hoping to keep it that way. Every decision was made toward performance/weight.

I was thinking mechanical as well but was hoping for a more elegant solution with something like 5200 or other adhesive really good in tension.
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Old 24-02-2020, 07:01   #9
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Re: Structural Reinforcement WITHOUT Using Epoxy?

Does the beam have an arch to it?
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Old 24-02-2020, 07:02   #10
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Re: Structural Reinforcement WITHOUT Using Epoxy?

5200 is somewhat flexible and has pretty good tensile strength. As long as there's enough surface area relative to the load it would probably work. Flanging the top of the beams to make their contact surface wider might be beneficial for that option. I assume the beams will be attached to the walls or something and not just suspended from the ceiling, correct?

With a foam core, unless the bottom skin is pretty thick I don't think there would be a good way to mechanically fasten the beams, so we can probably toss that option unless someone can think of a way to secure the fasteners without having to epoxy a threaded insert into the structure.
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Old 24-02-2020, 07:06   #11
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Re: Structural Reinforcement WITHOUT Using Epoxy?

I think you need to have it done by someone else with you nicely tucked away in a resort nearby

btw, I recommend to glue a foam core to the ceiling, then glass over that. You can buy pre-shaped cores for this but not sure if they are available where you are. You need good radius corners so the glass will accept it. I would use 4 layers of 1708 with the first one the largest so as to feather out over the ceiling.

You have gravity working against you, I did something similar last year; you need multiple persons, minimum one holding up the rolled up glass and one or two attaching it, working down the beam/stringer as you go.
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Old 24-02-2020, 07:08   #12
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Re: Structural Reinforcement WITHOUT Using Epoxy?

I'm a little confused about this beam wanting to fall away from the ceiling. Is it not there to support the ceiling's weight? or is it there to add rigidity to a flexible roof?



If the former, then the adhesive will not be under much tensile load, since the weight of the ceiling will press the ceiling against the rigid beam. If the latter, then most of your forces are in shear, which is where adhesives shine. Unless you are gluing this beam to the ceiling to then suspend a load from the beam.



Also, if there is a curve to both the ceiling and the beam, then that converts the downwards forces into shear loads.
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Old 24-02-2020, 07:11   #13
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Re: Structural Reinforcement WITHOUT Using Epoxy?

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Does the beam have an arch to it?
Yes. There is a slight camber to the roof. It's higher at the center than at the edges.
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Old 24-02-2020, 07:13   #14
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Re: Structural Reinforcement WITHOUT Using Epoxy?

Is the beam going to be supported at each end, by something at the walls?
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Old 24-02-2020, 07:16   #15
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Re: Structural Reinforcement WITHOUT Using Epoxy?

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Originally Posted by Muaddib1116 View Post
I'm a little confused about this beam wanting to fall away from the ceiling. Is it not there to support the ceiling's weight? or is it there to add rigidity to a flexible roof?



If the former, then the adhesive will not be under much tensile load, since the weight of the ceiling will press the ceiling against the rigid beam. If the latter, then most of your forces are in shear, which is where adhesives shine. Unless you are gluing this beam to the ceiling to then suspend a load from the beam.



Also, if there is a curve to both the ceiling and the beam, then that converts the downwards forces into shear loads.
Ok. You're right.

I think I was messing up my thought process in sheer vs tension.

There is a slight camber to the roof and the beam.

The roof, without the beam (or forward cockpit) will sag, making less of a camber and a floppy, unstable roof.

I need to shore it up with the beam, which I prefer to vertical poles as columns.

I'll pre-position everything with temporary stick supports everywhere as when the roof was initially built. Then bond the beam, then hope the adhesive works.
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