Structural Reinforcement WITHOUT Using Epoxy?

[Muaddib1116]

Is there anything preventing you from having the beam dded on top of the roof?

[Chotu]

Originally Posted by Muaddib1116

Is there anything preventing you from having the beam dded on top of the roof?

Just a couple solar panels in the way. Semi- Permanently fixed. I was about to ask this myself.

I have the long fore and aft beams going in that make the dinghy davits and provide more support in that direction.

Cambered beams athwartships outside might work too?

[Muaddib1116]

As long as they are sized properly and built into the roof properly, I don't see why not. It would definitely make laying them up in place viable. And if there's already stuff up there, then it could probably be made to look fine. And you could probably tie them into the davit beams, which wouldn't be a bad thing. As you've said, the roof is already strong enough to stand on, it just needs some additional strength and rigidity.

[Chotu]

Originally Posted by Muaddib1116

As long as they are sized properly and built into the roof properly, I don't see why not. It would definitely make laying them up in place viable. And if there's already stuff up there, then it could probably be made to look fine. And you could probably tie them into the davit beams, which wouldn't be a bad thing. As you've said, the roof is already strong enough to stand on, it just needs some additional strength and rigidity.

I'm a LOT more comfortable having some help do that very simple layup on top of the roof with epoxy. Plenty of dilution with air blowing by all the time and plenty of hot sun to cure it fast.

I'm thinking a nice strip of foam across the roof. Maybe 3" x 3"? Hot glued in place for the layup. Rounded over at the top edges with a router. Another triangular cross section piece on each side glued in all down the length to ease the 90 degree turn between the foam edge and roof. Then a cove with thickened epoxy and do a wet on wet layup of a couple layers of biax on that. Wet on wet from cove to final biax.

2 of the 4 solar panels pictured are currently in place. They are glassed (lightly) to the roof. We could grind that out to gain access to the whole roof for the beam.

And yeah. It's a bit like an RV roof. Lots of stuff up there already. It's got huge freeboard and the roof is about 12' off the water so you don't see the top of the roof from land or from normal size other boats. The beam running across wouldn't hurt aesthetics any more than all the other junk up there.

[Muaddib1116]

Keep the rounded edges to a small radius and the triangular sections small, or just make a fillet of caulking to break the corner. Most of the strength comes from the vertical side walls of the beam, so you don't want to reduce that too much. Personally, I would epoxy the foam beam down, although hot gluing it is probably fine. 3" high sounds pretty good, you could make it a little narrower without losing much strength. It's hard to say without seeing photos of the whole arrangement.

[s/v Jedi]

Originally Posted by Chotu

I'm a LOT more comfortable having some help do that very simple layup on top of the roof with epoxy. Plenty of dilution with air blowing by all the time and plenty of hot sun to cure it fast.

I'm thinking a nice strip of foam across the roof. Maybe 3" x 3"? Hot glued in place for the layup. Rounded over at the top edges with a router. Another triangular cross section piece on each side glued in all down the length to ease the 90 degree turn between the foam edge and roof. Then a cove with thickened epoxy and do a wet on wet layup of a couple layers of biax on that. Wet on wet from cove to final biax.

2 of the 4 solar panels pictured are currently in place. They are glassed (lightly) to the roof. We could grind that out to gain access to the whole roof for the beam.

And yeah. It's a bit like an RV roof. Lots of stuff up there already. It's got huge freeboard and the roof is about 12' off the water so you don't see the top of the roof from land or from normal size other boats. The beam running across wouldn't hurt aesthetics any more than all the other junk up there.

Good solution! I am 6’6.5” so was taken aback by the interior height

I would not use hot glue for the core though. Pro’s use Core-bond which is a polyester based product I think. You want it stuck there permanently.

Are you in the US? If so, you can order about anything

[Cadence]

Originally Posted by Thumbs Up

With temporary stick supports you can camber the roof and have clamping force at the same time. You could do it out of 1x4 lumber, stagger the scarfs if you cant get 16'. try to find some clear fir or mahogany, it wouldn't hurt to run it through a thickness planer a few times, do 4 layers (4x5/8=21/2"). Some tube adhesive for the first layer then Titebond (yellow glue). Dress it up when you are done with a planer or belt sander and upside down router trick. Then just paint or varnish it.

I doubt he would need to worry about scarfs with thin enough laminates and staggered butts.

[blubaju]

Originally Posted by Chotu

The reason:


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.

...

I absolutely can't use epoxy without possibly dying. Things are getting worse in that department.

Try Polyurethane glue.

For Epoxy, I am quite sure your problem is not the epoxy resin but the catalyst. West system have a quite neutral smelling one, quite good epoxy we have in the Philippines, but stinks like urine. You could test it out, but might not be fun.

Anyway, as with all chemicals, work in a well vented area!

[Lightwave99]

Why are you having such a reaction to epoxy? Are you using surgical gloves? Are you wearing a rebreather when you work with it? If not, that is why you and your girlfriend are having problems. We built our whole boat (a catamaran) with epoxy (epoxy & wood for the cuddy cabin/bridgedeck and epoxy and foam core for the hulls) and extended it twice with epoxy. As has been said by others, it is the best glue--if you mix it properly and don't let it get hot--then it is unusable. Buy a 100-pack of surgical gloves at Home Depot and a rebreather for yourself and your girlfriend and PUT THEM ON before you even open the epoxy parts (2 parts).

You can see our boat and our extension process at lightwave99.com.

[exMaggieDrum]

I have seen others build as close as possible irregular camber surface for a tight fit using several spanning pieces of "door skin" (thin plywood often veneered) and a compass to scribe the inside surface. I hope you get the idea with this terminology. You would have to do it fore and aft and get it all aligned up and off. They they would use thin coosa plywood which they scored with a saw so it was bendable and bend and attach it to the "mold". They would dry fit this piece (which might not be possible to get inside your house unless cut in pieces which you might have to do with the built up support anyway. And then make the inside roof on top of the coosa board. I have seen some very nice looking semi-complex parts made this way.



They added "beams" to the inside of the part and laminated or glued those to fit the roof pieces. With a camber with the high part in the middle, it would have large compression strength. The inside roof part would be glued up to the existing roof with close tolerances so that a variety of glues might be used. Anything would have to be gap filling though as you can never get it 100%.



I may have completely misunderstood your requirements though. And I certainly am not a structural builder or engineer. Just a thought.

[doog]

My two cents in this case would be to do some steel or aluminum structural work which can be done with aircraft style technique, pop rivets and marine alloy aluminum. I just built a lightweight cockpit cover and chose epoxy/ply in stitch and glue technique but was considering aluminum as well.. Good luck! Thanks for explaining the issue with epoxy.

[hirondeller]

You don't need to pay a premium for 'marine adhesives'.


At big box stores (Lowes & Home Depot) you can buy Loctite PL premium and Sikaflex Pro in large format tubes; in order to really save $$$ you will need the 'big boy' caulk gun, the cost per ounce is dramatically lower than 3M 5200. Get the 28oz tubes and gun. Seal the cut tip carefully with tape and put the tube in your fridge. Both keep for over a year.



Both are polyurethane adhesives suitable for interior and exterior work. The Sikaflex is more expensive but, like epoxy, it is 'immersion proof' (after seven days of drying). The PL is described as 'waterproof' but not suitable for immersion. The PL premium dries harder and faster and elongates less under tension.


For your project, try the PL. I have been using Sikaflex Pro as a replacement for 3M 5200.


Parenthetically, last week I ran out of 'rubber cement' and used the Sika Pro to patch a bicycle tire inner tube, so far so good. Scuffed the rubber and clamped on the patch for 24 hrs. Amazing stuff.

[merrydolphin]

Wow, so sorry to hear about your reaction. Best solution, get a metal boat!

I know, wishful thinking at this point. My Cal 46 uses aluminum box beams for stiffing both longitudinally and athwartships. The large house is supported from keel and up the hull, accross the decks and up and over the cabin top including around the mast partners. These vessels are very strong many many have circumnavigated. They are all at least 45 yrs old and if given even half way normal maintenance, are still going strong. The beams are mostly glassed in but also in some places bolted instead. You could use aluminum beams and through bolt them. With backing plates or bands. Just a thought. Again sorry for your allergy and goodness, be careful.

[Oldseabee]

You might check out some of 3M's structural tapes. A friend of mine is going to use the VHB tape to mount his solar panels to the roof of his camper. There are some excellent videos on it's strength.

[Redreuben]

Have you considered a methacrylate adhesive like Plexus ?