Infusion Q&A

Infuse With Stringers?

I would like to know if infusing a boats hull with the longitudinal and transversal beams of the floor is possible all in one shot?

It would be fairly convenient,because then the hull will come out reinforced and in one piece without extra glueing of the longitdinal and transversal beams.

It might produce some printing in the outer surface of the gel coat ??

someone knows ??

 

We do something very much like this when we infuse a mold. We put on all the reinforcements into the dry-stack and shoot the entire thing in one go. The idea was to hold the overall shape better. I don't think print through would be too bad if you set everything up on top of the core. Without core, I'm betting you'd see them.

Actually we do one part, liner, that has a bulkhead infused into it and it doesn't show any print through from the bulkhead.

-jim lee

 

Here is a picture of a boat hull, the inside infused with the reinforcing grid in 1 go.
The outside of the boat was done seperately, as the boat was built from strip planks.

 

Good thread. Here are the results of a good resin Q&A thread. No dry spots!

 

What do you guys normally do when you end up with a wrinkle that gets locked in by Infusing?

 

I think I had two small wrinkles in the first two half hulls in the same spots.
The next two I replaced the traiaxial in this area with a DB & UD cloth and this eliminated it.
For peace of mind I ground the wrinkle flush and put a patch over the top.

 

Hi Herman;

In the boat you have shown, since, as you said they infused the inside and then the out side is not exactly what I want to do, what I mean is apply the skincoat, even with some extra thickness to avoid printhorough under where the reinforcing grid ( or beams as I called them) then place the corecell cores with the shape of the beams over the skin coat off course place the necessary reinforcement fibers and infuse it.

If I recall it right Everglades boats in the US makes their boats this way but I am not totally sure.

What do you think should it be feasible??

 

The next boats they did, were infused in 1 big shot: outer skin, core, inner skin, reinforcing grid. (this was after they built an (infused) mould, of which I showed a picture as well, with my colleague spraying barrier coat. (after the barrier coat, a skincoat was applied, then the reinforcement stack infused))

Make sure you have a permeable layer below the grid. This could be Soric or CFM (Unifilo)

 

From my humble point of view I think that placing vaccuum lines on top of all the pieces that constitute the reinforcing grid should eliminate any possibility of those high points remaining as dry islands ............

But apart from the problem of making the resin to go to all places under the plastic, what worries me is that when the resin of the hull wants to contract it might find the beams opposing that movement and this might cause some superficial distortions ....


On the other hand, being pieces of the same size and same material should contract the same and thus not induce surface defects ............. but not sure which of the two theories is the valid one .........

 

The permeable layer below the reinforcing grid should dampen distortion as well. This specific customer does not have shrinkage problems.

Oh bummer, he uses epoxy resin... Not polyester.

Why not making a test piece on a glass sheet, then you can see the effects with your materials.

 

Hi folks! I have a resin infusion question or three and this is probably a good place to start. This is a little off-beat from what you folks are accustomed too, but bear with me.

I'm scratch building a model hull of a three masted vessel from 1750 for radio control. The hull is 40" stem to stern with about a 10" maximum beam. Its framed with 1/4" plywood and planked with 1/8" balsa. That was smoothed with bondo and sealed with resin. After sanding, it is being planked with 2 ply African Mahogany strips that are about 1/2" wide. This is not a scale model project, but I am making a scale hull form for sailing.

I want to vacuum bag a layer of light glass over that mahogany, then infuse it with marine resin and clear hardener.

I have a Dayton Speedaire 1 HP vacuum pump that while old, still develops 17 inches of vacuum. I've made a resin trap to put between the vacuum pump and the work, and I am working on selecting the proper materials to use that will give me the smoothest finish while maintaining the right density and glass/resin ratio, etc. I'm going to order Fiber-Glast's infusion test kit; it gives you three different materials to try with your resin and vacuum system.

Since the hull is convex, I plan on using one of the highly elastic bagging membranes and vacuum each side of the hull independently.

There is enough room to put sealing tape all around the perimeter of one side of the hull, so all of the bagging pressure will be against one side of the ship, as opposed to putting the entire hull in a vacuum bag, which would probably crush it.

My questions are...

1. Is 17 inches of Vacuum too much for a small project like this?? What is the best vacuum range for me to shoot for, or is the sky the limit?? I'm using pretty small diameter tubing to evacuate the piece and inject the resin, and I have the vacuum side of the pump drawing from the resin catcher via 3/8" copper tubing. I can install a brass ball valve to throttle the vacuum with if I need to, but do I need to? Do I need to worry about squeezing out the resin before it can gel?

2. What kind of peel-ply, or what ever the proper brand name for the right material is, should I use to leave a smooth resin finish over this beautiful mahogany? Should I resign myself to sanding after vacuum bagging, and then brushing on a finish coat of resin, or other product?

3. What weight of glass cloth should I use that will protect the mahogany and still remain clear, while still allowing the resin to infuse properly? The object is to see the wood finish when done, and I do not intend to paint any portion of the hull. Can I properly infuse one thin light layer of glass??

I'm very comfortable with hand laying of epoxy resin and fiberglass cloth, and have successfully completed a couple of other hulls, and other models that way. This won't be my first excursion into basic vacuum bagging, but resin infusion is new, this is the first time I have used this particular pump, and I appreciate any advice anyone can give.

Thanks!

 

Hi Herman, we have finally decided to use vinylester resin instead of epoxy ( mainly to avoid postcuring or issues with the skin coat delaminating from the epoxy )

Still, what you said about the permeable layer under the grid, I do not fully understand, because it may be permeable during the infusion, but contraction happens during the curing process, some of it after the initial curing so the stack is already hard and non permeable, so I do not see why should this dampen the distortion ..

 

Chieftain:

If you like to achieve a 100% clear coating/laminate, please do use a good, clear epoxy resin, and a very lightweight cloth, 80 gr/m2 or so.

I suggest a hand laminate instead of infusion. Your pump is not capable of pulling a decent vacuum, and the risk that some glass will not infuse properly, is too high. The excersise is just not worth it.

 

Jiggerpro: keep in mind the fillet which exists at the base of the reinforcement grid, will be the most visible, as there the most resin accumulates. If there is something like Coremat, or even unifilo, this will dampen things. However, if there is a core in the hull laminate, the problem is less dramatic. Still you need the permeable layer under the grid, to infuse properly.

 

Thanks Herman, but your answer leaves me confused. How much vacuum would be necessary to infuse it?? And if 17" of vacuum is not enough for infusing, is it enough for just bagging??

Can you give me some pressure ranges to work with??