Composite (glass/foam/glass) For Beginners?

What do you mean? Your tests indicate differently with what? Are you saying less glass is needed outside a foam cored hull than a plywood hull (say... 10mm ply?)

Also, what's "super foam?" Is that Corecell?

 

Yes on the corecell and what plywood core?

 

Catbuilder; your largest panel is more likely to be only 1.5m x 13m, its only the flat topside not including the turn in the bilge. Say that the panel would be 20mm core and 1200gsm laminates, for this you will only need 45kg of resin. Also say that the infusion will take 10 minutes, that is close to 5kg/min, thats why I say use the pump you already have. Large pump does not make things faster, and you do not need large amount of reserve capacity to absorb air leaks as there must be none. By the way the difference in weight for the above example is 140kg for hand laminating and 114kg infused.
Also 1200gsm laminates is at the crossover point where the material cost of hand laminating and infusion is about the same. But infusion will be more hours.

Richard and Herman have given you some very good advice, you just have to decide which material you prefer to work with, unfortunately for most of us cost comes into this.

A question for you, how many hours are you counting on to build this cat? I had the impression you only had 12 months to build.

 

Hmmmm... good points about infusion and having a bag with no leaks.


Unless cost is 50% difference, I am not going to consider it. My object is to build the best boat I can in the most simple way I can with the least grief possible.

I figure I can always buy that spinnaker later on or other things later on. I can never go back and get the hull right, so I'll make the best one I possibly can.

Oddly, I have been talking to another builder of a Kurt Hughes who is doing it in foam/glass. He is using infusion and has already made bulkheads and connectives. He has had no trouble at all and is really enjoying infusion. This doesn't make the choice any easier to make.

Will I come out with a stronger and better bonded hull using infusion techniques?

Should I make the bulkheads and connectives and other random bits using infusion, then hand layup for the hulls? And if the hulls aren't vacuum bagged, do I stand a better chance of delamination down the line?

 

I wished I was more clear as well, about the pump issue, and I will quote myself:

For all out there that did not understand, I will explain my quote (in simple words, and short sentences):

You would need to do some testing with infusion.
These tests are made on a very small scale.
Small means 1ft x 5ft.
Your Robinair pump should be capable of doing that.

[back to normal modus]
Hi Catbuilder, your Robinair pump should at least make you some test panels (which you can use in boat for whatever purpose, even if it is just mixing putty on it). It will also make you some bulkheads, the pump should manage that. By that time I guess you can make up your mind on infusion or not.

About drawbacks:
extra materials needed
extra thought needed, also beforehand
thinner laminates if the amount of glass stays the same

Advantages:
Better fiber to resin ratio
Controllable way of processing large amounts of resin
Less weight
All crevices in foam / wood filled with resin
Clean work, less hazardous

 

SO that was set straight! Thanks Herman............

Now to the main issue, building method.

Catbuilder,
you can of course go for the original (changed to foam core) design. And making smaller parts like bulkheads for testing cannot be wrong or cost you much. (that might even be a good solution in general, to make bulkheads and some cabinetry in lightweight, cored panels)
Flat panels on a rigid table are the easiest way for a successful infusion, sure.
But here we are again at the problem which screwed up your first attempt!

Handling these large hull panels is just impossible by one person. No matter the weight, the sheer size does not allow for that.
Whereas strips on a jig do allow for single handed building.
Wood or foam is not really a question of performance or material properties. (apart from design aspects)
You have stated on other occasions that you are not very familiar with wood. I assume you don´t "feel" and "understand" wood. So, for you going for foam strips or planks over a mold of bulkheads would be the easier and more "natural" solution. And it would not need a different design, you just need some additional lofting, and the missing frames drawn and built in cheap chipboard or something equivalent.

Sure that is more effort, and the structure is heavier in the end, than with a one piece injection.
But you can handle it.

Regards
Richard

 

Can you show some photos of what you have now? With any method, you would need something like a mold. Would you use frames, and strip plank (wood, foam) over that, or would you re-use the half-hull mould?

Using frames and strips, you would not need anyone to help you, but with these large panels you need some help every now and then.

Anyhow, turning the hull is an operation which requires a bit of help. Although I even have seen people do that alone. (4 people are useful)

If you choose infusion for the hull, I would hand laminate the outside, and infuse the inside. Not for weight or strength issues, but for reasons of handling and ease. I never liked laminating inside a hull.

 

You should always "wet bag" the laminate for one if not infusing and second always do a test run on a small panel that will give you all the info needed to work out infusion strategies with your laminate schedule and the resin system.

 

Makes me wonder what you went wrong with your wood layups.. your testing setup is testing what properties? Numbers and facts please.. (CatBuilder allready asked but you failed to answer)

 

I did answer catbuilder but he never answered me ,Let's see mechanical like a 50# drop hammer from 5 feet in a lab, your plyrot would be in the dustbin, and Hydromat testing to 65 PSI the limit of the rig.

LOL "Wrong" ???? The wood failed is what happened ,My race boats had no room in the weight allowances to carry wood which is heavy useless and self destructive as aircraft would be carrying a cast Iron airframe.

Here let me help you; the material I use follows Hooks law, absorbs energy without failing on the graph that "porch" is the area of safety, engineering plastic foam can offer this ability to get you home, Well steel can as well! http://www.gurit.com/page.asp?secti...99+A%2DFoam+%2D+For+Hulls+%26+Dynamic+Loading

 

Well I thought it looked very much like Brents hammering.. But let me quess.. Poly?? no epoxy?

 

VE as I understand on the impact and epoxy on the Hydro mat.

 

Thanks.. Is further quessing a necessity or might you share some more.. Shedules of the test sampels, breaking loads etc??

I'm sorry if I sound a bit cynical but do you think your test setup is realistic.. Anyway I can't remember when was the last time there were 50lbs hammers floating around.. (sorry.. just couldn't resist.. )

 

Realistic Hell Yes ,LOL 50 Pound hammers????????? Thousands of them much larger in my World :http://www.youtube.com/watch?v=esxxtLg8qJ4

 

Here knock yourself out:http://composite.about.com/library/PR/2001/blgrpguru1.htm