Composite (glass/foam/glass) For Beginners?

Lets not bugger up a good thread people, theres more than one way to skin a cat here(couldn't resist).

 

Catbuider, how much time do you have/willing to put into this build? seriously no one wants to see you get set up for another disappointment.

 

Now only if you guys would argue with as much passion over if I should do regular vacuum bagging or infusion!

This is a good thread, despite the disagreement. I am learning a lot.

I think I will try the infusion on the bulkheads and connectives. This is good practice and it won't cost a fortune if I make mistakes.

For the hulls, I will probably go with strip foam because it's more simple and I can go at my own pace. I do worry about weight though. I will speak with the designer about this when he next writes back to my email.

The foam and epoxy is definitely a material I understand better than wood. For all my years, I have make ugly things from wood, split it when I didn't want to, etc... The only thing I can do well with wood is burn it in a wood stove! ha ha ha My wife is more of a woodworker than I am.

Herman: Here is a picture of what I have.... the first picture is one of the hull panels under vacuum on the mold.



The second picture is a picture of the open "cylinder mold" that you lay the plywood over. The issue is that your plywood "half hull" does not come off the mold in final form. As you can see in Charly's "Hughes Daycharter 36" thread, you must then wrestle the bows in and bend the thing up to get the hull shape. So, the mold may not be of any use for a foam/glass panel.



BTW: It took a while to build that mold! It is biaxial, meaning there is a curve that you can see for the turn of the bilge, but the mold is also higher off the ground in the center and tapers off to the ends. It is suspended over a very rough concrete, which is why I can't use dollies to move things and must hire people. Nothing rolls on that floor.

 

Wise decision!

 

Everything is in here somewhere, I would go Bead and Cove Corecell

 

Ok, now how about the question of Divinycell vs. Corecell?

Many have said I need to post cure my epoxy. This means 140F, correct? I believe I can't post cure if I use Divinycell, is that right? The 3/4" corecell for my boat looks like it will cost about $27,000. Which should I go with and why?

 

Refer to my test video, you could use Divinycell on the superstructure but on the hull I would not.

 

I'm sorry again but you have measured results.. right? Much easier to refer to numbers than funny vids in youtube..

 

Ok.. you don't have any numbers.. Have nice day!

 

What numbers???? You got the hammer weight,It was a God Damn impact test!! Hello out there !!!!!!!You mean if I hit samples with a sledge hammer you would expect me to calculate the force instead of looking at the ones that survived?? You do not get it HOW in the hell are you going to use ultimate load numbers when one sample gives and the brittle one fails ,understand what you are looking at here.Thanks for the laugh!

 

It's ok to test impact resistance, but no harm to know how big impact is needed to destruction.. but however more common stress to fail for such laminates are the cycles of somewhat smaller slamming forces. So to determine the best structure for the task you need more testing than pointless hammering. Different core materials also need individually calculated skins and if done properly anyone of the tested materials should pass your hammer test done, lets say, 10000 cycles.. just if they are designed to do so. Then of course, when there's no difference in strength the final choice could be done purely by other properties like weight, cost and the ease of construction.
BR Teddy

 

Teddy I know what you are trying to say here But the hammering is far from pointless,One more time everything was MADE equal and 2 Types of core survived, Now I guess the ones that failed could have been given 1" thick glass skins but for what purpose?? The cyclic testing I can get from SP if I ever needed it and why should I have to use more material over an inferior Brittle core and build a noncompetitive boat? that is the point you miss by a mile.

Years back in the late 70's I lost the bottom in my raceboat coming across the Gulfstream from Bimini (Magnum marine Bahamas 100),The net result was I decided to build my own boats ,spent a year looking for a system that could take a pounding and I found a good resin system (urethane Acrylic vinylester) and a core material they were using in lifeboats "Airex" that were dropped from Oil rigs and eventually "S" Glass from the sailboat guys.

I have been dealing with these supercores for a LONG time. Do not try this with your wood. I used Airex for a long while very successfully ,then switched to Corecell

Here a example.

 

Sorry, Andrew. I missed this post.

I have 3 years, full time or however long it takes me. Trying to finish in 3 years though, with a very simple, all white interior, dressed up with colorful cushions and things, rather than a bunch of heavy and intricate woodwork or anything.

I'd like to launch in 2 years, then fit out interior stuff in the water during the 3rd year.

I'm 100% full time, but would like to use a method that will get me to the water as fast as possible. Unlike many here, I don't like building boats. I need to build one because (and I've seen Apex1 disagree about this elsewhere):

1) It costs less to build one (not including my hours) than to buy one of the same caliber.

2) There are no used cats around that fit what I am looking for under $500K

Richard, I know you have argued against this before in other threads, but the catamaran market is very different. There is a demand that far outstrips the supply. They have junk 45' available for $300K, semi-decent for <$500K and good boats for $500K+. You can build a good catamaran for less than the junky used ones go for.

So I have the time, but I don't want to waste any of my time either. I'd like to go the most manageable, easiest, fastest way that is not a kit. The kits were too expensive to still have to glass, fair and fit them out, IMO.

 

Ok, so how about Airex vs Corecell?

And... can anyone say if I should use a male mold and make an entire hull at a time, glass, then roll over to glass the inside?

Or... should I use a female mold and make "hull halves?"

My initial reaction is I would like to use a male mold. The designer's foam strip planking literature talks about bagging the fiberglass layup onto the foam to achieve a lighter boat. Do you all think it might be a good idea?

 

Another question:

Herman, you wrote:

I'm not sure I understand how to lay up the glass. I'm guessing the fibers are oriented the "long way" on a roll of fiberglass, rather than "across the roll." In other words, they run along the meters of glass, not across the smaller width of the roll.

If they run the long way, how do I account for the fiber orientation when doing vertical laminates?

Do I do small 1m x 1m "squares" that are not the full length of the boat? Does this matter? Will this affect structural integrity? How do I overlap them or handle the places where the squares meet?