Hard Chine composite, preglass panals before or glass in place?

ive just been playing around all day trying to get some foam sheets around a male frame and batten temporary mold... had to kerf cut the sheets to take the radius, then had to figure out a way of holding the foam onto the battens... i envisaged needing a million screws to hold it all down after i did the first sheet of a 35ft hull...

So what did i do....? removed the only sheet of foam, then pulled the entire frame and batten mold apart! went back to the computer and redrew the frames for a female frame/batten mold... they will be CNC cut in the next day or 2... then i can try again using the female version which will work much better for several reasons and much easier get the foam to lay where its supposed to and take the radii i need it to... i figured and extra couple of hours this way, would save me days of headaches in the long run...

Wish i could see everything in my head before starting out, and find all potential problems before they happen, but alas its quite difficult to do it ALL the time and SEE EVERYTHING....

Spent the rest of the day welding up a steel frame for a giant and flat glassing table to infuse flat panels on... (both sides for gentle curves, one side only for tighter curves) with rebated edges where the tape joins will join panels together (panels that join compound curved areas which cant be made on the table)... edges of cutouts will be pre-filled with rovings and bog prior to infusing the main laminates over it. Once infused, simply trim back to the filled edge and its done, with reinforced edges and already fair...

Topsides - full size panels pre-glassed bothsides will be pulled around the bulkheads as the curve is only gentle for the slender hulls of cat`s and tri`s.

Compound curved areas will be strip planked with foam + uni glass bonded to one side strips, then glass over the outside - i cant think of a better way?

 

be inventive and get creative !!

Ok before you start trying to bend a whole sheet how about bending a strip of foam about 120mm wide !!
How thick is the foam you using and whats the density ?? sounds thick and hard !!
How would a strip of 5 mm thick foam bend round the same curve ?? easy ?? what about 3mm thick ??
Remember the cuts need to go to the inside of the bend so they parly close up when it bends and not open up !!
The closer the cuts are together the easier the bend will be , by now you should be starting to get my drift !!
Cuts 25mm apart are going to form a harder bend with flats on the foam, cuts 10mms apart or even closer will make a easyer better bend !,
If your foam is 20 mm thick you just need to leave 5 mm or there abouts of uncut foam to play with and be able to bend !!! just do some exsperimenting !!
We got divinicell H80 foam, 20mm thick to go round a 50 mm radius without it breaking and the sheets were 1.2 mtrs long and forming a cone shape !! took about 30 minutes to work it all out and we had 8 boats to make, so it had to work and had to be simple and easy to do ! .
Heating was completely out of the question !!, cutting worked well !!! ,just had to find the right combination of number of cuts , spacing of the cut and the deepth of the cut .
Once you find the right combination its a breeze and you have learned something completely new !!!

 

yep, figured all that before i started... just didnt think of the foam wanting to spring away from the forma on the tight radius - because its a male frame. The same thing reversed on a female frame, it will want to press itself into the forma instead of springing away... smallest details like this - you cant always think of everything, just have to suck it and see, learn from mistakes... no big deal, the forma only took an hour or 2 to knock up with a nailgun... the CNC router makes easy work of those frames rather than lofting them all out by hand and jigsaw!!!

 

The thing about learning is not to forget and next time add to it !!
At work soon we will be making a small fly bridge cowling and from the past exsperiance i know what has to be done to get the 30mm foam into the curve at the bottom of the mound so i can cut and shape the panels with curves and chamfered edges all before i enven start doing all the cuts in the top of the sheets . Plus i will get to use a band saw i resirecked and made it work months ago . my guys love to use knives and bits of wood as straight edges and spend hours sanding things !! , me i use the table saw to do my cuts and then the grinder and completely finish everything so its fit and bag and not have to clean up when its ready to glass-!!

 

As a reference point, it takes me 2 days of work to get half a 45' x 8' (keel to deck) hull made thermoforming Corecell in a female mold. This is foam only, no glass at this point.

As Tunnels said, the key is small, long pieces. Compound curves (such as a hull) are no problem with longer, thinner strips. My strips were about 1/2 the width of a laptop computer (didn't feel like figuring out how many inches they were, then converting to metric).

You will probably be happier with the female mold you switched to. I spent several days screwing around with kerfing and things too on my first half hull. You're not alone there!

Though Tunnels will get a little bit of vomit in the back of his mouth when he read this, I thermoformed everything on both hulls, excluding the sheer curve (where deck and hull meet). On my boat, it's a tiny little curve, so I just strip planked that. No bending necessary.

 

Hi
If you are comfortable with using heat then good luck and i take my hat off to you !! I have never even been in any place that had the right equipment or could get it right so i stay away and do what i know works for me ! some people pick up on differant ideas and are able to make them work !,just never seem to be able to find page two of the manual to be able to move on !

 

For future reference Catbuilder, how did you heat the strips of corecell? simply with a heat gun, or a make shift oven, or heated plates or...? i was paranoid about ruining the surface of the foam and getting delamination issues, so i didnt dare try it with a heat gun... ive used it sucessfully on thinner foam, but the thick stuff really needs alot of heat as it insulates itself...?

 

I have found that heated Core always seems to get harder and so the density you started with just went out the window ! along with the hardness it became brittle and even to the point of shattering if you hit it ! due to the brain storm of my supervisor on one job 20 sheets of 40mm core were written off because he wanted to degas and cook it in a container ! my exsperiances have never been good when it comes to heating core !