Help vacuuming bagging panels

[James Mills]

With partners in the boat, I'm redoing a modified Stilletto 27 high performance racing catamaran. It was originally built using Nomex core, prepreg epoxy laminate and cured in an autoclave. We are replacing all of the plywood horizontal bulkheads and shelves with Plascore or Nomex cored epoxy panels vacuum bagged on a mold board.

Suggestions for the amount of vacuum for making panels. ??? An initial test piece with a lot of vacuum didn't work out so well. The other side of the panel with less vacuum seemed to have a better core to laminate bond.

Hope to make some test pieces this weekend with various laminate schedules.

Any suggestons from the group is greatly appreciated.

James Mills

[rturbett]

The only advice I can give is make the parts light if you want to bring the Stillettos performancs up to "high"

[James Mills]

Rturgett, thanks for your reply.

SwimMart, the Stiletto 27 is pretty high performance now. Mike Speth, the primary partner, who worked at the factory building the boats, has modified her quite a bit: daggerboards in the hulls, beefed up beams, an articulating spinaker/screecher pole and greater sail area. I've sailed on the stock boats -- SwimMart is much faster and a more balanced boat than the stock Stiletto 27. The modified Stilettos in the area sail circles around the stock boats.

Since the boats were built in Sarasota, there is quite a little cult of former factory workers and multihull enthusiasts in the Stiletto fleet. The owners of the modified Stilettos keep working to make them faster still.

Panel making suggestioons still very much sought after.

James Mills

[rturbett]

I apologize for the dig- I have a friend who has one up here-slightly neglected, and without the upgrades. We run circles around it. It looks very sleek and imtimidating with those cockpits, though.

I haven't vacuum bagged yet- the closest I've come has been plastic wrapping layers of glass, balsa core and epoxy together, without the vaccum. Pretty effective, but not quite as good.
good luck- there have been a number of posts, so searching the threads may yeild your answer.

[Jimbo1490]

How much Vacuum? The most you can get is the equivalent of one atmosphere, about 28"Hg, or~900 millibars, -14 point something PSI, (I think you get the picture. If the thing was originally cured in an autoclave, this was likely done to achieve compaction pressures exceeding one atmosphere, otherwise they would simply have used vacuum and an oven.

So the answer is:

Use all the vacuum force you can muster; the best you can do will still be inferior to the original process.

Jimbo

[waikikin]

I only generally pull in grid score or perferated foam/balsa into adhesive applied to laminate & generally dont use a big pressure- the ooze factor seems pretty good at 10-12 on the gauge at the bag itself, your problems might be specific to honeycomb, dont know cos I've never used it, maybe you can make your skins & then bond em to the core if the're flat- gives a smooth finish both sides then, read up on the resin cos some specify a max vacuum so you dont suck vital ingredients from the chemical blend. Regards from Jeff

[James Mills]

Jimbo1490,
I was wrong about the autoclave. The hulls were cured in an oven.