Infusion Plan

Ok I've read some interesting pdf's from the manufacturers... Seems the joint design determines what method is ok or not and t he specific adhesive required. They do specify bulkhead to hull joints although typically done with a flange. Interesting looking at the failure modes and specifically in shear, the lap length is of little to no importance. The width of the adhesive edge is of greatest concern ie perpendicular length to the join. Makes sense...

Specific types, looks there is widely varying mma's and urethanes with respect to flexibility. How does one determine the ideal adhesive flexibility for a particular joint in a boat? I'm seriously considering running with this to finish my boat...

Definately looks like wet tabbing is a legacy from polyester boat building whee the adhesive qualities of the polyester made for poor joints. Seems to have simply been carried over to epoxy building without good reason other than hats just the way it's done...

 

Its not what you say !! its the way you say it !!

I know what you saying but its not quite as simple as it sounds ! the glues have amazing strength and it will rip the glass to shreds so to prevent that happening you first need size and area to make it work properly !!
In some racing yachts the decks were glued to the hull flange all way round the boat bow to and including the stern, the designer had a 30 mm wide gluing surface but we increased it to 60 mm purely because of the glass peel ability factor !! we made test samples and used the 6 ton crane and dyna bolted and chained the panels to the concrete floor it ripped the bolts out and the 60mm wide glue join never budged so we made the sample narrower where the glue join was to 30 mm and the glass ripped and peeled but the glue still never let go!!
So the size of the glued surface and the thickness of the glue layer is really important as with any thing that glued !!
We used a semi flexible epoxy adhesive based on the west system epoxy called HPR25 !!

 

Completely depends on the joint design tunnels, whether the join is in tension or shear or peel or cleavage... The test you did only tested for one type of stress, doesn't mean the same applies for all conditions... Think about it...

 

Bondline thickness is really important. The design needs to control this. Lots of joints fail becuase we overclamp and get a zero thickness bondline( a neverbond) Spacers or steps work well. The bondline edges need to be thicker to provide peel strength. A thicker line (eg a cove or chamfer) can stretch more then a thin line. Obviously the bondline design is important and needs to be commensurate with the type of loads transfered. Then also we need to design the substrate to suit. But all of this is doable and saves time vs putty, coving, cover taping and clean up. Cheers Peter S

 

See told you didnt i !!!

when you tell a story don't forget to tell the whole story and nothing but the whole true story . !!

 

what ever strength you want to call it, it never showed signs of coming apart at all
shear strength never happened
peel only happened because the glass gave way!! ,
tension!! in what direction !!:?:

 

Ok, Great Information!!

I found a steel angle to use as my mold and I am going to use the Plexus.

My deck isn't going anywhere, it's taped to the hull flange all around boat and on both ends and in the middle where the stringer sections project through, I just wanted some cushioning or a solid attachment to stringers in case the deck did not lay exactly flat and somebody jumped on it causing it to slam into the rounded stringer top edge.

Even just with the flat angles I am sure that would be good enough, with the adhesive, after reading this, I have no doubts.

 

This link is from a pdf somebody posted on this site - I guess - and discusses the methods of bonding. I found it looking for the Plexus and figured somebody might find it useful, here it is

http://www.google.com/url?sa=t&rct=j&q=plexus%20ma%20425&source=web&cd=16&ved=0CFMQFjAFOAo&url=http%3A%2F%2Fwww.boatdesign.net%2Fforums%2Fattachments%2Ffiberglass-composite-boat-building%2F15643d1188127369-foam-core-deck-cabin-bulkheads-bonding_composites.pdf&ei=Uu-1UfK5KZG50QHEoYHICQ&usg=AFQjCNEAjzJjJG3N1dw2yXCpOxEcJjETSw&bvm=bv.47534661,d.dmQ

 

So if taping isn't needed, then the whole theory of bulkhead hard spots and diminishing widths of tape to gradually and evenly spread loads is/was sort of a fairy tale? Or does this only apply to certain types of construction with certain types of material?

I've also found somewhat questionable (especially with woodwork) the explanation of joint failure, where it's stated in a joint failure that the adhesive still being stuck on one piece with fibers or pieces of the other piece still stuck to the glue proves the glue is stronger than the material being glued. Since the break is almost always in the immediate area of the joint, it seems to prove only that the glue is marginally stronger than the weak joint.

 

The stuff is costly -

3 380 ml cartridges of plexus MA-425
Manual application gun
6 mixing sticks
$459.33

Here are a couple of related links on how to use and how much you will use

http://www.curbellplastics.com/technical-resources/pdf/adhesives-applicator-demo-plexus.pdf

http://www.curbellplastics.com/technical-resources/pdf/adhesives-plexus-bead-chart.pdf

 

Look harder, I am distributor of the stuff in Europe, and for your order I would charge 215,50 euro excluding shipping.

This is some 288 dollar with the current rates.

The gun is the expensive part, at 86 euro.

 

Hi Jorge,
We pay less in Oz as well. I do recommend the concentric cartrideg of the plexus. We have used other brands that have the catalyst and resin in seperate offset tubes. These occassional leak (back into the cylinder) as the gun is not stiff enough to keep the seals concentric. Wastes a lot of resin and also makes me uncertaian of the mix ratio of the resin. We have had some patches not go off proper because of this. So the concentric cartridge is the go. Peter

 

does anyone know of a calculation to determin how much resin is required per infused square foot?

 

How accurate? Thumb calc says equal amount of resin as cloth by weight (glass fiber).

 

Yes, broken sheer. I have available an Excelsheet which does need some work, but is very easy to use when it comes to resin calculation.

It takes into account different materials (glass, carbon, foam, etc)

There are also some other initiatives, which are even more sophisticated, but as usual usability goes down as number of functions go up. I should look them up for you.