Infusion Q&A

There is 2 approaches:

1 is where the second part is just holding the first in shape, or read "no extreme forces in the joint line". It is OK to hand laminate these joints. This is what is done mostly.
For instance bulkheads in boats.

2 is where the joint line is experiencing the same forces as the 2 parts, and should react the same. In that case you will need to infuse the joint. Depending on the design this can be tricky or can be easy. Planning ahead is the key.
Also you could investigate other means of joining, like a structural glue (epoxy or methacrylate) depending on your needs.

Designing such that joints will never be "in line of fire" is always a good thing, and can lower labour hours and cost price.

 

Rudder Infusion - Tomorrow!

I have all the glass stapled in place using Raptor composite staples and I'm getting ready to start laying out the infusion stuff on top of the glass. I have some questions:


1) My rudder is 24" (60cm) from leading edge to trailing edge at the widest point. I am using MAS Infucure low viscosity infusion resin (consistency is like 0% fat milk). Do I need to run enka channels across this distance, or is that distance no problem for the resin to bridge?

2) Please see attached photo for rudder orientation. It will stay in the same place for the infusion. My planned setup is to have a single length of 1/2" spiral tubing running along the trailing edge of the rudder and a single length of 1/2" spiral tubing running along the leading edge. The trailing edge (lowest point) will be the resin feed line. The leading edge (highest point) will be the vacuum line. Is this the way you would set it up?

3) The top of the rudder (closest to boat) is 24" (60cm) wide and I am infusing across this distance. The bottom of the rudder (close to sea floor) is 10" (25cm)wide. Does this pose any type of problem? It didn't when I infused the composite ribs for the rudder, so I assume it will be no problem here either. Please let me know if you think this is a problem (infusing over different lengths).

Any general tips? Any suggestions?

This is my 9th infusion, but the others were very small parts with cheap stuff from the regular hardware store. The 8 pieces I have already infused (the ribs for inside the rudder) came out well. Now, I am using the real stuff: Airtech peel ply, Airtech green flow media, Airtech release bag and tape, etc...

Just seeing if anyone sees any grave mistakes in my plan.

Thanks for any critique.

 

Staples !! Glass!!! infusion ?????What are the staples going into ?????

 

Sounds sensible. The trick is going to be getting the seal in place around shaft and at the point of the rudder. Are you using a complete bag or using sheet material for bagging. A trick that I watched the other day was to pipe the pump up so that, through valves, you can make the input into another vac out. That way the excess resin is sucked out of the resin rich inlet area.
Good luck with this...the key as ever is getting the seal right. Do a drop test!

Mick

 

Thanks, Mick. That's an interesting trick with the resin supply line. Thanks for the idea. I am using flat bagging sheets. Will form them into a bag and stick the rudder stock through, using bagging tape to attach to attach bag to stock. I had to bag it earlier for making part of the rudder. That approach worked.

Tunnels: I don't want this turning into another diesel electric thread. Please do some reading before you post.

 

Yes your approach will work.
Personally I would have attached some CSM or lightweight stitched glass at the trailing edge so that the inlet and vacuum lines were parallel say 800mm apart.
The green flow media to cover the ruder blade only ie stop well short of the vacuum line.
I would make the leading edge the resin inlet and the vacuum line at the excess end ideally CSM.
The reason why CSM is better for the excess is that resin travels slower through CSM than it does through stitched fabrics. When the resin front reaches the shorter span at the bottom end it will slow down and allow the wider section to catch up. If you calculate the correct amount of resin required for the job the resin front will stop before it gets into your vacuum line.

 

Andrew, I have done exactly what you have suggested. Thanks for the tip. It worked out well. Rudders and dagger boards - DONE!

 

LEAKS!!!

Ok, I am infusing the outer skin of a 45' LOA hull right now. I am doing 2/3 of the hull in a single shot. That includes the entire deck, around the sheer and down to the keel.

Question:

I am only able to pull 18 1/2" Hg right now due to leaks I cannot find. There were plenty I could find, but right now, I'm stuck finding any more.

The pump is a 6CFM unit.

Is this sufficient vacuum to do a quality infusion, or do I need to buy an ultrasonic leak detector.

While I'm at it, what is the best leak detector, other than your ears?

I can hear even the smallest leak, but I think my foam/hull is leaking around the unfinished edge or something.

Any ideas?

 

If you want a good infusion job there must be no leaks at all.
Do not be tempted to start infusing thinking that you will be able to find all the leaks by their tell tale signs of bubble streams tracking through your transfer mesh.
If you have only 18" of vacuum and can not hear the leaks it means you have many tiny leaks for which you will need a leak detector to find. I dont have one just borrow one when I can not find a small leak, can not think of the brand.

What surface are you sealing on to? When infusing in sections I paint on a narrow strip of peel ply with resin on to the bare foam first.

Did you drill any holes through the inner laminate at any stage? eg to temporarily hold bulkheads in position?

 

Forgot to mention that a poor mans leak detector is a hose held to the ear.

 

On a big job one of those fancy ultrasonic thingies is probably worth renting or borrowing. On smaller jobs I used a $3 "Spy Ear" thing we got on e-bay. Designed for bird watching or some other silliness it actually works really well.

 

Ah, I already spent the money on a king's leak detector. An ultrasonic unit that will be here today already (overnight shipping).

I will use it today to hunt around for any leaks I can't hear. Maybe I can eBay it after the boat build.

I'm doing the outside shell of a hull that has the interior finished with bulkheads and all. I am placing the tape both on the hull's normal surface (corecell with bog between) and on the corecell edges in some places. I also have a large open hole where the bridgedeck will go that is like a large "window."

In many cases, the leaks were from unfinished bogging on the half of the hull that is still in contact with the mold. Gaps in the bog and that type of thing. It would pull air up through a gap to the bagged area in some cases. I am hoping most of the leaks are small ones, rather than some strange hull leak.

Here are the pictures of the area I'm infusing. It doesn't even all fit in one picture!

 

This sucks. I have nearly 20 hours in looking for leaks. I can't get below 18 hg. And I'm using an ultrasonic leak detector for the past 4 hours.

 

If the leak detector can not locate the leak/s then I would think they are coming through the foam or the boged edging you sealed to.
I did much the same as what you are doing, I spent two days looking for a leak and still could not locate it. But was able to narrow it down to the first bulkhead about 1m from the transom. I ended up taking the bag off this section and hand laminating about 300mm past this bulkhead. The next day resealed the bag on to this laminate and all was good.
Observations from your photos, my preference is to have the infusion layout in reverse to yours. I like having the vacuum lines around the perimeter and feed the resin in the middle. As you can see when you are infusing without a solid mold it can be difficult to get a perfect seal. Having the vacuum lines where the leaks are most likely to be means that you do not drag air through your laminate. Leaks in the bag are easily detected by the leak detector and are also most of the time easy to spot and seal when the resin is in.
Also the resin risers appear a bit long for the spacing, ie close to the vacuum lines. The resin may get to the vacuum lines before the gap between them is fully infused. But I have not used the flat feed lines so dont know.

 

Thanks, Andrew. Good advice and good perception. I am fairly convinced that I have a large leak in the foam core somewhere as well, so I am not able to hear it with the leak detector.

I am going to spend all day tomorrow starting over from scratch, looking for a core leak.

I have a few other tips from friends (pull bag wrinkles to see where leak is generally located). That should help me get to the proper section of the hull, anyway.

The resin flow channels are set up properly for my application. I have been very fortunate to have been at the infusion of a sistership - same hull. I have set everything up the same way that successful infusion was set up. It should all wet out fine, as the other one did too. I didn't have to invent the plumbing and go through much trial and error, though on my dagger board infusion, I forgot to put in a "resin stop" between the flow media and the vacuum line.

I will start fresh in the morning and see if I can find the foam core leak. I have been over the bag many times. It's not leaking. I have found a few core leaks and plugged them up. There is just a major one somewhere to find... I think.