Infusion Q&A

Infusion time

When I project any infusion job, I put enough lines and branches to fill the hole part in maximum 40 minutes. This boat spent around 20 and the resin was prepared with a 40 minutes pot life. It´s better safe then sorry, specially when you are doing alive in a Boat Show.


Att

ED

 

Hi to all, I met Herman once in a boatshow and there he told me something that has been amazing me since then (despite his efforts to explain and mine´s to understand)

I asked him if the sequential method for filling the infusion void cavity would not be safer than the fishbone way and much to my surprise he replied that the fishbone was better.

IMHO, the sequential looks safer to me for several reasons:

1) the speed at which the system has to be fed with resin is slower and thus easier to achieve giving also a more uniform speed of sucking resin.

2) it looks like if it starts to fill from the bottom to the top, any air residue or gas or vapour should tend to move towards the vaccuum line leavin our intended piece.

3) In the many pictures I have seen on the subject, most of the boatbuilders seem to use the sequential rather than the fishbone (in no doubt Herman does for sure know a lot)

any comments .....

 

The sequential one is OK for mostly flat(ish) structures, but you run the risk of resin seeping down to the bottom of the part, once you are halfway up with your infusion.

Gravity-wise, feeding at the lowest part of the part, and vacuum at the top part is the safest way. It usually is not too difficult to design a runner system that fits in between.

Resin speed is not so important. It is amazing how much resin you can feed through a small inlet (10mm dia hose for example.)

The parallel system is used in rotorblades mainly, and in USA boatbuilding. The fishbone system tends to be used in European boats. Very nice to see these regional differences. In any case, there is not just a single solution, which is good.

How is your project coming along?

 

Hi Herman;
Nice to be in contact with you again, our project is going along well, slowly but we believe doing good, things have taken more time tahn expected due to the fact of we departing from scratch in regards to the neccessary equipment, we have bought a large size CNC router, an industrial screw compressor (15 Kw) and have started by making a scale model prototype which its plugs are almost ready for splashing I will beg pardon for a little hihacking of this thread to put a couple of pics maybe I should start a thread here.
I will hopefully contact you soon in regards to a pump and a few other stuff.

 

Reading this I guess we tend to use sequential.

But there was not much theory in the choice. My idea was that if things go slow and it starts to kick, if we fill the bottom first it'll kick off down there before going up the walls and causing too much pressure build up.

It didn't kick early, so we still don't know if that was a good idea or not. But it worked well, so we kept with it for other parts.

Knowing that our method was just something pulled out if a hat, I'm a little surprised that there are regional favorites.

-jim lee

 

Regardless of the undoubtful superior knowledge level that Herman has when compared to me, I have to say I have had with him this "conversation" several times and we always arrive to some "comfrontation point" but this time I am going to do my best to get deeply convinced of the goodness of the fishbone theory .... and I will start by saying that what herman said: The sequential one is OK for mostly flat(ish) structures, but you run the risk of resin seeping down to the bottom of the part, once you are halfway up with your infusion. is an idea that IMHO does support itself because if the resin where to seep down to the bootom of the part due to gravity, It would do so equally probable either the resin feed lines where paparalell or fishbone shaped because in both situations it can equally seep down since the fishbone has nothing in its configuration, that could stop this from happening

 

Think of it this way:

If you have water in a tank, and you open a valve halfway the tank, water will seep out, due to the static pressure.

If you open a valve at the bottom of the tank, water will seep out faster, as the static pressure is higher (more water above the valve)

Same with resin infusion:
At the position of the resin inlet, the pressure in the resin is ambient. If this is halfway a high structure, (and the laminate and infusion mesh is permeable enough) there is a possibility that at the bottom of the part the static pressure of the resin gets high enough to push the vacuum film up, crreating a resin puddle.
You do need certain circumstances for this, but it can happen.

About resin speed: Always make sure you know the characteristics of your resin. Make several tests with each new batch of resin you receive, you will notice that curing speed can differ from batch to batch, and you will need to adjust the ratio of additives to get the results that you need. This way (with suitable resin) you can easily create geltimes of over 2 hours, and still have a good final cure.

@ Jim: There is not a wrong way. You are building boats, and you infuse seemingly without problems, so there is nothing wrong with that. Just keep in mind that there are more solutions, and at one point you might have a part in your workshop that needs a different approach.

You are doing what most of us want to do: setup a boat company. And I have a deep respect for that. I just sell stuff, and infuse boats at customers requests. (the nice thing about it is that I always do the first infusion, so there is a healthy amount of excitement every time.) after that most customers can handle things theirselves.

@ Jiggerpro:
May I compliment you with the looks of your workshop? Plenty of space, clean and light. Well done! I like the floor at the CNC mill!

 

What you say about " If this is halfway a high structure" does not neccessarily have to happen, you could always place your resin inlet (the pot with resin from where it is sucked) at a low in height level at the same as the bottom of your laminate and then there is not a reason for it to puddle ........... and to make this more diffcult to admit your theory is the fact that you seem to have adopted all by yourself that when "fishboning" your bucket will be appropiately placed low and while "sequentialling or paralelling" the bucket was going to be at half height as this assumptioon does not have to be the case, the disadvantage you claimed about puddling in the low parts of the laminates does not need to happen placing the buckets low, exactly the same as if you where fishboning your infusion.

This was a "anything infusion thread" .......... just what I was looking for to try and solve this .-for me.- long lasting paradox of the way of thinking.

I also heard recently, from a good source that many English boat manufacturers do apply and are proud of doing so the application of gelcoat to the moulds by brush or rollers, while studies have shown that is no good due to the brush marks and joints in the cured gelcoat are prone to induce suraface imperfections and that Americans consider this to be a poor technique something I have to ( theoretically) agree with.

I mention this because for me, Americans have the most experience in boatbuilding and some just like us Europeans do try to do things best they can and if so many of those experienced builders across the pond do believe sequential infusing is better ...... their word has a deep sense of credibility, maybe both are equally good and thus the apparent controversy.

By the way, how much would cost your presence in our workshop for the first infusion (taking into account I still plan on purchasing part of our needed struff from you)

 

In regards to our workshop, thanks, as we are departing from scratch we are going to try and keep the shop tidy and clean since our idea is to build on demand on a semicustom basis, we will decorate it and keep it quite like a "relatively luxurious" small industry where a customer might enjoy to pay a visit and see some interesting procedures. Off course we are also doing it for ourselves and in the belief that to make good things you need good tools and those tools should include a very nice work place.

 

I think you are on the right track with that. Your workshop looks top.

As for my presence: I will contact you about that.

 

Although I haven't used the fishbone setup the main advantage that I see it has for large jobs is the greatly reduced number of resin inlets. Which is a significant advantage.

 

Indeed, I rarely use more than 2 inlets. Saves a lot of time nursing resin pots, and there is no descision to be made when to open the next line.

 

As I believe it should be convenient to run feed lines along the corners to help the impregnation due to there being double thicknesses of laminate ( maybe wrong theory due to racetracking) I find impossible to match a fishbone shape to those corners since the fishbones run mainly perpendicular to those corners that (mainly) run along the length of the hull, foru sure it would work, but I find the sequential approach flowing in a more natural way with the sahpes of the hull, this fact could lead to obtaining "some" advantage ( its a feel which I cannot completely justify)

And now the big question for which I would like to get good answers ...

If more then enough resin lines are used, the ease of impregnation should be improved and then the chances for a failure should diminish so for a simple piece like a boat hull, it should help or almost assure the success ...

True or false ???

 

another option:


Run a main channel over the keel, with fishbones. Keep the fishbones some 20-30cm short of the chines.

Run another channel through the chines. You will always have some racetracking, althoug I do recommend to be as careful as possible to get all teh fabrics in the corner. (still racetracking cannot be avoided completely, or at least not excluded).
This channel through the chine has fishbones upwards, up to some 30 cm short of the deck.

Apply a vacuum around the deck flange.

This will give you a 2-step infusion.

Can you make a drawing of that?

 

I will make the drawing but can not now ....