Infusion Q&A

I understood your two steps sequential-fishbone and will draw it soon, but I have to say that I have detected that your preferred is the simple fishbone which I assume (please confirm) it would be your best bet so I have drawn that approach first. the vertical resin lines are spaced 60 cm and 30 cm have been left from the top of the mould to the ends of of the fishbone verticals

 

And this should be what you meant by splitting the fishbone in two steps,

In doubt about it with what to do with the transom, buy maybe should be infused together with the bottom fishbone and be left open until complete impregnation

 

I usually prefer the single fishbone, but when you reach a spot where race tracking is a risk, I prefer designing a runner there. That way race tracking cannot spoil your infusion strategy.

If it was me infusing the boat I would use the double fishbone here.

The transom can be done with the first step. The vacuum line of the transom can be split from the sides and closed once the resin reaches the vacuum line. Use a resin "brake" at the transom (vacuum line separated from the laminate, with only a connection through some peelply)

The front will take the longest. Probably a good idea to have the vacuum line touch the laminate there, to prevent a pressure drop. Either shut down the resin supply early, so the front will be impregnated with excess resin pulled from the area around the inlet ports / main runner) or design the system as such that you can pull a vacuum on the inlet port (resin catch pot needed) so that excess resin is pulled out. This saves a couple of kilos of resin, which I think is beneficial to this design.

 

We are still a bit far from reaching the infusion point, but it is my main worry, I understood everything you said (after thinking for a while).

I have taken account of what you said about sucking from the inlet point.

Another thing you said, that shocks me a bit is what you reccommend about using full vaccuum while some other forum colleagues say that if full vaccuum is used it is very likely to get bubbles in the laminate ... I would say that for cosmetic and integrity reasons if a couple of kilos of resin guarantee no bubbles those some kilos of extra resin are well worth particularly considering that degassing is not practical at his scale.

In regards to minimizing bubbles I also plan on doing a test consisting in a tube filled with scothbrite with inlet and outlet in opposite sides thorugh the tube the resin will get sucked and a bit down the line a T connector allowin the sucking of this first front of full of bubbles resin to be discarded and not allowing it to enter the laminate.

In your opinion, is this worth doing ??

What a wonder of those times is the possibility to have this interesting conversation with you .. still amazed with internet.

 

My experience: Get a full pull, this will greatly enhance laminate quality. Keep the vacuum on for at least a couple of hours before infusing, to get rid of any moisture.

Above is true for both epoxy and polyester resin.

I would not worry about the formation of bubbles, this usually occurs when moisture is present. (make a test: mix 5% water into epoxy resin, then let cure)

You can always make some tests beforehand. (you should do anyway)

 

As for degassing: preferably yes, but if there is no opportunity, then let the resin sit for 5 minutes before infusing.

Will you use polyester, vinylester or epoxy?

 

we will use epoxy, and as is normal a gel coat layer then a vinilester skincoat and after that the epoxy infusion which will also have a corecell sandwhich core.

Maybe using some spheretex as a complement of the skincoat ( already ordered some samples, maybe purchasing from you since you have it)

Also thinking about using spheretex in their thickest versions as the core for the transom instead of the (advised by the Sp Systems engineer) corecell, because I believe that at a density laminated of 400 Kg/m3 it should have a much better compression resistance plus being "all plastic" I believe it would be more suited to allow the many perforations that a boat like the projected one should, have due to the fact that "no foam no water absortion" ( we planned on making some solid inserts of epoxy+microballons+some mineral load around where any holes where going to happen in case of using corecell for the transom)

You have not said anything about waht I questioned about the tube with scothbrite.

I am also surprised as how little are the people in this forum participating and chiming in about diferent subjects .... only scientific personalities here and very silent by the way ....

 

Don't bother. You might have some initial bubbles which will enter the laminate. However, most of that will pop within the first couple of minutes, the rest soon after. Bubbles move faster then resin, overtaking the front and disappearing.

 

I'll chime in. Make sure you -really- want to mix the epoxy reinforcement layer with a gelcoat skin layer.

I've been told that this is what they tried on the Farr 40s. It ended up being a disaster. I was told that the skin layer separated from the reinforcement layer after the boats were delivered to customers.

What is driving the decision to use epoxy?

-jim lee

 

I have made several tests, and found the following method to be effective:

-apply iso-npg gelcoat
-apply vinylester skincoat (2 layers CSM225 for larger objects)
-apply peelply (non release coated)
-let cure for at least 2 days. make sure you get rid of the styrene, so either extract it out, or have an open transom, or tilt the mould
-strip the peelply (use a very small angle when pulling, and narrow strips at a time, to prevent pre-release.)

Only after that, infuse epoxy. All other methods I tried, including agressive sanding, sprinkling nylon, glass fiber, sand, cotton, or do nothing at all, failed.

I have infused quite some vinylester boats now, and I must admit that they do not disappoint me. Todays modern vinylesters are much more efficient than older ones. (in terms of shrinkage, geltime control and strain)

 

I would do as Herman said except infuse the transom with the topsides.
The scotchbrite as you describe is a waste of time, you can not filter out air.
Mixed in air will escape, if you want to reduce the dissolved gas forming bubbles after infusing at full vacuum back off to 80%. Providing it is OK to run your pump at that level.

 

Hi Jim;
The reason for using epoxy is a double one, first it will allow for a lighter boat since no mat will be used in between layers of reinforcement and second reason is the non reactivity with sea water to avoid problems osmosis related problems, another reason could be its superior mechanical properties or its friendlier nature being much less smelly.

In regards to the failure of the gelcoat/epoxy interphase I am surprised to hear about its failure because if epoxy is such a good adhesive I find strange that with such a huge interphase surface it does delaminate.

I am in a slight doubt in regards to using epoxy or vinylester but mainly to avoid the unnecessary step of post curing in a "low temperature chamber/oven" which is compulsory with epoxy ( if you want all the properties you alredy paid for)

In fact to simplify our production process ( if there is ever one) we might consider building the hull with epoxy and the rest of parts that are above the water be made with vinylester.

Good and nice to see some intervention from other experienced builders apart from Herman, nice to hear different opinions and points of view from " across the pond"

 

Changing of subject a bit, we are facing now a problem with the last coat for our plugs, we tried using Scott Bader´s Crystic Glosscoat and we are experiencing some fisheyes, we even bought a new screw air compressor ( not only for this offcourse) with the very best air filters we could find ( Sagola 5300) to ensure air purity, but the proof of the problem lying in the product was some tests we conducted applying it by a (new) brush instead of spraying it, the fisheys are less but still some are present.

I remember you (Herman) telling me that this last glossy coat neccessary to get a nice surface plug could be done using two part polyurethane paint ... is this correct and is it a good procedure for the last coat on a mould plug ???

 

Jigg,

We use ve for the same reasons. Its stronger, doesn't need mat between layers when infused and won't blister. Also, it has no issues with the gel layer.

I -think-the trouble with epoxy on gel is the styrene. From what I've seen and been told, you never completely loose the styrene and it monkeys up the epoxy in some way. I colud be wrong, but that's my theory.

As for plug finish, do you have Duratec in spain? This is all we used, spray it on, sand it smooth then buff it. Makes a great finish when buffed and is really easy to use.

-jim lee

 

I have never done any infusion molding. Looking at the videos, I am surprised that saturation is seemingly easy to obtain on the mold side of the core.
The core material must be specifically designed with capillaries to allow the transfer of resin?