Resin infusion

[lucas adriaanse]

Seamonkey, we've found that it is not entirely without risk to infuse. Hand lay up is easier to control (check and add resin locally). We have infused doublesided on flat panels and found out that if you don't use double bleeders on the side that's against the mould, you will always get a 'shy' resin infusion on that side. It's not difficult to get a 'rich' laminate on the topside (probably 50/50). For this reason we haven't tried doublesided infusion on complete foamcored hulls. I've seen demonstrations on RTM in closed moulds, which works perfectly. But for our yachts we use vacuumfoils/bags, not counter-moulds.

About the slices on contour foam: they should be filled all the way, no voids ! It is part of the construction of a sandwich.

Lucas

[Danielsan]

Thx to all of you guys,

This was a lot of good info and I think it scared me off a bit (not realy), but the reason for wich I was looking for the resin infusion thing was because I tought, that when you are working with hand lay-up you couldn't go on with the same part for some time once the resin got cured. It was a kind of a misunderstanding in some manual I read. Now I know that you can go on with the hand lay-up whenever you want to.

But I think that in case I get nice result and some interest from other people with my project I might go on with it. Maybe than it could be affordable to get into R.I. ???

I like doing the research the calculations (where possible) the designing of the individual parts and the main idea, I hope to do it a lot cheaper than most things on the market. I hope that some things I make would be comparable in quality.

PS I dont calculate the time I spent on designing those things and that's probably the greatest cost.

Greetings,

Daniel Peeters

[Herman]

Dear Daniel,

If there is a need for it, do contact us and we can see if we can introduce you to someone who is doing a resin infusion project. Nowadays in Holland quite some homebuilders are using resin infusion.

About resin infusion:

Pro's:
-setup of materials can be done without the clock ticking
-even and high quality laminate (also for first-timers!)
-safe for people and environment
-saves weight over hand laminate
-difficult or time consuming constructions like stringers can be infused in a single shot with the hull.

Con's:
-extra cost over hand laminate, extra equipment needed
-with polyester larger chance for print through, especially when sawcut foam is used
-calculations or at least some knowlegde is needed for the layout of resin feeders, vacuum points, runners and the like.
-when using epoxy resins with long open times, a post-cure is almost inavoidable. (In Florida, they just roll the hulls in the sun for a couple of days)
-airtight tooling is needed. Multi-part tooling needs a good seal.

In general, the thicker the laminate, the more there is to gain. But this is just a rule of thumb.

[60minmacd]

Herman

Here in Florida, a couple of hours in the sun will produce a tack free surface, and depending on the pot size and mix ratio, sometimes faster than that.

Which is why boatbuilders in Florida take off and go snow skiing in the winter.

[Herman]

You are changing mixing ratio to get different gel times for epoxy? I don't hope so:

Changing it too much will decrease many characteristics, like Tg, flexural modulus etc.

Changing it within tolerances does near to nothing with pot life neither with time to gel, temperature when gelled or peak temperature. I have done a lot of testing with off-ratio mixing, in various conditions.

[Danielsan]

THX Herman,

When and where is the project located? BuT as I said, I probably will go on with the hand lay-up as a first timer. But it might be interesting to see what it's like to do the RI.

Greetz

Daniel

[Herman]

We have several projects going on, mostly in Holland, but also some in Belgium. However, as hull construction is just one thing, not all projects are interesting to see. We just did a project in Gouda, but also have projects in Hilversum, Rotterdam, and many other places. I really should check.

Hi Daniel, I am in Belgium and have a lot of used and new drives and gimbal housings. We can also do the laminating for you if you want. my email info@raffshore.com

[Danielsan]

Hi thx could be interesting.
At the moment I am looking at different ways to get myself a good plug. I get around 8000eur only the plug? I would like to reduce cost to the max. Maybe I have to simplify the hull part? I would be good to know if you have some good 2nd hand parts that would fit my needs because they will determine my final hull design.

I will try to get in contact with you later this week.

Greetz,
Daniel Peeters

[hp-zigzag]

Hi Danielsan,
Just a little tip regarding vacuum pumps. If you know a farmer or sombody who knows somebody..etc.. you may get an old milking machine for nothing, or close to nothing. I got two identical ones from local farmers (and even spare parts). The machines are said to run forever if nicely treated. Some of them dislike going lower than -0.5 for long periods, but for the time it takes to infuse your 25' hull it should be no problem going 0.6 -0.7 (I am not an expert though) I guess you could reduce vacuum a little when the fiber is wetted. According to Diab, Norway you can do well with -0.4 if you use grooved cores. Are you building sandwhich? Remember weight if you use grooved cores.

cheers

[Herman]

Do NOT reduce vacuum once everything is infused. Too many people make that mistake, and too many people end up in trouble. Just leave it as is.

Also, to take an old milk pump is a bit of a gamble. Remember that if your pump quits, or power goes down, you will lose a part. Keep that in mind when buying one...

[hp-zigzag]

Hi Herman,

Thanks for correcting me on reducing vacuum. It seems like you are in posession of some know-how on RI, so I hope you do not mind a

fiew questions.
(ofcourse, inputs from all of you are very much appreciated)

I am an amateur boatbuilder who has almost everything left to learn. Despite our lack of experience, me and my brother have embarked on

a gigantic sailboat project (two 66' sailing proas) and for various reasons we intend to use Resin Infusion for the hulls. We experienced

that useful information about RI was hard to come by, so when our materials dealer offered to teach us their technique for "free" if we

used their stuff we thought this would be a safe way to get into the business. The agent promised a lighter and stronger product

compared to conventional vacuum bagging. They are using core groovings as a medium and we knew this would add some weight, but it

would not be mentionable according to the agent. Later he told us the core he would use for our sandwhich had 2x2mm groovings spaced

only 20mm. A spacing like this would add nearly 100kg to a hull that was supposed to weigh 600kg! The boat is a high performance

multihull so carrying around 1kg of dead meat for every sqm of sandwich would be horrible.

Is it really neccessary to keep the groovings that close? Another salesman in england tells us that the contour cut core will be medium

enough. Who is right?

We aim at infusing both sides of the core in one shot using a female mould. This may be hard to do if we do not use groovings, or what?

Have heard of resin distribution nets lying on the top of the laminate, but I assume it is hard to ensure the layer next to the mould is

wetted properly using this.

Are there good alternatives that does not add so much weight and also conserves the benefits of a female mould?

Detailed information desperately needed!

sandwhich is 25mm with 800 triax each side.

At the moment I am building a 27' beach proa partly for the training purpose. Vacuum bagging etc. Will infuse one of these before we start

with the big monsters.



Regards
Terje

[seamonkey]

Originally Posted by hp-zigzag

Hi Danielsan,
Just a little tip regarding vacuum pumps. If you know a farmer or sombody who knows somebody..etc.. you may get an old milking machine for nothing, or close to nothing. I got two identical ones from local farmers (and even spare parts). The machines are said to run forever if nicely treated. Some of them dislike going lower than -0.5 for long periods, but for the time it takes to infuse your 25' hull it should be no problem going 0.6 -0.7 (I am not an expert though) I guess you could reduce vacuum a little when the fiber is wetted. According to Diab, Norway you can do well with -0.4 if you use grooved cores. Are you building sandwhich? Remember weight if you use grooved cores.

cheers

,,,,,,..if you get old pumps from dutch milk-farmer,,,please realise that your molds will NOT 'moo' if the vacuum fails!!--if you get equiptment for 'nothing,or next to nothing',,it is probably worth just that!!!--in north america ,the 'DIAB' people seem happy to send a crew in to your workshop to make sure that you have a sucessful 'first product',,which tells me that there's some competition in that marketplace,,and if you play your cards right,,,you'll have a perfect 'one-off' without the risks of 'teching-up',as long as you convince them that you're in for a 'BIG' production.
From listening to the full spectrum of accounts....I'm more and more convinced that the best way to get the highest strength/weight/$ ratio for a 'one-off' would be with cold-molded cedar.......and that you will only get your value in infusion once you have gone through a learning curve,or get some 'pro's' in.--If you can already do a reasonably efficient hand layup,,you'd HAVE to be VERY skilled in infusion to make it worthwhile on your first product!!!

[Herman]

For a cost effective one-off laminate, I would not recommend cedar. At least, not in Holland. Over here it is horribly expensive. Quite some more than any foam that is available. elsewhere it can be a different story.

It also depends on what your looking for. One of our clients built an Int. 5.5 meter. This boat needed 9 kilo's of material in the hull structure. (class rules)
They used red cedar to reach that number without creating a very thick laminate, which they did not want for several reasons.

For amateur boat builders, you can look at things in both ways:
laminating and producing a high quality laminate, is something one really should learn by experience. So the hull (one of the first projects) will be moderate quality, and the last drawer in the master bedroom will be high quality.

However, with resin infusion, if all stacks of material are in the right place, and all tubing is correct, there is no difference between a professional or an amateur who opens the resin valve. getting the setup right is something everyone has to learn, professional and amateur. Over the years, we have developed some layouts that work for nearly every simple projects. (boat hulls are simple).

About infusion of a cored construction: Grooves will help, but do remember that a groove is a disruption in your PVC foam, which tends to crack on those disruptions, when stressed to the limit. also the weight gain is considerable. The grooves and drill holes will fill with resin, but also the wetted area of the foam is greatly increased.
We have good experiences with "double cut" foam from Core-Cell. This is cut on both sides, about 2/3 through the foam. The cuts intersect, so there is a resin path to the lower laminate. testing is important to get the lower laminate right. Infusion speed is important, and also the glass can influence results.

Over here we mainly use a resin distribution net on top of the laminate. This ensures a good flow, and gives greater freedom for the reinforcing layers and cores used. also a runner system is used. for these purposes we have developed our own products, a resin net which is flexible and has a goad and steady flow, equal in all directions, and a cheap and flexible runner, which will not pierce the bag, and does not collapse under vacuum, even when the resin gets warm.

For your proa's, try and get some double cut foam, and do some experiments on a flat sheets. Experiment with materials and pressures, and you will quickly find out how far the resin will travel in a reasonable time window, and how the quality will be. With this information you can develop a setup that works in your situation.