Calculate resin req't for hull infusion

I use a polyethylene shrink wrap film which i buy in a 4m wide roll, 100m length. Its cheap. Not as vacuum tight as a proper commercial laminated nylon type vacuum film, but it seems to be good enough for general infusions with epoxy - its not compatible with styrene resins. I would not use it for a highly critical part such as a carbon mast or similar, as there is a little bit of porosity in it from time to time, it seems to vary in quality along its length and i do find the odd pin hole in it.

Its not the film im worried about tho, its the hull your sealing to. If the entire hull is faired and painted on the outside, you should only have to worry about the edges - but id imagine its not painted yet... Youd be surprised how such a tiny hole can work through your hull - the vacuum will find its way there. Ive had no end of trouble trying to keep my table vacuum tight...

with the outside glassed, and the inside resin coated, youve got the best chance of minimizing leaks, you should be OK. Sealing the gunnel area will most likely give you the problem areas - how will you make the flange you need in this area?

 

Yes it'll be faired & primed with some anti-fouling on the bottom. The inside will get at least 1 coat of neat epoxy, maybe more if I think it needs it. I'm not too sure about the gunnels. They're pretty square as they are. I was going to try making a flange out of some rigid plastic panel I can get locally and fix it to the bulwarks & transom (on the outside) with two rows of mastic tape. I can seal the lower outside edge with another run of mastic tape. That'll give me a flange surface to fix the vacuum line to with a decent peel ply resin brake.

If worse comes to worse I can paint the bulwark & top of the transom for a better surface to seal a flange to. It won't be finish faired till just before the boat leaves the shed. I did something very similar to a friends mold when he didn't have a wide enough flange. It worked perfectly.

 

Whatever works, works. Just always have it in the back of your mind, how can I do it so there is the least risk of leaks.

You also need to pay attention to the distances between feeds. Ideally you need to keep the distances all the same in all parts. For example, you need to setup the elliptical rings by measuring back from the chine feed, and placing the previous feed equidistant in all places. This leaves you with a problem at the transom corners. So here you might add little branches to fill out these corners where there is further distance to flow between the box keel and transom corners.

Following a vacuum tight preform, the strategy is also very important.

 

I just figured out :idea: I have to increase the area of all my panels to take into account the fabric overlaps. That'll double the resin required for those areas.

My brain hurts now!

 

Somewhere on here Herman posted a pdf it shows resin consumption for the green 75 also the red 60.
I cant find it now but green was 400g ^m and red was a little less.The red I tested was thicker but much more open,it consumed a little more then the green in my tests.

What changed the consumption was when the infeed was closed,when done early it allowed some of the resin to keep moving thus using less.

Jorge was using green 75 maybe he could throw in his 2 bits.

 

I've got some green here and I'll likely do a few tests this winter. See how well infuses, measure the stuff etc. see what I come up with. Groper says he has pretty good luck with the shade cloth. I've found a source that's pretty economical. Might see if I can get a sample to try.

Really looking forward to it now! Should be flipping the boat over in about a week & a half or so.

Thanks for looking in Tungsten.

 

My shade cloth numbers for consumption are bang on with what others have posted.I just don't get near the speed or distance others have posted.I suspect its because I'm not able to get full vac.

 

Only 3 factors effect speed and distance.
1. Resin viscosity
2. Permeability
3. Vacuum pressure.
Going slow gives me better results and it wastes less resin, the distance required is simply solved by adding more sequential feed lines.

 

Using the green flow media, perf film, peelply with red stripe, and three layers of 12oz of cloth - two +-45 and one 0 90 I would mix up 185 oz of resin for a 4' x 8' panel. The bucket would be tipped by end of infusion, very little left over.

I'm now a huge fan of infusing in. Just make sure you got no leaks on your flange or you will drag air all the way through your part. If you find you calculated wrong, have some unmixed resin weighted out and standing by just in case. I used the Gurit prime 20 LV which is good stuff!

 

One other thing, I think your boat is ply right? make sure to seal that plywood or else it will suck up a ton of resin and be heavier than ever ))

 

It's already soaked up over 55 gallons and that's on the outside!

Don't worry, got it covered. Thanks.

 

ok good luck!!!!

 

Ya I tried infusing some meranti that wasn't sealed first.After cure the glass on both sides peeled away with the peelply.