knottyBuoyz III The TW28 Project

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laporter
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Vacuum processes - Sorry, long post.

Post by laporter »

Jacques/Joel

I want to do some rough estimates of consumable materials required to vacuum bag or vacuum infuse the hull of the TW28 so I have a few basic questions.

1. What is the total surface area of the outer hull of the TW28 including the keel & transom up to the sheer of the deck? I suppose I could figure it out myself but I'm lazy. Doesn't have to be exact, maybe +- 5% or so.

2. Vacuum bagging & vacuum resin infusion methods will result in a thinner laminate (especially if infused) than a cold molded composite panel. This won't necessarily, from what I've read, result in a "weaker" panel but one that is more flexible. What if any changes to the glass lamination schedule would you recommend?

3. What would you consider to be the optimum epoxy/glass ratio to be in a bagged or infused composite layup for the hull of the TW28? I've read it's anywhere from 40/60 to 70/30 so there's a lot of differing opinions. Would a target of 50/50 be reasonable? For example:

Lets say the hull was 100 sq yrds. The laminate schedule called for a total 30 oz/yrd layup. If we're aiming for a 50/50 ratio of epoxy/glass that would equal 187.5 lbs of epoxy or (Silvertip System 3 = 9.5 lbs/gal) approx. 20 gallons. Sound about right? Would +10% for wastage be reasonable or should more be mixed? That's about 2 gallons or $150 in this scenario.

4. Is it possible to machine stir (hand drill powered paint mixer type) large amounts of epoxy for these types of processes? Does it change any of the properties of the epoxy? Or, is it even necessary?

My reason for asking is purely economical, in that, these processes can result in a much better finish requiring less sanding and fairing. As well they can result in less wastage of epoxy. I've read that the throw away consumables for boats of similar size to the TW28 would be about $500 which isn't too bad if you consider the time, effort & consumables of sanding, filling & fairing a conventional cold layup. These processes also seem to be more user friendly in that you don't require the Tyvek suits, respirators, gloves etc.

Anyhow, for the record, I'll build smaller boats before tackling anything this size. There will be experiments that I'll document & share before we get to this point. There seems to be a evil force in the universe that doesn't want me to start this project (more costly truck repairs) but we'll get to it eventually.

Thanks fellas.

Rick
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Rick, Lori & Shadow

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Re: Vacuum processes - Sorry, long post.

Post by jacquesmm »

laporter wrote:Jacques/Joel

I want to do some rough estimates of consumable materials required to vacuum bag or vacuum infuse the hull of the TW28 so I have a few basic questions.

1. What is the total surface area of the outer hull of the TW28 including the keel & transom up to the sheer of the deck? I suppose I could figure it out myself but I'm lazy. Doesn't have to be exact, maybe +- 5% or so.
Look at your nesting drawing. Take all the hull panels, that's what you need: around 30 sheets for hull and deck. I say around because I don't know how much you will do in foam, how much in honeycomb or plywood etc. You could do everything in foam sandwich. In that case, it takes the same number of sheets than plywood sheets, very easy.
Warning: the thickness of the foam is NOT the same than the plywood.
WARNING: the type of fiberglass and number of layers is VERY different in foam sandwich.

2. Vacuum bagging & vacuum resin infusion methods will result in a thinner laminate (especially if infused) than a cold molded composite panel. This won't necessarily, from what I've read, result in a "weaker" panel but one that is more flexible. What if any changes to the glass lamination schedule would you recommend?

We would need 10 pages to compare infused to cold molded. Which cold molded? Which infused laminate? I can make either one stronger or weaker.
I build my first foam sandwich boat in the 70's and have more experience than many in that field.
I can calculate a laminate schedule, we do it for those who buy the supplies from us. I could give you at least guidelines but it will be on my long list of jobs.
This is not a change in laminate, it is a very different one.

3. What would you consider to be the optimum epoxy/glass ratio to be in a bagged or infused composite layup for the hull of the TW28? I've read it's anywhere from 40/60 to 70/30 so there's a lot of differing opinions. Would a target of 50/50 be reasonable? For example:

Lets say the hull was 100 sq yrds. The laminate schedule called for a total 30 oz/yrd layup. If we're aiming for a 50/50 ratio of epoxy/glass that would equal 187.5 lbs of epoxy or (Silvertip System 3 = 9.5 lbs/gal) approx. 20 gallons. Sound about right? Would +10% for wastage be reasonable or should more be mixed? That's about 2 gallons or $150 in this scenario.
It's not a matter of opinion or personal preferences. This is science, physics. You will be limited by what your skills and equipment can do. 50% glass will be good and that is what I aim for but, in order to get there, you need some experience with fiberglass. What is your level of expertise? Did you ever try to vacuum bag? Infuse? Do you understand what you are in for? Would it not be more reasonable to keep it simple and do a good open mold job instead of taking a chance to have dry spots that you will not see?
We calculate our BOM's through elaborate spreadsheets, 30+ pages for the TW28. I don't like to guess how much you will need without doing the whole job but foam sandwich cost around twice what plywood-epoxy cost in materials.


4. Is it possible to machine stir (hand drill powered paint mixer type) large amounts of epoxy for these types of processes? Does it change any of the properties of the epoxy? Or, is it even necessary?
Not worth considering at that level.

My reason for asking is purely economical, in that, these processes can result in a much better finish requiring less sanding and fairing. As well they can result in less wastage of epoxy. I've read that the throw away consumables for boats of similar size to the TW28 would be about $500 which isn't too bad if you consider the time, effort & consumables of sanding, filling & fairing a conventional cold layup. These processes also seem to be more user friendly in that you don't require the Tyvek suits, respirators, gloves etc.

Anyhow, for the record, I'll build smaller boats before tackling anything this size. There will be experiments that I'll document & share before we get to this point. There seems to be a evil force in the universe that doesn't want me to start this project (more costly truck repairs) but we'll get to it eventually.

Thanks fellas.

Rick
Good idea: build a small boat with the open mold method (our standard method) first, then a second one same method, trying to use less resin, then build some parts using a vacuum bag and if all that works fine, try a small part with infusion. Next a large part with infusion then maybe a hull. If you try to infuse a hull without following that learning path, it is guaranteed to fail.
I have poly/vinylester infusion experience and used the method in production, I took an advanced SAMPE seminar about infusion a few years ago and try to keep up to date on the technique. Last year, Joel and I fabricated some infused panels and I messed up a few by keeping the vacuum too high and other errors. Each wasted panel was $ 400.00 of good resin, foam and glass. To mess up the infusion of a TW28 hull can cost as much as $ 15,000.00, all wasted in a few hours. I would not do it.
Jacques Mertens - Designer
http://boatbuildercentral.com

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Post by laporter »

Thanks for the response Jacques. I know you're busy and appreciate your time.
jacquesmm wrote:Look at your nesting drawing. Take all the hull panels, that's what you need:
I was going to ask you for the scantlings in foam offline when the time is right. If I go the foam route (I can get some CoreCell at half price right now) it would be for the cabin sides & cabin top as recommended in the plans, I'd stick with the marine ply you specify for the hull & decks. I'll do my homework and figure out the areas from the drawings.
jacquesmm wrote:We would need 10 pages to compare infused to cold molded. Which cold molded? Which infused laminate? I can make either one stronger or weaker.
I should have been more specific in my hypothetical scenario. It would be the exact scantlings specified in the stock TW28 plans built exactly as you instruct. The whole idea was to produce a fairer hull. I think the TW28 is big enough to benefit from vacuum bagging or vacuum infusion even considering the cost of disposables involved.
jacquesmm wrote:It's not a matter of opinion or personal preferences. This is science, physics. You will be limited by what your skills and equipment can do. 50% glass will be good and that is what I aim for but, in order to get there, you need some experience with fiberglass. What is your level of expertise?
What is my level of experience? Zero! This is why I'm doing some research. I will try all the methods we've discussed to gain that experience. I have worked on "Big Ship" & "Little Ship" construction projects and have an appreciation for what's involved, hence the pre-planning & research. My professional qualifications are in marine engineering logistics so, by nature, I have a tendency to think big and scale everything up which adds an increased level of detail to everything I do, for that I appologize.
jacquesmm wrote:Did you ever try to vacuum bag? Infuse? Do you understand what you are in for? Would it not be more reasonable to keep it simple and do a good open mold job instead of taking a chance to have dry spots that you will not see?
No, haven't done any of that yet but soon. From my research I have a pretty good idea of what I'm in for or I wouldn't be posing these questions. I intend to try all the methods available on a wide variety of materials so that I can see what's going to work. I'll document and share those experiences with everybody here for our collective benefit.
jacquesmm wrote:Good idea: build a small boat with the open mold method (our standard method) first, then a second one same method, trying to use less resin, then build some parts using a vacuum bag and if all that works fine, try a small part with infusion. Next a large part with infusion then maybe a hull. If you try to infuse a hull without following that learning path, it is guaranteed to fail.
Absolutely will do that. Start small, gain experience, experiment, figure out what works for me then move up. Sounds like a great plan and sage advice.
jacquesmm wrote:I have poly/vinylester infusion experience and used the method in production, I took an advanced SAMPE seminar about infusion a few years ago and try to keep up to date on the technique.
I knew you would have this experience that's why I asked the question! I also knew you'd be a decent enough fella to share your knowledge and experience with us, that's what sets Bateau ahead of everyone else.
jacquesmm wrote:Last year, Joel and I fabricated some infused panels and I messed up a few by keeping the vacuum too high and other errors. Each wasted panel was $ 400.00 of good resin, foam and glass. To mess up the infusion of a TW28 hull can cost as much as $ 15,000.00, all wasted in a few hours. I would not do it.
You can probably write off your mistakes as a "research & development" failure on your corporate income taxes. We don't have that ability. All this pre-planning and research I'm doing is to avoid exactly that scenario. I try to learn, firstly from those who have gone before then try what they recommend to see if I can make it work for me too! I'm not a rich person with tons of money to throw away on a boat project like this so I have to do my homework. Otherwise I'd pay someone else to do it but that's not why we're here.

My only desire is to build a well engineered and nice looking boat that's reliable and safe.

Rick
Yours Aye!
Rick, Lori & Shadow

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Post by jacquesmm »

If I understand correctly, all what you expect from infusion is a fair surface. In that case, use the "poor man's peel ply" solution: a sheet of polyethylene over the wet resin. That's all you need.
Last coat only because most plastics leave a residue.
Jacques Mertens - Designer
http://boatbuildercentral.com

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Post by laporter »

jacquesmm wrote:If I understand correctly, all what you expect from infusion is a fair surface.
No that's not all I expect. Maybe that didn't come across in the discussion.

A boat engineered to be: Strong, Light, Economical (minimal waste of materials) and looks good (as good as any professional boat builder could do with the same materials). That's what I want and I'll figure out how to achieve it. If it means spending $5 on 100 yards of Visqueen or $500 on consumable vacuum infusion materials, so be it, money isn't the issue. I'll shut up now.
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Post by tech_support »

laporter wrote:A boat engineered to be: Strong, Light, Economical (minimal waste of materials) and looks good (as good as any professional boat builder could do with the same materials). That's what I want and I'll figure out how to achieve it.
In that case then just build it as designed :D

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Post by laporter »

shine wrote: In that case then just build it as designed :D
Yes Dear! :wink: Sorry, couldn't resist. I defer to the experts and take their advice. I'm going to waste some sticky stuff and glass this winter so we'll see what kind of mess's I can make!
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Post by laporter »

Joel

I had to return an e-mail on that small order for the trial kit etc. It went back to orders at e-boat.net. Will you get that mail or was it from an automated account? I have one small problem with the order, that's all.

RIck
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Post by tech_support »

send it to orders@e-boat.net - we can fix it

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Post by laporter »

shine wrote:send it to orders@e-boat.net - we can fix it
That's the addy I used. Thanks Joel.

It's amazing how heavy the 1708 & 1208 is! Having never seen or held it before it's quite surprising. Looking forward to getting real sticky real soon!

Thanks again.

Rick
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Rick, Lori & Shadow

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