Subject: Re: {Disarmed} Re: {Disarmed} Re: {Disarmed} Re: [harryproa] VRI - stupid newbie questions
From: "Henny van Oortmarssen" <henny@fram.nl>
Date: 10/30/2008, 7:03 PM
To:
Reply-to:
harryproa@yahoogroups.com.au

Hi George,
 
First of all, I never did any testing and the first thing I ever infused was a 15 sqm half float hull. That was not too difficult as the infusion strategy has been modelled by computer. After another few hulls I started with panels and bulkheads. I'm a bit lazy and infuse the panels as I do the hulls with one difference, infusing both sides at once because of the mold on one side (the vacuum table). Also in all kinds of shape and the flow medium on both sides is my assurance that everything will go fine. I never had any failure, dry spot etc. except for one occasion where I forgot the release film between peelply and flowmedium. Not a real problem, just hard work to get the flow medium apart from the peelply. Now I think of it, there was another occasion where I used the wrong mixing ratio (I use two diffferent kind of hardeners, 30:100 and 55:100). When the panel was finished I made another badge, but know with the right mixure, and just continued the infusing, till the second bucket was empty also. I hoped the wrong mixure was in the resin trap by then. After curing I've noticed no problems so I guess it's OK.
 
I know it is possible to use the flow medium just on the top side, with some testing with my materials to see how it goes, but I just don't like to do that and fiddle on with what works for me. I'm concentrating on building the boat and not improving the system that already works for me in quite a perfect matter.
 
Of course, when using gel coat and/or infusing hulls in a female mold that will be quite another thing and very worthwhile to develop a method without flow medium on the mold side. However, I know that builders use a more permanent kind of flow medium that will be part of the laminate (and prevent print through) to be sure of a sufficient resin content on the mold side. But this adds extra weight, unwanted for a multihull.
 
Mold table finish is not important and even unwanted as panels and bulkheads are parts that need further construction with other parts, tapes etc. and peelply finish is just great.
 
I'm a epoxy fan, without any polyester or vinylester experience (OK have build 20 polyster kayaks long ago somewhere in the seventies). I think there is not much difference, besides of the fact that one have to deal with the shrinkage problem in a mold when not using epoxy. I'm using Bakelite Epoxy 04908 with 120 mPa viscosity, geltime about 8 hours, potlife I don't know, I guess about two hours or so. All my infusions are not taking any longer than one hour, be it a 40' hull or a 4'x8' standard sheet panel. Resin buckets are empty within 45 min. or so. This is a little different from other infusion methods I think (like the parallel feeding systems, where I use the fishbone method for the big parts like hulls)
 
Another thing with panels is that after some experience one can use just the right amount of resin, with just a very few drips of excess resin going in the resin trap. For this one needs some nerves as the bucket is empty when the part is filled for 60% or so.
 
Henny van Oortmarssen
www.fram.nl
 
 
 
 
 
----- Original Message -----
From: George Kuck
To: harryproa@yahoogroups.com.au
Sent: Thursday, October 30, 2008 10:37 PM
Subject: {Disarmed} Re: {Disarmed} Re: {Disarmed} Re: [harryproa] VRI - stupid newbie questions

Hello Henny,
 
With perforated core it is possible to flow from top side, why do you also flow from bottom ?  Is it for extra insurance that you get full coverage ?  Do you prefer a peal ply finish to the mold table finnish ? 
 
I will be making panels without gel coat at least to start so I can see the results and correct any voids in resin (hopfuly will not have any flaws).  I have had good results with Hydropel R 015 vinyl ester resin which is made for resin infusion but noticed you are using epoxy. Do you do anything different with the epoxy then if using vyle ester resin or have you only used epoxy ?   There is no need to get into prose and con of using epoxy, that's already been hashed over enough and I expect you are not going to change in middle of project.
 
  
Happy sailing,
George Kuck
Chesterton, MD
 
PS; My 22' x 4' table is now complete and I am now putting mold release wax on it, and hope to do test panel on it over seam to test in the next few days. 
   

--- On Thu, 10/30/08, Henny van Oortmerssen <henny@fram.nl> wrote:
From: Henny van Oortmerssen <henny@fram.nl>
Subject: Re: {Disarmed} Re: {Disarmed} Re: [harryproa] VRI - stupid newbie questions
To: harryproa@yahoogroups.com.au
Date: Thursday, October 30, 2008, 4:58 PM

It's consumable flow medium, no way to leave it on. Finish is normal peel ply structure, weight is 3035 gram per sqm (15mm Corecell T400 with 600 gm glass both sides)
 
Launch day when it's ready, ha, ha  o well, it's a 8000 hours part time project and despite the fact I've had more time this year because Blind Date wasn't ready to sail (I'm volunteer skipper) (but you know about that, yes) progress lately has not been too good.
 
By the way, I've organized a resin infusion workshop this weekend with visitors from Venezuela, UK and Holland so if anyone more ones to come, let me know (but you have to hurry then)
 
Henny van Oortmerssen
 
 
----- Original Message -----
From: Rob Denney
Sent: Thursday, October 30, 2008 1:09 AM
Subject: {Disarmed} Re: {Disarmed} Re: [harryproa] VRI - stupid newbie questions

G'day,

Do you leave it in, or remove it? If the latter, what sort of finish
does it leave? If the former, how much weight does it add?

When is launch day? ;-)

regards,
Rob

On Thu, Oct 30, 2008 at 3:32 AM, Henny van Oortmerssen <henny@fram.nl> wrote:
> I'm using flow medium on both sides of pre-perforated CoreCell foam. Lost
> and lots of square meters of panels and bulkheads for my 12m. trimaran with
> great success.
>
> Henny van Oortmerssen
> www.fram.nl
>
>
>
>
> ----- Original Message -----
> From: Rob Denney
> To: harryproa@yahoogrou ps.com.au
> Sent: Wednesday, October 29, 2008 12:38 PM
> Subject: {Disarmed} Re: [harryproa] VRI - stupid newbie questions
>
> G'day,
>
> On Wed, Oct 29, 2008 at 2:32 PM, Herb Wesson <squirebug@yahoo. com> wrote:
>>
>> I have finally managed to get most the items I need to begin
>> experimenting with VRI, but have some questions:
>>
>> 1. Is it sensible to infuse both sides of a panel at once? If so,
>> how do you tell if the bottom is infusing properly?
>>
>> On your test pieces, use a sheet of glass for the mould and as it infuses
>> watch underneath. If you drill 1/16" holes at say 4" centres in the foam,
>> the resin should go through no trouble.
>>
>> 2. What is the best sort of pipe/hose to use to deliver the resin and
>> suck it out?
>
> One that will not collapse under vacuum. 3/8" id should do.
>
>>
>> 3. Will any sort of nylon work as peel ply or is a special kind required?
>
> Any sort should work, but some are treated and the treatment stays on
> the epoxy, stuffing any secondary bonds. Thin peel ply is sometimes
> hard to remove. I would start with the good stuff and as you l;earn,
> try the cheaper.
>
>> 4. What is a good method to connect the outlet tube/pipe to the shop vac?
>
> Via a resin trap so no resin gets in the pump. A press fit should do
> for the actual connection as the vacuum sucks it on. A shop vac may
> not have enough grunt.
>
> regards,
> Rob
>>
>> Thanks for your help. I will post pictures eventually, hopefully by
>> the end of the year. The first project will be a small dory, followed
>> by Elementary next year.
>>
>> Best regards
>> Herb
>>
>>
>
>

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