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Carbon Fiber Critchfield....Hope I am on the Right Track!!
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Author:  Hounddog [ July 17th, 2015, 1:16 pm ]
Post subject:  Carbon Fiber Critchfield....Hope I am on the Right Track!!
HISTORY
I got this NEW Critchfield a few years ago. The problem was the build was so poorly done that you could not safely run the boat. It would destroy its self. I knew that when I got it and my plan was to disassemble it and rebuild it using Carbon Fiber after removing all the fiber glass. Basically strip in down to the gel coat and lay it up with Carbon Fiber. To get it to that stage was like working on an EGG. I am now ready to do the carbon fiber. The complete boat shell with deck and rear cowl weighs less than 100 pounds.

I am experienced with working with Fiber glass. Never done any carbon fiber work.

First off this stuff is costly! So I don't want to make any mistakes.

Questions:
[1] What weight of cloth should I use? I plan and using the carbon fiber tunnel sleeves for stringers and wide 50 inch cloth for the inside. Good idea??
[2] I thought I would do the transom with laminated pre cut thin carbon fiber sheets and bond them together as I assemble the transom in the boat. The floor will be done the same way. Good idea??
[3] I am thinking of using the West slow drying system. Anyone used it and knows the lay up timing?
[4] Would I be best to have a helper or two when doing the lay up?
[5] Any experienced people intersted in helping?
[6] Best place to buy the materials??
Author:  beavertonae-21 [ July 17th, 2015, 2:32 pm ]
Post subject:  Re: Carbon Fiber Critchfield....Hope I am on the Right Track
depending on where you are Noahs or Canada Composits.
Author:  jake@elsey.ca [ July 22nd, 2015, 5:06 pm ]
Post subject:  Re: Carbon Fiber Critchfield....Hope I am on the Right Track
Sounds like a sweet project. I would LOVE to help. Just, I cant really be out in bala too often... and i dont have much experience at all with vacuum baging glass work.

strong box idea is a no go?
Author:  mattmak [ July 22nd, 2015, 5:13 pm ]
Post subject:  Re: Carbon Fiber Critchfield....Hope I am on the Right Track
Just curious how you are holding the eggshell hull in shape so everything stays straight and desn't warp or twist until it is strengthened with the carbon and epoxy?

cheers,
Matt
Author:  Hounddog [ July 22nd, 2015, 8:14 pm ]
Post subject:  Re: Carbon Fiber Critchfield....Hope I am on the Right Track
Jake, I have several ideas for the strong box including the jockey seat/strong box and a Critchfield long deck version, I will decide after I get the hull portion completed.

Matt I have the hull braced to keep it straight, I will have it in a jig while the carbon fibre is done.

I think I with use a lighter weight of cloth so it will bend easier. I with use more than one layer.
To get some experience and get an ideal of drying time, I going to lay up the separate pieces for the floor and transom. I will then prefit everything so I can layup everything in the hull all at the same time.

Once I am at that stage Rob Scythes and I will to the assembly and add the unique special features to the boat. T850 guys need not worry, this boat is designed as a GT30 and T750 boat.
Author:  OMCFORME [ July 25th, 2015, 10:59 am ]
Post subject:  Re: Carbon Fiber Critchfield....Hope I am on the Right Track
Interesting project. Who built the defective hull ?

I'm doing a somewhat similar project - see the 21 Scarab resto thread. I'm also dealing with shitty (but not outright dangerous) original lay-up, but I did not take it down to gel. Here's some input corresponding to your questions.

1) Cloth style (weave and fiber orientation), weight, and number of layers are critical decisions. To figure this out you can (a) Do a bunch of research in composites books and online forums to figure it out, (b) have Vectorply design it for you, or (c) try to nail down the lamination schedule of a similar, successful boat and copy it. You didn't mention core - will this be a solid carbon boat ? If so, how do you know you'll achieve adequate hull thickness to be stiff enough ? (yes, carbon is good for that but still a valid question).

2) You can do the transom that way, but how are you going to hold them together for a good bond ? If vacuum bagged, yes could work well. Again, what else will go into the transom - will it be plywood-cored ?

3) WEST actually has 2 different SLOW hardeners (#206, 209), not sure which one you mean. I have been using WEST and blending hardeners to match ambient temperature for my project but it's really not an ideal laminating resin. The viscosity is too high, making it too slow and painful to wet and squeegee out, especially for a layup as big as you want to do. The only reason I've been using it is because I have a lot of experience with it, it's reliable and versatile, and I get it at wholesale prices. Upon the advice from Composites Canada, I recently bought some PTW&W 410-series laminating epoxy to try out. Lower viscosity for easier wet-out and no amine blush, I'm looking forward to trying it. If I were you I'd also look at the System Three Silvertip laminating resin. WEST is overpriced for what it is and isn't really intended for building a whole boat.

"Layup timing" ? That's a million dollar question (ha ha carbon fiber joke !). There are many variables - ambient temperature, hardener, batch size, how fast you layup/squeegee, how many layers you do at once (i.e. exotherm from first layer affecting the next). Have you used epoxy in big quantities before ?

Key question - are you vacuum bagging this boat ? If so, you need to consider how assembling the bag works into the "layup timing" question. If not, how are you going to assure a good (secondary) bond to your gel-coat eggshell ?

4) Yes, I'd suggest 2 helpers if they are truly help and not a hindrance. I'm not trying to be a prick, but if they do not know what they are doing they could cause more problems than actually help. One to help layup, one to mix batches and be general third pair of hands.

5) Keep this thread going, I bet you'll find some young T-boat guys who want to help.

6) As mentioned, Noah's and Composites Canada are both good. Composites has a wider selection of epoxies and reinforcing fibers and better tech help (JP Pozzo) than Noah's.

Here's some more questions you may wish to consider:

Have you verified that you can effectively squeegee down into the keel/pad areas from outside the boat ?

With respect to vacuum bagging (yes/no), if you aren't, what prep are you going to do between layers ? Are you using Peel-Ply ? Especially with WEST, the amine blush is an issue.

Don't forget the safety issues associated with epoxy. Get LOTS of nitrile disposable gloves. Skin contact with either epoxy resin or hardener can lead to a phenomenon known as "sensitization". This means that a later exposure (even very small) will cause a severe allergic-type skin reaction. In some cases it can be so severe that you can't work with epoxies ever again. Don't use latex gloves (themselves can cause allergies and have no actual chemical resistance), or vinyl (cheap, bad dexterity). Noah's has a pretty good selection of gloves.

Good luck,
Matt


Hounddog wrote:
HISTORY
Questions:
[1] What weight of cloth should I use? I plan and using the carbon fiber tunnel sleeves for stringers and wide 50 inch cloth for the inside. Good idea??
[2] I thought I would do the transom with laminated pre cut thin carbon fiber sheets and bond them together as I assemble the transom in the boat. The floor will be done the same way. Good idea??
[3] I am thinking of using the West slow drying system. Anyone used it and knows the lay up timing?
[4] Would I be best to have a helper or two when doing the lay up?
[5] Any experienced people intersted in helping?
[6] Best place to buy the materials??
Author:  Hounddog [ July 27th, 2015, 7:08 am ]
Post subject:  Re: Carbon Fiber Critchfield....Hope I am on the Right Track
Thanks for the excellent reply. The original boat was built by Charger boats. It is the only one they built for Top Gun Marine. The gel coat is fine. The fibre glass and wood were the problem.
Because the hull is new I had no problem bonding. I tested that already. As long as you sand the surface to dull first. There will be ballistic core in the transom. I have that in one of my other Critchfields. I may add core material. I decided to have Rob Scythes take the lead. Rob is a professional race boat builder and has worked a lot with all of the composite materials. Rob and I have worked together on many projects.
I just finished the mock up for our T750 OMC. It looks like a T850 motor! It has a 3 cylinder cowl, Yamaha Pro 50 trim and both a nitro or SST 60 gear case. Big advantage is you can remove the head without having to remove the lower cowl! One difference is the steering arm is longer that the 3 cylinder so you do not need to cut the bracket on the Pro 50. The shirt does not fit. However a Tohatsu one does and unlike the OMC shirts, it does not attach to the lower pan. It is a better set up compared to the original and the trim is a major up grade being a 3 ram system. Next step is to get studs for the head, power head and mid. The threads are a mess on the mid where they replaced the gear case.
Author:  jake@elsey.ca [ July 28th, 2015, 2:04 pm ]
Post subject:  Re: Carbon Fiber Critchfield....Hope I am on the Right Track
awesome! keep us posted!
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