Building a high performance whitewater kayak- going to need some help

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#13

I am in the process of getting my materials in order to start molding the boat. My plan is to start by casting and infusing a few helmets, and maybe make a wakeboard before I go to the boat.

The single thing that is the most frustrating right now is a lack of a workspace. I can’t find an indoor space that is clean and dust-free that isn’t also the intake for a central air system. Hopefully something will come together when I move in a month.

Also does anyone know of a good writeup on how to do a gel-coat with an infusion?

#14

Since your plug is another boat. I don’t think your going to want to try infusion for making the mold. I just think that would be asking for trouble. I don’t even know where to start on making a flange that would be able to handle vacuum. The plugs I infuse are all machined out from Ren tooling board, which allows me to machine the flange into the plug. Once I have a plug that can handle vacuum…

[ul]Tape the perimeter off, this is the area you will stick the double side bag tape too. You don’t want release agent or surface coat here.[/ul]
[ul]Seal and release coat.[/ul]
[ul]Spray Gel or Epoxy Surface coat and pull the tape off carefully then let tack.[/ul]
[ul]Now you can stick your bag tape to the clean perimeter.[/ul]
[ul]Layup… Glass or Carbon, peel-ply, flow media, spiral wrap, and vac bag.[/ul]
[ul]Pull vac, do leak test, leave vac on to boil off any remaining moisture. I only wait 20-30min. I have heard of others waiting hours… :wondering:[/ul]
[ul]Mix resin[/ul]
[ul]Infuse[/ul]
[ul]Cure[/ul]

Done!

#15

Nice! Sounds pretty standard, although taping the flanges before spraying I somehow hadn’t thought of yet.

Another thing I just wanted to throw out there just in case: No matter how much I baby the plug boat it is going to get scuffed up a bit and I will need to do some buffing for a perfect mold. Should I just do what I can with the boat and spray a little extra gel coat before laying up the mold so I can polish out any imperfections? We are talking very small scratches from rubbing on the bed of my truck here.

#16

As long as you took proper steps there would be no problem infusing that. You just need a good flanging material such as MDF or other ridged material, and make sure you seal it good against the plug. Duratec after will fill micro purosity and pinholes. And when you lay the surface coat or gelcoat for the mold you seal it even more. Obviously you should do a vacuum check before getting to that stage, but its not that difficult over all.

#17

I’ve been working on choosing an epoxy system. I’ve been looking at marine grade systems, but does it really make a big difference? West Systems is a name I know, but I have also been looking at MAS. Anything else anyone can recommend?

#18

If I do infuse a mold is it worth looking into an epoxy specifically made for the job like ToolFusion? http://www.resininfusion.com/toolfusion.html

Also how sturdy would my flanges need to be?

#19

well it depends what type of mold you are making, high temp ones you would want to use a infusion resin specifically designed for tools with repeated high heat cyles. A regular VE or PE or epoxy would be sufice for the standard room temp(or slightly higher) molds. As for the flanges they should be sturdy enough that they wont move and crack, creating a leak. Biggest thing with infusion is very good vacuum integrity both in the bag, but also the plug/mold. Best to do a vacuum check first on the plug/tool before.

#20

Thanks Hojo!

Still trying to decide on an epoxy. I need something that will be tough, clear, UV resistant, and be able to deal with being immersed in water.

#21

use west system epoxy and paint the boat white with some carbon fiber reveals. get fancy and do a nice scarab pattern. plus white tends to hide bad body work a bit better than darker colors.

you could use white gel coat as well on the bottom half of the boat for durability and have the top show off the laminate.

#22

as dallas said west epoxy do some good epoxy resins that are ideal for boat manufacture, I would say from my very limited axperience of builing anything that sits in water that a gelcoat would be a must.

#23

Thanks for the advice! That was my original thought, glad I was on the right track!

#24

ughh… there so many better epoxy resin system out there that are way better than west sytem/proset in my opinion. Im not a big fan of them personally

#25

It’s marketing and availability… Once you really start looking into the specs you see they’re weakness. What systems do you use?

#26

I do agree with that, the only thing I think west system is good for is quick crude repairs on the road. As for resin systems we use I cannot specify unfortunatly, dont take it personally. I share what I can here, but specifics I cannot. That being said theres so many resin systems out there that are available that are way better than west/proset.

#27

Thanks for the honest feedback! I’ll keep looking. Shoe any reccomendations?

Is there really a need for a “marine grade” epoxy?

How much overlap would you guys recommend for the part overlap? I was thinking of using a strip of double-sided tape to step up off the plug since its about 1" wide and roughly the right depth for the deck to set neatly into the hull. I could use the wax method to build up inside the mold itself, but that would limit me to about a 1/4" in places of overlap which is a bit small I would think. Anything wider and I am forced to build flanges on the plug twice to give myself sufficient overlap (which was my plan all along).

Also any recommendations on adhesives for joining two parts like this?

Once again I would like to thank you all for all of your help!

#28

http://www.systemthree.com/

#29

[FONT=Tahoma]The glass transition temperature of standard West Systems and epoxies that you can get at Tap is really low, like 140F. Early on in my learning I made some parts that taught me all about glass transition temperature; funny now but hard lessons… Mechanical specs of these are nothing spectacular either. For my good stuff I use MGS, but I’m looking to move to Resin Services stuff. This stuff isn’t cheap.

I do use West Systems for non-critical stuff around the shop.

You should check out this thread: [COLOR=purple]http://www.rcgroups.com/forums/showthread.php?t=1135513

This will give you a good idea of the considerations you need to think about. There’s a resin for every application.[/FONT][/COLOR]

#30

kayak… no you dont have to use marine grade. i suggested west system because its very easy to get… bondo poly being the easiest and crappiest (walmart).

as for your overlap… i dont think you understood the wax method.

.5" to one inch would be sufficient overlap for a strong joint.

how the wax works is you buy this stuff called sheet wax. it comes in rolls and flat. it is usually 1/8 to 1/4 inch thick and as wide as you order it…so… lets say you buy a roll of 1/8"x1"x60" roll or you make one. that is good for a 1/8" inch joggle with a 1 inch flange 60 inches in length…

tape the long one inch strip and place it half way into the (clean non released mold) with one half inch sticking out. release the mold and lay up over the wax joggle…you can also do it a different way… your jumping steps here…

have you got the boat on saw horses yet? if not do that take a picture and post it… im trying to get you to start this thing vs. drag your feet.:slight_smile:

#31

PTM&W has a couple of choices. PT2712 is for your hull and PT5714 is for your mold, both are infusion resins. http://www.ptm-w.com/index.asp?pgid=180

Or you could try MVS for your hull, it’s an epoxy designed for marine use. http://www.ptm-w.com/index.asp?pgid=190

#32

Thanks for the info everybody!

Dallas, no I totally understood the wax method, but it would decrease the height of the part, and since the parting line isn’t entirely on a flat surface I would also have an odd joint which would have a lot of space being filled by the adhesive, making for a weak seam. Last I do intend to pull multiple boats from this mold once made, so I would rather invest the time now and have it be very simple to infuse and pop out boats in the future over having to mess with the wax.

I will be altering the deck of the bow considerably to add volume where it is lacking, part of that will be to build up a better parting line since if you look the bow tapers down to less than .5"

As for getting started I am still stuck here waiting to graduate college and then move to an island where I will be for a while. Once I am settled there I can start working.

I am still a bit nervous about my stern though. I have seen another boat builder take on pretty much the same project and manage to pull boats by parting the boat lengthwise down the center for both the deck and hull which I was planning. Still I am pretty convinced that the angles are a bit too sharp to pull the part. Have a look.