I'm building a fairly large canoe in October/November and am pre-buying my supplies. I'm looking for a formula to figure out how to estimate how much Epoxy Resin I'll need to purchase. Any one out there have a good way to figure it out?
Submitted by Sloughcanoe on Thu, 09/15/2011 - 8:27am
Just use prepreg. Way easier to measure out how much you're going to use.
You just need a decent sized freezer to keep it in.
#1 Thu, 09/15/2011 - 9:28am
try ask the guy who is selling you your materials. or it may say on the cantainer. any pic's?
Mulus
#2 Thu, 09/15/2011 - 7:55pm
work out your surface area in square yards (metres here) , then the amount of fabric you will need in square yards , then convert that to weight in ounces? (grams here) and if you are going to get 50% fibre fraction you will need the same weight of resin/hardener (plus a bit extra for justin "case" )
#3 Thu, 09/15/2011 - 10:50pm
if building a fairly large canoe for the first time use polyester resin. mistakes are much cheaper
#4 Fri, 09/16/2011 - 11:48am
Here's how to make your own pre-preg
#5 Fri, 09/16/2011 - 1:32pm
I suggest don't make your own pre-preg and the main advantage of styrenated resins ( PE and VE) is its compatibility to dissolve the binders of CSM (Chop Strand Mat) and the chemichal bonding you get to regular gelcoats , Epoxies will give always give the longest working times and the best properties(If a post cure happens) but doing a proper post cure is often difficult . Lots of epoxy products are cooked and painted afterwards ,compared to gelcoats first and no cooking.
#6 Fri, 09/16/2011 - 7:33pm
Don't have a way to cure the pre-preg in the place we'll be building at. And definitely not in october/nov. Either way with my calculations I'm looking at 10 gallons. So I'm thinking I might be a tad off. I am a bit worried in the fact that I've bought all Port Orford Cedar...which has higher oil content than other woods so I might be looking at some delamination process if that oil starts to come through. But ...I'm not really sure how to eliminate that other that a good solvent/surface clean and hoping that the wood soaks up the epoxy. Would've it been better to use a doug fir or something a little less oily?
No pics yet Mulus....I'll post though when we start building the strongback.
#7 Fri, 09/16/2011 - 7:36pm
Polyester is cheaper and could be used but expect bubbles. pre coats could help. use unwaxed. Two or three coats then do the cloth and flood coats. I will use it more than cold cure. for my personal canoes. what type of canoe is it ?
#8 Sat, 09/17/2011 - 11:49am
32' westcoast style. My cousin said he uses polyester...but I've been reading up on it..and I'm still leaning towards the epoxy 'cause it's suppose to shrink less.
#9 Sat, 09/17/2011 - 3:21pm
niiiiice
#10 Sat, 09/17/2011 - 3:25pm
Slough:
Sounds like a fun project. I reccomend returning the port orford for kiln dried clear western red cedar. Also don't forget to account for the matrix (resin/hardener) needed to do multiple layers on the deck, seats, wai, tabbing and taping. It makes that little surface area calculation a bit more involved if you know what I mean. Also if you are laminating which I am assuming, then it is good to know that glass and carbon tend to have different optimum fiber volume ratios and retaining ability i.e. carbon likes to drain so best to slap a layer of 4 oz glass on it to help retain the resin. Thats getting into the details a bit more than you will need especially if you are doing hand layup. If you are able to vacuum bag your layup them major kudos! Bagging will help optimize weight and fiber volume ratio.
I lend you this advice purely from experience and not book reading, not that I haven't done my fair share of that either. I set out no that long ago to build a one off canoe and have recently helped build a few. In my pursiut of this same knowledge I spoke with a rep from the Gougeon Bros they advised me that 1 gallon of epoxy matrix would cover 10 square feet of area for lamination purposes. Of course that didn't include what I was laminating or at what temperature so it was a rough figure at best. I doubt you would expect anything more than a rough figure.
Good Luck
#11 Sat, 09/17/2011 - 6:20pm
Thanks for the advice Gaucho. Found out my pops already had the POC milled out...so I'm stuck on that ....although I'd like to double laminate strips of doug fir on the bottom (to have some extra weight down there). But definitley no carbon...just glass. I wish I could vacuum bag it...but think I'm over the extent of my skill level with just the hand layup...so I'm going to try not to screw that up.
The curing temperature is where I think I might have some problems as well. It'll be Oct/Nov....(with lots of moisture in the air) and I'll be in a outdoor shed...so I'll have to figure out how to dry it out in there a bit.
#12 Sun, 09/18/2011 - 12:17pm
As far as curing goes, heat lamps work well. Be careful though and don't get them too close to the layup as the epoxy/resin will soften up. You just need a decent ambient temperature for that glass and resin to harden.
During the layup make sure to angle the layers of fiberglass. For example, if you lay up a layer of cloth in the 90 degree direction, (the fibers going straight up and down in a "+" type direction) do a layer at 45 degrees (where all the fibers are laying in an "x" fashion. This will add to the overall strength of the craft in multi-directions.
Example:
Layer 1 (90 degrees): +++++++++++++++++++++++++++++++++++++
Layer 2 (45 degrees): XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Layer 3 (90 degrees): +++++++++++++++++++++++++++++++++++++
and so on.
#13 Mon, 09/19/2011 - 5:09am
If you use heat lamp be sure that they are electric and not gas or propane. I built a canoe in an "outdoor shack" and moisture was a concern of mine as well. Don't worry about it so much, as long as the kanu isn't getting rained on. Be careful though if your wood strips are too thin they may warp out of position in the presence of moisture. You might find thin spots running along the bilge where the two sides meet (if you are strip-planking) especially in the nose and tail. Also try to eliminate any standing water, or lingering humidity in your shop by keeping some fans running and keeping a push broom and wet/dry shop vac handy.
I am curious where you are building this thing and what is a west coast style 32'?
Gaucho
#14 Mon, 09/19/2011 - 7:50am
Thanks Gaucho...that's all great information. I'll be building it in Coos Bay, OR (southern Oregon Coast). It's smack dab in the middle of Port Orford Cedar country. All of our (old trawlers) fishing boats are built out of it....so my father wants that wood...so pretty much have to go with that. 32' westcoast/chinook style canoe is an ocean going tribal canoe. Same type of canoe that was used from West Vancouver Island all the way down to Coos Bay by tribes. It should hold up to 12-16 paddlers. We don't like our ocean traveling canoes over 36' cause they start to span the crest of two waves and don't fit in the trough as well. I've attached a picture of a 27' canoe...it's fast but we need one just a tad bit bigger to fit more people in it.
#15 Mon, 09/19/2011 - 8:58pm
2nd attempt attaching this photo. Hope it works.
#16 Wed, 09/21/2011 - 11:35am
Very good choice on wood, Coos Bay is a tough place to build an epoxy boat that late in the year. US composites in Florida is a great place to buy glass and epoxy. Use the thin epoxy and fast hardner. Cool damp weather affects the epoxy big time. I finished a 32' OC3 last June and it took just 3 gal.epoxy glassed 6 oz. inside and out. Sounds like you design is a bit wider so I'm guessing 5 to 6 gal. Your boat sounds like a fun project, Have fun with it, Terry
#17 Thu, 09/22/2011 - 2:40pm