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Yet another first(ish) time builder

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Churchwarden

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Greetings all. I have been cruising over this forum for the last month or so, and felt that the time is drawing near (let's be honest, i plan to start in June) to start my first full build. Now, i canoe over very rocky areas and i have many kids, so the idea of a cedar strip canoe, while beautiful, does not appeal to me. I fear i would be in a constant state of cringing as my beloved boat got scraped and scratched over and over. I have been involved in a couple cedar strip builds already, and have made 2 sets of forms for others to build. Being a hobby woodworker and a career carpenter i feel quite comfortable with the strip canoe method. But, i want to build a composite canoe, and i have several big questions, so hopefully i can glean some help from this group....

Now let it be know that this is in the planning phase. I am ready to be called a fool, and be made aware of my follies.

I have available to me both the prospector 16 forms and a set of freedom 17 forms. I could make a different set, but these are 2 canoes that i like. I am leaning towards the prospector. I already own a nova craft Tripper, and while stable, i would like a bit more rocker. Also, the freedom with the low bow and stern looks a little... bland in my opinion.

My plan is to create a strip canoe out of pine (as i said, i have already done 2 cedar strips, but just only involved for the stripping part), and use it as a form. I would sand smooth, skim with body filler, sand, coat with mold paint, sand, fill, polish, done... I looked through some of the other posts here, and people tend to use the outside of the boats as a form. Why is that? When looking at how some of the professional companies do it they use the inside of the boat. This is one major question i had. Also, if i create a prospector where there is a bit of a... round over at the very top, how to get out of the form? Do i leave an end of my form just screwed together and open it up? Can it flex and squeeze enough to get it out? Or do i leave the ends of the canoe unfinished and finish it separately later?
I have done a very tiny bit of vacuum forming, and have been obsessively watching the "easy composites" youtube videos, and want to do a vacuum formed infused epoxy build. I think it called a dry layup. If i do a layer of innegra basalt as outer layer, then divinicell football and ribs, then some other layer (kevlar or fiberglass or open to suggestions here) then on the inside another layer of innegra basalt is that enough? Will canoe be sturdy wih 3 layers or do i need more?
oh, and remember when i said i had many kids... the reason i want to do this and do it with a form and such is that i would like to build at least 3 canoes.

I think that is all i have for now... please help me, you are my only hope.
 
I think if you're going to vacuum bag you're missing a big step. 1. Build your strip and finish the outside with tooling gelcoat, that becomes your plug. 2. Use the plug to make a mold starting by using a release agent, then going gelcoat then usually just layers of fiberglass because of cost. 3. Use the mold to make your boats. That's the simple description, tons could go wrong and you would have spent a lot and get nothing.

I don't know if you could vacuum bag off of what I call the plug and trying to get the inside of a stripper smooth enough to use that way would be tough to say the least.

In answer to your question about getting a canoe out here's a pic of the end of a mold showing that it opens.

1619047283037983472312640211165.jpg
 
Maybe, how smooth could you get it is the question. The issue might be getting it to release, I know nothing about vacuum bagging so I don't know if one layer of fiberglass over wood would work or not.
 
First there are Male molds, and Female molds.

Female molds are used in Factory canoe building most often. For good reason! Each Female mold must come off a Male plug. Once the Female mold is made, and used ? The hull that comes out of them basically needs only to be trimmed, and they are ready to go. If building several canoes ? A Female mold is the fastest, and best way to go !

Male molds can simply be another canoe, covered with plastic, or coated with a release agent. Once that it done, apply multiple lavers of cloth and resin, will produce a hull. The draw back to this, is the Outside of the Hull will need a lot of sanding and finish. More labor intensive than a Female molded hull !

To date I have used the Male mold method for 5 composite hulls. I didn't plan to get into a Production situation, just make a lighter more durable hull.

There are several build threads on this site, in fact the most I've seen anywhere.

A bunch of slightly different methods, to chose from.

A Good book you might be interested in is the James Moran http://bwca.cc/tripplanning/equipmen...oebuilding.htm

Amazon is price gouging big time on used books, right now. Like 3X the original prices . Check a library first !
 
I was looking for a book on composite canoes but didnt come up with anything, so thank you very much. The cheapest i could find is $48 for a used copy, but i guess it is better than not having the book and making a very expensive mistake....

So, what about the laminations? Innegra basalt seems very strong for the price. But i would want more than just the 2 layers (right???). I know at least 1 canoe conpany uses 2 layers of innegra with a layer of kevlar in the middle... but canoe kevlar is very expensive. Like twice the price of the innegra. If i have the innegra on the inside and the outside, do i need a thick kevlar in middle.or can i go thin? Are there any other materials that would be recommended instead? I guess i could.go fiberglass in middle too... although that typically uses resin and i planning on using epoxy infusion..... hmmmm

The plan is to build a strong, relatively light 16' or 17' canoe for $1000 or less, not including the price for the mold/plug.
 
I would recommend two layers on each side of a Divinycell core. If your heart is set on innegra go for it. But a full foam core and two layers of glass will provide plenty of strength. You may need some additional abrasion resistance, which is best provided by a layer of Dynel. IIRC, Alan built a hull with up to 13 layers and still wasn’t fully satisfied with the stiffness, I’m sure he’ll chime in with details.
 
Thanks. I will contact sweets and see what they say. I have read through the entire black pearl post several times. Looks beautiful. Really well done. It inspired me.
There is quite a decent aerospace industry here in Winnipeg and i can locally get divinycell as well as some fibres, and i have been looking at Noahsmarine out east for other stuff. This is still very much in the planning phase, i'm just getting started but have many questions.
Jim.Dodd if you happen to have a kevlar boat building book you are looking to sell, i can save you the hassle of putting on ebay :) ;)
 
So.... about this foam core....

Do people use a full foam core or just a football with (or without) ribs?

my current plan is to go with a innegra basalt outside, then layer of 6580 then a football with ribs of 1/8" divinycell, then another layer of s glass, and then a layer of IB on the inside. A couple of questions... 1. Is just doing the football with ribs enough? Or should i do an entire layer of foam (expensive and seems kinda difficult).

2. Should i do a support layer over the football and ribs? Just an extra layer over the pertinent areas.... if i did this, do i need a full layer of s glass over the football areas, or will the inside layer of IB be enough?
 
I used 2 layers of 5.5 oz carbon and 2 layers of 4 oz glass (or maybe 6 oz?, have to check my build thread), with the carbon inside and glass outside. It was waaaaay flexible when I popped it free from the plug. It would have been easily damaged had I tried to use then.
I added a full football layer of 1/8" H80 Divinycell to the inside, epoxied in place, covered with a single layer (sort of) of the same 5.5 oz carbon fiber scraps.
The increase in stiffness was nothing short of amazing...take a look at the pic below. I'm a welterweight, fully clothed probably 155 lbs, and the cradle supports are about 7 feet apart. There was NI discernible deflection. In the water, the hull is as stiff as any thick stripped stripper.

Edit to add link to build thread: https://www.canoetripping.net/forums/forum/paddlecraft-construction/58166-carbon-copy-kite

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Do you think then i would need another layer or will 4 be enough with a football.layer and some ribs? Also, you went with carbon on the inside. IB apparently has good abrasive resistance (unless i am mistaken-?) So that is why i was going with that on the outside. The stuff available seems to all be the 7.8oz variety, so a bit heavier than the carbon you used...

Choices choices... i guess if i make it, and it is not sturdy enough i can always add another layer after, even if the original layers were vacuum injected. I would just add a wet layer in that case.
 
All deflections are a function of the materials modulus of elasticity (E) and the structures moments of inertia.
The modulus of elasticity for carbon ranges from 15e6 psi to 80e6 psi, your basalt is nearly the same as fiberglass cloth ranging from 5 to 8e6 psi.
For simplicity sake and comparative values, you can consider the canoe hull (or parts of it) to be a simply supported beam. The moment of inertia in the plane of interest is an inverse function of the beam (hull) thickness to the 3rd power. In other words, double the thickness (keeping all else the same) and you'll decrease deflections by a factor of eight.

So with the deflections a linear function of the modulus, and also a function of the thickness cubed, you can see there's much to be gained by simply making your laminate thicker. How to do that with respect to strength and weight most economically? Use an adequate sheer strength material of the least density possible...you can see where this is heading. It's far better to increase the space between your cloth layers than to add more layers. Even if the layers are super high modulus, the epoxy that encapsulates it is not. Your laminate will always be compromised by the epoxy modulus.

Ultimately, IMHO, carbon fiber and other high modulus and high priced materials are overkill. Plain old E glass and Divinycell will provide adequate strength with minimum weight. Remember, that super low density carbon or basalt is fairly thick, requiring quite a bit of resin.

OK, finally, if your hull ends up too bendy, just epoxy in some foam and glass it in place. Whether that's a full football, or selective stiffening with ribs is up to you.

Oh, and a disclaimer...I'm a highly biased retired design engineer that spent most of my career in R & D...I was never a production guy. My opinions are strictly based on purpose built design superiority, not cost to manufacture or impressive marketing hype.
 
Thank you all for the assistance. This has been extremely helpful. As a carpenter (and carpentry instructor) the beam/engineering explanation was extremely helpful.
I am not looking to build the lightest boat possible - just something solid, sturdy, and somewhat portagable. My current boat is 65 lbs, and if i could build one the same weight or a little lighter i would be very pleased. I have no real goal, but i think if i came out at 58 lbs (just a random nice number) i think i would be over the moon with excitement. Also. Needs to be less than $1000 cdn, just because - large family.

So i think what i will do is this: i am going to make a stripper out of pine. However, i am only going to glue one side of bow/stern to the stem. I will make a piece that adheres to the outside of the body on both sides, so the ends can be separated to facilitate removal. I will attach extra wide gunwales to the outside. I will do a coat of fibreglass on the outside for strength and to reduce the chances that changes in humidity will bugger up my mold. I will then remove the shell from the forms and set it in a cradle. At this point i will glass the inside and run it out over my extra wide gunwales. This will provide a surface for adhering the double side tape for creating a vacuum. I will polish that sucker smooth. Coat with a mold paint. Fill, polish, fill, repaint, make perfect... then put in my IB, then a layer of 6580 fibreglass, then a football of 1/8" divinycell and ribs (im thinking 4" wide)... at this point im not sure if i should do a layer of glass just over the ribs and the football as an extra support layer or just skip this and go with a full layer. Anyways, above the football is a full layer of 6580 glass, then a layer of IB on the inside. Vacuum it, and release. I really like the look of wood, so am planning on using cherry for gunwales. Not sure if i should kerf the wood and slide it on or do a inside/outside gunwale. Open to suggestions!!! Please!! Then seats, (cherry again) ends, etc etc etc. I plan on starting this is June (i am making a new kitchen table for a friend as a gift that i need to finish and i promised my wife i would finish the woodwork on our house first). When the time comes, i will start posting pictures and sharing my mistakes/learning processes.

Oh, for those that create their own seats.. i have seen some contoured seats. They look comfortable. Is the contoured piece of the frame typically made of one thicker piece and cut to shape, or steam bent, or bent laminations?

Again, you all have been extremely helpful. I am beyond grateful. Thank you.
 
This is more of a general question but it does relate to your build - why do home builders use twice as many layers of various cloth when building vs manufacturers who only use two or maybe 3?
 
If you're happy with a 58 pound canoe I'd just build a cedar strip. It will be a lot faster and cheaper. If you don't like the thought of seeing a pretty cedar canoe get scratched it's easy to paint them, which is what I do.

As others have said the male mold is the practical way to go for composites and many here have done it. Most save the mold and finish it off so they end up with two canoes. I've done it that way and I've also done like you propose and make the mold sacrificial, which saves time and money because you can use junk wood and use all the filler you want.

The problem with a disposable mold is that you pretty much have to use it as a male because once it comes off the forms it won't be stable enough to use as a female mold without fiberglass inside and out, so you just leave it on the forms. This makes it difficult to add foam or partial layers in the initial layup since those seams and bumps would show on the outside of the hull. What most of us have been doing is laying down a few full layers of cloth and then removing the composite hull from the forms and supporting it well before adding reinforcements to the interior, which now unfortunately must be cleaned and sanded to remove any mold release compound and to give a scuffed surface for adhesion.

I always wanted to go all the way and use the stripped canoe as a plug for a female mold but I could never justify the time and expense. Others on here have done it, and done it well, which was fun to watch but also reinforced that for me, personally, it's not worth it.

My composites were made to be tough rather than light and I used solid fabric with no foam. It took a lot of layers for stiffness (which equates to thickness) but a more rounded hull shape would have gotten there with fewer layers. I believe most of the manufacturers are just using a couple full layers starting from the outside, then a foam bottom, and then a couple partial layers to cover to foam and in the stems or other specific spots. You'll notice, especially if you remove a set of gunwales from one of these foam core boats, that the side are very thin and floppy. It's only the bottom that's stiff. Since the commercial hulls don't seem to be suffering any failures it wouldn't seem necessary to add a lot to their proven designs.

A note on carbon and kevlar cloth (not sure about innegra). I (and I believe some others here) have started to think that we're not making any weight savings by using them instead of fiberglass in a hand layup. For similar weight the carbon and kevlar cloth are much thicker than fiberglass, which seems great, but in a hand layup that seems to mean they use a lot more resin too, perhaps enough extra to offset any weight gains.

The real weight gains with composite cloth seam to come from either vacuum bagging or infusion, which keep resin usage to a minimum.

Alan
 
Alan. Thanks. Some good insight. The reason i wanted to go with a form is that i really want 3 canoes. I have some experience vacuum bagging and would like to give it a go on a canoe. I figure if i can make a good mold from a stripper it would be strong enough and if i glassed it - smooth enough to use as a mold for canoes.
From what i can ascertain the innegra basalt is a strong fibre that is very resistant to abrasion. My fibreglass hull needs repairing every season, and innegra basalt is super cool looking.
 
I missed the part in your original thread where you wanted 3 identical canoes. A full on mold might make more sense in that case but I'd still rather built 3 separate cedar strip canoes. Molds take a lot of room to store and with a mold you're locked into the same hull every time you build. If you're going to use your currently available forms to make a direct female mold just realize the canoe that comes out of it will be smaller than the canoe the forms were intended to produce.

Curious what type of paddling you do (plan to do) and what parts of your fiberglass canoe require repair every year. The usual damage occurs at the stems, which most of us remedy by adding a layer or two of dynel in just that location.

But if you're set on making composite canoes then go for it. Not trying to talk you out of it. I do plenty of things just for the fun/experience of doing them and one of those things was building some composite canoes. Just that for me personally I've found, for most uses, I can make a cedar strip suit the job for less money.

Alan
 
Hey, i am new to this, and as i said before this is a planning phase, so i value any feedback greatly. Yes, i do repairs to the stems. I heard that adding extra layers there slows the canoes down, so i was avoiding it. I have a Nova Craft tripper. I was thinking of repainting it this spring. A previous owner did a fairly.... heavy patch over the entire lower bow and then rattle canned it with a different shade of green. Not too noticable, but it annoys me...so i guess i could add the layer then. The canoe is supposed to be 65 lbs, but i feel it is already a couple pounds past that. However, It has been good for us. We do just small lake tripping so far, but as my kids are getting older i would like to get into doing some longer trips, and some rivers. I am thinking of making a 16' prospector, which i guess would come out at about 15'-10" if i used my stripper as a female mold. I have no access to clear cedar, at least not at a decent price, and the price of strips for a canoe is more expensive than going with BI and foam. Also, if life circumstances change (and they often do with one income and 5 kids) and i need to sell it, i feel it will be easier to sell a cool composite canoe than a cedar stripper, but i could be wrong. That, honestly, is one of the main reasons for going Basalt Innegra... oh, and the super cool black weave colour.

-Andrew
 
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