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Fiberglass before assembly?

Jimmy W

Well-Known Member
May 1, 2006
611
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north georgia, USA
I'm thinking about building a pirogue similar to Uncle John's, but with the bottom of the sides cut as in the "cheap canoe" for less rocker. The panel joints will be butt joints with fiberglass and maybe blocks. It will be glassed on both sides of the plywood. Has anybody tried applying fiberglass to the wood at least on the inside before putting the panels of the boat together. Then just filleting and taping the joints afterwards. It seems like it would be easier to apply the fiberglass smoothly that way. What problems do you see with this.
 

JEM

Well-Known Member
It could be done. Usually the argument against it is that you're applying the glass to a flat panel and then bending it, thus sort of "pre-stressing" the fibers instead of conforming to the shape of a bent panel.

But two things: 1) You're doing this to the inside of of the hull, on a concave bend, and 2) this style hull doesn't have any extreme bends to it.

So in this specific case, I say why not? You'll still have to spend the effort glassing the seams with tape, but you'll have full protection on the inside of you hull.

If it were a shape with more panels and bends, then I'd say it would not be worth the effort.
 

oldsparkey

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Aug 25, 2003
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One person was talking, a while back, about fiberglassing the whole boat (In sections) and then assembling it but I have not heard anything after the suggestion was made.
He was talking about doing both sides of the wood not just the inside.

It would make the glassing a lot easier but I can see some disadvantages to doing both sides.
I know you are asking about just doing one side.

The boat would have to be trimmed out to the fraction of an inch so it would fit together when made. This is going to leave all of the seams open (Not Glassed over) which would still have to be glassed (taped) to seal them on the outside and filleted on the inside. Doing it the old fashion way then the glass is in one piece when covering the boat.

If the boat is not trimmed out to the fraction of an inch then it will have to trimmed when put together and doing that with glass on it is going to make it a lot harder (Time consuming) to do then just with bare wood.


Chuck.
 

nobucks

Well-Known Member
When I was building my sailboat I did the inside glass before I assembled the boat. The outside is easy to reach everywhere, while the inside is a little more of a pain to get a nice lay of the glass. The fillets and tape on the inside were still a little tough to reach inside the peak, but I was glad I didn't have to mess with trying to put any more glass in there than that, since the rest was already done before installing the panels.
 

Jimmy W

Well-Known Member
May 1, 2006
611
1
north georgia, USA
Thanks for the replies.
Matt, I had thought about the prestressing of the fiberglass and on the inside it would be under compression, but I was mostly thinking about doing this on the bottom panel which, as you say, will have very little bend to it. On the outside, there are no ribs to deal with, so it would be easier to have a one piece covering to the boat as Chuck mentioned. This will be my first boat construction project.

What do y'all think of the plans for an Uncle John's type boat with reduced rocker and would 1/8 inch plywood with fiberglass on both sides be strong enough to handle being high-centered on a cypress knee? In my younger days working at a state park in Mississippi, I had to repair several fiberglass paddle boats that were damaged that way. Those were cheap fiberglass strand boats and not fiberglass cloth.

I have been lurking here for some time and enjoy the site. I am originally from the Mississippi delta near Greenville and still enjoy paddling in southern swamps as this boat is mainly intended for. I also own an old Bluehole Canoe that I have paddled in many whitewater streams in north Georgia, Tennesee, and North Carolina as well as south Louisiana swamps, and I also own an old Hobie Cat sailboat and an aluminum jonboat and an aluminum canoe, which is still in Mississippi, and which I have used on the Buffalo and Little Red rivers in Arkansas.
 

oldsparkey

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Aug 25, 2003
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If you make it from 1/8th inch ply then what you want to do would not be a problem at all. That thinner wood will bend really easy, even when glassed, especially if it is only on one side.

I have made several of them from 1/8th inch ply and they do need to be glassed on the outside and inside and then run three stringers down the length of them for additional support or the bottoms will oil can on you really bad.

On mine I used some pine lattice stripping to help stop most of that problem, it still wants to oil can a little but in the water it is not a problem... One is at 15 1/2 feet and came out at 32 pounds and one I stretched out to 18 feet weighed 40 pounds.

For a test run I paddled the 32 pounder for 4 nights and 5 days thru the Okefenokee Swamp.

Dam... I paddled one of my canoes down the Buffalo River when the rangers shut it down, right after we left, and it was made from 1/8th wood but glassed on both sides. Never said I was smart. :roll:

This one darn fool told us there were no bad rapids on the river ... Right .... No bad ones at all ..... all of them were killers but my canoe and I are still in one piece and still paddle rivers today.

If you graphite and epoxy the bottom of the pirogue then you should not have any problems.... It has saved me a lot of grief when paddling in bad areas.

Take a look.......... I took this from the trips section............... http://www.canoe-suwannee.com/oke12P1.htm

If you are going to make it from 1/8th ply then keep me/us informed on the steps because there are some things you need to do to keep from breaking a rib in the pirogue when building it and we can save you a lot of grief.
We are here to help you , unless we have the boats in the water and are out enjoying life paddling and camping. :D

Chuck.
 

Tom @ Buzzard Bluff

Well-Known Member
Aug 25, 2003
196
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Ozarks of N. Central Arkansas
Jimmy W said:
I was mostly thinking about doing this on the bottom panel which, as you say, will have very little bend to it. On the outside, there are no ribs to deal with, so it would be easier
The bottom, even on the inside, is the easiest to work with. It is the sides that seem to create the most problems with runs and sanding.

I think Chuck's reference <One person was talking, a while back, about fiberglassing the whole boat (In sections) and then assembling it but I have not heard anything after the suggestion was made.
He was talking about doing both sides of the wood not just the inside. > was to a private message I sent him detailing some ideas I want to try if and when I ever get back to work on my boat. It is an 8' jonboat and I want to try the ideas on it before doing the pirogue in case they don't work. Since writing to Chuck on the subject I have retreated from the concept of doing the panels on both sides before assembly but not from doing the insides. Properly done they can not only be preglassed but end up with a glass smooth finish as well.
If you are interested in the technique let me know and I will write a detailed description of the process.
(Swampy! Quick----send me a copy of those instructions I wrote for you so I don't have to retype them! :wink: )
 

Jimmy W

Well-Known Member
May 1, 2006
611
1
north georgia, USA
Thanks, I'm still undecided between 3, 4 or 6 mm plywood. The 4mm might be the best compromise.
Chuck, I am interested in your steps to keep from breaking a rib. I had planned on using either a mortise and tenon type joint or routing out a slot for inserting a piece of plywood for connecting the side and bottom ribs. I liked looking at the site about your Okefenokee trip. I have been to Big Water a couple of times from Stephen Foster State Park and have been into Chesser Prairie from the east side, but those trips were in the jon boat using an outboard for power. On the Chesser Prairie trip, the weather was very cold but the motor overheated and quit due to the water pump intake getting clogged. I have been interested taking a longer paddling trip to see more of the area.
Tom, I am interested in learning of your process also. It seems like we have been thinking about the same thing.
 

oldsparkey

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Aug 25, 2003
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Jimmy W

As with any pirogue when you make it and after the sides are attached to the end pieces and the ribs then run the outside rub rail on the boat, this will keep the sides from trying to flex out as the boat is lifted. If you DO NOT attach the outside rub rail and then try to lift the boat (To attach the bottom piece) the sides will flex and snap a rib before you know what has happen , especially with the thinner wood. Even with two persons lifting the boat.

You still have to be careful till the bottom is attached.

Chuck.
 

Tom @ Buzzard Bluff

Well-Known Member
Aug 25, 2003
196
0
Ozarks of N. Central Arkansas
Jimmy W said:
Tom, I am interested in learning of your process also. It seems like we have been thinking about the same thing.
OK, but let me interject a few lawyer type weasel phrases first. So far I have only used the technique on small, model size jobs so in the application we are interested in it is only theoretical at this stage.
I found the page I wrote for Swampy so I'm just gonna copy it in below. In his application he was thinking about emulating Chuck and gluing up panels of stripwood. I think in that scenario it would have a great advantage and doing both sides before assembly would be the best tactic.
------------------------------------------------------------------------------------
1. Sand to smooth and level and vacuum up all dust

2. Give it one or more saturation coats of epoxy thinned with acetone to a watery consistancy.

3. After the last saturation coat sand to fair again and vacuum.

4. Assemble the supplies so they are at hand and ready to use---you won't have time to get things ready once you start. You'll need poly sheeting to cover your work surface plus a piece of unwrinkled poly sheeting at least 6" wider on all sides than the part you're going to cover. A piece of thin foam rubber such as carpet padding slightly larger than the laminated sheet. A piece of 1x plank or scrap 3/4" plywood slightly larger in all dimensions than your laminate. A staple gun loaded with 1/4"-3/8" long staples along with more staples. Half a dozen concrete blocks or something similar for weight.

Now you start stacking your 'sandwich'.

5. Place the part to be 'glassed on an oversized piece of poly sheeting on a smooth work surface that will accept staples.

6. Apply a layer of fiberglas cloth and epoxy to the part.

7. Unroll the top piece of poly sheeting, that is bigger in all dimensions, on top of the glass and, stretching and pulling out wrinkles as you go, staple it down to the work surface all around so it is tight and totally wrinkle free. One or more helpers would be nice at this stage.

8. Lay the foam rubber atop the poly/laminate sandwich.

9. Lay the 1x board or thick plywood atop the foam.

10. Weight down the board with the concrete blocks, paint cans, spare ammo or whatever you have. Just use plenty of it. You're preparing a 'poor boy's vacuum bag' in effect because the weight should help squeeze out excess resin.

11. Leave it alone for 24-48 hours!

12. After it has had time to FULLY cure start unstacking your sandwich. Peel off the poly sheeting, and if you performed all steps properly you'll see a finished surface far smoother & sleeker than you could ever sand it. Even the weave of the cloth shouldn't be apparent unless you got cheap with the resin. The edges will require trimming and sanding, but that's the price for a piece that should require no further work.

Warning!!! I have NOT done this on such a scale. I HAVE used the method on smaller projects with great success. I have merely given it a great deal of thought on how to do it relatively simply and inexpensively on a larger scale for several reasons. One reason is that I am familiar with the level of finish possible, but the main reason is that my old back and shoulders cannot tolerate much sanding without laying me up for a long time. The success of the method hinges completely on how well you execute each step. If the piece isn't sanded level and smooth it will be a failure. If you do it on a rough work surface it won't work right. If you don't pull ALL wrinkles out of the poly sheet on top of the layer of glass you'll see an unspeakably ugly piece of s**t when you peel it off. If you don't weight down the cover board (which must ALSO be smooth) enough it won't work. Like all projects every step must be executed well and in the proper order to achieve the desired results. I HIGHLY recommend a trial run on a smaller scale before attempting it with that labor & $ intensive piece of boat you've expended so much sweat and profanity on already.
And last, but hardly least, I don't guarantee diddly squat! :lol:

Oh----and if you try it please give us a report on how it worked, mistakes made by either myself or you and your recommendations. Tom
 

Tom @ Buzzard Bluff

Well-Known Member
Aug 25, 2003
196
0
Ozarks of N. Central Arkansas
oldsparkey said:
Jimmy W

<As with any pirogue when you make it and after the sides are attached to the end pieces and the ribs then run the outside rub rail on the boat, this will keep the sides from trying to flex out as the boat is lifted. If you DO NOT attach the outside rub rail and then try to lift the boat (To attach the bottom piece) the sides will flex and snap a rib before you know what has happen , especially with the thinner wood. Even with two persons lifting the boat.>

Wouldn't adding a temporary thwart across the top of each rib before you even start assembly short-circuit the problem also?
 

oldsparkey

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Aug 25, 2003
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When I built the stripper pirogue I laid all of the pieces out on the work table then placed them where I wanted them to be and numbered each one so when I started putting them together I would know where they went.

Next I bundled all of them in there respective bundles and started on bundle #1.

Took the pieces and laid them out on some plastic which covered the work table. When they were in the right sequence I applied some Tightbond wood glue to the edges and then used some clamp's to hold them together till the glue dried. I also covered them with plastic and then put down some folded towels with a board over the towel and a weight on top of the board to keep them flat. Repeated this process till all of the panels were together and ready to make a boat.

Next step .... I sanded them and epoxyed saturated the inside portion of each panel to make sure they would hold together when being attached to the bow and stern pieces.Then butt jointing them into a 16 foot side pieces and bottom

They formed or shaped the boat without any problems by being epoxy saturated on the one side so I would be willing to say that glassing one side would not create any problems.

TOM
Yes a temp Thwart would do the trick but you would need three of them ... It is simpler to just add the outside railing which covers the whole boat.

An example of a regular pirogue and one made from thinner wood you can see in this picture. The one (32 pounds) is from lighter wood and is on the right side of the picture. You can tell it from the three strips running down the hull to keep it from oil canning while the one on the left is made from 1/4 inch ply and does not need reinforcing and weighs 50 pounds.


Chuck.
 

Jimmy W

Well-Known Member
May 1, 2006
611
1
north georgia, USA
Tom, your method seems like it would work, but I don't think that I will try it on this boat. I don't have a large enough work surface except by laying it out on the floor of the porch and that is probably not smooth enough on this old house. I also don't really want to staple into the floor and I don't have a large enough cover board. Actually it seems like the coverboard could be in two pieces with the seam weighted down with blocks. That probably wouldn't show with the padding under it. Besides I was planning on giving this boat a drab camo paint job and it doesn't need to be that pretty under the paint.
Chuck, thanks, I had not thought about it being so flexible since this will be my first boat. I will add the rub rails and maybe put on temporary thwarts also.
 

Tom @ Buzzard Bluff

Well-Known Member
Aug 25, 2003
196
0
Ozarks of N. Central Arkansas
oldsparkey said:
<I sanded them and epoxyed saturated the inside portion of each panel to make sure they would hold together when being attached to the bow and stern pieces.Then butt jointing them into a 16 foot side pieces and bottom>

We're definitely on the same page Chuck. I just propose taking the process a further step to reduce future labor and achieve a superior finish with the same process. Try it on a piece of scrap. Have it sanded fair and waiting along with a piece of poly sheeting and foam rubber with a board big enough to cover the sandwich along with something to weight it down. Next time you have a bit of left-over epoxy build the sandwich and see how it comes out. If everything in the sandwich has a smoothly faired surface then the finished laminate should have a finish EXACTLY as smooth and slick as the poly sheeting. The only thing left to do before lacing up the pieces is sand the slick surfaces to give them some tooth to help the fillets, tape and finish varnish to adhere properly. By working the seams 'wet on wet' and cleaning up excess resin before laying in the seam tape and rolling strips of poly on top of the tape it is concievable that the only remaining step before varnish would be breaking the glaze on the taped seams.
All of that said let me be the first to point out that there are a LOT of unvoiced IFs in that description along with several handfuls of assumptions. You must be impeccably prepared with a firm course of process in mind. You must have all supplies to hand, pre-cut, pre-measured and ready to use without further preparation. You must be intimately familiar with your resin and the working time in hand according to prevailing weather conditions. All of these things imply experience. So I suspect it isn't a process a first-time builder should expect to be a dead cinch on his first try. That is why I would suggest it not be tried on a first project but a bit later down the line. Even then I would advise several test pieces be made to validate process and gain experience.

<They formed or shaped the boat without any problems by being epoxy saturated on the one side so I would be willing to say that glassing one side would not create any problems.>

Frankly on a strip built panel boat such as your last one I don't think glassing both sides before assembly would be a problem. If the sub-strate is thoroughly saturated with epoxy before laminating the 'glas on it then it should be stabilized at a molecular level implying no creep of the lignin between fibers. While that is a vast (or half-vast) oversimplification and massive assumption I think that the mechanical bond of 'glas/wood/'glas 'plymaterial' would be sufficiently strong to withstand any minor internal stresses imposed by the modest bending moment in a pirogue hull. In point of fact the compression stress on the inside of the bend along with the tension stress on the outside of the rigid outer glas/epoxy laminates should offset, practically eliminating transmitted stress to the wood core.

<Yes a temp Thwart would do the trick but you would need three of them ... It is simpler to just add the outside railing which covers the whole boat.>

Being a belt AND suspenders sort I might----oh never mind.

:lol:
 

Jimmy W

Well-Known Member
May 1, 2006
611
1
north georgia, USA
How wide is the bottom of the pirogue. Could I rip in two a sheet of 1/4" for the floor and use a sheet of 1/8 for the sides without making it too unstable? The Uncle John's plans show cutting two 10" side panels and one bottom panel from each sheet.
 

oldsparkey

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Aug 25, 2003
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Jimmy W said:
How wide is the bottom of the pirogue. Could I rip in two a sheet of 1/4" for the floor and use a sheet of 1/8 for the sides without making it too unstable? The Uncle John's plans show cutting two 10" side panels and one bottom panel from each sheet.
When the pirogue is done you will have the 10 inch sides and a bottom about 28 inches wide and 31 or 32 or so at the top.

If you want to do the 1/4 on the bottom then you would need two sheets of 1/4 in ply...28 and 28 = 56 not 48 and I would not go less then the 28 or it will be really tippy :oops: and you are swimming, the 1/8th side will help to cut down on the weight. By using the 1/4 on the bottom then if you wanted to you could increas the sides a little more on the height. Cut 4 ....12 inch sides from the one sheet of 1/8th and the bottom from two sheets of 1/4 in.

One member did just that and for the life of me I can't remember who it was but with some luck they will speak up.

Chuck.
 

Jimmy W

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May 1, 2006
611
1
north georgia, USA
In point of fact the compression stress on the inside of the bend along with the tension stress on the outside of the rigid outer glas/epoxy laminates should offset, practically eliminating transmitted stress to the wood core.
I would think that would tend to compress the plies of the plywood tighter together, but that might be more beneficial than harmful.
 

Jimmy W

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May 1, 2006
611
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north georgia, USA
Thanks for the dimensions Chuck. I just now happened to notice page two and found your last post there. I didn't get the email notification. I'm now thinking that I should be able to get two wider bottom panels out of one sheet of plywood if they were laid out with the pointy ends facing opposite directions. The plywood would have to be ripped at an angle. I will try to draw it out in TurboCad or a scale model on a large piece of cardboard when I get a chance. I'm managing to make a simple boat more complicated before I even get started. :)
 

oldsparkey

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Aug 25, 2003
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Jimmy W said:
I will try to draw it out in TurboCad or a scale model on a large piece of cardboard when I get a chance. I'm managing to make a simple boat more complicated before I even get started. :)
One method of learning is to think of things, then ask questions and see if the answers match your thoughts by folks who have done it then proceed from there or you can use the trail and error method.

Personally I like to ask questions and if the answers are not there then go with the trial and error.

Then there is the dangerous ground where you think of something that no one else has done so you walk on quicksand (uncharted territory) doing it and hopefully you don't sink, sometimes I have sunk to my knees in the sand but so far I have not sunk any further and still ended up with a boat (completed) to paddle.. :D

Like you ... when I am not sure of something it is cardboard that works for me.

Chuck.
PS. You are going to throw things at me when I say this but the bottom measurment for the pirogue at 28 inches is allowing for some wood to overlap the sides ( 1 1/2 inches on each side) so it can be trimmed when the side boards are installed. The actual width of the bottom on the compleated boat is 25 inches on the outside.
I was going by my construction measurments and not the compleated measurments... I allow some overlap for easy trimming on the bottom pieces.