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Thread: Balsa canoe build
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7th September 2020, 04:48 PM #1
Balsa canoe build
There are 4 kayaks in my fleet but sometimes it would be nice to take another person or dog out on a quiet stretch of water so a canoe would be handy. For various reasons I wanted to keep the size down but there are very few tandem canoe plans in the under 14 feet range so I used Kayak Foundry to design my own. Length is 4.2m (~13' 9”), beam 81cm (~32”). As with my fishing ski I don't really know if the stability will be OK for 2 but with the experience of past builds I have enough confidence to go ahead. At worst it will turn out to be a lightweight solo.
On the subject of light weight I've had Boatmik's balsa canoe in mind for some time so thought I would try balsa too. Mine is larger and will probably have a bit more paulownia and cedar in places so won't be as light but it should still be an easy 1 hand carry to the water. It also won't have the hollow ends that Mik's had so directional stability could be lacking but with 2 up this should not be an issue.
Turns out it is very difficult to find reasonable lengths of balsa (I haven't found anything over 1.2m) however there was a source of 35 by 70mm pieces at about 2.3m long that were made up of short pieces finger jointed into long slats and then laminated into thicker pieces. This means the final appearance will be like a patchwork but I'm calling this a point of interest rather than a defect.
I wasn't sure this would be strong enough but decided to take a risk. As soon as I had it home I cut a couple of strips off two different pieces and found that they supported their own weight when held near 1 end and also had enough flexibility.
This photo shows some of the pieces cut. First step was to rip the 35 by 70 into 3 pieces 35 by 22 and a bit. These can each be cut into 5 strips of 22mm width and 6mm thickness. Two lengths give a bit more length than the hull so offcuts can be used to stagger the scarf position. Not that this is a big deal because there are joins all over the place anyway.
Balsa on bench [800 x 600].JPG
The extent of materials planning is:
- paulownia strips at sheer line
- WRC gunwales with WRC or paulownia inwale spacers (thought about using balsa for the spacers but that pesky voice of reason in the back of my head is saying they will be likely to break)
- WRC for strips at the keel line and keelson
- 2 oz glass and epoxy inside and out with double layer at bottom
- thin hardwood stem at each end
- 2 thwarts, paulownia or WRC
- small decks bow and stern probably WRC
- PVA glue for everything up to the glassing stage, epoxy for everything after that
The plywood box beam strongback I made for the fishing ski build turned out to be just the right size so that was handy. Managed to cut most of the forms from recycled cupboards etc that were on hand so only had to buy 1 small piece of chipboard.
Strongback and forms [800x600].JPG
At the moment there are 8 strips on each side and it's just getting into the real curvature so more bevelling of strips will be needed from here.
Fitting strip 9 [800x600].JPG
Surprisingly the balsa is a bit more difficult to scarf than paulownia or WRC because the balsa tends to clog the mouth of the block plane.Cheers, Bob the labrat
Measure once and.... the phone rings!
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7th September 2020 04:48 PM # ADSGoogle Adsense Advertisement
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13th September 2020, 05:34 PM #2
A few more strips are on and the compound curves are starting to appear. The balsa is easy to bend in both directions but getting the bevels right is difficult now.
P1100851 [800x600].JPG
P1100854 [800x600].JPGCheers, Bob the labrat
Measure once and.... the phone rings!
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27th September 2020, 10:34 PM #3
Now that the strips are ending along the keel they are being tapered at each end to help stop the curves from increasing.
Tapered strips [800x600].JPG
One strip broke in 2 places and another strip broke after shaping so can't be used now. The strip that broke twice seemed to have done so due to lack of glue in the finger joint. It was saved by applying PVA and clamping up for a while. Overall the glued up pieces have done quite well but continuous lengths would be better.
Broken strip [800x600].jpg
About 6 more strips are needed on each side to close the hull.
As at 25-9-20 [800x600].JPG
It looks like 2 more strips will need to be cut - almost got it right but not quite. At least the bandsaw is still set up so that any new strips cut will be similar thickness to the others.Cheers, Bob the labrat
Measure once and.... the phone rings!
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14th October 2020, 04:40 PM #4
The hull was closed a week ago and the ends then trimmed to accept cedar stem strips.
Hull closed.jpg
The stems are built up of thin laminations bent with a heat gun. They don't retain the full curve but have enough permanent curve to allow fitment. The first 2 are about 3mm thick, others just under 2mm. Tried a 5mm strip first but the curve was very uneven and would not sit in place without gaps.
The third pic below shows the strip after bending and released.
Stem lam bending 1.JPGStem lam bending 2.JPGStem lam bending 3.JPG
First lamination for each end was glued on using epoxy thickened with WRC sanding dust.
First stem layer on.jpgCheers, Bob the labrat
Measure once and.... the phone rings!
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29th November 2020, 02:08 PM #5
I've spent so much time dithering about which glass to buy that by the time I settled on 2oz S glass it was sold out . On the bright side the E glass I bought instead is cheaper and also wider. Thanks to Allan N for checking out the supplier and giving me some feedback.
Some of the resin pack sizes were also sold out but the resin is ordered now as well and should be available early next week.
Sanded the hull exterior yesterday. If this was cedar or paulownia I would have used 60 or 80 grit paper but the softness of balsa had me a bit wary so 120 was used instead. It took a bit over an hour and has come up quite well. Might have got away with 100 grit but I think the 120 was a good choice. I know from bitter experience that a ROS with coarse paper can abrade through a hull in a very short time if care is not taken.
There are a few gaps to fill, some from bad fitting of strips on my part and some from voids in the balsa stock. Also need to do some hand sanding on the stems. Hoping to get some glass on it late next week.
The design images indicated that there was little or no hollow in the ends but there does appear to be a bit. Not sure if it will help with tracking but it certainly won't hurt.
Rough sanded 3 qtr view [800x600].JPG Rough sanded bow view [800x600].JPGCheers, Bob the labrat
Measure once and.... the phone rings!
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10th December 2020, 09:22 PM #6
Applied glass to the outside of the hull on Saturday and added some fill coats.
This photo is with 1 run of glass on and shows the extent of overlap. It gives a double layer down the centre of about 380 mm width. The glass conformed reasonably well but I did not try to wrap it around the stems.
P1100953 [800x600].JPG
This is with both runs and also with a strip of glass on each stem. At least 1 more layer will be added.
P1100971 [800x600].JPGCheers, Bob the labrat
Measure once and.... the phone rings!
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31st January 2021, 02:38 PM #7
Interior glassing did not go so well. There were some areas where the glass pulled away from the strips and I ended up having to cut out and replace some large areas. This has always been an issue for me but I think better lighting might be the key. I just could not see the problem areas until after the resin was set and the hull was tilted to do more work on it. So it's not as tidy as hoped but it is done.
Glued on outwales of 8 * 30 mm WRC.
IMG_20210113_211500 [800x600].jpg
Glued up deck blanks.
IMG_20210114_153432 [800x600].jpg
Cut them to size.
IMG_20210114_162010 [800x600].jpg
Cut 54 spacers and sealed the end grain with epoxy.
IMG_20210127_225055 [800x600].jpg
Here it is with spacers and decks glued in and the inwales clamped in place ready for glue.
IMG_20210131_123859 [800x600].jpg
Still not sure how to install the seats at this stage. Most info on the net shows them hung from the inwales but my inwales are not exactly robust so I'm thinking some other method would be better. I bought Canoecraft by Ted Moores in the hope that it would have plenty of info on making and installing seats. It actually has nothing about making seats and only shows the standard method for installation. This book is often referred to as the "canoe builder's bible" but after having built a couple of strip kayaks and read up a lot on canoes it turns out to have been no use to me.Cheers, Bob the labrat
Measure once and.... the phone rings!
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3rd February 2021, 09:22 PM #8New Member
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That's a nice canoe base.
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11th February 2021, 11:21 PM #9
Thanks Redpen and welcome to the forums.
Finished installing the inwales, sanded the gunnels and decks and then applied 2 coats of epoxy.
P1110005 [800x600].JPG IMG_20210211_212613 [800x600].jpg
Took ages to brush the epoxy onto the gunnels due to the 52 scuppers. I've taken to mixing a batch of about 70 - 80 g, putting the mixing cup in the shed freezer and taking small lots from that (about 10g) to use. It doesn't freeze hard so a glob can be scooped out easily with a stirring stick and it defrosts completely very quickly. This avoids time and material wastage associated with mixing small batches.
Weighs just over 8kg (about 18lb) at this stage.Cheers, Bob the labrat
Measure once and.... the phone rings!
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12th February 2021, 06:26 PM #10
Hi Labr@
I have just seen your canoe build. Not sure how I’ve not seen it before. It’s looking great!
I started planning my first canoe build a while ago but just haven’t started yet. I think you have reignited my enthusiasm. I have the plans for a Guillemot Nymph.
It’s a small 14ft, light weight single canoe, but I intend to stretch it out to 16ft because I’m a little larger than average [emoji849].
[IMG]https://uploads.tapatalk-cdn.com/20210212/0b0ef891e28cb7d8402df0cec033e749.jpg
This is how the seat is installed in this model.
[/IMG]
I will enjoy following your progress.
Regards
Pete.
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12th February 2021, 09:36 PM #11
Howdy Pete, thanks for that link.
The Nymph is a double paddle canoe, designed to have the paddler sitting on the bottom, hence the low seat. It does show that a seat can be mounted on the bottom so is something to consider - it would just need to have legs in mine to raise it a bit. The front seat could also be on rails for adjustability.
Keep that enthusiasm up - it would be great to see a Nymph build on here.
Regarding materials, the balsa is very light and is strong enough when glassed but is easily damaged before the glassing stage so I don't plan on using it again. Paulownia for the hull with WRC for contrasting gunnels, decks etc is highly recommended.Cheers, Bob the labrat
Measure once and.... the phone rings!
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13th February 2021, 10:16 AM #12GOLD MEMBER
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Just out of interest I saw this YT video on building a light weight foam canoe. At first I was sceptical but the finished result looks quite good and he did a few follow up videos to show it in use.
CHRIS
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11th March 2021, 11:51 PM #13
Been experiencing the joys of wet sanding - at least in my opinion it's a joy compared to dry sanding. Getting there but still a long way to go before varnishing.
IMG_20210311_211548 [800x600].jpg
Going to use 25mm webbing on the seat frames. Frames are ready to attach webbing.
IMG_20210311_211810 [800x600].jpg
Bought a 10M roll of Grunt brand polyester webbing from the big green shed. The plan is to use stainless screws to attach it to the frames but a test fit showed that tension would elongate the screw hole in the webbing. Did a test with a coat of varnish on the 20mm at the end and this held quite well. So here are the straps cut for 1 seat waiting for the varnish to dry.
IMG_20210311_212029 [800x600].jpg
I'll need to buy another roll to finish the other seat. If I did both seats with the 10M the straps would be spaced out so much they would be uncomfortable and not look good. It seems that with 30 odd foot of Grunt they would be nothing to crow about .
Also made some rough carry handles. These will go on ropes that run through the decks.
IMG_20210311_211943 [800x600].jpgCheers, Bob the labrat
Measure once and.... the phone rings!
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27th March 2021, 10:12 PM #14
Managed to finish the sanding and varnishing, install the seats and attach the carry handles. So at this stage the hull is done and weighs 10.3kg (just nder 23lb). One paddle is complete and the other is an old one that I made as an emergency paddle for the kayaks. The handle was really too thin so it is being beefed up with laminations front and rear. Still need to finish shaping, sanding and oiling it.
IMG_20210327_210815 [800x600].jpg IMG_20210327_211118 [800x600].jpgCheers, Bob the labrat
Measure once and.... the phone rings!
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6th April 2021, 06:57 AM #15
Looks beautiful Labr@, well done.
When is her maiden voyage?
Pete.
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