Light Weight Solo Tripper Build

[Cruiser]

This will be a somewhat ambitious build ( at least for me), the design will be a 15' solo cedar strip with a max weight of 30 pounds and still be tripping tough. I also want to take a hand in the design portion and I don't intend to resort to one of the standard CAD programs as they are just a tad confusing and seem to suck the joy out of the design process (again, for me).

I thought it may also be useful to include some of the thought behind the decisions, the time it took to do some of the operations and the cost of various materials/decisions.

My last solo weighed 39 pounds and was a 16' modified Freedom Solo .... so before I do anything, I need to figure out a way to achieve a 9 pound weight reduction on paper to make sure the build is even doable.

My last WRC hull weighed in at ~19 pounds using 1/4" strips ..... so I changed materials to Northern White Cedar to get a 10% density advantage and save 1.8 pounds off the top.

Next do I really need 16', the answer is that a 15' should do fine, that will save another 1.5 - 2 pounds.

Now the hull composite, can I change that up to save some weight?

First thoughts are moving to 4 oz fiberglass and maybe reducing the strip thickness, but this all could be a slippery slope as far as strength and integrity for the planned usage.

During my research, I found this nice little table on the epoxy works site ( https://www.epoxyworks.com/index.php/how-tough-are-they/ ) and it provided the information I needed, going from 6 oz to 4 oz cloth will give a nice weight reduction at the cost of significantly reduced hull strength. Surprisingly, with 6 oz cloth, reducing the strip thickness from 1/4" to 3/16" gives the best weight reduction with virtually no loss in hull strength.

So moving from 1/4" to 3/16" strips should provide a further 4.75 pound reduction (at least).

That brings the potential weight savings to 8.5 pounds, almost there (on paper at least) and eliminating decks will put the reduction about where it needs to be (fingers crossed).

Since I want to have some hand in the design, most of the software programs suggest starting with a known design and modify from there. On paper, I will start with the basic shape of a friends 14' solo I like and modify the bow and stern sections to incorporate a re curve, stretch the length to ~15' and modify the width to be slightly less than my Freedom Solo.

Next post I will actually start on the build process.

Brian

 

[Alan Gage]

What does "tripping tough" mean to you? Not everyone will have the same answer. If running rapids isn't in the equation then I don't think tripping tough really needs to be all that tough.

I think 3/16" strips are great plenty for most solo boats. I've only built one solo with 1/4" strips and that was my first. The thinnest have been just over 1/8" thick.

If you're afraid 4oz cloth will be too weak you could do a double layer of 4oz cloth on the bottom. That gives you 12oz of cloth on the bottom of the hull (same as if you'd used 6oz cloth) and 8oz on the sides. The thinner fabric takes a good deal less epoxy too. Not just for wetting out but for filling the weave.

Aluminum tubing is cheap and easy for thwarts. They don't look half bad when painted black.

Make the gunwales thin and flare them out thicker where the thwarts/seat will attach (assuming they'll be bolted in place).

If I was building a lightweight lake tripping hull it would probably be 3/16" strips with a single layer of 4oz cloth inside and out with dynel at the stems.

Alan

 

[dogbrain]

In addition to what Alan said, I think using strip thickness and glass strategically is a good way to save weight. If you're serious about counting ounces you'll want to weigh the boards before you buy them. Average density of white cedar is less than red, but individual boards can vary quite a bit and you could easily end up with heavier wood if not careful. Boards with sapwood will weigh more than hardwood (heartwood, i hate this so-called spell check). The lightest boards I've found are the dark, all heartwood old growth wrc.

On my next solo build I'll use 3/16 strips for sure and might go with something less than 4 oz glass inside and out, but will use a 4oz s-glass partial on the outside football. Composite envisions sells 2.1 and 3.1 oz e glass. The s glass with 2 or 3 oz e glass gives you 6 or 7 oz of glass where it counts. For an outer hull football, S glass is more expensive but it has advantages over e glass in strength and abrasion resistance. Remember that you can always add glass partial on the inside where you think it's necessary after you've had a chance to test the canoe on the water.

I agree with using aluminum tubing for thwarts, and eliminating decks. I assume you'll also build stemless. Your final weight considerations will be gunwales and seats. What are you planning there?

 

[Alan Gage]

I found this nice little table on the epoxy works site ( https://www.epoxyworks.com/index.php...ough-are-they/ ) and it provided the information I needed, going from 6 oz to 4 oz cloth will give a nice weight reduction at the cost of significantly reduced hull strength. Surprisingly, with 6 oz cloth, reducing the strip thickness from 1/4" to 3/16" gives the best weight reduction with virtually no loss in hull strength.

That was interesting to look at. But I wonder if they should have used more panels and averaged the results for more accuracy. Some things just don't make sense (2 layers of 6oz cloth on 3/16" strips was stronger than the same layup for 1/4" strips).

It's interesting to note the deflection at which the panels broke. I've often wondered if in some situations you actually gain strength by using a weaker cross section that has more flexibility. When experiencing a sudden shock a more flexible panel might be able to better absorb the impact by flexing and never reach the amount of force it takes to actually fail.

Alan

 

[alsg]

I suspect those flat panels probably weren't sanded. Keep in mind that on a canoe, when you start with 1/4" strips, by the time you end up sanding and fairing the inside and outside, I'll bet most of the strips are pretty close to 3/16" and maybe thinner. If you start with 3/16th strips, they'll be thinner still after sanding/fairing.

 

[Cruiser]

Allan
... bad assumption on my part to assume everyone can read my mind, Tripping tough is just capable of portaging, week long trips, the occasional rock and to bring me back in one piece with no worries (no rapids). I forget the trips some folks here take and those craft need to be Tough.
... I fooled around with shifting to 4 oz with double layers at some areas, it very quickly eats up any weight savings, I concur that the table has a few "funny" numbers, but I think it is a good guide to overall considerations of glass layups.
... aluminum likely won't be considered, like using staples, I just can't see myself doing that ... nothing wrong with either, it just isn't in my vision.

dogbrain
... you an Allan both made the points about swapping to lighter cloth and I did run a few calculations to see what that may buy me, when compared to the 6 oz. "old standby" there didn't seem to be very much weight savings to be had and multiple layers increases the amount of work ... so if there is no clear advantage, is that work really worth it?
... S glass is a little harder to come by here in the north, I did want to actually try that, I figured 4 oz s glass in place of the 6 oz e glass would be a good swap ... but it worked out to over 10x the cost to get it here.
... I will be building with stems, again, IMO both methods are suitable, I realize there is a running debate over how strong or how much more weight, but to be honest, I haven't seen any facts to back it up. So much of what people say depends on what they actually do in the build process. For example, it doesn't seem to be required, but I have read several accounts of folks adding an epoxy fillet to the inside of stemless builds .. at ~ 100 pds/ft3, this will quickly eliminate any weight advantage, but only if you do it that way. I am keeping track of all the weights of the stems and so far it is not looking to be very significant .. that will be posted with the stem layup post. To be clear, there is a weight cost and a work cost (hours) to use stemmed over stemless ... the work I am willing to do, I like the look, the weight I would like to quantify ... just so I know how much it cost me in ounces. One other point about using stemless for this build, I am also using the kootenay style bow/stern, so it could get a bit messy with recurve at both top and bottom.

I have to be honest, I do the build documentation for new builders,for when I get stuck/confused/need advice and for those folks who just like to follow along. I have been a little delinquent in posting on this build, it is actually further along and the documentation is playing catchup .. I will try and get a couple of installments done and posted in the next few days.


Brian

 

[Alan Gage]

I've never measured but I'd be surprised if anything close to 1/16" is being removed by sanding. My strips have faint but noticeable saw marks on them which are probable 1/64" or less. Usually after the first couple rounds of sanding those marks are still present on many strips because I've been hitting the high spots where strip edges meet on a radius (which will be thicker in cross section to begin with). When those saw marks disappear I quit sanding.

That doesn't mean I haven't had a small section that wasn't fair where I sanded off more material (a couple times all the way through) but overall I don't think much is removed. I once weighed the dust I collected from sanding the inside and outside of a 17' tandem hull and it was 2 pounds.

Alan

 

[memaquay]

I'll be happy if my next build comes in at 40 pounds. My canoes have never met a rock they didnt like.

 

[Patrick Corry]

Cruiser,

I for one will be anxious to follow your build. I've been toying with the idea of building a solo strip canoe as well since I have all the necessary tools and skills for the woodworking portion of such a project, as well as the time (semi-retired from the building trades) bus alas, no fiberglassing experience. Please do document your work! Thanks in advance.

Pat

 

[Cruiser]

Moving right along with this build, it is obvious these strips are not being done this time of year. I did them last fall knowing that I would be building in the winter and knowing I didn't want to try this in the snow.

I selected Northern White Cedar as the strip material, as I understand, it is one of the best materials for weight and strength. Some 10% lighter then WRC, only down side is that it is generally not available in longer clear lengths and it's a bit more regional in availability.

Lucky for me ... I know a guy (lol). There is a small sawmill a few hours north of me that specializes in NWC and I have made several purchases from there and the owner is just a great guy. I called and asked about longer lengths of select NWC and he said he had a few pieces, I said , hold it, I am on my way.

Scored 4 - Rough 1" x 4" x 16'and 1 rough 1" x 6" x 16'




These are "rough" boards and are not all the same thickness, so although I don't need to plane them for finish, I do need to plane them for a uniform thickness, for sawing, knot evaluation etc. ... so that gives us these



I am a big believer in "order of operations", so the next step is to mark any knots and stabilize them. There are a few knots and some of them will loosen during the strip cutting process, so I mark, tape and saturate each knot with epoxy. No broken strips, no knots flying anywhere, if I don't like the look of the knot in the strip, I can still just cut it out and butt join on the boat. But for prep and cutting, it just makes strip handling much easier (IMO).

There where only a few pencil size knots, here they are marked out (FYI, the other side is sealed with tape)




Once the epoxy setup, I scrape each knot so it's smooth and we are ready to get the strongback setup to cut strips.



Step 1, mark the boards, so I can put the strips back in cut order and board source.



Strongback setup is pretty standard for the skilsaw method, add the sacrificial strips for the boards to rest on, I used one of the other boards as a rest board to get the most strips from each 1 x 4. The rest board is held by clamped wood piece that just jutt above the sacrificial strips along the 1 x6's length. To hold the board that is being cut a piece is added to the end at an angle that catches the board being cut and prevents it from moving during each cut operation (nearest end shows this).



With the strips now cut, we move on to the beading and coving operation

To setup the router, I first take a spare batten and blacken the edge.



Now when i do adjustments to get the cuts correct, it is much easier to see when the router setup is good (I learned this on Nick Shade's site)



This is a shot of the stabilized knots after strip cutting, I believe this would have broken if it hadn't been stabilized, the advantage is that the knots don't fly apart and disrupt the sawing operation, plus it gives me the choice of using the knots or just removing them later, without having to try and keep the broken bits together for matching.



Bead and cove setup, strip production



Bundling strips to store in racks. Since the wood is pretty uniform in colour, texture and grain, I will be foregoing book matching the strips and just use them as I go.



A little discussion on the strip process is likely warranted at this time.

Since weight is one of the design parameters, I decided to calculate the density of the white cedar I purchased, I labeled the 4 - 1 x 4s as boards 1 thru 4, and the 1 x 6 as 5. The 1 x 6 was too heavy for my kitchen scale, so I passed on that one, the others measured 1 - 23.0, 2 - 21.6, 3 - 20.6 and 4 - 21.6 (lbs/cubicft). This pretty well spot on to the 22 listed in the wood database.

The purchase cost of the wood was $89 and yielded 77 strips, of which I will likely toss 5 or 6, leaving a cost per strip of ~$1.25 .... and this should be more than enough to complete the boat. I did a quick search about buying strips and came up with costs in the range of $1200 Canadian for enough strips to complete a "standard" boat.
I spent 14.5 hours getting the strips done, which includes planing the rough lumber, cutting strips and bead/cove, bundling and making a set of accent strips from some leftover WRC .... if I paid myself $20/hr, bought a router and bits, bought a decent home planer, I think i would still have money leftover compared to buying the strips, plus I would have new toys.

However, since i do have those toys, my cost stands at $89 and 14.5 hours so far ... I intend to keep updating the dollar and time costs as I go along, I think it will provide some useful info on building, that I don't recall reading elsewhere.


Brian

 

[Jim Dodd]

A Great build thread so far Brian!

Also some great advise from Alan and Mark ( dogbrain) !

The S-glass also gets my vote ! A shame it's that much higher for you !

Technics for reducing resin in your build and actual hull design should be discussed.

Fill coat reduction, is one I've ignored in the past, but could make a big difference. I would consider a Vacuum bag. Peel Ply, if it would conform to the hull shape without wrinkles.

Maybe Shrink wrap instead ???

OK, a little far out, and too late, as you've already machined your strips. But consider 1/8" strips. No need bevel, or bead and cove.
An extra layer of cloth, Only where it will serve the purpose, of adding strength. Not a full blanket coverage !

Now for hull design. Stem and Shearline height reduction. I love a tumblehomed hull, but believe it adds weight opposed to straight sided hull.

Kootenay stems don't equate to hull flare. Hull flare will bounce you over a wave, as compared a Kootenay that will cut into the wave.

Don't take hull design lightly. Both Alan and Mark have the experience in Serious tripping hull design.

I'm excited to follow along ! I've failed in the past to properly document my builds thoroughly. I know your's will be better !

One more thought ! A Composite build ! Use that stripper, as a Male mold.

Jim

 

[Cruiser]

Thanks Jim ... I will look into what it would cost to get my hands on some 4 oz S glass again.
... also, depending on execution (as everything does) there may be some savings for application and fill, but i think short of vacuum infusion, I would not expect "big" savings there
... with the weight reductions, I am trying to look at the actual saving that a change could net me and selecting those changes, while trying to stay within the skill set and shop capabilities I have at my disposal. The Kootenay bow/stern, I believe actually save some weight because the sweep back uses less material ... however, they were a vanity change, but if they save a little it works for me
... I spent so much time on hull considerations, i did actually get to where I needed to be, but it was a pita

As I said, I am delinquent in getting this written up and will try and get the posts up-to-date with what i am actually doing now, but that is going to take a little time.

Allan, a question about aluminum gunnels, what would they weigh on a 15' ? ... the cherry gunnels on my last boat came in around 3.5 pounds for 16', it just seems like there is just not a lot more to be saved there. I had that discussion with another builder doing carbon gunnels and he agreed, but I have zero experience with aluminum.



Brian

 

[dogbrain]

Those are some nice white cedar boards Cruiser. What were your final strip dimensions? You may have said it above, but I couldn't find it.

Mark

 

[Cruiser]

Hi dogbrain, it wasn't there ... it seems like no matter how time you spend making sure you include stuff, there is always stuff that gets left out.

The rough lumber was ~1" and a bit thick, with one piece at just over 1.25" .... I planed them down to 7/8", which will yield a fitted strip of 3/4". This is a little wider than I usually use and I hope it doesn't come back to bite me in the rear. I just couldn't keep taking more and more off the cedar planks, it felt like wasting wood.

Brian

 

[alsg]

What caught my eye was the stand for your DW735 planer. I've built a very similar one.

 

[Alan Gage]

Allan, a question about aluminum gunnels, what would they weigh on a 15' ? ... the cherry gunnels on my last boat came in around 3.5 pounds for 16', it just seems like there is just not a lot more to be saved there. I had that discussion with another builder doing carbon gunnels and he agreed, but I have zero experience with aluminum.

I agree that if you've got your wood ones down to 3.5 pounds there probably isn't a whole lot to be saved by using something else. I'm not sure what aluminum gunwales would weigh. I put them on my very first canoe (kite) but didn't weigh them. They were the two piece Bell design and I had to modify them to fit over the thick strips. I don't think you could get standard aluminum gunnels on a stripper due to the hull thickness.

I wish I could remember what the finished Kite hull weighed. I used 1/4" strips, single layer of 6oz, sliding pedestal seat, aluminum gunnels and thwarts, and bell plastic deck caps. Seems it was right around 40 pounds.

But while there might not be much (if anything) to gain on the gunwales it's also important to remember that if you're going to go as light as possible you do have to worry about the ounces. There aren't many places to save a lot of weight but there are a lot of places to save a little weight and it adds up in the end. Of course this always gets balanced against aesthetics, time, money, functionality, and simple preference.

My carbon over cedar gunwales weighed around 5 pounds total on a 16.5' solo. Most of that weight was the cedar so foam would save a couple pounds. But those were built to be strong and light, which I think they are. I didn't have any high density foam to experiment with at the time so don't know how it would compare for sure.

At the time I was making canoes one after the other I was having a tremendous amount of fun trying new things. I learned a lot but I don't know if I'll be doing the composite covered gunwales anymore. They worked well in the end but took a ton of time and a lot of expense too. At the time when I balanced all the options they tipped in favor of light weight and trying something new. Now it's more likely to tip towards a little heavier, faster, and cheaper.

I'm very much looking forward to seeing this build progress.

Alan

 

[Alan Gage]

Hi dogbrain, it wasn't there ... it seems like no matter how time you spend making sure you include stuff, there is always stuff that gets left out.

The rough lumber was ~1" and a bit thick, with one piece at just over 1.25" .... I planed them down to 7/8", which will yield a fitted strip of 3/4". This is a little wider than I usually use and I hope it doesn't come back to bite me in the rear. I just couldn't keep taking more and more off the cedar planks, it felt like wasting wood.

Brian

I've used different width strips on the same hull. Wider strips for flatter sections and narrower strips for the curves. Just something to consider for the future when dealing with rough stock where you have a choice.

Alan

 

[Cruiser]

Thanks Allan, all good things to think about, I agree with all of it. As far as the build goes, I read something somewhere, I think it was the Paddling Light website, it said some thing like "there is light, very light, stupid light", the idea was that when it may not bring you back was too far.

In this case there is a specific weight goal set, that gives me a sounding board for build decisions

I usually use narrower strips to get around tighter curves as well, with this build I am committed to using the wider 3/16" strips ... if I want narrower strips for anything, that means hauling out tools and redoing some of my existing stock, which I really want to avoid in the winter ... with my limited space, that means open the heated garage in winter. We will see.


ALSG ... you made a similar, but much nicer base than I did. Although I added the Wixie thickness gauge http://www.wixey.com/planer/ Model WR510. It is so worth it, if you have the coin, consider it.


Brian

 

[stripperguy]

Brian
I built a 16’8” DY Special that ended up at 32 lbs I was aiming for 30 lbs so it was an abject failure
My woodstrip kite was built strong, I do class II plus with it and it was 39 lbs much like Alan’s

The DY had 1-1/2 layers of 3.25 oz cloth in and out it developed a crack on the inside right up the keel line after 7 years of use and some abuse from my 220 lb nephew

The kite is bomb proof

If you’re designing your own hull pay particular attention to total sq footage
Also, I am sold on composite gunwhales but not using carbon fiber most is too thick and the weight of the resin negates the weight savings from the carbon
If you go that route, be sure to use a good quality foam of at least 5 lb/ft^3

I’ll be watching your build closely, I have a few more boats that I need to build and I too need them to be as light as possible

 

[Cruiser]

Hi SG ... you have been keeping a low profile lately. My last build was a 16'3" modified Freedom Solo, which was intended to be used by my son, at 6'4" and north of 300#s ... it needed to be strong but I was determined to break the 40 pound mark with it and it came in at 39#s, it has survived quite a few trips now and my son totally loves it.

I talked with Randy (Patricks Dad over at BM) who just finished his composite Freedom 17 with carbon gunnels (about the best ones I have seen), about gunnel weight, and he agreed that there comes a point where the work and cost aren't realized by the savings involved. I personally feel that gunnels are the one place people tend to overbuild and it is also the easiest place to pack on a lot of weight. I like to use cherry and I have the size dialed in enough that i wouldn't realize more than a few ounces going to composite (if that).

As far designing my own hull, I am not naive enough to think I can just jump in and design something from scratch. The intend is to "have a hand in the design" which means I will start with a hull shape I like, but would like to add a few changes to. I have already lofted the shape of the donor and converted it to a lofting table. It has been widened a bit, lengthened a foot and I have designed the new kootenay stems like my last build, modifying 4 mold shapes at bow/stern to accommodate the new shape.

I made the point above that I am not trying to be "as light as possible" ... just trying to attain the goal of 30 pounds in a boat that I can take out tripping for a week. It's part of a drive to lighten my gear and also challenging myself in the shop, I find it very tough to just repeat a build, I want to learn and do something new each time.


Brian