Dugout canoe with a more modern design?

First I'd like to mention I discovered this forum 8 or 10 years ago when I was building a cedar strip freighter canoe with intentions of travelling the entire (navigable portion) of the Mississippi. I asked a few questions and was amazed at the helpful responses. There are some really smart people here. I finished my boat in 2018, took it to Minnesota, and travelled downriver to the Gulf in 13 days. I met some amazing people along the way. I'd like to build another boat for a different purpose. I participate in ultramarathon paddle races, usually with expensive carbon/kevlar long skinny boats. This year I did a 1000 mile race down the Yukon along with some shorter races. One race, the MR340, has a dugout class but no one has finished the race in this class. To my knowledge, no one has made it to the first check point in the required time. I've seen two of the boats that attempted it and they were very large, thick, and log shaped. I'm not knocking anybody's design. I admire anyone that made the effort to turn a tree into a boat and attempt to compete in a 340 mile race. Here is my question....how practical would it be to turn a single log into a boat shaped just like a Wenonah Minn IV except with it being 2 or 3 inches thick. The Minn 4 is shaped like a traditional canoe. The dimensions for the Wenonah Minnesota IV canoe are: 23 feet in length, 35.5 inches in maximum width, 34 inches in gunwale width, 33.5 inches at the waterline, and a center depth of 14.5 inches. The bow depth is 21 inches and the stern depth is 17 inches. If I were to make patterns off of a Minn IV and carve a boat to the same shape except 2 or 3 inches thicker, would it float and perform like a very very heavy Minn IV? With 4 paddlers over 340 miles?

 

I think that you can make a dugout that is much thinner than 2 inches. It is not required for it to last years of use. With modern tools it is easier to make a thinner hull with stringers/frames let thicker for reinforcement. What species of wood are you planning on using?

 

Gonzo, I'm encouraged by the fact that it could be built much thinner. You are correct that it would not need to be built for years of use. If it finishes one MR340 within the 100 hour time limit...I'd call it a success. I'm unsure of how thick it would need to be but there would be about 1000 lbs of people and water in it. Race strategy would be to go 20-24 hours between stops so need food and water for 4 paddlers burning lots of calories. You bring up a great point about modern tools. To my knowledge there are no specifications published for this class at this race and opinions vary, even among my paddling friends. Everyone agrees that it should be made of a single log with the hull constructed as a single piece. Most agree that it should not be sheathed with fiberglass, carbon fiber etc. About 50% (informal poll) think it should be made using only hand tools or hand tools and a chainsaw. I know that some people have the resources to put a log into a CNC lathe and create a perfect hull rather quickly but I don't think that qualifies as a dugout. Generally I think using a chainsaw and hand tools is appropriate and using oils or varnish to protect the wood is OK. I think seats and thwarts could be added as separate pieces. I think glue or epoxy is OK for mounting seats and thwarts and to repair broken pieces of the hull but only enough to make the repair, not to reinforce the hull. I think my preference would be to use Red Cedar but those are not very common in my region. I do have friends with large gooseneck trailers and I don't mind a long road trip but have not started looking to see what is available. What is pretty common in my area is Southern Pine and several friends with timber properties have said they have some pine trees large enough to get a log big enough for this. Another wood common to this area is Cypress. If I could find one big enough it would be really expensive but maybe worth the price. I do appreciate your input.

 

Completely doable. Either by hand or CNC, or both.

Red cedar would be my first choice; ease of tooling, light weight...
I think the challenge would be in getting a tight grain, clear ( no knots ) log.
That's going to be an expensive purchase and/or find.

What a great endeavour.

 

If you do a little research about dugouts, both historical and contemporary (from regions where they are still used for subsistence) you will find that they are seldomly over one inch thick in the topsides, and often less then two on the bottom.

As to wood species, cottonwood is local to you and a common choice for dugouts back in the day. As a bonus it's inexpensive, resonably light and available in the needed size.

Now about the shape. However you make it and whatever wood you use (even balsa), the result will be significantly heavier then a modern composite boat. This weight must be offset by additional underwater volume, there's no way around it. This means if you use the exact shape of a Wenonah Min 4 it will sit much lower in the water, because you already start 1-200lbs heavier. You need to select (or design) a shape that can carry the total projected weight and still be safe for the journey.
I would start with finding out the total surface area of the Wenonah 4 and its max. cargo capacity that still allows for a safe freeboard. With the surface area, chosen species density and hull thickness you can calculate the theoretical hull weight (it will be higher because the wood will soak water even if you manage to dry it beforehand). To this you add your 1000lbs of people and food and see if you're still in the safe zone.
As an approximation I would expect a 4 person canoe to become a 3 person filigran dugout or a 2 person battleship if the shape is identical.

 

Rumars, thank you for your suggestion to use cottonwood. I never see it at lumberyards or sawmills but you are correct that they do grow here and I have seen some large ones along bayous and riverbanks. I'm not married to any particular shape but most dugouts I see look like battleships as you described. I'm sure I could get a uniform hull thickness much less than 3 inches, I just have no idea how thin it could be and still be robust enough to carry 4 people and gear, be trailered 1000 miles, and survive floating logs and landing at boat ramps. Without adding epoxy fiberglass or similar. I mention the Minn 4 as I have access to one for a pattern. This is a race and the boat needs to average at least 6.17 mph for the first 74 miles. The river generally gives you 3-4 mph of current. The speed average between checkpoints drops, especially at night but some downriver legs are 5.4 mph avg. I did this race a few years ago in the Dragon Boat class. It was fiberglass and in general it looks about twice the size of a Minn 4. We had 17 people in this boat and in the first 24 hours we paddled 200 miles. I'm used to paddling as a 4 man team that works well together but I am limited by the size of an available log. Any comments are appreciated.

 

Probably somewhere in the world exist species most appropriate for the task .
Kind of special machine could be designed to eat lumber from inside , leaving frames and stringers .
Special "varnish" can be used to improve hull strenght.

Are you sure that we talking about dugout canoe competition ?

 

Dugouts were often widened by filling them with water and tossing hot stones until the water boiled. The wood softens and can be deformed. Are there rules about what a dugout is, or just a consensus? That is critical to the design and build. You guys are in Louisiana. There are plenty of giant cypress logs floating around. A chainsaw and a minigrinder with a chainsaw blade are good for gross cutting. Chisels and adzes are good for medium and fine cutting. Finally, a grinder with #24 grit discs will finish the job. I would leave ribs to reinforce the hull and try to finish it to no more than 1/2".

 

You don't see cottonwood because it is an industrial wood, it goes to paper mills, chipboard factories, plywood producers, etc.
The biggest problem with a dugout is splitting from drying, shrink wrap well for trailering and don't leave it in the sun on land.
As to thickness, one inch is the maximum I would use, maybe a little more on the bottom if I know it's regularly going to be dragged over sand and rocks, but longevity isn't a concern for a race canoe. Floating logs is another thing altogether, wich modern canoe exactly is guaranteed to survive such an encounter? Just keep your eyes peeled and remember that people used birchbark canoes in the same waters, and they weren't in the habit of filling their boats with inflated animal skins to keep them afloat. There's no need to go battleship, for a race canoe you go to the limit of structural integrity.

 

There may be official rules or definitions for dugouts at some competitions but none are published for the MR340. Likely because no entry in the Dugout class has ever finished. I would suppose whoever finishes could be instrumental in setting the guidelines for future races. 411 boats in about a dozen classes ran this race this year. Some races that I compete in have very specific rules for various classes. A canoe is not just "solo" or "tandem". Material, length/width ratios, max lengths are some specs that are put in place at some races. At others, if your canoe is kevlar, you are bumped to an "open" class where you are competing with things other than canoes. At the MR340 the original rule was "human powered". It was all paddle boats, then some pedal powered craft became competitive and they created a class. Then "rowing" boats entered so that is a class. They have even invited rowing skulls to participate but none have taken them up on it. My preference for the dugout class would be more traditional such as hand tools only and no space age coatings. I'd prefer the race be won by paddlers toughing it out for 85 hours on minimal sleep than by CNC programmers. Gonzo, I truly never considered leaving wood in place as ribs and a keelson for strength, and then going thinner in strategic places. Thank you.

 

The only dugout canoe class that I'm familiar with is in the Ruta Maya, four day staged race in Belize. Rules are 20' long, three man canoes. The few that participate in the dugout class are tough dudes, the dugouts are narrow and tippy, require paddlers to sit low in the boats.

A lot of good advice has already been offered here, I second the use of chainsaws and properly equipped grinders. My only suggestion to add is consider an outrigger. There are a lot of outrigger styled boats in the MR340, there are no portages required. An outrigger would allow you to go narrow and long, better suited to a log and take away the nasty balance problem.

Hope it works out for you, I'll probably be following the race in person next year, I've got a couple of new designs that will probably be competing in the race.

 

Hi Skip, Thanks for your feedback. Yes, there are a lot of ama (outrigger) equipped boats in this race, and some, like the Riverhawk are about the fastest out there. And using one would certainly stabilize a tippy design. To me, that moves it further away from being a traditional dugout though. And I feel the same way about using power grinders and sanders VS hand tools only. Others will disagree for sure but those topics aren't really what I'm asking about.
I think it's cool that you have (a couple) hull designs in this race and am intrigued as to what's different and who's paddling them. Good luck. I will be in this race, it's one of my favorites. I have until the Jan 1. registration to see if I can come up with a dugout plan but if not I'll do the race solo in a Stellar kayak with a goal of 48 hours. The race is the end of July so I would have about 6 mos to build.

 

I respect your approach but would point put that there are any number of outrigger style dugouts paddled throughout the globe ;-)

 

Are the hull designs you created for this MR340 an outrigger design?

 

I am totally unsure if 1 inch thick would have the structural integrity needed. I'm not saying it doesn't because I truly don't know and that's one of the important pieces of information I was hoping to find here. It seems that if I made a hull with dimensions of a Minn IV and was made of 1 inch thick cottonwood that would be 18,843 cubic inches or 11 cubic feet X 28lbs per cubic foot = 308lbs. This number includes ten cross stringers of 2x2 along with a keelson that is also 2x2. That 308 lbs is 241 lbs heavier than a fiberglass Minn Iv. So is it as simple as building to the same dimension as the Minn IV but then using it as a 3-man boat? Take out a 200lb guy and some of his gear and you are now about the same weight with the dugout compared to the Minn IV.