How large gas motor on flat stern canoe?

I am considering using my Grumman 17’ flat stern canoe for a week long fishing trip in northern Canada. The lake is large 200 mi long and the distance one way to a base camp is about 50 mi one way. I have out rigger floats for the canoe and its capacity total is 825lb its beam is 36". I have not put a motor on it before but want to move along at as fast as is reasonably safe maybe 20mph? I am considering a 5 hp 4 cycle for both fuel economy and environmental concerns. If I could go larger I will. Also, anyone have any ideas how many hours at full throtle these engines run? Any help would be greatly appreciated. Thanks.

Call Manufacture
Call and see want it’s rated at.

Data Plate should say.

– Last Updated: Apr-03-05 11:02 AM EST –

A boat made for a motor is required to have a data plate on it and that should tell you.

Suggest looking around the area of the stern for the metal data plate.

If not, do call the manufacture.

Happy Paddl'n!


Oh yeah, the current name of the company is Marathon canoes, I believe.

have you been to this lake before?
if so, what’s the potential for large wave activity? I was up on a 15-mile lake last year, and several days got into conditions that were white-knuckle, pucker-factor moments in a 16’ lund v-hull. Being out in a canoe would have been an absolute NIGHTMARE. And, 20 mph seems pretty dang fast for a canoe-our v-hulls topped out around 13-15 mph with 15 hp mercury’s on back. Maybe people actually go that fast in a motorized canoe but I sure as heck wouldn’t want to do it–especially on a lake that size.

what mick said
I have owned a coupleAluminum canoesand they both hadplates that suggested the maximum motor size. My 15’ Michicraft was 5 hp.

20 mph seems super fast on the water in a canoe. I would be freaked out.

I agree with darkwolf
You won’t get 20 mph out of that boat. My 16’ fishing boat with a 20 hp and just little ol’ me inside might be able to go that fast, and it is by no means slow.

Outriggers will slow you down a bunch too, unless they don’t touch the water. If they don’t touch the water, be prepared for some nasty jolts when they plow into waves. Be careful.

I’d also suggest you totally forget that 800-pound-plus load capacity. Usually such high ratings are made assuming it’s okay to have an extremely low amount of freeboard (six inches or less), and though your outriggers will help keep the boat stable when loaded like that (usually a canoe with that much weight has stability not much better than a floating telephone pole), the risk of swamping in the chop will be great.

Outboard motors usually have ratings for how long they run on a given quantity of fuel at particular throttle settings. As others have said, if you can’t find it in the owner’s manual, ask the maker - they’ll know. Then take that rating and give it a substantial safety factor. Your canoe probably won’t plane as well as a normal boat fitted with the same outboard (especially with a big load!), so fuel economy is likely to be quite a bit worse at full throttle than what the manufacturer says. On the other hand, fuel economy is likely to be better than with a normal boat at low throttle settings, because a canoe is a much more efficient displacement hull than the average small motorboat.

The Lake
The lake is Reindeer Lake in norther Saskatchewan. It has 5000+ islands 90+ tributaries and is the 22nd largest lake in the world. I have seen 5’ rollers before, and obviously one needs to sit it out, the base camp location is in a sheltered area with open water of only a mile or two, however to get there, requires crossing some big open stretches with only rock islands every few miles. I have fished it before in 18’ Lund Alaskans, however, this time I plan on getting into some lakes adjacent to the main body so I need to take a canoe, to gain access. The lakes I plan on exploring have not been accessed and likely never have been fished. Last time I went into one we boated 50+ walleyes in the only two hours we fished. Our largest northern pike from the main lake was 43" and several others were over 40". No doubt this is more of a fishing exploration trip than pure canoeing. Thanks.

Thanks for the helpful information. I just tested the freeload at 580 lbs and the free load was 8" and my out riggers were not touching on on calm water.

I was up in northern Manitoba once and saw a conservation officer with a large motor on a pontoon rigged canoe. (I would guess it at 10+ hp) and he passed my 14’ fishing boat with a 25 hp motor. I suspect he was going 25 mph plus. I know this sounds like a far fetched but with wide pontoons maybe about 3’ extensions on each side, his canoe was more like a catamarand (sp?).

What free load do you feel is safe when using a canoe as a freighter?


How fast?
After I test the system with whatever motor I get, I’ll post some speed numbers at different loads.

Which outboard are you thinking of?

Reindeer Lake
I worked at the north end of Reindeer Lake from Jan. to 1970.It is a beautiful lake.As I recall the fishermen and trappers there mostly used 16ft cedar canvas canoes with 10 horse motors.

Largest outboard on a freighter canoe
A long time ago I was out on a big lake (South Indian Lake Manitoba) in a canoe with a 20 hp motor. I would not recommend it. I was the bow ballast. Good thing 17 year olds are immortal. The usual was 9.8 hp, if I remember correctly.

Motor Considerations
I am thinking of the Honda 5 or 6 hp four stroke with the possibility of bumping up to an 8 hp. (All in short shaft). The 8 is getting heavy to portage since many of the remote areas do not have portage trails.

Bow Ballast
I have been bow ballast before when I was sure that the boat (a 16’ aluminum fishing boat) was going to buckle under crashing from every 5’ roller. I have never fished Southern Indian but have fished the Churchill River leading up to it. It is nearly identical to Reindeer and thanks for the information.


an idea…
take your canoe with a small outboard, and tow it behind your regular v-hull fishing boat. Once the boat gets up on plane, the canoe actually rides the wake fairly well. Then, you have the canoe for portaging into small lakes, and the large boat for stability and power getting across large open water.

Motor Considerations then.
The Honda 5 is about 56 pounds I believe. Should hang on that transom ok but like was mentioned, follow the USCG ratings BUT… make sure the ratings are not based on horsepower alone. A 6 HP rating does not necessarily mean a 4 cycle 6 HP. It may mean a 30 pound 2 cycle 6 HP. I don’t think there is much I can show as proof of this but that is what I have been learning over the years. The advent (and it’s about damn time) of smaller 4 cycle outboards is introducing more transom weight for the same horsepower, albeit badly needed.

Thanks for going 4 cycle!!!

I have a Briggs and Stratton air cooled 5 HP 4 cycle (I’m poor, grin) that I just love. 56 pounds though! While I can curl that all day when I hang it on my 13 foot sailboat she gives me a look…(grin) I built her transom (Ash and marine ply laminate transom with an ash and two cherry knees) to take the thrust and weight but she really puts her transom down in the water until I get in as mid-ship ballast.

Make sure your rating will accomodate the weight as that is going to be a big factor in how the construction of your boat holds up. Get a documentable (e-mail great) response from the manufacturer on transom weight caps as well as HP if you can.

Good luck!