physics questions.....

…just out of curiosity, what would happen if you put a strip of lead down the inside centerline of a canoe? Would it have a righting effect when the canoe tipped sideways? Also, I’m aware of the Raddison canoe’s side flotation pads, but it doesn’t look like a very efficient hull. If you split a pool noodle lengthwise and glued the halves to the outside of a more efficient hull, just below the gunwales, would it add anything to secondary stability? I’d ask my engineer brother, but he built airplanes, not boats.

scuba time
ahhh…If you capsized it might sink?

thats why
i keep my water bladders along the midline…would like to glue down some tabs so i could more easily strap them to the hull.

my sons
wood stripper is very squirelly when we take it out unloaded. put in a couple of packs at about 35-40 lbs and it is really stable.

centers of
bouyancy and gravity will determine. As long as first is above the second, no worries. After that is torque along the movement arm. Shift the weight too far and you get wet. Think weighted keels on sail boats.

Let us know what works for you.

Wha Ho, Pilgrim;

Reverse polarity, man! Reverse polarity… that always worked for LeForge on Star Trek.

Fat Elmo

yup reverse polarity or…
check the dilithium crystals…that’s old school

I’ve always leaned towards …
… the thought experiment where you place not one but two lead pipes as far out away from the midline (and each other) as possible. By that I mean curving them around along the chines. This would resist beam waves from lifting one side of the canoe “abruptly” by the dampening effects of inertia where it “counts”. It’s much easier to spin mass consolidated into a single axis than it is to twirl it when it’s arrayed outward from such an axis.

In the real world, one could “hang” 2 gallon water bags (say, four on each side) from the gunwales so that they nestled along the chine area on either side (like saddlebags hung out of the way). With 60 lbs of low-situated water ballast along the hull sides (120 total), I think the canoe would not be as prone to being “jerked” around it’s longitudinal rotational axis … not as quickly anyway … by beam waves. This is the same thing that you see when skaters open up or center themselves to effect changes in spinning speeds. Weight “splayed out” to the sides of the bottom of the hull (and thus away from it’s theorectical centerline) will resist waves wanting to lift up the chine area. Soft chines help alot also … by not giving the wave a hard edge to lift abruptly (displace). “Splayed ballast” is an easy way to dampen the ride motion without having to change the shape of your hull (think Cadillac). It should work better than centerline ballast … just don’t position the weight at a significantly higher level … keep it fairly low in the chine area. As soon as the center of buoyancy starts moving up, other factors rapidly enter the equation and significantly alter “ride motions” in ways you don’t want (pendulum effects, etc.)

lead in my k1
I have to use about 4lbs of lead to get my k1 up to legal weight for sprinting. Placed on the floor directly below the seat it does stabilize the boat a bit. The boat will event sit upright now when I place it in the water before getting in.

Question about canoe stability?
I would email Jim3727.

He seems to know a lot about canoe stability.

Yeah, more than anyone else here

When loaded with gear on the Dolores
my MR Synergy was certainly more stable. Didn’t help enough when a thunderstorm gust almost forced the downwind gunwale under, down by the toe of Muleshoe. If the boat had been unloaded, it would have skittered sideways across the water.

If you have to carry extra weight in your boat, obviously you want to keep it as low as possible.

Lead is toxic. I’d leave it alone. Stability comes from ability. The better paddler you are the more stable you will keep your canoe. Adding weight slows and fatigues you.

“stability comes from ability”…
…that’s why Pacific Islanders use outriggers-they’re incompetent paddlers.

Outriggers were hollowed out logs that were made for ocean travel. I doubt Pacific Islanders know how to do a high brace in their boats. Your canoe handles better than that.

I don’t think anyone intended to put
lead in their boat. I used lead to optimize damping by a listing board in my clavichord, but I carefully varnished every exposed edge of the lead sheet to see that the oxide didn’t travel. In human powered boats, adding weight that isn’t gear is almost always a mistake.

“Mistaken” ballast thoughts
While it’s true that adding weight to a boat increases it’s resistance and dampens it’s manueverability … that’s not always at odds with what we’re wanting to do. If you have to make due with one boat design rather than own many specialized boats, then I think ballast additions to enhance stability (for wave/wind conditions, fishing, photography, binocular usage, etc.) are best to extend a boat’s range of usefulness.

For instance, if I were to own just one canoe, I would choose a long, lean wilderness tripper that could do everything OK … but would likely give up a fair amount of initial stability for efficiency and secondary stability in big water. A few waterbags distributed judiciously can make such a boat have a much calmer demeanor when used for local daytripping (fishing, sailing, etc.). And if you loan such a boat to others with less experience, advising them how to use ballast to trim the canoe for what they want to do … is doing them a favor.

Adding ballast (waterbags, not potentially toxic lead!) is the easiest way to “trim” canoes the for prevailing conditions of your trip … a way of “balancing” the hull for better motion control, levelness (trim) and enhanced stability. Anyone who’s ever stepped into a small boat knows instantly that weight location is critical. Ofcourse, when efficiency and quick manueverability are the priorities, a less displacement is always advantageous (less resistance, i.e. surface area, form and inertial varieties) … as long as it doesn’t lead to the paddlers falling out.

I’d rather have some load in a boat
when on big lakes or very wide, flat rivers, but not when negotiating rapids. I do recall some times when, on going from whitewater to a long, flat, windy section, I have placed a 40 pound rock in the boat to have something to adjust trim.

My Vagabond solo tends…
…to be aft-heavy with just me in it, so I have a

heavy plastic water carrier with probably 1-1.5 gallons in it, smack against the bow. Really levels the boat. I’ve put a line on its handle, thinking If need be I can pull it back some, and shove back forward with a paddle. I found the carrier at Fred Meyer, and it’s a flexible bag w/handles at both ends.

Or you could just…
put a deck on your canoe and have a kayak.