My prospector paddles better with 6 gallons up front. I’m not sure if the nose is the best place. If I move it back, besides displaying Bogan, would it work any better or would I just need more weight?
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Ballast Placement
- Thread starter Black_Fly
- Start date
First off, I am absolutely no expert on boat ballast. However, I do know that 50 lbs (6 gallons of water) placed 4 feet from a fixed point creates a moment of 200 ft-lbs. If you shorten the lever arm to 2 feet (for example), you would need 100 lbs (12 gallons of water) to create the same effect. But if you displace Bogan, that factors in as well. You need these formulas:
(50 lbs x Dw) + (Wb x Db) = M1 [this is what you have now, and can measure and fill in all the numbers to solve for M1]
(weight of the water x distance from your seat to the center of the jug) + (weight of Bogan x distance from your seat to center of Bogan) = Moment 1 (which is what you have now).
(Ww2 X Dw2) + (Wb x Db2) = M2 [ this is what you are trying to figure out]
You can measure the current distances and his weight, and have a solid number for M1
If you want to boat to behave exactly as it does with the current setup, then M2 will equal M1, which you know.
Then you need to decide two of the following: Db2 (where should he sit?), where do you want the water? Or how much water weight do you want to use? Then plug those numbers in and solve for the third variable.
In the M2 equation, Bogan’s weight and the total M2 moment are the only known numbers, and you will have to arbitrarily assign two based on what you want (I would suggest figuring out where Bogan would be most comfortable, for Db2, then figure out a good location for the jug (Dw2) based on that, and then figure out how much weight you need.
Depending on Bogan’s weight, you might find that what you have now is best.
(50 lbs x Dw) + (Wb x Db) = M1 [this is what you have now, and can measure and fill in all the numbers to solve for M1]
(weight of the water x distance from your seat to the center of the jug) + (weight of Bogan x distance from your seat to center of Bogan) = Moment 1 (which is what you have now).
(Ww2 X Dw2) + (Wb x Db2) = M2 [ this is what you are trying to figure out]
You can measure the current distances and his weight, and have a solid number for M1
If you want to boat to behave exactly as it does with the current setup, then M2 will equal M1, which you know.
Then you need to decide two of the following: Db2 (where should he sit?), where do you want the water? Or how much water weight do you want to use? Then plug those numbers in and solve for the third variable.
In the M2 equation, Bogan’s weight and the total M2 moment are the only known numbers, and you will have to arbitrarily assign two based on what you want (I would suggest figuring out where Bogan would be most comfortable, for Db2, then figure out a good location for the jug (Dw2) based on that, and then figure out how much weight you need.
Depending on Bogan’s weight, you might find that what you have now is best.
I think that many tandem canoes paddled solo will want ballast forward. I use ballast routinely in sailing canoes, I sit in the bottom aft of the thwart, the ballast goes forward. I've used water jugs, bags of sand, concrete blocks and exercise weights. Yesterday my wife and paddled my most recent canoe tandem for the first time. It was a bit tender. At 50# with an arc bottom and two tall people in it, I'm not surprised. Next time I'll use ballast.
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Very impressive response by JCH-Ski! If it were me, I would just try various locations and weights until I found a combination that satisfied me.
Aw, shucks PaddlingPitt. Once a mechanical engineer, always a mechanical engineer, I guess.
JCH, Michael Pitt went to Berkeley in the 1960's. Not many there and then were focused on equations. In fact, as I recall, he got a Ph.D. in grass.
Black Fly might appreciate the mathematical approach rather than the stevedore approach to ballasting since I believe he's still recovering from injuries and surgery.
Personally, I used to factor into my ballast equations special relativity and quantum tunneling . . . before I left my physics and brain cells in a bar near Columbia University, also in the 1960's. Now, I just eliminate the dog to make things easier.
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You always entertain me, Glenn!
“Special relativity and quantum tunneling”
. You are (were??) certainly out of my league.NEVER eliminate the dog! Especially when he’s as cute as Bogan!
So if Bogan is constipated, it might throw your equation off. I need a Bogan.
Umm….Bogan doesn’t look big enough for the weight difference to be a real issue, but then…….I suppose……maybe……..
I try to put the ballast as far forward as possible. 
Bogan is 55 lbs. I like the water jug where it is, And have played with different amounts of water. I was just wondering if there was something I didn’t know. I’ve contemplated moving the seat or adding another water jug. Fast current and wind often makes it squirrely, but it’s still fairly responsive with 6 gallons. I don’t want it too lethargic because of obstacles, but I don’t feel I’ve found the sweet spot. That could all be in my mind, given the speed of the river. Maybe I’m just too used to relaxing on river paddles. This one at high flow requires vigilance and correction. Fishing on the fly is tough. I think the fish all drowned anyway.
