I’m hoping someone can help me out with an argument I’m having with my friend…
This past weekend some friends and I bought an hour on a banana boat - basically, a long inflatable log with small pontoons on each side. This is pulled by a speedboat, which tries to fling you and your friends off by turning left and right. Of course, you want to try to stay on.
I was sitting anchor (the last seat), and we were doing pretty well and not falling off. I was telling everybody to lean into the turn - if the boat took a right, we would lean right. I thought that it was similar to riding a motorcycle - because of the higher center of gravity you being on the banana boat creates, you would be pulled to the outside of the curve, and as a result the banana boat would flip over. Therefore, you need to lean in to counter the centrifugical force created by the turn. However, my friend says you’re suppossed to lean in the opposite way of the turn, because they were leaning in to the curve too and still flipping over.
So which way is the correct way, if you’re trying to keep the boat afloat? Do you lean into or against the curve?
Whichever works is the ‘correct’ way, I suppose.
So, when your friends leaned into the curve and flipped over, which way did they flip over? Into the curve or out?
If you don’t lean into the turn at all, your weight (that is, your inertia) will tilt the boat to the outside of the curve, and you’ll fly into the water (there is a counterbalancing force on the bottom of the boat, which might save you). If you lean to the outside of the curve, you’ll definitely flip. If you lean too far into the turn, you will (a) overbalance the boat and (b) probably submerge an outrigger, leading to greater and more complicated drag.
The forces on the boat are not like forces on a motorcycle, because boats do not have tires; they sit in the water and slide through it, a little sideways and a little forwards. Add the tow rope to that and you’ve got a mess.
at first look I’d intuitively agree to turn into the curve, but a friend’s experience in a competition of who can stay longest, his group won with the strategy of tilting the other way. now I was trying to see how it could be plausible. let’s look at the factors.
*shape - the shape of any boat is to push it up while going fast.
speed - even with the absence of wind from weather, higher speeds can cause the banana boat to hover above the water, due to its shape and buoyancy. the headwind will lift the banana boat starting from the front, to the whole thing at higher speeds.
*weather condition - affects wind and waves, high winds and rough/tall waves can increase chance of flipping over.
*weight of group - heavier they are requires higher speeds to lift the banana boat.
*height of group - the taller the people ( even while seating) the higher the centre of gravity, which is a huge factor when you consider the banana boat’s low density (even if there was a counter weight). this is the main reason for tilting towards the curve that applies to bicycles, motorcycles and cars.
but here is the factor I think most people would overlook (i did until I wrote this post), this is a floating boat on water, being dragged on water.
*angle and friction of the water - when dragged at high speeds and at higher angles (imagine extreme of right angle), will most likely overturn the banana boat if it was tilting into the turn.
what would make sense for tilting out, for me is if tilting out - let’s say right, while boat is curving to the left, is the counter tilt would cause the banana boat to heighten the left side, while the towing boat is pulling to the left, would stabilize the boat.
compare to tilting into the left while towing boat goes left, might expose the bottom right of the banana boat to the headwinds while being pulled to the left, which would add up the forces to overturn the banana boat.
I would like to see an experiment, maybe done by mythbusters to find the truth of this matter. in any case, the only certain thing for me is to lower the centre of gravity by bowing forward, and to reduce of headwinds by getting heavier people. but for now I’m leaning towards agreeing with my friend who stayed on the banana boat. I’ll be testing this when I get the chance. I hope anyone can try it out and report their results. after all, according to Michio kaku,experimentation is the only way to keep theoreticians honest
You speak of the boat “staying afloat”. Does a banana boat have an open top, like a canoe, such that it can fill with water? Or is it a solid cylinder that one straddles?
