not the Washington State Ferry…

the canoe/kayak ferry

http://www.bask.org/technical-and-gear/tech5_currents/

I like the Coaster in the picture

Good article

Always nice to read a well done article and am generally impressed that so many come from BASK.

Thanks for the post,

Rick

OK, but…

The simulations are nice, and illustrate the necessity of assuming a bearing angle relative to the direction between oneself and the desired destination to get across a channel efficiently. Basically, one assumes a bearing angle so that the streamwise component of one’s velocity exactly cancels the current.

Example 3 is the most efficient crossing. The bearing angle results from pointing the boat velocity (3 knots) at an angle to the left of the target, such that its streamwise component will be 2 knots. To do so, the bearing angle of 41.8 degrees gives the right value, i.e. 3 knots * sin(41.8 degrees) = 2 knots. The resulting actual speed across the channel is the component of the velocity in that direction, i.e. 3 knots * cos(41.8 degrees) = 2.24 knots.

However, the calculations of distances paddled in the examples is mystifying. In Example 3, how a boat crossing a 300 yard channel in a straight line travels 409 yards is beyond me. Maybe they mean distance paddled relative to the water, but that’s kind of irrelevant. In comparing examples where the boat moves at a fixed speed relative to the water, the only meaningful comparison is time - i.e. the most efficient path is the one that takes the least time.

In the glossary, I have to pick nits and say that a bearing cannot be a distance, as angular measure is, strictly speaking, dimensionless. Degrees are really just a specific fraction of a full circle, it isn’t actually a proper unit. Bearing is the angle measured between a reference axis (the longitudinal axis of the boat) and a ray drawn from an observer to a target.

paddling across

If you paddle the route without the current then you go 409 yards.

But doahn quote me.

The ‘thinking about ferry angles’ sets your head up for getting kayak/canoe mind-planning in the groove for a successful crossing.

The more you set up in tune with conditions at the beginning the more potential exists for success during the crossing.

The course may very significantly as you paddle across.

I’m not an expert. The serious crossing to date for us was misread at the beginning but started where I wanted to be and with a well chosen ferry angle for the destination.

I had to pee. In that I was blown downwind 3-400 yards to the correct line for crossing..with a lesser ferry angle in a joining current eddy stream.

Burch has more information. Read Burch, Kayak Navigation. Burch is cleaner in math disturbances.

I wanted to

add…

The ferry route I needed was a reduction in wind velocity, a reduction in current disorganization, and a stronger current flow toward the destination.

But getting there required a correct ferry angle at the start.