Hey guys,

I posted a short while ago about landing on a river where I just purchased a home,

(https://www.backcountrypilot.org/forum/ ... h-my-17279)

Well after a OCD level of research I figured all was good did a few inspection passes and landed, with the current and into the wind, completely uneventful.

I have a few of the better books on seaplane ops, plenty of info on all sorts of stuff, but none have all that much to say about river work.

The river isn't raging by any means, pontoon boats frequent it as to little fishing boats, water level is regulated.


Any tips, tricks or lessons learned, I'd love to hear them.


Thanks

With my limited seaplane experience, I'll stay away from that--none was on a river. But I have lots of experience with flowing water and boats, some on rivers, most on tidal currents. Some of what I have learned comes from a Coast Guard Auxiliary coastal navigation course, but most of it comes from just doing it, and getting burned at times.

The hardest thing for me to learn was to let the moving water do the work, instead of fighting it. For instance, if I were doing it, I'd come in up river from where I want to land, and let the river bring me to that place, rather than trying to go against the current to that place. With a boat and I presume a seaplane, as soon as you cut power, you're no longer where you thought you'd be. But if you sail into the place you want to be, using the current much like you were taught to sail with the wind, you can gauge where you will go more easily--the current is probably pretty constant. Just like docking takes learning by practicing how much the seaplane drifts after the engine is cut and how much rudder is needed to straighten out the floats to parallel the dock, some practice with the river will pay dividends.

But I'll bet MTV has chapter and verse to suggest for you!

Cary

NineThreeKilo wrote:Hey guys,

I posted a short while ago about landing on a river where I just purchased a home,

(https://www.backcountrypilot.org/forum/ ... h-my-17279)

Well after a OCD level of research I figured all was good did a few inspection passes and landed, with the current and into the wind, completely uneventful.

I have a few of the better books on seaplane ops, plenty of info on all sorts of stuff, but none have all that much to say about river work.

The river isn't raging by any means, pontoon boats frequent it as to little fishing boats, water level is regulated.


Any tips, tricks or lessons learned, I'd love to hear them.


Thanks

I can't remember if you mentioned whether the current was flowing FROM the bridge near your place, or TOWARD that bridge from your place. If it is going toward that bridge from your place, in my opinion, that's going to be one of the biggest threats to your operation. Watching a good seaplane being inexorably torn apart under a bridge by even a slow-moving current would be a horrible sight.

Using the current to pin you to the dock on the upriver side will make docking a lot safer - and reminding yourself that as you water-taxi towards your spot that you're going to have to be ready to move quickly and sure-footedly is important, too. Don't forget to undo your seatbelt/shoulder harnesses as you approach and be sure that the mags/ignition are OFF before you climb out. Nothing like a hot prop to ruin your day when you're desperately trying to grab something if you slip. (I'm not recommending anyone grab a prop if they slip!)

Other than that - practice, practice, practice! I'll take dealing with a little extra wind any day over dealing with a little extra current!

Oh, Man....Float operations on Rivers..... A book couldn't cover that topic thoroughly. This is the float equivalent of wheel landings versus three points as well.

When asked whether I'll land or takeoff upstream into the current or downstream with the current, my response is always: It depends. I know, really helpful so far, eh?

But, the problem is every seaplane performs differently....different time to get on the step, different performance once on the step, etc, etc, etc.....

What's the wind doing? Just because you're landing on a moving surface, you can't just discount the effects of the wind. A combination of a significant wind and a current can make docking incredibly difficult, depending on the combination of forces.

What's your load like? Granted, this is a takeoff issue, rather than a landing issue, but it's significant. This goes back to the performance of the airplane and the floats its mounted on.

What are the obstacles, how high are they, and how far are they? What are the "escape routes" in the event that a boat comes around a corner just as you're touching down? Does your airplane have the performance to make that escape?

So, landing downstream, you'll find an easy touchdown, since your touchdown speed relative to the surface (the water) is slower than it would be on still water or land. A ten knot current makes this difference significant. So, you settle off the step, BUT--now you're moving downstream at river speed plus taxi speed.....and if you hit something....like the bottom, a rock, a snag..... It's gonna do some damage. And, you're motoring down stream at a prodigious rate. So, where are you going? Did you plan your touchdown such that you'd settle off the step right next to your intended docking/beaching spot? You should have....landing upstream or downstream, this is a critical issue:

Never taxi any farther on a river than you have to. There are things in there that can hurt your airplane and it's floats. Minimize taxi to the extent possible.

How about landing upstream, into the current? No problem there either.....except that now you're touching the water at substantially higher speed than on still water. That should not be a problem, as long as you touch at an appropriate pitch attitude.

But, again, make sure you come off the step in the immediate vicinity of your intended docking/beaching area.

As far as taxiing, I prefer to taxi upstream to a parking spot. Why??? Because things are happening much slower this way. Taxi downstream, pass your point, and by the time you get turned around, you're way past the spot.

So, which way to land, up current or down? To me, it depends totally on other issues....wind, obstacles, curves in the river, where I'm parking, etc.

Okay, now takeoff.....upstream or down? Many more variables here. This is where airplane performance really makes the difference.

Some seaplanes literally leap up on the step and then accelerate nicely to flying speed. I should say, some airplane/float combinations do so. Others, not so much. Some seem to take forever to get up onto the step, but then accelerate fairly nicely once on the step. Some are slugs getting on the step, then accelerate VERY slowly to takeoff speed.

And, of course, loading significantly changes the performance of any seaplane.....much more so than it does with a wheel plane.

So, consider that your task as a seaplane pilot is to convince this machine to accelerate to flying speed. That is a pretty simple task, right?

Not on floats, and certainly not on moving water.

On wheels, the resistance to our forward progress and acceleration is primarily the drag produced by the wheels rolling over the surface.

Same is true of floats, but consider the amount of "wetted area" of the floats that is in contact with the water at any given point in a takeoff. A lot, to say the least.

Our goal on floats is to reduce that wetted area, and its associated hydrodynamic drag to the extent possible, initially by getting the airplane up onto the step, or planing. This reduces the hydrodynamic drag considerably, but there's still a lot of water drag on those floats.

And, now what we're trying to do is to accelerate to FLYING speed (slightly above stall speed if you prefer) while on the water so that we can eliminate that hydrodynamic drag completely, and deal exclusively with aerodynamic drag. So, we have to drag those floats through the water at least fast enough to get the wings to flying speed.....think about that.

Now, if we're headed up stream, that means that we have to drag those floats through the water at an even greater relative speed than normally required on calm water. On some floats, that simply won't work. On some airplanes, particularly heavily loaded ones, that simply won't work.

So, never takeoff upstream, then, right? Not exactly. Consider an airplane that has very good takeoff performance on floats....a Husky or Super Cub for example. And, a confined area. These airplanes will climb up onto the step almost in one spot......then accelerate nicely to takeoff speed, all the while using a minimal stretch of waterway in the process. A heavily loaded 206, not so much.

Okay, let's takeoff downstream. Now, we've got the water accelerating the plane before you even start the takeoff run....all good. Except I'll remind you about obstacles, rocks, bottom, etc. Things that can hole a float or worse, and going downstream, you'll hit them hard.....maximum damage.

But, a heavily loaded seaplane may have no choice but to head downstream. But, the takeoff run is going to take greater distance in the length than it would on calm water. How much? I can't tell you. You're going to have to figure that out for your plane, that current speed, etc, etc.

Now, insert a wind. A downstream wind with a heavy airplane just plain sucks. And, depending on where the obstacles, curves in the river, etc are, a wind may simply make takeoff impossible in some conditions, or at least not safe.

So, there's a quick primer on river ops.

Oh, and did I mention that there can be obstacles in these waterways? I once landed regularly in a fairly shallow river, no problems, just land in the river, downstream...... Then one season, water levels were really low. For some reason, probably wind, one day I landed upstream, pretty much right in the middle of the stream.....and as I settled off the step, I slid over something really big. I beached and borrowed a raft to go explore this obstacle. Turned out it was a large (very large, actually) concrete block with a steel eye in it, placed there by the military when they used that area as an R and R site. They moored their seaplanes out in the middle of the river. Nobody had ever noticed that big concrete block before, because the water had always been high enough to hide it. Fortunately, when I found it, I was at minimal forward speed, and no damage done.

FWIW

MTV

Zero float time here (yet), but a good bit of boat time.

Boats have forward and reverse, most planes do not. It strikes me that if you are taxiing up-river you have thrust to move forward and current to move backwards. Not so much bi-directional control coming down-river.

CapnMike wrote: Watching a good seaplane being inexorably torn apart under a bridge by even a slow-moving current would be a horrible sight.

Using the current to pin you to the dock on the upriver side will make docking a lot safer

You seem to contradict yourself there,Mike. I don't want to be pinned to anything by the current, which will want to pull the upstream float under...

To add one thing to MTV's post.

If you are going downstream, at the same speed over the bottom as upstream. The water flow around your water rudders is going to be speed over the water plus current while down stream over rudder speed is over the water MINUS current. This could mean you may have very little rudder control if you try to keep your relative speed to the dock constant between the two directions or if you are trying to turn in a constricted space.

Also docking upstream also means you will sometimes show up at the dock on the right side of the aircraft. which in my Maule is a real gymnastic event to get from pilot side to passenger side before I am pushed downstream.

Tidal currents are a real adventure.

Matt 7GCBC wrote:

CapnMike wrote: Watching a good seaplane being inexorably torn apart under a bridge by even a slow-moving current would be a horrible sight.

Using the current to pin you to the dock on the upriver side will make docking a lot safer

You seem to contradict yourself there,Mike. I don't want to be pinned to anything by the current, which will want to pull the upstream float under...

Hehe - like MTV said, it depends! A little bit of current is one thing. A little bit more current and I'd be looking for a ramp!

Thanks for the info guys

The bridge is just after the right bend.



With the prevailing winds I've been landing the 185F on 2970s towards the bridge, down stream and into the wind.

I still don't know what I want to do for the dock ramp situation, based on what you guys are saying, when I make that last turn in the bend to the right, I'll be dead slow. Luckily there isn't much of a current.