Hi
Whats better about each type of floats and which one has better water performance (ie takeoff taxiing landing)

Flat bottom floats, like flat bottom boats, have a lot of lift on the water, but they ride hard and without a keel, they don't track well and are hard to steer.

V bottom floats, like V bottom boats, ride softer and track much better on take-off and landing. They also steer better in a crosswind. If the floats are sized right, the slightly lower lift of the V bottom is not a problem.

If you want to spend as little time as possible on the water, use flat bottoms. If you want the airplane to handle well on the water, use V bottoms.

Jim

Jim is exactly right, the flat bottoms plane out quicker, but can and will slip sidewise. I think you should consider the water you intend to fly off of. If it is usually smoothe, flat bottoms will be ok, but if is a bit choppy you will want the vee bottoms to cushion the shock of the waves............Seaplane

One other point to consider is that V bottom hulls and floats create a lot more spray than flat bottom one's do. I found this out the hard way with my V bottom twin engine seaplane. Big spray rails are required whereas flat bottom hulls don't need them.
Peter

Peter:

Spray is related to a lot of things, but primarily the angle and the sharpness of the edge between the bottom and sides of the floats. The edges should be as sharp as possible and the angle should be at least 90 degrees, the more the better. That's why the better V bottom floats have slanted or rounded sides and/or a reflex in the bottom along the edges ahead of the step.

You are correct that a flat bottom float with flat 90 degree sides will make less spray than an identically configured V bottom float.

A well designed V bottom like the Falcon Trading ARF float will make less spray than either of them.

Jim

ALso, V-bottom floats tend to give smoother landings. With flat-bottom floats, it's hard notto get a skip or two on landing.

I highly agree with all of the above posts.

I think that for the average trainer set up on floats, flat bottom is the best way to go. They take less time to construct and are great performers. For the more scale, and higher performance planes, "V" bottom just seems to be a better fit to the plane. This has been my experience, as I had a Kadet MKII on flat bottoms and a Cloud Dancer 60 on "V" bottoms. Both planes worked out great and were a blast to fly. My Sea Cruiser II is a flat hull, and I think the performance is fantastic. I have a bud that has a very nice home made "V" bottom flying boat that was built around a Aerostar wing. He's had a lot of difficulty getting it off the water. Both have their strong points and can be really fun in the right situation. Great question.

I guess I was looking for a scale-like performance and looks at the sacrifice of easy take offs and landings. This I knew from the beginning and I think I got what I was looking for. Once I am through the transition from taxi to take off every thing is fine. The problem is that the plane sits a little lower in the water than I had anticipated and for the first few moments the spray comes right over the nose and into the prop arc. It looks like a hive of bees around the engines until it gets up on the step. As soon as I gain a little speed the spray rails lift it out and every thing is fine.
It's amazing how much more power two 25's have than one 46 or 50. Power cures all.
You pays your money and you takes your chance.
Peter