Roddie's flat-bottomed boat..

Levent Suberk wrote:Interesting design roddie  

Thanks Levent.. It's a prime candidate for the jet-pump.. but will have to see how the test tub/fixture works out first..

That is so smooth looking roddie.  Looks like you are building three variations.  Drift boat?  No Keel? I'm interested to see how it will turn out.  Power/sail/jet pump or one of each?  You have me guessing.

rsv1cox wrote:That is so smooth looking roddie.  Looks like you are building three variations.  Drift boat?  No Keel? I'm interested to see how it will turn out.  Power/sail/jet pump or one of each?  You have me guessing.

I only plan to build one. The .030" Polystyrene bottom wraps-around the front.. to form the top in one piece. I made a couple different shapes at the top end.. but am partial to the U-shape which provides more access up front.





I may try a pair of stationary rudders (fins) either side of the transom for some directional stability. The Cox .049 driven jet-pump is the plan here.. so there shouldn't be as much (if any) of the paddle-wheel effect that's found when using a surface-drive propeller. The little pump needs to mount to a flat floor that's also thin enough to sandwich between the intake port and grate. The test fixture that I built for the pump has the same polystyrene floor.








The sides being of 1/2" foam should provide enough buoyancy to keep the model afloat in case it takes-on water. Actually.. let's see just how much buoyancy the sides alone provide..  

I've got the pair of them placed under a cooling-rack in order to support a vessel for adding weight.



I used everything including the kitchen sink for this test...  



24.2 oz. is quite a bit of buoyancy.. and actually; the number is a little higher than that.. but the fixture is tricky to balance. As it was; the sponges were needed to act as baffles.

Roddie, Wouldn't you consider a stepped hull? The contact with the water surface will be a lot less and the boat will be flatter on the water.

OVERLORD wrote:Roddie, Wouldn't you consider a stepped hull? The contact with the water surface will be a lot less and the boat will be flatter on the water.

Hi Lieven, do you mean a stepped V-hull? My little RC Sprint Boat has a jet-pump drive and it does have a V-hull.. albeit a shallow Vee.

No, what I mean is a step in the flat bottom as on airplane floats.

OVERLORD wrote:No, what I mean is a step in the flat bottom as on airplane floats.

That's actually what I thought you meant.. but I don't think it will work with the jet-drive. As soon as the hull starts to rise.. the intake will start to suck air. If I ran a "surface-drive".. (exposed propeller) it would be a different story.

The boat remains a tail dragger and the stern will always stay in the water.

Spotted this ..



Mini bluebird boat with Cox tee Dee 010

Peter Maylor
65 views Nov 2, 2019
Mini scale blue bird built from scrap box as a ducted fan propulsion but needed a bit of extra
power so added IC .so when engine stops can bring back on edf.