Water pickup drag testing

[Fluid]

The biggest problem with sponson-bottom pickups in hydros is that a SAW Hydro at speed really floats over the water, so the mechanism for water pickup doesn't exist for much of the run. The Germans and some Americans who run big cats often use a pump system as the boat rests between passes to cool things down. It works well for them, but the efficiency depends on a low water temperature. In Summer and Fall water temps are higher, meaning you can't cool things lower than the pond temperature.

In recent years hydro record holders super-cool the motor and ESC buy pumping ice water through the cooling lines prior to the run. This drops the starting temps below 40*F; by the end of a couple passes the temps are lower than if conventional cooling was used. Plus the starting temps are lower so motor and ESC efficiencies are higher. But it does limit most boats to just two passes.

Bottom line, there are miltiple ways to get there. Just like most things FE.



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[kfxguy]

On top speed record boat some guys use a strange cooling system, some time i read "high pressure" cooling system or air/water cooling...
No more info on the web, but tubes are so small...
Some pic there:

http://www.hpr-powerboats.com/sale/

What do you know about that?

See post #11

That's probably what your talking about. It pulls the water out as it's being sucked up. I kinda dropped the ball on this after doing the hull pickup test and seeing literally no mph difference in having pickups and not having them. I will still test the rudder pickup when I finish the test boat for that. May be a couple months However. Doing a prop wash test is not something I'm planning anymore because the in hull pickups were so efficient.

[TRUCKPULL]

On top speed record boat some guys use a strange cooling system, some time i read "high pressure" cooling system or air/water cooling...
No more info on the web, but tubes are so small...
Some pic there:

http://www.hpr-powerboats.com/sale/

What do you know about that?

Francesco - The first boat has no water cooling installed, it does have intake ports in the sponsons.
The second boat- Air cooling (every motor has that to some point, some large motors also have fans in them)
This boat also has a 12V water pump in it, with the intakes in the sponsons.

Larry

[banixj]

On top speed record boat some guys use a strange cooling system, some time i read "high pressure" cooling system or air/water cooling...
No more info on the web, but tubes are so small...
Some pic there:

http://www.hpr-powerboats.com/sale/

What do you know about that?

[martin]

The advantage of no water pick up in the rudder is a thinner rudder or better still a knife blade rudder producing much less drag.

[kfxguy]

Well I was working on having a couple rudders made (just like the one on the Rivercat) but with no pickup so I could test that also. Sounds like water pickups in the rudder or the hull add no drag. Interesting.

[jim82]

Late time to answer but it is a rudder supply

[kfxguy]

I tested my mini sprint today with and without water cooling saw no difference in speed.

Awesome! What kind of pickup dioes it have?

[jim82]

I'm one of those kind of people that like to find out things first hand rather than believe everything I read. There's many things I've read and tested for myself to find out what I read simply wasn't true or entirely accurate. So in the quest for more speed I decided to test different water pickup types on a couple different boats I have. One will be my zelos and the other will be my Rivercat. I'm not starting the testing until this weekend as I'd like some feedback on what you guys think and if you think what I have planned will be accurate enough. First one in testing is my zelos with bottom pickups. What I plan is getting a baseline run. One nice long full pass. Then I'll use some ultra thin packing tape to block off the pickups and make another pass. That should tell me the difference don't you think?

Next my Rivercat. Baseline with a rudder pickup. Then block it off. Then I'll try a prop wash pickup. I devised a setup last night that will allow me to add one quickly so I can do it at the lake for more accurate results. What do you guys think?

I tested my mini sprint today with and without water cooling saw no difference in speed.

[kfxguy]

Travis, is the smaller pump actually considered an "air" pump?

I'm not sure.....it pumps water well tho.

[kfxguy]

kfxguy: How are those pumps working out for you? Didn't you find a good small diagrahm pump?

The smaller pump actually works the best. I haven't got around to putting it in the boat just yet.

[T.S.Davis]

Travis, is the smaller pump actually considered an "air" pump?

[dmitry100]

kfxguy: How are those pumps working out for you? Didn't you find a good small diagrahm pump?

[Hotrods]

Has anyone ever tested the small aluminum bilge pump from Kinetic Racing?
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[kfxguy]

Yes if it's just a straight hole. The zelos came with pickups that hung out the hull. I thought they would cause some drag but they didn't. Plus I didn't want them snagging anything so I made them flush.