Prop Strut Depth

[FloatDaBoat]

I’ve just received the Octura .130 cable system with 3/16" shaft stepped down to 1/8", & three 1/8” props (X432, X435, X632) I ordered from OSE. Is it fair to surmise that I’ll need to lower my initial drive strut depth a mite from where I’ve been running it on larger diameter 3/16” props (X637, Grim Racer 42X55)? I also have an X438 & an X440 that haven’t been tested yet.

The boat’s a 30” cat running a 3,000 KV Novak HVPro powered with NiMH batteries supplying 16.8 volts.

Seems like a logical conclusion, even though testing will tell the final tale. Anyone have any thoughts in this area?

[Fluid]

Wow, it would have been better and probably cheaper to have bought a new motor instead of the flex shaft and the new props. Those small props will not be very efficient on that large hull.....

Not knowing where your strut is set now nor how well it ran with the current setting - no one can really answer your question. But in theory, you might need to drop the strut 1/16" to 3/16".

Where in Texas are you?

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[Jeff Wohlt]

Also, you are asking alot from a small prop to push that big hull. 3000 KV and 16.8 is not what you want to push a big hull. Once on plane it may be ok but the rpm will be crazy. Either you are going to cook that small cable or burn the teflon. You can try hand launching it (give it a throw in the water and punch it)

You reall need lower KV motor and bigger props. My 29" Mean Machine runs a 9xl and pushes a m545 on 4S. No issues with heat to speak of.

And the more you lower that strut the more amps you will draw. Mine usually start where the hull is on a flat surface and the strut is also level and equal to the hull and flat surface.

[FloatDaBoat]

Fluid: Thanks for the reply.

The Novak HVPro System is sensored, & according to Novak’s documentation, the ESC won’t operate with a sensor-less motor. If I had access to some schematics, it might be possible to jumper some pins on the sensor wiring harness in order to make it work.

I’m in El Paso "Farthest West", Texas - - Only one LAKE to run an FE Boat; we’ve got endless stretches of BEACH !!!

Jeff: Thank you.

It never crossed my senile mind that I might encounter cable problems due to the increased RPMs of the smaller props. The design of the strut I fabricated allows me to inject lubricant (2 parts O’Reilly Oil Treatment mixed with 1 part Marvel Mystery Oil) directly into the strut/stuffing tube just ahead of the prop shaft - - that may allow me to prevent something from burnin’-up. "Myrtle, Grease-Up DaCat"!!! Guess my initial effort will be with the X632. If DaBoat has a problem getting on plane because of excessive cavitation, I’ll cease & desist.

I really haven’t progressed past the set-up phase on DaBoat since I snapped a 1/16" piano drive wire during early testing, & I have no clue as to what kind of performance I’ve achieved so far (no GPS or data logger).

I’m hard headed enough to try & give it a shot, anyway. It’ll probably be a while before I have any results.

I might have to end-up saving my shekels in order to purchase a new ESC/Motor Combo. Oh, well….

[norbique]

Jumpering the sensor pins won't help you. There are 3 hall-effect sensors inside your motor, each positioned so to conduct when a given phase is active inside the motor (current running through it). So they switch on and off rapidly and this is analyzed by the ESC to synchronize the switching. With no sensor signals the sensored ESC won't do anything.

[FloatDaBoat]

Thanks Norbique - - Was just wishful thinking on my part for a cheaper alternative.

[FloatDaBoat]

I took DaBoat down to the lake to test the new 1/8” prop shaft Assy utilizing the X632 prop. I lowered the strut so that the top of the prop hub was level with the pads on the sponson bottoms. I moved both 7 cell NiMH packs forward one inch, in anticipation of having a problem getting on plane. That wasn’t necessary, as it jumped-up on plane - - no problem. Due to the weigh forward configuration, the hull ran wet, not riding on the pads as it has in the past. Some big black storm clouds were moving in, so I quit without moving the COB rearwards. Guess I’ll BSP the X435 before my next session, but I really need a GPS to evaluate actual speeds.
Does anyone know of an inexpensive GPS that doesn’t cost $100.00 plus??? Until I hit the Lotto, I’ll remain on a very limited budget.

[wizard122]

Hi check this one out it the one I use one works great their where 3 used ones yesterday on Ebay but they are gone now this ones from REI http://www.rei.com/product/798002?cm...4-000423c27407

[FloatDaBoat]

Thanks for the info wizard. Guess I’ll have better luck locating an El Cheapo GPS if I include overstocks & used/refurbished units in my search. New is nice, but …