Help with props?

[Harold Duncan]

My cousin is running a 3.5 K&B on a Dumas Hot Shot Sprint. We've got the boat running good. Now we need a little advice on getting the right prop or props for it. Any advise we could get would be great.

 

[Robert Elder]

My cousin is running a 3.5 K&B on a Dumas Hot Shot Sprint. We've got the boat running good. Now we need a little advice on getting the right prop or props for it. Any advise we could get would be great.

I haven't been playing with mine for too long but the suggestions given to me so far are x437/3, x438, x440, x442 cut down, Prather 215 & Prather 220.

So far, I am finding the best result with the x440. I have a modified version on the way that should help it unload out of the corners better. I am finding that, unlike the FE experience, changing the prop means a whole bunch of testing to get the height and angle right for that prop. Start with the angle at 0 degrees and the center line of the prop shaft in line with the bottom of the sponsons. Keep raising the shaft a little at a time until the boat starts to porpoise and then fall back one step.

Good luck and have plenty of fuel

 

[Ed.R]

M440

Grim 40X53

Grim 40X52 3 blade

 

[Harold Duncan]

Thanks for the info. When you guys say "cut down" when talking about props. I take as; reducing the diameter. How much do you have it cut down, and who can you get to do it. Also the Grim 40x53 & 40x 52, are those Grimracer Props from Aquacraft? I've heard about the guys at props-4-U. Is there anyone else yall recommend for prop work.

 

[HTV Boats]

Harold your over engineering your needs here. Ed gave you the best list for you boat and motor setup. Hint, I know for a fact that the 2009 Internats winner in sport 20 had an Aquacraft Crimracer 40X53 prop that was out of the box, thinned and sharpened. Checked the balance and it was fine. On the boat and the rest is history. That and an M440 are the bread and butter must have props for a basic 21 tunnel. Mark Sholund at Props for U is great and resonable if your not comfortable working your own. He has worked most of my best props.

Mic

 

[Harold Duncan]

I'm not over engineering anything. I'm just trying to figure what yall are talking about, and some of the terms yall use. This is coming from someone who is new to R/C Boats and R/C's all together. However I'm not new to racing. I don't want make anyone mad or disrespect anyone. I'm tryig to get simple answer to complicated question that have alot of different answers. I also don't want to waste alot of money on stuff that just want work. Again thanks for the info it is a great help.

 

[Harold Duncan]

Are the octura x440 and the 1440 the same prop?

 

[engineman351]

Harold,

While the X440 and 1440 are the same diameter and pitch, they are not the same. The 'X' series props are 'non-lifting'. The blade shapes are different with the 'X' series looking more 'cleaver like', and the 'non-X' (or standard as some say) having a more rounded shape, especially at the tip. Octura developed the 'X' series for applications where you do not necessarily want to lift the rear of the hull out of the water...like a mono hull. On a hydro where you would want the hull just riding on the prop, the non-X props may work better. I like to get the dia/pitch in the range for a particular hull/engine combo, then try both X and non-X to see which performs better. RC

 

[TUNLBOTR]

Harold and William PM sent.

RP