Prop selection for 32" Mono

[dmanning]

I have a few questions about prop selection.

I currently have a 4mm threaded drive shaft and I am currently using a 2blade 48mm diameter 1.4 pitch carbon fibre prop
with a Feigao 9xl on 18 cells. This is in a 32inch mono hull. The boat is currently only running about 40mph.
I tried a 42mm 1.4pitch prop but it wasnt large enough to get the boat on plane.

I was wondering if buying a few more props with a higher pitch would get me a better speed increase.

I was thinking of getting the following from either OSE if they were mailing internationally or from this website

http://www.astecmodels.co.uk/products.php?posted=1&selection=props

g2305 - Graupner 47mm 1.6 pitch carbon fibre prop
g2327 - Graupner 42mm 1.6 pitch carbon fibre race prop
g2299 - Graupner 42mm 1.4 pitch carbon fibre 3 blade prop


Will the g2327 be to small to get the boat on plane?
will the g2299's 3rd blade help at all?
should I get a larger diamiter prop?
The other option is that i get the 4mm threaded shaft to drive dog adaptor and buy some expensive octura x646 prop, would this be a smarter buy?

[steveo]

not plane fast enough you mean, that seems like a good prop for that combo to start, what kind of temps are you running first

[RMZDADDY]

I don't know if this info will help, but I run a 32" Toysport Triton with a 12xl geared 1.33:1 on 24 cells, making about 30100 no load rpm at the prop. With an X642 octura the top speed was 43.7mph, with an M645 top speed has been 51.1mph. If my math is correct, you're turning around 40k no load at the prop, I can't say for sure if the M645 might be too much for the 9xl on 18 cells. I have had great results with the 1.6 octura props though.

[dmanning]

With the 42mm prop it will not plane at all, ie 6mph

With the 48mm prop Motor doesn't evan get warm with the water cooling, cool to the touch. Esc is warm and not evan close to its auto shut off temp. And thats at 40mph.

[NorthernBoater]

Are you sure you have it setup right. I am running the 9XL on 4s LiPos in a mono hull that size and the 42mm prop has no problem getting it on plane. Can you change your esc so it has more starting power.

[saleens7]

edit: i misread the post

[dmanning]

I dont think I can change my ESC its a Pulso 100Amp.
What you have to keep in mind is that 4mm threaded props have smaller blades for the same diameter due to the larger screw on size of the prop itself.

[astecme]

You definitely have something wrong here. Check your boat set up.

The 2305 is probably not suitable.

Allan

[dmanning]

You definitely have something wrong here. Check your boat set up.

The 2305 is probably not suitable.

Allan

What do you mean? what do you think is wrong?

LOL i though the g2305 would be the only one that would work

[astecme]

The boat should be doing 50 ish on the original set up - so I would guess your set up is wrong. Where is the C of G and have you a pic of the hardware set up?

Bigger prop does not automatically mean more speed.

[dmanning]

I can do better than a pic, i have the entire build including videos documented in a Thread at rcuniverse heres the link.

http://www.rcuniverse.com/forum/m_5951400/anchors_5951420/mpage_1/key_/anchor/tm.htm#5951420

The centre of gravity is 9 inches from the transom, so thats 28% of the boats length.

I also thought the boat is going slower than it should, I have been suspecting either the batteries or the props. Hence the original prop question.

Maybe the batteries simply cant provide enough amps.

[astecme]

OK -

1) you say the motor is a 9XL , 9XL what - it's not running the way I would expect that motor to run. Even with a 540XL17 you would go faster than that.

2) Your c of G is out it needs to be 30% to start with

4. Can't see where the prop is in relation to the bottom of the boat. the boss should run just on top of the water.

[dmanning]

Hahaha you are finicky arnt you.

Here are the finer details:-

The motor is a Feigao 540 9xl 1853kv Brushless Motor

The C of G being 28% instead of 30% makes no difference thats 2% thats 0.64 inches. I can move the Cof G forward 2 % by moving 1 battery 0.86 inches forward but I fail to see the point.

The prop is perfectly centred as a surface piercing prop, so the centre of its axis is 1.2 mm above the bottom of the boat, and it is mounted 79.3mm behind the transom. The drive shaft points downward at a slight 92.3% from the transom.

The batteries consist of three 6 cell packs of GP3300 all mounted in series.

So any ideas why its 10mph to slow?

[part time]

u said u had the pulso 100a controller right? i thought those were only rated for 16 cells. mabey the controller is limiting it self to prevent damage to its self.

[ReddyWatts]

Raise the prop.