Neptune mod, or late to the party.

[bigdave]

I found a deal on a used Neptune sub I could not pass up and decided to finally get one.
Like I said, late to the party as usual.
A lot of my friends have the sub and are quite happy with them.
Besides being a good beginner sub, they are a solid platform to base a build on or just for a knock around boat.
My plan is to hopefully some day wrap it in a different body.
(More on that later)
For now I want to just have some fun running her.
All my friends that have the sub decided to repaint the body a different color than the beautiful yellow it comes in.
Not naming names,
I have decided not to change the looks and concentrate on the guts. Or more specifically the motor.
The one problem I think the sub suffers from is power or lack of it.
The others have actually done a good job adding a larger prop to take more advantage of the high torque low RPM motor that it comes with.
A 1.5" prop and 6000 RPM do not move a sub with a profile of a rounded brick very well.
But in the subs defense a slow speed makes it better for beginners and the small prop is very fuel efficient as the stock battery is only 2200MA.
But hey not being known myself for slow watercraft I need more power. (Cue the evil laughter)
No comment Mr Pita.
I have attacked the power issue on two fronts.
First adding a fan type pump jet prop I had in my parts bin.
Second was adding a Venom 60 turn rock crawler motor in place of the stock 550 can motor.
Even though the motor is actually smaller in size than the stock motor the power output is much higher and the RPM is 12000.
The installation was basically plug and play too and was very easy.
Now doing this mod means my run time on a 2200 battery basically went in the crapper.
But not to fear I have also added a larger 5000 MA Lipo battery.
This also being done by most of my friends to increase there run times.

Now just because I have this extra power does not mean I have to use it.
Or does it.

[JWLaRue]

Re: Neptune mod, or late to the party.

BD,

Yea, I saw where you picked up that Neptune.

So now you're going to have baby Neptune and a daddy Neptune!

-Jeff

[salmon]

Re: Neptune mod, or late to the party.

I just picked up a fixer upper. It will need some TLC to get running. So, reading this is good because someday (once it is running), it will of course need modifications.
I am undoing some of the modifications that have been done to it (like removing the planetary gear reduction). One modification I hear that shows immediate improvement is a prop. What one do you recommend?

[bigdave]

Re: Neptune mod, or late to the party.

The prop is Raboesch.
174-07
This is the one the guys are using.
It needs to be modified to fit.
I will post the info on the modification. BD.

[Guest]

Re: Neptune mod, or late to the party.

I would look into the Kort nozzle props from prop shop-

http://prop-shop.co.uk/index.php?id=32& ... n=products

Simon will cast them in aluminium, silicone bronze (looks like brass but much tougher) or Stainless steel.

These are investment cast props, really very nice indeed.

I'd look at a three or four blade model, these have lots of blade area, so you don't need lots of blades. Go for the largest diameter that will fit in the shroud. The close the blades are to the inside of the shroud the better the efficiency.

Wouldn't be in too much of a rush to dispense with the gearbox.

[salmon]

Re: Neptune mod, or late to the party.

Thank you for the information on the props, I will check it out. Andy, the gear box was in a PVC pipe glued to the plexiglass, it was broken off at some point. So going back to original design first to trouble shoot any leakage and have a baseline for improvements.

[greg w]

Re: Neptune mod, or late to the party.

you said I can't comment but you know I'm gonna. Yours will be the first neptune to do a torque roll . Of course you have to "bump" the throttle once in a while to show it's got a hemi in it

[bigdave]

Re: Neptune mod, or late to the party.

Ha!
I am not sure a hemi would even be enough to make the sub torque roll.
It has about 4 pounds of weight hanging off a rod under the cylinder. BD.

[bigdave]

Re: Neptune mod, or late to the party.

174 07
45 MM 4mm shaft. 
Raboesch
The modification of the prop is the dunce cap has to be removed so there is no interference with the rear planes coupler.
Then the threads have to be removed by using a 4 mm or #21 drill bit.
As the stock prop uses a set screw.
Then a set screw has to be added to the prop.
Any Bubblehead should be able to do these mods but if not a modified prop was available from Loyalhanna dockyard last I knew.
I will check with D3 from Loyalhanna.
The larger 4 bladed prop makes a big difference in thrust. BD.

[crazy ivan]

Re: Neptune mod, or late to the party.

All my friends that have the sub decided to repaint the body a different color than the beautiful yellow it comes in.
Not naming names,
I have decided not to change the looks and concentrate on the guts.

What, you're not going to paint it?

I'm shocked.

[bigdave]

Re: Neptune mod, or late to the party.

You know I can't break tradition George.
Besides I do love yellow.
BTW Don at Loyalhanna Dockyard said he could supply the Neptune props modified or unmodified.
At one time Mikes Subworks was doing them as well.
Not sure if Mike still does.

[salmon]

Re: Neptune mod, or late to the party.

O.K. This is great info. Probably will modify a Raboesch prop. Hey if you guys are doing it, then it has been tested enough for me!

[bigdave]

Re: Neptune mod, or late to the party.

Everybody I know did the prop mod.
I will too if the pump jet fan does not work.
It actually goes fast enough for the planes to have an effect on the trim now with the larger prop.
It is so slow stock that they are useless. BD.

[JWLaRue]

Re: Neptune mod, or late to the party.

I agree...the TT stock prop is too small. However the TT optional prop provides more than enough speed to push the sub along nicely and to give the planes good control authority.

-Jeff

[bigdave]

Re: Neptune mod, or late to the party.

We tried it and although it is a bit better than the stock prop it does not hold a candle to the power of the Raboesch.
You should try that one Jeff.
As the old adage went.
"Try it, you'll like it" Ha.