Spetz

is a flex shaft just the same as a prop shaft but it flexes?

What benefit does it have? That the prop can be faced at different levels?

I need to get a longer prop shaft and wondering if I should look into a flex shaft?

Hydro Junkie

A flex shaft is a multiple wire cable that can be used in place of a hard shaft. It must be run inside of a tube, usually copper, to keep the cable from whipping and due to it's flexible nature, lets the strut and prop angles be changed easily. Depending on which boat you are dealing with, a flex cable can either be purchased ready to install or made to fit. I f you could let us know what boat this it for, we might be able to let you know what to expect

BB Modss

I think you were trying to say most stuffing tubes are made of brass.

Hydro Junkie

can we say oops? I was close

Spetz

It's a Kyosho bluestreak 800GP

And basically the rear is an outdrive setup where the prop turns with the rudder
Pic of this:
http://teamdiamond.co.kr/acecart/bin/photo/41901.jpg

And the U joint there gets warn out way too quick, like in a couple of hours of running or so.
So I want to put a different rudder on it, and get the prop to be stable and not turn with the rudder
But I need a longer prop shaft for this
And just wondering if I should go a flex shaft? and just leave the setup that is on now?

What kind of angle can a flex shaft take?

Hydro Junkie

if you plan on changing the shaft to a flex and leave the rest alone, it will just break the flex. In this case, either do or don't, don't go half way.

Spetz

Well I need to do something
I guess then the original plan of adding an aftermarket rudder system, and just getting the prop to come straight out of the hull
How do you think that'll be?
The only think I am worried about, is that now the prop sits 80mm behind the hull, as opposed to something like the 30mm or so it'll sit unless I use something like a stinger?

Spetz

Why is it copper/brass material?

My standard tube looks like it's alumnum. Would that be fine?

Hydro Junkie

brass is preferred because it's more resistant to corrosion while being soft enough for minor bends and hard enough to not wear out quickly. Aluminum tends to corrode very quickly by comparision

f16man

I notice the drive comes right out the transom on that boat whitch will make any strut adjustment impossible , you will need to angle engine and run the flex shaft tube thru the bottom of the hull,what you are doing is kinda reinventing the wheel on this boat but anything is possible I guess. The reason they put that sort of drive on the hull is manufactuing cost is much less than the way it should have been done,, they knew the ujoint would not hold up when they designed it.

Spetz

Well, can I just get a longer prop shaft and run the prop directly behind the "transom"?
I just need to get rid of the U joint as it comes in a bag of a lot of other stuff and really isn't worth the money to replace is all the time especially considering how quickly it wears out, not to mention how much quicker it'll wear out with a more powerfull engine

f16man

If you put the tube thru the bottom with a flex shaft you could use aquacraft hardware on the rear and have an adjustible strut and the hole deal, you could even run aquacraft .18 and pipe.

Spetz

hmmm...
I could.... my engine mount is adjustable as well as I can lean the engine forward/backward

What are the advantages of having the prop come out the bottom rather than the rear?

f16man

I just ment the tube under the hull , the prop and strut will be behind the boat, the tube is suspended thru the hull and into the leeding end of the strut. this makes for a easy adjustable set up.Anything would be better than what is on there now.

Spetz

Well, the way it is now, besides the wearing down issue it's pretty good
It's stable, and turns well into corners and has a tight turning circle
In fact, I'd expect it to become worse if anything?
I would like to keep the current setup but unfortunately I don't want to be replacing things each time I run it


I noticed that a Jetstream 800 from Kyosho has a similar setup but it has a universal joint instead of a U joint
I'm just wondering if I can implement that on my boat??

glennb2006

Spetz,

in all honesty, I think your best option would be to get rid of this entry level boat that you have now outgrown, and to buy something new that will really perform as you want it to. Upgrading motors and drives, and stern gear on RTR's such as this one really is not worth the effort financially or in man hours.
Just my opinion.

Glenn

goldendesign04

I will chime in here too,
Spetz for the the variety an frequency of your posts I can tell your itching to get your boat faster but on the other side of that coin you neither want to spend a lot of money nor do you have a large amount of time to devote to the project. Im only surmizing from your posts on here an others youve made stating you dont use often, dont want to dump a lot an so on.... firstly the parts to hop up this boat will be just costly (downer one) secondly you will need to devote countless man hours to modifying the boat to accept these changes (downer two) an finally will spend a vast assortment of time in the water trying to adjust with you newly made frankenstien trying to get it to run right (downer three). Now Ive called these downers an some may argue that thats all part of the fun an to me it is. But given the nature of some of your posts it shows you have a lot to learn, dont feel bad we all do at some point an hopefully we all learn daily but these things can leed to you biting off more than you can chew. So if your looking to play an as you stated the boat works well for you then by all means play. If you want more out of your boating expierance then look to a more advanced boat (that boats just an overgrown toy you have there) something that will challenge you but in the end reward you also.
Best of Luck
-Wayne

Spetz

Thanks guys for the advice
The main issue is that this boat was a birthday present from my brother and therefore holds strong sentimental value to the point that I don't want to "replace" it and have this sitting around
As the second point, I have no idea how often I'll be using a boat either. I am moving countries soon, and where I am going the closest water would be the beach
Thirdly though, I have "solved" the power issue by planning on running a 15CVRX (with marine heads on it) and then using a larger engine in my car, which I also wanted to do but could never justify it as the 15 in it now is very new and performs well. Just when I bought the OS engine, I didn't realise 18 would fit as well.

So, in reality I am left with 1 problem, that being what I stated above that the U joint wears out quickly.
The other posts asking about struts and rudders, was just trying to gather information about doing a whole rear end swap so the prop is stable and doesn't move.
Of course again, depending on how much use the boat gets, it might still be cheaper and more worth my time to just keep replacing that U joint. I have a spare one still, so I am assuming I should have a good few 10 or so hours before it really is time to do something about it. I guess by 10 hours though, I should have a better idea of how much I'll be using the boat


So this is why, I am trying to find a cheap and easy alternative to all this