Straight shaft in a BBY SC21?

[RPC1]

Is it possible to put a straight shaft in one? If so, what are the pros and cons of a set up like this? My plan is to put a 1/8 shaft with a 7.5* strut mounted to the bottom of the hull offset 1/8-1/4 to counter prop walk, and center the rudder. I think it will create a lot of bow lift, so CoG and prop choice will be very important. Any input would be greatly appreciated, Thanks.

[RPC1]

Anybody?

[Avanti]

I'm sure you can do it, but I believe, straight shafts are not as fast as flex shafts. Mainly due to the lack of adjustability. I have a scatcat21 here that I will be putting twins in, but that project is on the back burner as it will require a bit more extra cash than I have on hand right now.

[smm_cbf]

i have a sc 21 but i run a single shaft. if your looking for speed i don't think the boat will handle tons and tons of speed. im sure you can get 40-50 out of the thing on single motor. what motors you planning on? remember there is not alot of room, so lipos is a must.

[RPC1]

I was planning on a Scorpion outrunner 4400Kv on a A123 3s2p pack. It is a six pole motor and is rated at 500watts continuous. I hope the voltage drop of the A123 cells will bring the rpm down so that I can use a decent prop...not too small. If the motor doesn't work out, then I will buy a more appropriate one. This project is more about seeing if I can get this type of set up to work and have fun, not about every .1 mph.
Also, I have no idea what size prop this hull likes, any thoughts? Thanks for the response

[Simon.O.]

Straight shafts have one advantage over all others. Near zero resistance and therefore minimal transmission losses.
The important thing with staright shafts is to know where to put the prop, because once you have set your shaft adjustments are very limited.
There are others such as Ray, and Jeff who can shed more on this side of the game.
I have a sort-of-shovel hydro that began life with a straight shaft and then I went to a wire to get the adjustment options that I needed for R&D on air packing hulls.
long story there !!
Bottom line is: If you know, or can find out from some experienced user where the sweet spot is regarding prop placement for this hull then you can consider a solid shaft.
Here is my opinion.
Any non-V hull is ripe for the fitting of a wire drive due to lower running resistance and and better adjustment options over a solid shaft.
V hulls love wires too !!
I can qualify my findings from a LOT of Trial and error ( mostly error ) using solid shafts and now being a convert to wire drives. I make my own W-D's now.

Fire up a couple of pics of your boat and I am sure there are many people here that are keen to help. I am !!

[Jeff Wohlt]

Straight hardshafts are the most effic. of any drive made....using bearings in the tube. If you can get the angle you need then it is fine but I doubt you can in a cat. A little neg angle is fine but most likely it would be too much neg angle.

They work great in mono,hydros etc.

The nice thing is that an 1/8" hardhaft can handle all the power you can put to it.

Now if you decided to do the drives out the end of the sponsons then you could be good to go but sounds like you are not wanting twins.

[RPC1]

OK, so I have started work on this boat as a straight shaft. I will start a thread in boat building forum and post pics of the progress. Thanks again