Mud Motor

Well I need some expert advise. I did not get any reply on another thread, so I thought I might try one more on this site. Building a pontoon that I need to go into shallow water with weeds. I want either a hyd. drive or a straight shaft off a inboard motor. If I do a straight shaft, I am looking a building it with a reduction through a pulley system. The pulley or pulleys would attach to the engine shaft. the belt or belts would drop straight down through the floor of the pontoon and connect to another pulley or pulleys that would drive the shaft to the prop. My question is this. I was told that for every 10 hp., that I would need an extra set of pulleys and belts as for the slip that could happen going through weeds. Does this sound right, or would it make a difference on the size pulleys and belts? I want to run an engine around 50-80 hp. Any advise would be appreciated.

 

In weedy water the first thing to get bound up will be the belt drive down to the prop shaft...why do you think nobody does this ( well 1896 yes they did)

first thing to hit the bottom is the pulley .....and you carnt put 50 hp thrugh a 1/2 inch belt !!!!

why not fit an outboard at the back and a depth sounder at the front with the alarm ON..



Or why not one of those tail drives like you see in Tailand ..you can get them commercially or easy to make

 

Instead of a V-belt you could use a timing belt. These are made in sizes that can handle far more horsepowers than any V-belt and do not slip. The only disadvantage is that they require more precise alignment. Look at gates.com for details.

 

Thank you CDK.

I don't think Pin understood the question. The pulley will not be in the water, it will be on a bracket and the shaft attached to it running into the water. With a timing belt, would you have to worry about hurting the engine if you do hit rocks or stumps? I think you are saying that the timing belt will not slip. Or will it slip a little if you hit something hard. The idea of the belt is to protect the engine, prop, and shaft from shock.

 

No, the timing belt doesn't slip unless severely overloaded. If hitting rocks or stumps occurs regularly, a friction coupling is needed. If it is a rare event, you could use a spring loaded roller to supply belt pressure. The belt will jump over a few teeth when the maximum torque is exceeded, but there will be some minor visible damage.

 

If you are building a pontoon then it has two hulls...are you having two of these things ??? I had assumed one in the middle hence the under water drive...Toothed belt not a good idea ..if it hits a rock usually rips the belt and you loose teeth even if spring loaded....always look at how others solve the problem ..see what is tried and tested...put an outboard on the back and a sounder on the front ...then go into shallow drive mode when its shallow....or buy a jetski and put it between the pontoons at the back and push it along ...Seadoo did a great boat like this ..think its discontinued...

 

I was thinking of a v-belt because of the problem of wrecking the belt if it did slip. My question was was size belt is needed for a 50 to 100 hp engine if you use a v-belt type system?

Thanks for the input.

Mark

 

I think you should forget the effort to invent the wheel again. It has usually a good reason if such system is not customary. :?:
Have a look here:
http://www.schottel.de/eng/r_produkte/SPJ/uebersicht.htm
That works on a hankie with snot. (in weed too, if no hankie at hand).

Regards
Richard

 

you will be looking at multiple belts possibly 5 .....all to keep in tension equally ...forget it get the outboard !!!

 

Here is a drive for shallows and weeds.www.shareaproject.com/pages/projectTut,p,62,00.html

 

nice on tom ..I think what you are saying is that the motor if an outboard can move up and down vertically rather than "tilt" so as you slow and the hull sinks the drive can be raised above the bottom of the hull ...clever

Wish I had seen this before I glassed over the tunnel in the bottom of my jetski as the boot from a car drive shaft would have been easy to fit ..

Like I said get an outboard and a sounder and now add an electric jacking plate !!!

 

Many many small engines are available with reduction drives built right on. The ultimate in simplicity would be one of those with a straight shaft. Engine angle is sometimes an issue due to oil level and carburator, but that can be researched. Reversing is another question.

 

The trouble with using an outboard is that for the outboard to kick back or tilt,the power and forward thrust to the propeller has to stop.With the pivotal drive there is a cam like action when the drive hits bottom and this is a smooth action and the drive just drops back down in deeper water.there is no need to power off,the skeg lifts the drive automatically.Jack plates do not help in this way as the force is to great with power on.

 

One of many ways you can pivot an outboard to get a cam like smooth action,but you need to counter balance the weight of the outboard.www.boatdesign.net/forums/attachmen...5103-building-aluma-jet-pivoting-outboard.png

 

Pivotal drive for shallows and weeds or general fun, carefree boating would be difficult to match for cheap or sophisticated drive or surface drive.and you can build it yourself.