Why not a shaft universal joint?

[hertfordnc]

I'm sure there is a good reason and I have no desire to re-engineer what works but the question has been bugging me;

Why is the shaft on most boats connected with a rigid coupling that has to be lined up perfectly straight rather than a universal or CV joint?

Of course, if this is an idea whose time has come and if 100 years of convention was just wrong, i plan to install a shaft with a universal joint coupled to a perpetual motion engine I've been working on.......

thanks

[celenoglu]

You do not need to use a rigid coupling. There are a lot of couplings whch work similiar to universal coupling with elastic material in between. This type of coupling allows some degrees of freedom and reduces the noise due to propellor or engine.

[deniseO30]

there is an outfit that makes a shaft coupling made up with UniVersal joints so engines can be mounted level. I'm sure someone on the site will remember the name.

[Maine Sail]

Originally Posted by deniseO30

there is an outfit that makes a shaft coupling made up with UniVersal joints so engines can be mounted level. I'm sure someone on the site will remember the name.

The Evolution Company in Rockland Maine..

Evolution Company (LINK)

[hertfordnc]

So there's is not some compelling reason for the rigid coupling?

I just figured that given the challenge of lining it up and the consequences of not having it lined up that there must be some reason why thios is the convention.

THanks

[WouldaShoulda]

Look how long it took to get dripless stuffing boxes!!

I'd think the engine would lube itself more effectively as well.

Mouting brackets, everything would work better (it seems) if made veritcle.

[tommays]

They do make them agua something.

The first thing i can think of is the lenth it takes on installs that are allready pretty cramed to fit under steps.

I guess if you have a bigger boat with the motor under the kitcken sink there might be more space.

If you really look at one and see all the extra support bearings required you might feel a bit different about it.



I dont know what happens on a sailboat BUT when the fail on a powerboat they do some pretty wicked dammage

[boatpoker]

Universal joints and thrust bearings have been around for decades. Two reasons you don't find them on most boats are 1.) Cost. 2.) Space.

[TomL]

...complicate
and your perpetual motion engine...who wants to hear an engine running 24/7?
KISS

[bubb2]

The reason you don't have universal joint on a boat is in most applications it is not needed. In a car your drive shaft is connected to a axle that is moving up and down constantly. Thats the flex the universal makes up for in a car which is not needed for a boat.