Transom forces with a sterndrive

[Alumination]

The part of the transom where the sterndrive will mount will still be at the standard 12-14 degree lean back angle. The rest of the transom will be "reversed" or "rocket ship".

 

[gonzo]

I see. So it will be kind of a vee?

 

[Alumination]

I see. So it will be kind of a vee?

I'm not visualizing what you mean by a "vee".

A transom which looks like this but with a center section angled opposite.

 

[gonzo]

It's a vee sideways. You have the standard 14 degree so the transom shield works without modifications and the reverse transom for looks. It is a simple solution.

 

[DCockey]

Thanks for all the good info PAR and Barry.

As I typed the first post yesterday I didn't expect anyone to comment as soon as y'all did except I did expect Gonzo to respond with doom, gloom and disapproval, thanks buddy, we can always count on you!

What I had in mind was something like this which shows high and low pressure on a vehicle body at speed.

...only showing the forces on the stern of a boat, even if it was just a drawing and not an actual measurement.

The car analogy for your question is the forces the drive wheels exert on the car structure, not the aerodynamic forces which would correspond to the hydrodynamic forces on a boat's hull.

For engineering design purposes you will need to include the "steady state" forces originating from the propeller thust and other hydrodynamic forces on the submerged portion of the I/O unit, both going straight and turning, and the dynamic forces originating from the boats motion as it goes over waves, etc. If the boat will be trailered then the dynamic loads due to the motion when the trailer goes over a bump, etc need to considered.

 

[Alumination]

It's a vee sideways. You have the standard 14 degree so the transom shield works without modifications and the reverse transom for looks. It is a simple solution.

Exactly.
But since that transom won't be one continuous flat plane from gunwale to gunwale I am wondering how to best go about compensating and/or improving the design of the transom in the areas where it is most important and necessary.

Sure most boats have a similarly designed transom to which an outboard or sterndrive gets mounted, however the transom wasn't originally designed as the optimal way of doing this, the transom was already there as it encloses the stern of the boat. Also most typical transoms are beefed up on the inside, tied into the stringer system, floor, etc.

The car analogy for your question is the forces the drive wheels exert on the car structure, not the aerodynamic forces which would correspond to the hydrodynamic forces on a boat's hull.

For engineering design purposes you will need to include the "steady state" forces originating from the propeller thust and other hydrodynamic forces on the submerged portion of the I/O unit, both going straight and turning, and the dynamic forces originating from the boats motion as it goes over waves, etc. If the boat will be trailered then the dynamic loads due to the motion when the trailer goes over a bump, etc need to considered.

Have you ever seen a diagram showing how a sterndrive or outboard acts on a boat? How the power is transferred? What type and direction the forces are applied etc. ?