I have put a long shaft outboard on a short shaft transom (inflateable) and it worked ok. Since you are using a relatively small outboard, I don't think you will encounter the dire consequences suggested. The long shaft will slow you down, and you are more vulnerable to hitting bottom.
Your short shaft motor can also be sold as a long shaft with a Bay Kit. A long shaft motor can be sold as an extra long with a Bay Kit. Motors can be easily converted back to fit any customers need. Bay Kits come complete with all parts needed to make the conversion.
If you set the motor back far enough without jacking it up, a short shaft will work on a 20" transom.
1 : the long handle of a weapon, tool, or instrument the shaft of a spear the shaft of a golf club. 2 : one of two poles between which a horse is hitched to pull a wagon or carriage. 3 : an arrow or its narrow stem. 4 : a narrow beam of light. 5 : a long narrow part or structure especially when round the shaft of a
The shaft diameter is defined as the diameter of the hole in the iron laminations that contains the shaft, as indicated with the red arrow in Fig. 1 (and not as the actual diameter of the mechanical shaft, which can be much smaller).
Shaft is a common and important machine element. The shaft is generally acted upon by bending moment, torsion and axial force. Design of shaft primarily involves in determining stresses at critical point in the shaft that is arising due to aforementioned loading. Other two similar forms of a shaft are axle and spindle.
An outboard that is mounted too low will limit your boat's optimal operation. You can often tell that an outboard is too low if you are experiencing sluggish speeds, poor handling, excessive spray, porpoising, or even water pushing up into the cowling.
A boat rigger's rule of thumb is that the motor can be raised one inch for each eight to 10 inches of distance between the transom and prop.
If your boat has a Transom Height 15"-16" you will need short shaft and if it is 20"-21" you will require long shaft engine. Auxiliary engines for yachts usually require a long shaft engine so as to make sure the propeller remains well submerged when the boat is in a seaway.
For electric outboards, the shaft length is measured from the top of the clamp bracket to the center of the propeller. For gas outboards, it's measured from the top of the clamp bracket to the anti-ventilation plate.
Just because you change the way you use your boat doesn't necessarily mean that you need to change the length of your motor's drive shaft. Converting your long shaft outboard motor to a short drive shaft does, however, mean changing more than just the drive shaft.
