EPropulsion outboard-How to Find Your Shaft Length

1
How to Find Your Shaft Length

• If you are looking for an ePropulsion Electric
  Outboard Boat Motors, choosing the correct shaft
  length is important. If you go too long it would
  still work but it may lack performance. You will
  also risk hitting bottom or submerged objects
  more frequently such as rocks. If you go too
  short, that's the worst scenario as you're more
  than likely going to cavitate.
• Please note that ePropulsion has a different
  shaft length measurement from gas-powered
  outboards. 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.

As you can see, our XS is close to S from
Mercury. Our S is close to L from Mercury. Our L
is longer than L from Mercury. See below.
2
To find the suitable shaft length, the principle
is to make sure the top of the propeller is
matched to the lowest point of the transom with
at least an extra 10 cm (4") space to ensure good
water flow underneath the boat. Hard to put it
into practice? Well, in order to get the right
outboard shaft length, follow three easy steps
blow Step 1 Measure the transom height which
is the length from the top of the boat transom to
the bottom of the boat, as illustrated in the
image below
Step 2 After you get the transom height, add the
radius of the propeller (check the user manual,
and then technical drawing for the number) to
calculate the minimum shaft length needed to make
it work. Step 3 Add another 10 cm (4") to the
previous calculation for the final ideal shaft
length.
3
Let's take the Spirit 1.0 Evo Remote, radius of
whose propeller is 5.5" as shown in the technical
drawing, for an example. To match the 1964 16'
Starcraft aluminum boat with 21" transom height,
the shaft length is supposed to be calculated as
the following 21"5.5"4"-30.5"
So the long shaft outboard motor should be the
best choice according to the shaft options
available Spirit Series Products
4
Navy Series Products
To make things easy for you, here is a chart to
match the ePropulsion outboard shaft length with
the transom height directly for your quick
reference Shaft Length Recommendation

• This chart gives you a general idea of how to
  choose the outboard shaft length according to the
  transom height of your boat. To be more specific
• For most small dinghies and aluminum boats under
  15ft or 4.5m, extra short shaft or short will
  work depending on whether the transom height is
  over 40 cm / 15.7 inches or not.

5

• For boats with the transom height higher than 50
  cm / 19.7 inches, a long shaft version

• There are also extra tips if you are using
  daysailers, one-design racing sailboats, sport
  boats,and other sailing boats
• For daysailers and short one-design racing
  sailboats, the ideal outboard shaft length
  depends on the position of the outboard mount. If
  you choose Spirit 1.0, we suggest you keep the
  outboard mount at a lower position to make the XS
  shaft length work. That's because XS takes less
  space to store inside the cabin.
• For daysailers, sports boats and other sailing
  boats it's best to measure the distance from the
  water line to the top of your outboard mount.