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Questions and answers about sports

What is the length of a short shaft outboard motor?

6 min read

Asked by: Michael Ceniceros

Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts.

How do I know if my outboard is short or long shaft?

The way that we do that is we take out just a standard tape measure or a yardstick you measure from the transom all the way down to the keel transom to the keel.

How long is a short shaft transom?

Shaft Length Recommendation

Transom Height Shaft Length
30 cm / 11.8 inches – 40 cm / 15.7 inches Extra Short*
40 cm / 15.7 inches – 50 cm / 19.7 inches Short
Higher than 50 cm / 19.7 inches Long

How do you measure a short shaft?

Measure from the bottom of your outboard’s engine compartment down to the bottom of the cavitation plate — the horizontal metal wing above the propeller. If the measurement lies between 19 and 21 inches, it’s a short shaft. If it’s about five inches longer than that, it’s a long shaft.

How do you measure the shaft length of an outboard boat?

And the rule of thumb is that you should keep the cavitation plate level with the bottom or keel of the boat. So you should just measure the height of the boat’s transom from the center down to the lowest point of the hull, and compare transom height with the outboard shaft length numbers.

How far below the bottom of the boat should the prop be?

If you have a short shaft motor, the top most part of the transom and the lower most part of the boat should be about 15 to 16 inches. For a long shaft, I think 20 to 21 inches is correct.

What size outboard do I need for a 15 foot boat?

15 – 25 hp (36kg-52kg)

This hp range is quite popular for use with inflatable boats 10-14ft, aluminium fishing boats 12-16ft, jon boats 12-16ft in length, fibreglass boats 12-16ft in length.

What happens if you put a long shaft motor on a short shaft boat?

Re: Longshaft motor on a short transom skiff? It will will *run* fine, but it can cause bad handling. Also trim position settings will have a greater effect. No harm to try it, carefully, and see how it goes.

How do you measure an outboard motor?

You multiply your boat length by the transom width. Then you take that number, which is known as the “factor,” and match it to a horsepower capacity according to the Code of Federal Regulations Table 183.53 — Outboard Boat Horsepower Capacity, shown below.

Can you turn a long shaft outboard into a short shaft?

If you change to a short drive shaft, you’ll need to change the other shaft that runs through the exhaust tunnel, as it will be too long as well — you’ll need to install a new, shorter shift rod.

What is a short shaft outboard?

Generally, short shaft outboards are 15 inches, long shaft outboards are 20 inches, and extra-long outboards are 25 inches. Since the length of the shaft of your outboard is associated with the size boat, smaller engines will generally have shorter shafts.

What is transom height?

The transom is the flat vertical section at the rear of the boat. It is where the outboard is mounted, and some boat owners place the name of the boat. The height of the transom is calculated by measuring from the bottom of the hull to the top of the transom, using the center line.

How high should my outboard motor be mounted?

Industry standards dictate that for short shaft engines the transom height should be 15″. A long shaft engine requires a height of 20″ and extra-long shaft engines will need a transom height of 25″.

What happens when outboard is mounted too high?

If it’s too high, the propeller tends to ventilate, losing its bite on the water and blowing out while turning and in steep seas. “If the prop consistently ventilates when heading down a steep wave, the outboard is probably set too high,” says Dean Corbisier, advertising and public relations manager for Suzuki Marine.

Should cavitation plate be underwater?

your cavitation plate should be right at the water level. As a rule of thumb it should be 1 inch above the hull for every 12 inches back. (if you have a eurotransom, or bracket or something.) If your cavitation plate is under water you might get better performance if you raise the motor.

Will raising my outboard stop Porpoising?

By changing the engine setback, propeller selection and motor height, you adjust the dynamic balance of the hull. All of these can have a great effect on the porpoising movement. By raising the prop shaft higher, you shift the Dynamic Configuration forward and further reduce the trim angle.

What is chine walk?

What is chine walking? The chine walking experience refers to the situation occurring with high performance vee-hulls as the boat accelerates, lift increases and the running surfaces raise out of the water.

What does Porpoising mean?

verb (used without object), por·poised, por·pois·ing. (of a speeding motorboat) to leap clear of the water after striking a wave. (of a torpedo) to appear above the surface of the water. to move forward with a rising and falling motion in the manner of a porpoise: The car has a tendency to porpoise when overloaded.

Why does the front of my boat go up?

Porpoising, or the bow bobbing up and dow, is caused by over-trimming at cruising speed; there’s no longer enough hull in the water to support the weight of the boat. Either trim down a little until the porpoising stops, or increase boat speed slightly to create more lifting force under the hull.

Should you leave your outboard up or down?

It’s best to tilt your outboard up when leaving your boat in the water to prevent marine growth from forming and from corrosion eating away at its metal parts.

How do you stop a boat Porpoising?

Start just a little bit bouncing up and down and it starts to develop a rhythm that gets worse and worse and worse the next thing you know you're really bouncing up and down.

At what speed does a boat plane?

You’ll typically get your outboard motorboat to plane above 15 – 20 knots. (depending on the type of boat, shape, weight, etc.)

How do I get my boat to plane faster?

Another thing about playing is your boats gonna be so much faster. And that has to do also with the surface area as well less surface area less drag. So your boat can actually hit it to top speed.

What pitch prop is best for speed?

The lower the prop pitch, the better your hole-shot. However, this comes at a price: top speed. The lower pitch makes the engine reach maximum rpm at slower speeds. Conversely, a higher pitch will deliver greater top speeds, but slower acceleration.

What cause a boat not plane out?

There are many reasons for a boat not planing efficiently. The most common are overloading and failure to distribute weight properly.

Why does my boat take forever to get on plane?

Here’s why a boat struggles to get on a plane or won’t plane at all. A boat won’t plane out either due to a bad propeller, improper motor placement on the transom, wrong trim position, uneven weight distribution in the boat, low engine performance.

How do you properly trim a boat?

Start out all the way. Down. Negative trim position put your boat in gear typically. Full throttle to get the boat up on plane. Bring it back to your cruising speed hold the button on the throttle.