What are advantages of having a sail boat with an outboard motor vs: having one with an inboard motor?

Question

Some larger sailboats are made using outboard motors. Is there any advantages to having an outboard motor attached to a 27' or larger sailboat over having one that contains an inboard motor? What abou fuel efficiency, etc.

Answer 1

Advantages are ease of maintenance and engine replacement.  Also, the engines can be swung out of the water when under sail eliminating the drag.   Fuel economy is probably about the same.

Answer 2

It all depends upon the displacement of your boat.  I prefer an outboard over an inboard due to the maintainance.  An outboard is easily removed for repairs where as an inboard is a major overhaul.  Inboards have thru the hull fittings and you always have to be careful not to sink the boat while working on an inboard motor.  Remember, the motor sits below the water line.  Get a leaky thru the hull valve fitting or a BUSTED  water line and boat floods fast.  And if you are a sailor, what the h**l do you need a motor for any way.  

Answer 3

inside motor is better because it does not   get jammed as easy

Answer 4

The only real advantage of an outboard is ease of replacement. Outboards don't have the same amount of torque as inboards, and are more likely to overspeed in heavy seas (due to the prop coming out of the water) and often can't recharge your onboard batteries. An inboard mostly negates the "advantage" of being able to twist the motor to vector the thrust because an inboard's prop sits in front of the rudder, allowing the inboard's prop wash to strike the rudder directly and allow easier turning (a boat with a fixed mount outboard cannot turn unless the boat is making headway).

Answer 5

Fuel efficiency should not be an issue. If you can afford a large sailboat, it is assumed you are relatively wealthy, so you can afford the fuel. Safety and reliability are the key issues with sailboat engines.

The advantage of an outboard is that they are cheaper and there are no potentially leaky hull penetrations, like those with an inboard which require a stuffing box. Many sailboats have sunk due to hull penetrations. The disadvantage is that in lumpy seas, outboards are more likely to become submerged and ruined. With boating, having your propulsion quit at an inopportune time can kill you.

Fuel volatility is a huge issue in boats. Gasoline is a bad boy, and many boats have exploded due to fumes. Diesel is far less likely to cause such a problem, but due to weight, there is no such thing as a diesel outboard.

If you analyze the auxiliary power of larger sailboats in service, you will notice a preponderance of inboard diesels. There is an experiential reason for this.

Answer 6

Steve gives a good answer.

Some other points to consider especially on a boat 27 foot or bigger

An outboard is designed to move a relatively light weight very fast.....like a 15 on a dinghy. A 15 on a heavy sailboat isn't going to be anywhere near as efficient as an inboard 15 hp diesel...........and I am going to assume there is NO consideration of putting an inboard GAS engine into your boat....

its very hard to mount an outboard on a transom of a boat that big....you have to mess around with the bracket endlessly to get it low enough so the engine is in the water but high enough so when you tilt the engine up it doesn't drag, especially on one tack or the other. It is then hard to easily reach the pull start cord and or the throttle/gearshift..

You HAVE to thru bolt the bracket otherwise the engine will leave you at a worst possible moment.

All that weight all the way aft....and I am assuming we're talking at least a15hp, and even worse if its a 4 stroke........will make the boat "hobby horse" or pitch fore and aft; if you are trying to motor sail somewhere or into a steep sea, the engine will alternatively be too deep in the water or running the prop in the air

Only advantage is you dont have a prop shaft to leak as you would with an inboard, save space down below and when the engine breaks you can take it to the mechanic.

Answer 7

You can remove the motor, for service or to shift weight.  The "systems" are self contained -- no shaft alignment, alternator connections, gear shift cables to run through the boat.  An outboard is easier to replace/upgrade.  On a small boat with an easy to reach outboard, you can sometimes turn the outboard to direct thrust sideways for slow speed maneuvering.  

Disadvantages: Transom hung outboards put the weight and thrust in the "wrong" place.  In some boats the prop will lift out of the water in waves.  Typically gasoline instead of diesel.  The one "system" that is often made part of the boat is the fuel tank and fuel lines.   All in all, I'm happy to have a small (9hp) diesel in my 33ft boat, even though I could have an outboard of the same or greater hp and less total weight.  

Answer 8

The first sailboat I owned was a 24' Kittiwake that had an outboard well, under a hatch at the back of the boat.  I had a 4 h.p. Evinrude and it worked well, but you couldn't easily get it in or out of the water. So, it was always causing drag.   When I went to the Helms 25, it had a outboard bracket on the stern and I used a Merc 7.5, this was ok but awkward to start and shift, and it wouldn't tilt high enough when sailing.  Then the 30 pearson I got had an atomic 4 which took a lot of care, but never missed a beat.  It was much easier to use.  So, based on experience, go with the inboard.  Unless your considering a Cat.