When it comes to advice on buying an outboard motor everybody seems to have an opinion as to which is best and which to stay away from. The reality is that all outboard brands have a problem occasionally. Outboard Brands Available Evinrude Honda Mercury Suzuki Yamaha Outboard Configurations Available In Board Twin Rig
And most importantly:
One thing to make sure of is that the motors have been fitted to the manufacturer’s requirements, e.g. a minimum battery size is usually specified, and I have heard of claims being denied due to this. Outboard Horse Power Available From 30 HP To 300HP
Outboard Fuel Setups Available
It is a common misconception that Four Strokes (FS) use a lot less fuel than Two Strokes. They do use less than Carburetted Two Strokes (CTS), but not less than Direct Injection Two Strokes (DITS). Examples of DITS are Mercury Optimax, Evinrude E-Tec, and Yamaha HPDI. Despite various claims, in reality all motors are within a gnat’s whisker of each other for fuel consumption. What is far more critical is the set-up. Correct engine height, and the correct propeller for the hull and its application, have far more impact on fuel consumption than the brand of motor you choose.
One thing that may need more consideration is the weight of the motor for a given horsepower. I know some of our boat models trim much better when the weight on the transom is kept down. Again, a boat that has a lot of extra motor weight will probably use a lot more fuel regardless of what the sales brochure tells you. Boats with an engine pod are more susceptible to transom weight than when the motor is directly on the transom too. I’m not talking about a little bit of weight difference here. If you do your homework you’ll find engine blocks are shared over a horsepower range. Some motors will be high power for a small block (weight) while others can be lower power from a large block. 175hp is a good example - some share 135/150/175 block while others share 175/200/225 block. This can make for an engine weight difference of more than 20% in some cases.
This relates to the jump between CTS to DITS to FS. A salesperson will tell you it’s worth spending the extra money to go to the fuel efficient model they sell because it will pay for itself in fuel savings. But they likely have no idea of how much you even use your boat. So let’s look at that for a minute. Using current 90hp RRP, an assumption is that the CTS motor is using a tote tank an hour (25L) and DITS/ FS use roughly two thirds less (as an example). The average boatie’s engine run time per year is 15hrs (remember this is engine run time not boat being used time).
I have used a rate of $1.70 per litre for fuel for the calculations below.
CTS average RRP $12,000. CTS will use about 25 litres per hour. For 15 hours running time per year it will cost you $637.50.
25Litres/hour X $1.70 X 15hours = $637.50
DITS average RRP $17,000 and FS average RRP $19,200. They will use about 8.33 litres per hour. For 15 hours running time per year it will cost you $212.50.
8.33Litres/hour X $1.70 X 15hrs = $212.50 per year
Add to this that FS and DITS are dearer to service but the extra oil the CTS uses will probably even it out. Of course not everyone does 15hrs only a year, so let’s say you want to see a return in 5yrs. How much boating would you have to do?
CTS uses 25Litre/hour X $1.70= $42.5 per hour DITS and FS use 8.33litre/hour X $1.70= $14.16 per hour
CTS vs DITS = Save $5,000 over 5 years at a rate of $1,000 per year
The calculation is:
Saving per hour X hrs / yr used = $1,000
Thus…$42.5 - $14.16 X hrs/yr = $1000
Simplifies to $28.34 X hrs/yr = $1000
Thus, the number of hours per year to be even is:
$1000 / $28.34 = 35 hrs per year
CTS vs FS = Save $7,200 over 5 years at a rate of $1,440 per year.
Following the same logic as above the number of hours per year is:
$1440 / 28.34 = 51 hrs per year.
*That is the equivalent of taking the boat 1 hour from the ramp every other weekend of the year! Did that surprise anyone? I have written the examples out in full so you can try other examples yourself. So, fuel consumption is not the be all and end all of decision making of course.
No Two Stroke likes to idle along forever. A DITS will do it for a couple of full days of game fishing but if you do a lot, like 10-13 hours a day three or more times a week in season, then a Four Stroke is probably a better option. CTS do smoke a lot more than DITS and FS and on hardtop boats travelling along the venturi effect of the hardtop tends to suck the fumes into the cabin (which can make people sea sick).
FS are the quietest with some DITS not being too far behind. But the FS tend to be the heavier for any given horsepower, although the gaps are closing.
It’s only once a year (or three years in some cases) but you will still curse yourself if you have to drive two hours past your nearest dealer to get to the one that has to service your motor so the warranty stays valid.
The team at Marco Boats
The information contained on this webpage is a guide only, it is the opinion of the writer and some parts contained may not be factual, any facts or figures quoted were either made up or accurate at the time of writing. The information contained on this webpage is a guide only. It is the opinion of the writer. Some information is either used for illustrative purposes only or was accurate at the time of writing.