minimum engine size

[surf1]

I have a 1977 mako 20 and I know the max engine size is a 200, what is the minimum engine size that would still be efficient?

 

[matt167]

Re: minimum engine size

75% of Max rated is the general rule for Min outboard hp

 

[surf1]

Re: minimum engine size

So a 140 would be pushing it then. Thank you, that is very helpful

 

[jestor68]

Re: minimum engine size

What is the weight of the package? Older boats tend to magically gain weight. The more stuff you carry. the more power you need to operate "efficiently"( not laboring the motor). A motor not working as hard will last longer.

I have always leaned toward putting the max, or near the max power on any boat. That way, you're not as likely to be wanting more power later on.

I'm reminded of that old oil change commercial where the guy always said; "you can pay me now or pay me(more) later".

 

[jestor68]

Re: minimum engine size

So a 140 would be pushing it then. Thank you, that is very helpful

Since the boat weighed 1775(boat dry) when new, a 140 could be propped to push it just fine; just not as fast. Again it all depends upon what it weighs now. Boat length is not the only determining factor.

 

[smokeonthewater]

Re: minimum engine size

well... I have no direct experience with the mako but I have a wellcraft v20.. deep V wide flair center console... those boats were rated as high as 235 hp depending on the year and on them a 115 is the accepted minimum. My v-20 has a '76 merc 115 on it and planes almost instantly with a 15" pitch prop... I haven't done a top speed run yet but it will likely be mid 30's.

 

[jestor68]

Re: minimum engine size

Here's a case study. Mercury prop selector says that boat with a 135(V-6) spinning a 19" prop at 5000 rpm could do about 41 mph at 10% slip.

That's not too shabby.

In the end, the "accepted minimum performance" is a personal choice. Some are satisfied going 35-40 mph, while others are not.

 

[cyclops2]

Re: minimum engine size

Put 4 to 6 200# people in it & run against wind / current. You will like something close to 90 % or more of the maximum....

Hard to borrow a engine as people board the boat.

More boats & motors are sold because of engines being too small.