I thought this was an interesting fact regarding Mercruiser ratio pairings....

San_Diego_SeaRay

Petty Officer 1st Class
Joined
Nov 9, 2014
Messages
337
I recently called Mercruiser Support to get some information about a used sterndrive I was going to buy. This is probably common knowledge to some people here but the customer service associate at Mercruiser told me.that Mercruiser does not choose engine/sterndrive combinations; that function is left up to the boat manufacturers. So, for instance, Sea Ray will test its new 27 foot boat with various combinations, and will decide which ones work best or most efficiently with that boat. So they might end up with a single 7.4 combined with a 2.20 Bravo 3. Or they might decide that the 7.4 is best matched w. a 2.00 Bravo. It's up to the manufacturer. Mercruiser doesn't have any input. I found it interesting as I always thought that it was Merc that decided the best combinations. That is all. :joyous:
 

Fun Times

Moderator
Staff member
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May 16, 2009
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8,776
Mercruiser doesn't have any input. I found it interesting as I always thought that it was Merc that decided the best combinations. That is all. :joyous:
Actually somewhere along the line they (Merc) does/did put in a general input as to say these gear ratios typically tend to work best with this engine size in general as Merc does a ton of water testing themselves plus they may mention depending on exact application of the boats size, weight and altitude above sea water, the drive unit may require different ratios too.

That mentioned, typically the boat manufacturer determines the best overall gear ratio to use while it becomes more depended upon the boat dealer to determine what the final gear ratio should be for where the boat is mostly going to be used at as far as elevation concerns whether the boat dealer orders a known special size drive unit that typically tends to work best in their area in higher elevations or opts to just change the gear ratio inside the drive at a later time at the boats owners request to help gain best overall performance and help with keeping the correct engine RPM ranges.

The above scenario goes the same for selecting the best overall boat propeller too.

https://www.seilermarine.com/info/me...atio-chart.php
 

SeaDooSam

Chief Petty Officer
Joined
Feb 15, 2016
Messages
575
It does actually make sense. Think of all the people Merc would need to hire to work on determining which engines and drives go on all the brands and models of boats!
 
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