operating RPM for 4.3 merc inboard

[Curt Hal]

Hi All,
I am new to boating & I am now a proud owner of a 2002 searay 185 I have driven the boat for approx. 5 hrs this weekend, I have a few questions, there is a 19 pitch prop on the boat, I would estimate( the speedo vacume hose keeps comming unattached in the leg) that at 4800 rpm the boat will do about 45 miles ab hr. Does this sound about rite. The general use for the boat will be tubing, some water skiing & cruising ( I like to cruise fast). I was considering putting a 21 pitch on the boat, there seems to be no lack of power in the boat does this sound like a reasonable idea. Also what would be considered reasonable operating RPM in a boat like this. I was told that anywhere between 4500-5000 RPM should not be a problem with this boat. I would appreciate any advise that an experienced 185 sea ray owner may have. Thanks in advance

 

[ruf1967]

Re: operating RPM for 4.3 merc inboard

i have an '06 185 with the 4.3 merc and it is actually a fairly narrow rpm band 4400-4800. what is the drive ratio on your boat by the way and what altitude do you boat at? mine came propped from the factory with a 23 inch pitch and a 1.81 drive ratio but i changed to a 21 inch due to water sports. with the 23 pitch properly trimmed the engine would turn about 4700 rpm. once i changed to the 21 pitch i can no longer run full throttle because the pitch allows the engine rpm's to exceed the rev limiter but it works out better for pulling skiers, toys etc. so i just have to be mindful when i do take it up to 4800 rpm, which is rarely.

check out this link for a sea ray owners manual for your boat: http://owners.searay.com/owners_manuals.asp

 

[Curt Hal]

Re: operating RPM for 4.3 merc inboard

thanks so much for your info. I am not sure if my 2002 has a rev limiter. what RPM do you generally run the boat at the operating window. also my speedo vacum tube gets disconnect in the leg all the time should i just replace the entire tube. I have a 21 pitch prop the boat came with a 19 so I am looking forward to getting it on today. I will tell you how it worked.
Thanks Curt

 

[SpinnerBait_Nut]

Re: operating RPM for 4.3 merc inboard

Mercruiser/Volvo/OMC I/O and Inboard troubles and repairs.

 

[ruf1967]

Re: operating RPM for 4.3 merc inboard

3000rpm for best fuel economy for my boat. cruise speed at that rpm is about 28mph. from time to time i will run it about 3/4 throttle for a few minutes at a time.