New Sea Ray owner performance questions

[jjthomas]

I recently purchased a 2004 Sea Ray 180 Sport that was not winterized and had a cracked block. I found a local parts dealer that had another 3.0 merc IO. I worked out a deal and had him do the swap. Now the boat runs great but the engine will not turn but 4k rpm's. I have a 21 pitch prop on it and the mechanic says that is all it will do with that prop and that I need a smaller prop. Now I never ran the boat with the old engine and all of my other boats have been outboard 2 cycle's. Im wondering if this sounds right and what I should expect. Also what should the top speed be on the boat. Again, the engine I have runs very smooth and cranks very easy. I was told it was a 2005 and only had 74hrs on it. Any info will be a great help. Thanks in advance.

 

[Mark RSA2AU]

Hey Mate

I have a '99 version of the same boat. My rpm at WOT is 4800 using a 4 blade 19 pitch. This is with all equipment and family on board. When I use my 17 pitch high5 I run 5200 rpm. I gave my 21" away as it is usless to me

 

[derekf]

http://www.mercurymarine.com/look_d...ection=mercruiserChecks&merc4cyl=13&mercV6=14

This link shows an engine test for the 3.0

My 5.0 runs @ 4,400 rpm max. Your 3.0 may be slightly over propped and that may drop your rpm's a few hundred.

Hopefully someone with a 3.0 can tell you what pitch prop they like best.

Here is a prop calculator that may help you as well.

http://www.rbbi.com/folders/prop/propcalc.htm

 

[dutchman]

The manual says WOT should be 4400-4800 rpm.
Your top speed should be around 40mph.
My 175 came with an OEM aluminum 14-1/2 x 19, 3 blade.
I'm at 3000ft and WOT is 4800rpm.

 

[jjthomas]

Thanks for the imput. I will put another prop on her and see what she does. The mechanic that did the engine swap has one I can borrow so cost to try is not an issue. I am also going to do a few mechanical tune up details and I will keep yall posted. Thanks again...