1995 Twin 150 Ocean Pro RPMs?

[Just Pluggin Along]

I bought a used boat last fall with twin 1995 Evinrude 150 Ocean Pros. Had it out today for the third time this season (I'm in Maine). I was able to open her up and was only getting about 4200 RPMs and 41 MPH on my sounder. They are on a Wellcraft 238 Coastal which I was told was about 5k lbs. Just wondering if that is what I should be generating or could I be incorrectly propped?

Also, if any knows what makes the difference in the Ocean Pro line that would be helpful?

Lastly, I don't have a fuel management system so if anyone has a recommendation on efficient cruising speeds that would be very much appreciated.

JPA

 

[jay_merrill]

Re: 1995 Twin 150 Ocean Pro RPMs?

Can you talk to the previous owner and get a feel for what his experience with the boat was? WOT RPM of 4,200 is probably way to low for those motors, but sometimes people do unwise things - you never know, may have propped the boat that way on purpose.

Of course there is another possibility - namely that one of both engines need some attention. The fact that the engines were pushing the boat at 41 mph does make me wonder about that, though.

 

[Chris1956]

Re: 1995 Twin 150 Ocean Pro RPMs?

4200rpm giving 41MPH seems a bit low. My boats usually have about a 500 RPM difference. ie 3600RPM gives 31MPH. You might verify the tachs or the speed, using a GPS. I do not know how accurate your FF is.

 

[dingbat]

Re: 1995 Twin 150 Ocean Pro RPMs?

Your boat is very similar to mine. I?m running a single 200 Ocean Pro twisting a 4 blade, 14? x 17? Renegade Offshore prop. I?m running 40 mph @ 5300 rpm.

Sounds like you have the wrong props on the boat. Is this a new problem or something that has existed since you got the boat? Its quite common for a previous owner to keep a good set of props and replace them with whatever.

What size props are you running? Should be running something like 14? x 17? or 14? x 15?? Need to get those rpms in the mid-5K range.

 

[Just Pluggin Along]

Re: 1995 Twin 150 Ocean Pro RPMs?

I was on the boat today and unfortunately had my 2 young daughters and forgot to check the prop sizes. I know they are 3 blade SS and they were on the boat previously. I can speak to the previous owner as he is in the same marina and will try to do so this week. My survey last year verified that the FF was the same as the surveyors hand held GPS for speed readings but I guess that could have changed since September. The RPMs the day of the survey were 4600 at 39.5 kts. I will run it at WOT again this week just to make sure my initial run was accurate and get an update posted.

Thanks,

JPA

 

[Fl_Richard]

Re: 1995 Twin 150 Ocean Pro RPMs?

Welcome to iBoats JPA -

I have the identical boat - 1995 Wellcraft Coastal 238 with twin Johnson 150's.

Fully loaded and full of fuel (135 Gallons) my engines turn 5800 trimmed up and screaaamming and 44 knots GPS. I have stock OMC props 14.5 x 19 which should see a prop shop soon. Prop P/N 389924 and it's counter rotating match.

I also have the FloScan fuel management system on board. My best efficiency is at 3200 RPM burning 1.8 nMPG. At 3800 I get about 1.6 nMPG and at WOT I get 1.2 nMPG. So she likes fuel at all speeds

As far as I can tell the OceanPro line has a stainless steel steering tube and all stainless hardware over other models. There may be some additional subtle engineering differences I'm not aware of. I've had my boat for going on five years, theres not much bad I can say about the engines. There easy to diagnose and work on and they have power up the wazoo. My boat will literally jump on a plane in three seconds flat.

 

[Just Pluggin Along]

Re: 1995 Twin 150 Ocean Pro RPMs? "update"

Re: 1995 Twin 150 Ocean Pro RPMs? "update"

OK, I wasn't able to get a check on the RPMs today but I did get some other info that may help. When I ran it the other day the engines were all the way down and I had not trimmed them up at all. I spoke to the previous owner who told me to trim them up once on plane. He recalled being in the 5000-5500 RPM range once trimmed properly.
I was also able to read the prop size while almost falling in the water as the boat was bow first in my slip. They are 14.25x21+ 3 blade SS counter rotating.

Please let me know what you think as I will not be able to run them WOT to recheck the RPMs until maybe Sat/Sun.

Thanks,

JPA

 

[Fl_Richard]

Re: 1995 Twin 150 Ocean Pro RPMs? "update"

Re: 1995 Twin 150 Ocean Pro RPMs? "update"

The RPM's at WOT are whats important. If you can run it WOT and get 5500-5600 RPM out of it I'd say your good. Some like to see 5800 but 5500-5600 is close enough.

If it's lower your slightly over propped. This can cause lugging and serious engine damage (I know firsthand). I'll probably go up to a 14.5 x 20 when it's time for my new wheels. I figgure I'll drop a few RPMS and maybe pick up a little speed or economy...

Props are a science and I'm an artist

 

[Just Pluggin Along]

Re: 1995 Twin 150 Ocean Pro RPMs?

I finally was able to get out on the water with the right crew and conditions to test the WOT speed/RPMs with the engines properly trimmed. I got it up to 5100 RPMs and 44 knots.
Any additional thoughts? Is this ok? Suggestions?

Thanks,

JPA

 

[Just Pluggin Along]

Re: 1995 Twin 150 Ocean Pro RPMs?

 

[Fl_Richard]

Re: 1995 Twin 150 Ocean Pro RPMs?

Sounds a bit over propped. I still like the 14.5 x 20.

For me I'd drop a few RPMS you would go up a few hundred.

Wish you had a fuel computer installed. It would sure be nice to know your cruse economy.

I posted this question in the props section. They dont seem to think I could ever re-pay the prop investment with fuel savings. So for me when I neeed new props is when I'll make the jump.

Richard

 

[jonesg]

Re: 1995 Twin 150 Ocean Pro RPMs?

I finally was able to get out on the water with the right crew and conditions to test the WOT speed/RPMs with the engines properly trimmed. I got it up to 5100 RPMs and 44 knots.
Any additional thoughts? Is this ok? Suggestions?

Thanks,

JPA

maybe post a question in the prop forum,

you might be able to have the props reworked to turn up more rpms.