Mercury 250 bluewater series

[JJEnner]

New to the boating world. I have a 2240 robalo with a 250 merc. Boat weighs 4900# fuel capacity of 140 gallons. I bought the boat for fishing. When running at 4000rpms the boats speed is only 20mph. Does this sound right? Should I be running it at 4000rpm or lower or higher? I need some help understanding engine concepts. Thanks.<br /><br />JJ jjenner@makitahead.com

 

[Navigator]

Re: Mercury 250 bluewater series

Long Island Ducks<br /><br />Is the 4000rpm at WOT? (Wide Open Throttle) or at 3/4 throttle cruising? <br /><br />A 250 Merc's sweet spot is between 5000 and 5800 rpm. If you're wide open and not getting there you may be "Over Propped". (Assuming the engine is running normally0 <br /><br />Over Propped means that the propeller pitch is too high and the engine is straining to reach its normal operating range. This is a bad thing and will result in early engine failure. <br /><br />We need to know several things to help you.<br />1) what is WOT RPM on your setup? <br />2) What is the pitch of your prop?<br /><br />If your WOT is in the range, and you're just cruising at partial throttle, then 20 mph may be all you'll get. It is a fairly heavy boat.<br /><br />Let us know.<br />Thanks,<br />Nav

 

[gunkas]

Re: Mercury 250 bluewater series

I have a 79 23ft SeaCraft, when they made them solid and heavy, 250 Merc with a 17 pitch prop x 14inch 3 blade Stilletto. I have 160 gallons of fuel, a huge live baitwell and have been known to load 2-3 coolers of ice and fish. My point is something is definitely wrong, I cruise at 5000rpm about 42-43mph, WOT is at 5700 and 50mph. I tried many different props with many different loads and thats the best for me. I agree with Mr. Navigator about the queries....Mark

 

[JJEnner]

Re: Mercury 250 bluewater series

Thanks guys. I happend to call mercury today and asked them the same questions. They also said try using a lower pitch prop. I love the boat in all other aspects. Will try and get the information to you guys. Also, the boat stays in the water all summer. Should I flush the engine everytime I go out or wait til I pull it in?