RPM'S normal but speed down 2 miles per hour.

[Mark B]

Boat ran perfect Friday night but yesterday noticed my hole shot was off a little and then at my normal running rpm's my speed was down about 2 miles per hour. Checked under boat and all looks normal. No noticeable difference in engine sounds. Any advise?

 

[Lazy Daze]

'Looks normal' - does that include the bottom is clean with NO growth? When you ran it Friday, did you also do a WOT test? Was the load in the boat (gas, stuff, people) exactly the same between Friday and yesterday? Is this 'speedo' speed or GPS? Where the conditions the same (including temp)?

 

[SCORPIO]

Aside from what was already mentioned, was there a wind or current difference?

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[Mark B]

No growth on bottom and all conditions were similar. Was able to run up to a little over 40 miles per hour easily. Normally at 3400 rpm's I am doing 28. Yesterday 26 and I could tell something just wasn't right.

 

[Lazy Daze]

Keep an eye on it. See what happens the next few times before you do anything major. Might just be time for a tune-up. Pull your fuel filters out and check for water. You checked the props, too? No dings or foreign material wrapped around them? Can both engines achieve the same MAX RPM?

 

[OldSkool]

2 MPH is not much and could be caused by, barometric PSI, wind/current conditions, humidity and the like. It's why racers carry a full array of weather measuring equipment with them. A small change can make the difference in winning or losing by mili-seconds. If speed drops off by 5 MPH or more then real concern about the boat/motor/drive is warranted. Just my opinion but east coast has been under some weather watch these last few weeks.

 

[Chief Alen]

Hidden water in the hull ?

 

[fwebster]

The speed differential occurred between Friday and Saturday….i.e. less than 24 hours. I'm voting on a piece of trash caught on an outdrive or wrapped between the props on one drive.

 

[Mark B]

Frank, I dove under and checked everything and all looked good. Not mechanically inclined but leaning towards fuel filters, water/fuel seperator filters, spark plugs etc.??

 

[pvan]

did you fill up the fuel tanks as you know weight is a big issue. Also water and or air temp increases can hinder performance as well. Any changes in oil pressure?