Changed to Prop Pitch, No Help

[Lastcall77]

I have a new (2009) Lund Rebel 1475 with a Mercury 25 HP 4 Stroke with Power Trim (also a 2009). I bought the boat brand new in December at a boat show in California. I brought it here to Colorado a month ago and put it on the lake for the first time. The lake is at 8000 feet elevation. The boat would not go over 6 knots, wide open. I called the dealer and they told me I needed to change the Prop pitch. It came with an 11 Pitch prop and they said I needed to come down to an 8 or 9 pitch (it's a 10" diameter prop). Also, when wide open I could only get 3000 RPM max... I just put on an 8 pitch prop and took it out today. It brought the RPM's up to 5000, but the boat speed, wide open only came up to about 8 knots... What am I missing? Could the trim be so far off that I can't get the boat to plane? The engine is running great, I just have no power.. The dealer is 1100 miles away and can't help very much... Thoughts???:

 

[steelespike]

Re: Changed to Prop Pitch, No Help

If my math is fairly accurate looks like about 8-10 mph @ 5,000 You need 6,000. .However if its not planing you may be missing 1,000 rpm that is over the hump.
Temporarily try careful removel of as much weight as possible move the gas tank to the bow, battery if any forward. If tiller steering get an extension tiller so you can sit forward.
Check the motor height.Antivent plate just above the prop should be about even with the bottom or a little higher.Check that the throttle opens all the way.
The efi may need to be recalibrated. Your a long way up.There must be a Merc dealer in the area that should know exactly what it needs.