Party Barge issue

[RaginCagin]

I have a 22 foot sun tracker party barge with a 150 mercury. With 2 people it always ran 38-40mph. about 1.5 months ago out the blue 31mph was all i could get out of it. The first mechanic did a complete tune up, nothing wrong with prop at all and he went run it. Still running 31 mph wide open at 5500 rpm which he said was the correct rpm. I bring to a second mechanic and he ran it and repeated the exact same thing as the first in that it runs fine and rpm's are where they should be. At a loss as to why i lost 9 mph over night.

[Walker]

Mph per a speedometer or gps??

[RaginCagin]

Mph per a speedometer or gps??

gps on depth finder and my son did it also from an app on his phone. I can tell a huge difference when pulling the kids on a tube. When I turn sharp it bogs down and take a little bit to recover. It didnt do that before.

[cj7zrcool]

Is your speedometer mechanical or GPS?

[Walker]

Trim position of motor??

[Quackerbox]

water in bilge?

[RaginCagin]

Trim position of motor??

Trimming the motor on the barge has never made much of a difference. at most makes 1mph difference.

[RaginCagin]

Is your speedometer mechanical or GPS?

I go by the gps on the depth finder.

[The BARn]

Added weight or top up? Water in the pontoons?

Wind/Water conditions different?
example: Our "Trancat" full tunnel, bay boat runs faster on "rippled" water than smooth.

just throwing these out there

[MacDaddy67]

prop bushing slipping slightly on the shaft.....have it rebuilt

or water trapped in hull...bilge

[RaginCagin]

Added weight or top up? Water in the pontoons?

Wind/Water conditions different?
example: Our "Trancat" full tunnel, bay boat runs faster on "rippled" water than smooth.

just throwing these out there

Top is up but was also up when it ran 40mph. Both mechanics checked for water in pontoons and said there was none.

[Texas Grown]

Check your pontoons for water. I spent a few years doing structural warranty repair. And there are certain places those logs develope cracks and leaks. And when they take on water, they will slow you down. Most folk don't notice till the deck is sitting really low in the water. There are baffling inside each log as well. If you shake the boat when it's on the trailer, you can sometimes hear the water inside, pending how much and where you are shaking it from.

The fish are biting and there's hogs to be kill-t. Gotta go!

[BrandonA]

prop bushing slipping slightly on the shaft.....have it rebuilt

or water trapped in hull...bilge

very good possibility

[RaginCagin]

prop bushing slipping slightly on the shaft.....have it rebuilt

or water trapped in hull...bilge

That was actually done about 3 months ago after my son sucked a ski rope into the prop.

Edited to say the sleeve was replaced.

[MacDaddy67]

That was actually done about 3 months ago after my son sucked a ski rope into the prop

and when did the issue start again?