RPM loss

[Bill G.]

Not sure where to look 1st I was out of commission for 2 weeks after almost chopping a finger off ran the boat Labor Day weekend and lost about 300-400 rpm's off the top end can't get them past 4k and my cruise at 3k rpm's dropped about 1-2 knots.I was thinking the bottom had gotten some growth and ran it Sunday but got the same results.The engines(230 Mercs) have some hours (1500) on them but did run fine at idle and pushing the throttles up no back fire or hesitiation could both go bad at the same time?.The only recent repair was an oil pressure gauge on the port side.Any suggestion would be greatly appreciated...TXS Bill G

[Kevin]

Bill,
If your speed is down at your cruise rpm and you can't reach wot rpm on both motors I suspect your own assessment of bottom growth is the culprit. Once the grass, worm coral or barnacles get bad enough you have to mechanically remove them. No amount of using the boat will remove it.

[Bill G.]

Thanks Kevin,the other thing I thought about was fuel maybe filters/separators.Is there something from the tank that may be cutting fuel flow?

[Kevin]

Bill,
Can't hurt to check the filters. Ethanol fuel as far as tank issues but your symptoms described sound like end of season shag on the bottom. Start with the simple stuff. Grab a mask and take a look under her skirt.

[Tony Meola]

Bill

Kevin is probably right. How long did she sit idle. I had one summer she sat up here in NJ for about 3 weeks, went to use her and had trouble getting her up and running. Could not hit cruising speed at normal RPM's. Had to pull her and an hour later after cleaning off the props we were good to go.

[Tooeez]

It does not take much to cause what you describe--I had the same condition caused by just a heavy coat of slime. I wiped the bottom off with a rag and was back where I belonged.

[Bill G.]

Thanks for the input guys always good stuff looks like I need to go for a swim.