2002 Merc 5.0 carb motor Alpha I gen II outdrive 2400 SCR Maxum

[bajakar240]

I haven't been able to get back to the boat in the last couple of months ( kept at a local fresh water marina) but it seems the last couple of times out the boat would seem to take longer to get on plane than normal. Once it did it almost felt as if the prop was slipping. The rpms would increase but where the boat was normally doing in the high 20's it was barely keeping up on plane in the liw 20's. It would take several minutes but then it would seem to settle back to it's normal rpm vs normal speed. The boat had only been in the water for about at that time. Its possible there is a fouled bottom but I've doing this for a long time and it's not the loss of top end that would normally be associated with that.
I'm pulling it out for the season to double check the condition of the bottom but I don't think that's the issue. The thing that bothers me is the feeling of a slipping prop that later seems to finally " catch " and then run normally.

To update this entry. I did pull the boat out of the water and it's now at my house. The bottom had some slime but nothing out of the ordinary. ( It has a multi season ablative bottom paint)
The prop was secured as it should have been. Everything was tight. The only thing I found that was out of the ordinary was corrosion has begun to develop on the blades of my 3 blade prop. There was some bubbling of the paint and corrosion beginning to form near the edges of the prop
I have aluminum anodes as I am near the brackish water of the delta in California and magnesium seems to be too soft from past experience. The anodes were definitely showing some signs off electrolysis. But would the corrosion of the prop surfaces cause the type of performance issues I am describing here? The prop is about 5 years old and has not otherwise been damaged. This type of corrosion is a new one for me. Especially after only being in water for less than a year and a half.

[yahoo82]

How was the condition of the prop hub? I had similar experience one season and it turned out that it was a spun hub. It’s possible for them to degrade/wear out over time.


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[mmwjr]

In my experience even a small amount of marine growth will impact the hulls performance with slower time to plane and lower top speed. Since i don't know the waters you are in i would suspect either you are using the wrong anode or there is a stray current leak near your slip. You said the magnesium anodes are soft, does this mean they are expended in less than a season or last the entire season. the job of the anode is to be sacrificial so that your running gear corrosion is minimized so maybe you should be using the magnesium based on the water conditions. Does the marine have power on the pier and are you or one of your neighbors using it? If so one of you may have a stray current leak causing the corrosion.

[donald]

Where are you located makes a big difference in water quality, I once kept a boat at Tiki Lagoon and Whiskey Slough, and though not far apart they each had different problems as fare as corrosion and growth was concerned.
That was the reason I stopped keeping a boat in the water. I only trailer my boats now.
I have not had a boat there in many years but I doubt that it has changed much except for the lack of good fresh water flowing through the area with the draught and all.

Don