Outdrive intakes in the Med

BruceK

BruceK

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Every year this time my boat starts to overheat. Every year it's because barnacles and critters just love to climb into the intake slits on the outdrive during June and July and slowly choke it by August. Not a marina issue as nothing can live in those waters but for estuary based boats its a yearly mid season chore. Now that I am on ali anodes and they are lasting longer I'd like to forgo having to beach the boat to clean the intakes. I believe Med growth can be quite bad but never heard of anyone else having quite this bad a problem. Are you? Is there any preventative measure that has proved successful?
 
You know the mufs you put on an out board to supply water when out of the water , would they cover the intake when not used .
 
seastoke said:
You know the mufs you put on an out board to supply water when out of the water , would they cover the intake when not used .
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Not a bad idea but I cant reach my outdrives under the swim platform or I could just as easily clean them from the tender. That put paid to a brief idea of putting the drives in those canvas garden waste bags too, in a combined effort to stop the props from constantly windmilling in the current.
 
You get a hard white / grey shell like deposit on the stern gear in the med a few mm deep .
It’s sunlight variable ,so if it’s shaded it’s limited .The sea is very salty and there’s not much in compared to the Atlantic or N sea .
So those fwd gill slits are pretty much ok for the summer .
Having said that remember it’s warmer 28 degrees and you are always in it .
Scraping props etc so it’s no bother to shove a knife up and give it a wiggle about anyhow .
 
BruceK said:
Every year this time my boat starts to overheat. Every year it's because barnacles and critters just love to climb into the intake slits on the outdrive during June and July and slowly choke it by August. Not a marina issue as nothing can live in those waters but for estuary based boats its a yearly mid season chore. Now that I am on ali anodes and they are lasting longer I'd like to forgo having to beach the boat to clean the intakes. I believe Med growth can be quite bad but never heard of anyone else having quite this bad a problem. Are you? Is there any preventative measure that has proved successful?
Click to expand...

I used to get blockages even in the uK so on my outdrive boats I fitted skin fittings for an additional inlet (per engine) and a Y connector.
On one I blanked the outdrive inlet and just used the skin fitting. Bad idea as the water flowing through the leg helps it’s cooling.
I fitted drive showers too after that. Keeps the leg cool if the leg inlet blocks.
 
BruceK said:
Drive showers? What are they?
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A bent pipe with holes in.

It’s u shaped, and goes over the top of drive and both the pipe ends face forwards just below the planing waterline.
The water is forced up and out of holes in the U literally showering the leg body.

Remember very little of the leg is in the water on the plane so it can get very hot.
I broke one by doing a crash stop after 100 miles on the plane - very hot in air to submerged in a second or so. Always had showers since then.
 
:encouragement:

Thank you. I did a little research on google and see they are popular after market add ons in America on Mercruiser legs. Nothing for Volvo that I can find but it cant be too hard to make one up. I have two skin fittings currently blanked for AC that has been removed that could come in handy as a bypass feed should they become necessary. What happens with the growth is it's all fine until it hits a critical mass. So there is no slow rise in temps to give you an indication. One weekend it's all normal, next you cant get on the plane without the alarm going off.

As for diving on the outdrives, not advisable in our fast flowing estuary with windmilling props, not advisable in our short chop outside the channel. All anchorage spots are a good 20nm away which on a overheating engine is a step too far. So unless it becomes a weekly chore to inspect it's easier to just beach the boat at low water.

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