Fresh water cooling question

[njsr2002]

I have a 2002 280 Sundancer with twin engines with alpha drives and fresh water cooling. Each engine has a thru hull with a sea water pump powered by the main engine. There is also the usual impeller-driven water pump in the alpha drive lower units. Do the water pumps in the alpha drives serve any purpose??
I can trace the flow from the main seawater pumps and it all makes sense. I tried researching a diagram that explains the role of pumps in the outdrives . Haven't found an answer yet. I replace all the impellers regularly.


Thanks

 

[SeaAyeOwe]

I am not sure if this is the same with alpha's as I have the same set up but with 2005 bravo III's with two raw water flow paths, one through the leg and one through the strainer. There are some boats where the leg side flow has been made inoperable but in my case the through hull and the leg flow are both still in place.
Until last week I was not 100% certain if the leg was blanked with the after market blanking plate conversion kit or not - but as I had it up on the hard I could tell that both raw water flows are in place (very important to know if you plan to change your raw water pump when in the water).
As it turns out - I decided to leave it that way, insurance if you like in case I lost the through hull for any reason when in water.