oily film on the hull at intake

[Daddio417]

All excited(!) to add the new bottom paint, being a good sailor, prewashing the hull to avoid pointing the finger at myself in the fall. I noticed an oily film on the hull about a foot square, around my raw water intake. Wiped it off and it appears to be a light film. Any thoughts on what this may be, no engine issues or oil spills in the bilge I can think of.

 

[Benny17441]

The only thing I can recommend at this time is to clean it, go ahead and paint your bottom and see if it reappears at next haul out. Since it is in the intake chances are you may have picked up a glob of oil near the water surface. Do you have any commercial shipping in your area?

 

[kloudie1]

Residue from lifting strap?

 

[Daddio417]

Thanks Benny, actually the haul out did occur at a different location and yes, there is a 10 fold increase in commercial shipping, some nasty stuff come to think of it.

 

[Daddio417]

very unlikely based on the pattern, but still possible

 

[Davidasailor26]

Residual antifreeze from winterizing the engine seeping back out the intake?

 

[Whatfiero1]

Residual antifreeze from winterizing the engine seeping back out the intake?

Actually it could be a sure sign your heat exchanger is mixing raw water and fresh and antifreeze leeking back down past pump (check that too) and out raw water intake

 

[Davidasailor26]

Actually it could be a sure sign your heat exchanger is mixing raw water and fresh and antifreeze leeking back down past pump (check that too) and out raw water intake

The heat exchanger should be downstream of the raw water pump. I'd think it's unlikely antifreeze from the closed loop could work its way all the way back to the inlet. I guess it doesn't hurt to check, but I'm not sure it would be my first guess.

 

[Ron20324]

Maybe seacock lube that drained out before the engine was started?