C30 23 HP diesel Airlock problem

[Uniscoot]

Hi-
We sail twice a week and when there is decent wind, we occaisionally heal the boat 20 degrees or more. On the return to the slip we start the motor but ususally loose the raw sea water pressure to the cooling system. The evidence of this is always a hot engine and no water being expelled trhough the transom opening at waterline. We have found that bleeding the impeller cavity is the remedy to the lack of raw sea water pressure. My question - is there something we can do to get back to sailing at 20+ degrees without having to bleed the impeller cavity?

[r.furborough]

Close your seacock for the engine cooling water after shutting down the engine and sailing. You may also have a worn cam and coverplate in your rawwater pump, also a worn impeller that is allowing the pump to loose prime.

[chucklesR]

20 degrees should not lift the intake out of the water IIRC. I don't own a C30 but spend a LOT of time sailing one with a friend (yes sailnet regulars, I do sail on monohulls once a week or so).
Closing the seacock might be the answer if that is the problem, but frankly I'd look at the impeller and possibly at doing a flush of your fresh water system. You might have a clog in your system, or since it's a C30 age unknown it might just be time to get all that gunk out (gunked up tubes can put too much back pressure on the system). Next look at exhaust system flow. Always look at simple fixes first - the boat was designed to sail at 20 degrees after all.