Dockside engine flushing with fresh water

An interesting part of Freya‘s history that I learned from the broker (and confirmed with some papers I found on board) is that she spent about 15 years on Lake Tahoe. In other words, she was sailed for about half her life in fresh water. After that, she stayed for several years on the Napa River where the water is also fresher than what you’d find on the coast. This had obvious benefits for the Volvo MD7A engine (still the original one), which is raw-water cooled: the build-up of salty deposits in the heat exchanger when sailing in seawater often leads to issues with overheating, and the eventual death (or costly rebuild) of the engine. Because of her time in freshwater Freya‘s engine is in much better condition than average: I want to keep it this way now that we moved her to seawater at Fortman Marina.

Based on numerous discussions on the Cape Dory forums (e.g. this one), as well as a recommendation from Darrel at Eskelund Marine, I installed a Y-valve after the raw water intake. In one position, the valve simply carries seawater to the engine. In the other, it is connected to a hose accessible from the locker in the cockpit. This hose can be put in a bucket filled with freshwater from the dock. After returning from a sail, I simply put the hose in the bucket and flip the valve to flush the engine with freshwater. I also occasionally add some Salt-Away to the bucket to remove salt deposits more aggressively. The system is simple to use and should hopefully extend the life of the engine significantly. While doing this, I took the opportunity to also add a strainer since there wasn’t any.

This project also led to a nasty surprise. During the survey, all the boat’s seacocks and valves were listed as being made of bronze, the best metal for underwater fittings. And indeed, most of the original bronze Spartan seacocks are still there. The engine’s intake valve looked newer though. When I installed the freshwater flushing system I had the opportunity to look at it more closely and found that it was stamped “CW617N”: it’s made of yellow brass! That’s heresy, given how easily that metal de-zincifies in seawater – I could have faced a bad incident like the infamous Random Harvest flooding, which led to unequivocal recommendations to avoid CW617N brass for any underwater use on a boat. I will replace the valve with a new bronze Spartan during a quick “hang in the slings” haul-out at Svendsen’s.