Renault RC8D & Salt Water

Sep 12, 2016
1
Hunter H27 Cherubini MA
Hi, I'm a newbie to diesel and was "gifted" a Hunter H27. The boat's in good shape but it came with a Renault RC8D (that actually runs). I want to use the H27 on salt water but I was told that the RC8D uses fresh water cooling. Is there a way to convert it to salt water? If not, can the H27 be retrofitted to take an outboard? Or, does anyone have a properly rebuilt Yanmar 2GM that they'd like to part with?
 
May 24, 2004
7,179
CC 30 South Florida
That is somewhat strange as the RC8D are usually raw water cooled as opposed to having a closed cooling system with a heat exchanger usually utilizing an automotive type coolant solution. Perhaps someone told you that the engine was fresh water cooled as the boat was operated in a fresh water lake. The thing is that a raw water cooled engine will operate in whatever type of water it is on. It will suck water (salt or fresh) from the intake thru-hull and with an impeller driving the water pump it will circulate the water through the cooling passage in the engine joining the exhaust gases at the mixing elbow going to a muffler and existing through the discharge thru-hull. In the h27 the discharge port is above the water line. The rubber impellers are quite sensitive to being run dry (without water circulation) as it will likely destroy it. When you turn the engine on watch for a discharge flow at the stern of the boat, it will confirm if there is water flow. The h27 could require a 15 to 25 HP outboard and it would not work very well as the prop will cavitate in any type of swells. The Renault is a good engine and if it is working I would keep it. Finding Parts for the engine here in the US is a problem but there are some sources. In England, Germany and France many parts can be found . Repowering the h27 with a Yanmar 2GM has been done successfully but it can be a costly alternative. You would need to do further homework to determine the pros and cons of each option.
 
Nov 8, 2007
1,594
Hunter 27_75-84 Sandusky Harbor Marina, Ohio
Great, detailed response by Benny.

My summary - go ahead and run the Renault!

By the way, when our original SB-8 died, we repowered with a 1GM10 with great results.
 
Nov 8, 2007
1,594
Hunter 27_75-84 Sandusky Harbor Marina, Ohio
By the way, the h27 is a great cruising boat. We have logged 7,000 miles on ours in Lakes Erie and Huron. Mostly the Admiral and me, but we have cruised 6 weeks with 4 aboard.