HopCar: I am half-way through the retrofit. Will let you know how it works out. I am keeping the engine-driven raw water
pump on standby, with capped hoses and belt ready to re-install, in case the elec pump fails. Easy to do this and provides redundancy (not immediate, but short time to implement). I have already installed the Aqualarm "Save Your Engine" raw water
capngeo: Thanks for the encouragement.
Cheechako: You would have to see my engine room to understand that retrofitting the existing raw water pump for easy belt adjustment and impeller servicing is not an option.
bzsmarina: I am using a Jabsco
50840-0012 electric pump with stainless steel
impeller and volute. I would prefer bronze, but can't find a 12V high flow/low head
pump in bronze. There will be no significant HP savings, as the electric pump efficiency is similar to the engine-mounted pump efficiency. In fact, I may be using more HP since the electric pump is constant flow rate, whereas the engine pump flow and HP vary in direct proportion to engine RPM
. Lower RPM
results in less pump HP.
I don't think this Jabsco pump would work for engines larger than 35 to 50 HP. Oberdorfer makes a 12V pump with higher flow and head rating, but would probably not be suitable for engines larger than 70 HP (Depco Pump Co. has it). There are probably larger capacity 12V pumps, but I have not found them. One could use 120V pump if boat had a suitable inverter
, but I would not trust reliability
of this approach.