JJ,
We've communicated several times on various projects: Jefa vs Garmin rudder sensor, Selden top down furler and general upgrades to our Visions.
In 2017, I debated a gen-set and honed in on Westerbeke and Northern Lights in the 6KW range. After the sticker shock of over $20K for the Westerbeke installed, I actually purchased a Honda 2200 and converted it to propane (tri-fuel) which cost around $1500. I also changed the propane locker around to fit two tanks with an auto switchover when one tank went dry. After all that I almost threw it overboard due to issues getting it on/off the boat and find a place to store it. So, I started looking at a genset again.
Then, my Father asked why I would "simply" not add a generator motor to the perfectly good diesel I had on board. After telling him everything I thought I knew about diesel generator from my extensive research, I started researching this concept and found a Mobile Power Systems (MEPS) genset, 6.5KW/7.5KW model. The unit is used in emergency vehicles and on marine response vessels. The system connects to the engine almost like a second, high capacity alternator except that it produces 230V/3PH power. I found one on eBay used for 25% of the quoted price from MEPS thinking that I had a 25% chance of getting it to work. I then went to work on designing the mounting for the generator motor on the engine, added a much larger pulley, determining a belt path, installing an auto transfer switch, rewiring shore power, mounting the controller box, adding a remote on switch (key switch) and mounting the power LED panel. After two designs for the brackets, two different ad-on pulleys, four different belts, rewiring shore power twice, rotating the impeller and rerouting the raw water lines I started the motor and it instantly worked. I new it worked with the auto transfer switch "clunked" over from shore power to the generator.
It produces 5.5KW at 900 RPM, 6KW at 1000RPM and 6.5KW at 1100RPM. The generator uses 1HP per 1KW, so at 900RPM which produces approximately 9-10HP, I'm loading the engine with 6HP, so around 60% which is actually a decent load. At 1800-2000RPM cruising speed, I engage the generator with the key switch, wired to the 12V panel, and feel and hear no difference with the engine whatsoever. On my Vision 46, I have two 30 amp shore sources, one which runs the forward AC with the rest of the boat, and the other which runs the main saloon and aft cabin AC only. Currently I have the genset switching the forward AC and the rest of the boat and I can run everything with no issues at 1000 RPM (hair dryer, shower, microwave, A/C, all lights, TV, stereo and more). I turned everything I had on, and did have to bump it from 900 RPM to 1000 RPM. But, I will never turn everything on like that so 900 RPM has worked (except for the hair dryer). Otherwise, idle runs the entire boat and charges the battery in half the time of the alternator.
My main reasons for not wanting a diesel genset: added weight, loss of storage, second engine (and maintenance), added complexity, added holes, extensive wiring, noisy pump, added exhaust and high cost. The MEPS added 40 lbs (versus 500 lbs), no loss of storage, no second engine, no maintenance, minor complexity but if it fails, no impact on any other system, no added holes, no added pumps, no exhaust and less than half the cost even with the multiple redesigns. The only downside is that if running the main engine more hours it will have more maintenance. But, we actually ran it less since the MEPS powered the batteries much faster, in 45 minutes versus 1.5 to 2 hours per day at anchor with the 80amp alternator. Plus, we cooled (or heated) the boat before turning off the engine and going to sleep. I added some photos and on one of them you will see the new rudder sensor.
So far, we are pleased with the unit and I was able to add it myself except for having the crank pulley removed for the new 8.25" diameter add-on pulley added. This is one of those project that if interested and wanted to do it, you should see it first. I have the drawings for a Volvo Penta D2-55F and Vision 46, but you would have to see if it fits your V42. It may be an exact fit.
There was several risks of failure: that it wouldn't physically fit, would not produce sufficient power at low RPMs and I simply could not get the belt aligned properly, but as soon as I aligned and tensioned the belt it worked with no issues. After 150-200 hours of run time and 60-80 hours of actually power generation I've had zero issues.
Sorry if I confiscated your threat, but I thought you and possibly others may be interested in this solution.
Stuart
