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Buizen 48 Sloop Fitting New Electromaax Alt and Serpentine Pulley

After deciding to try to trace the cause of an electrical leakage problem on my 20 yr old Buizen 48 – “Wavelength” and engaging a specialist marine electrician to conduct a thorough inspection and analysis of all on board electrical systems, it became apparent that a serious refit was in order in a number of key areas.

The main problem was identified which required a replacement of the bonding system and as I spoke more with these marine electrical specialists, we discussed adding a long desired extra house battery bank and doing a good “tidy up” of the existing systems.

Having been wired up over 20 years ago to a high standard of the time, it was obvious some areas needed re-working so a new battery and charging design was embarked upon.

Some of the old VSR’s (voltage sensing relays) were no longer working properly and I discovered that the engine alternator was only a 55 amp Hitachi unit which I thought was an 80Amp one ! As Wavelength is also fitted with a 6.5 KVA Onan genset and 70Amp battery charger, most battery charging was done using the genset or shore power and not the main engine – a Yanmar 4JHT –UTE 100HP model.

I started researching higher output alternators on the web and found Electromaax and sent of an email request.

I was more than pleased to receive a very prompt response from John Stevens, President of Electromaax and felt I had found a good supplier.

John was extremely good at responding to my detailed questions and even suggested a phone call to discuss the solution in greater detail. I liked this approach as I deal internationally in my business and prefer to be able to talk directly to suppliers, even if they are half a world away with an 18 hr time zone difference.

I sent John and his team various photos of my current setup and told them what I hoped to achieve. The existing setup had the one x 55A alternator and an engine driven fridge compressor both mounted to the port side of the Yanmar. Rather than just add 1 x 160 Amp Electromaax alternator in place of the 55A unit, I decided to install 2 alternators to have some redundancy in my charging system and also to better balance the “pull” on the crankshaft pulley and bearings. I would go for 2 x 120AMP Electromaax units. I already had a Balmar regulator installed so would use this on one unit and get a new external reg for the 120 Amp alternator for the STB side plus the custom built Electromaax bracket to bolt straight onto the engine.

John and Rob were very responsive to my emails and photos and they offered to send me various parts to test fit pulleys and belts for alignment etc before committing to all the hardware at once. Great supplier PR!

Its apparent there has been a lot of belt slip on both Alternator and compressor pulleys from the amount of black dust on the engine and around the engine compartment so it was timely to get a better system in place with much less chance of slipping. The serpentine belts would solve this problem for sure.

Fortunately the Buizen Pilothouse design allows great engine access from the saloon with a large sliding and hinged hatch in the saloon sole, as well as a front mounted hatch behind the 2 step companionway down to the galley.

I was able to remove both drive belts and swing the alternator and compressor out of

the way revealing more rubber dust. There sure had been a lot of belt slippage. No wonder I wasn’t seeing any great charge current even when underway and running the engine at 2600 RPM.


Of concern was the configuration of the extra pulley for the compressor drive and how it would mate back again onto the new aluminum serpentine sheaves supplied by Electromaax. We were sure we could work it out.

I planned to install the new dual pulleys in a back-to-back configuration as suggested by Electromaax per the sample image below emailed to me by John. NB: my 100HP engine has a 4-bolt pulley . Fitting the extra flange for the fridge compressor on top of this would be a challenge.



I first fitted the 2 new crank shaft pulleys which would take the port and STB alternator belts. I changed over the water pump pulley from the standard A section pulley to the new wider pulley –a straight bolt on. So far so good.

I then fitted the new 120AMP alt in place of the original alternator and had to make up a new spacer out of some tubing as the mounting lug on the engine block was not that wide and left a space of approx 40mm between the rear face and the rear lug of the alternator . I also needed to buy a new longer bolt to attach the alternator. Electromaax did supply a long bolt but I was not happy with its shaft diameter and opted for a larger, stronger bolt. With the alternator bolted in place with the lower pivot bolt, I then test fitted the serpentine belt and the supplied # 470 belt fitted OK.
I then went to use the existing top bracket to tension up he belt but the original Yanmar bracket hit the side of the larger alt housing and would not line up to allow a bolt to be inserted in the slot to line up with the holes on the alt body. I had a similar bracket for use with the 2nd alternator kit. Would it fit ? Sure did and allowed sufficient clearance to bolt onto the alternator and tension up the belt.


Alignment looked good so I was happy with this being a “bolt on” kit. The serpentine belt did run close to a cover plate on the front of the engine but there was around 3 mm clearance. As the belt needs to be tensioned tight, I hoped it wouldn’t rub on this plate during prolong engine operation. It didn’t rub but I found the water pump pulley to be sitting a few mm too far aft so had to space it out forward to provide precise belt alignment.

I then removed the alternator to test fit it to the new bracket on the STB side. The bracket bolted onto existing bolt holes around the secondary oil filler and felt pretty solid once all the supplied bolts were installed. I bolted the new alternator to the bracket but when I tried to test fit a belt, it was obviously sitting too far to the rear and the 2nd belt would not line up with the 2nd front pulley. I photographed this and emailed back to John and Rob at Electromaax for advice. The extra belts they had supplied were all to short and this was noted.


Electromaax responded suggesting a different (smaller diameter) front pulley on the crankshaft and also a different alternator pulley with extra spacers. Fedex promptly delivered and I changed over the front pulley and alternator pulley and this then looked pretty close to what was required for good alignment. I did suggest to Rob some fine adjustment to the alternator mount legs would be required and sent pics detailing what was required. Having satisfied myself I could correctly fit a 2nd alternator, I ordered the 120 AMP unit to be shipped plus a spare adjustment bracket since I had used the one supplied with the 2nd alt bracket kit in place of the original one on the Port side.

To be sure, Rob emailed me a pic of the modified alternator lugs mounted onto the same bracket to show me how he had succeeded to move the alternator about 12mm forward which, when combined with the 3 spacers and different alt. pulley, made it all line up.

He even figured out I needed to extend the lower adjustment /tension bracket forward as well and supplied a spacer the right length. But he did forget a longer bolt to compensate for the extra spacer. Lucky I had a good supply of longer bolts (note this for the amended bracket kit next time for the next customer).

Fedex delivered the 2nd Alt. and I wasted no time in bolting it on and everything aligned OK. I now had dual alternators fitted ready for my marine electrician to wire up to the entire new charging circuit we fitted including circuit breakers for both alternators and all other new battery circuits (sadly missing from the original build all those years ago).


The only remaining issue is how to get a third pulley mounted onto the front of the new dual cank pulleys so I can run the engine driven fridge compressor. This will require a rebuild of the compressor mounting plate and I fear I am constrained to using the old “A” section v-belt as I doubt I can get a serpentine type pulley to fit the compressor with its electric clutch arrangement.

But that’s another story for another time.

I cannot say enough about the service Electromaax provided from everyone including John, the President , Rob the Tech support manager and Brenda, the shipping/accounts lady. Its good old fashioned service like this that is so often missing these days in business. I already have, and will continue to recommended these guys to other sailors looking for a new charging solution on their yachts.

I have since done a few 5 hours runs under power in the yacht and the difference in charging batteries is fantastic. Everything is now running as it should and I now have the redundant systems I always wanted for peace-of-mind during extended cruising.

Regards to all at Electromaax and I hope you can use this story on your website.

By Phil Lack: owner “Wavelength” – Buizen 48 Sloop
SV Wavelength.