[C320-list] High Output Alternators

[Warren Updike]

Here are some things I think I learned doing my alternator upgrade.
My Perkins engine has a 3/8" pulley and belt. I understand most/all of the Yanmars have 1/2" belt. According to Balmar, about 100A alt is the max you should use on a 3/8" belt. Even so, I bought, on the advice of my engineer (thanks Jeff,) one that is 110A on the theory that a heaver alt will last longer if running with a lower output. Via the regulator, I limit the charging current to 80A. Fact is, even with the bank down to 50%, it hardly gets above 60A and that not for very long. This has worked very well. 

The Perkins has a mechanical raw pump, driven directly buy the engine (no belt.) If the same belt has to drive more than the alt, then that may affect the plan. 
There are kits available to replace the pulleys and belts with a (name escapes) wide belt with ribs that avoids the potential to slip. Not cheap, and space in front may be limited.

There is a tool from the old engine days used to tension the belt so the bolts could be tightened without loosening the belt. This tool fit between two of the pulleys and expanded to apply tension. May be hard to find but a good tool. (Don't forget to remove it before starting the engine. Done that a couple of times.) Belt should be tensioned so that the freedom of movement in towards the pulley is only about 1/2" on the longest run of the belt.

If I think of more, I'll post again.
Warren and Pattie Updike
1994 C320 "Warr de Mar" #62
Middle River, MD (Chesapeake Bay)



-----Original Message-----
From: Gerald Rouillard [mailto:pearson39b at yahoo.com] 
Sent: Thursday, November 22, 2018 11:59 PM
To: C320-list at catalina320.com
Subject: [C320-list] High Output Alternators

Now that I have access to some Catalina 320 focused experience, I want to solicit advice on a couple of issues that I've been wrestling since I bought it this past summer.  The first one is the alternator arrangement I inherited.

Wind Song is Westerbeke powered with a Powermax, 125 amp High Output Alternator.  It's driven  by a single belt, and that causes me some concern.  On a previously owned boat, I had upgraded my 30 HP Yanmar to a 125 amp alternator, and had to change back to the original 55 amp alternator when the single belt configuration failed to drive the alternator once we reached 1400 RPMs.  The belt would just start slipping and sloughing off belt material.

My mechanic advised me that the higher output alternator needed two belts to work well, and that's what causes my concern with this set up.  During the purchase survey this summer, we noted some looseness in the belt and some powdered belt debris in the engine compartment.  I replaced the belt with a Westerbeke part and tightened it up.  So far it seems to be working OK, but I'm wondering if anyone else has any problems with one of these high output units driven by a single belt.

Sailor Jerry
Wind Song, Hull #283
Shoal Draft, Wing Keel

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