Why are marine alternators so darn $$$!

I'm shopping for a new alternator. Imagine my sticker shock.
35 amp, 55 amp, $500+ $$. Are ya'll kidding me? God help you if you have the nerve to want a high output unit. You will have to get a home mortgage..
I want to know WHY? Any manufactures I've researched seem to be shy about the quality of materials used. I'm suspicious that they are really not that far from automotive grade in type of materials used.
When I can buy a auto reman for $35 or a new for $75, it seems I am ahead to replace more often. Just how MUCH longer will a marine alternator outlast a auto grade? Hmmmm, divide $75 into $550 = 7. Auto grade will last 2yrs? So 7x2=14 yrs minimum.
I'm lucky in that my diesel doesn't require a special body type to mount.
.
Anyway, I wouldn't care if I paid double or even triple BUT I need some good reasons to pay 7 times the price. Why?
Thanks,

 

Greedy ********?

 

Yep!
I just read an article that indicated automotive alternators on diesels are fine, AS LONG AS, the only batteries charged by it is strictly a start battery. A auto alt will kill it's self trying to keep a bank of deep cycle batteries (house bank), charged up.
It's all in the difference between single regulated (auto) & double regulated (marine) outputs.
Since I only have the engine alternator hooked to start batteries, I can get by with an auto grade alternator.

 

All settled! Good to see I was NOT needed to supply further red herring directions. See Frosty's advice on a drinking binge for some of the noisier ones.

Seasonal salutations!

 

A lot depends on the manufacture and especially where you buy it.

If your engine is enclosed, then a marine alternator is a must. Otherwise a very loud boom will be heard after just a short amount of use (sparks in the alternator, setting the fuel vapors off). Don't laugh, it happens a lot and people get killed, burned and boats destroyed or heavily damaged. Also, automotive units will corrode up pretty fast, particularly in salt water.

Without one you will fail a survey and if your insurance company finds out, you'll be canceled until you change it. Don't even let the USCG see one installed.

What engine package are you employing? Some are a lot worse then others. An example would be an alternator for a late 90's Mercruiser 305/350 stern drive system, which runs about $200 at full retail (God people still pay that too). This is a new GM style one wire rig and a remanufactured would be around $100 (depending on pulley and output). The modular case Prestolite styles seem to be the worst around $400. So again, what's 'ya got in your boat? A Chrysler, Hitachi, Motorola/Prestolite, Mando, Delco (GM style) single or three wire or what?

 

it is a '84 volvo AQD40A (diesel). although enclosed, I'm not worried about diesel fumes. Doing the math, i seem to be able to replace an auto grade every 2 years to come up even on cost.
There is a saying, I was born at night, just not last night. 7 times the cost is NOT reflected in the quality of a Siearra alternator, nor a Volvo genuine parts alternator, or a Kelsey, or... etc. It seems they are all very close in price. Hmmmm?

 

I would'nt worry about it. I would be slightly concerened if I had an enclosed petrol engine.

My very expensive Yanmars which are actually Toyota 1HD engines have full open alternators, I can see into it!!!!!! almost through it.

This is supposed to be a full marine motor.

A little bit of common sense is needed here.

 

Who said any of the rabid five - or more?, - had a little common sense? and are needed too? (well yes, we provide light entertainment and pearls of wisdom befitting our aged-benefits-gold-card, excess time to spare rendering community services, etc..) Oops again, realised wrong thread, sorry boss.

 

I like it when people worry about my welfare & take no offense.
In the middle of the boat ramp, Waweep marina, Lake Powell, AZ. is a burned out hulk of what was someones pride & joy. I saw it for the 1st. time 22 yrs ago & have never forgotten what gasoline fumes can do. That is why I have a diesel now.
.
anyway, I just found this site.
http://www.amarket.com/mes3149M.htm
Not familiar with Mando, but it is more inline as far as price. $150. Thats resonable huh?

 

Interesting about the burnt out hull. Do you know of another and how do you know it was ignited by some electrical spark from within the engine compartment.

I have never ever seen a small recrational boat burnt out ,I know not of one single one or ever seen one.

In the 50s 60s and 70s unmodified petrol car engines in small runabouts were all we had.

 

you pay a premium for one little word - "marine".

The other day I went to a boatshop to buy some marine grade stainless steel bolts and got the shock of my life.
Went to my local bolt & nut dealer and got the same bolts in 316L SS more than 3 times cheaper

 

volvo AQD40A
LOL! That explains part of your high price problem. The swedes do a fair job of engineering but are mighty proud of the spare parts. A fisherman I know replaced a perfectly running volvo, he was damned if he'd give them $1500.00 for a starter. He'd come to the end of his patience and was willing to start all over again with a cat rather than let the volvo boys bend him over again.

I've got a volvoized chevy and next time I swap risers I'm getting rid of the swedish manifolds and replacing the whole shooting match. Same reason as my friend.

 

So will I .I am told by Yanmar to change the mixing elbow every 2 years . What for? its four years now and nothing is wrong with them.

And when I do I will not pay 1000 dollars either. Ille bloody well have one made up.

I would fit car alternator and not loose a wink of sleep over it.

 

The revolution has started, Who else is going to join this revolting band of merrier sailor men? Me for two!

 

.
I'm sure that when it happened, it was a big deal for the area. It looks to be a 16-18 foot runabout IO. Hard to tell, back end is shattered. BOOM! The marina acquired the remains, had a welder build a stand & put it on display where it gets the most attention. You cannot launch unless you go to one side or the other as you start down the huge ramp.
It has a professional lettered sign that says" I forgot to run my blower, BEFORE I started my engine". It's like a damn monument to stupidity. Every public marina launch ramp should have one. It DOES get your attention, just when it matters most. By having to dodge it every time we launched, we never got used to it being there, like you do a sign that sits off to the side.
.
I'm stuck with the Volvo guys, I'll have to work around that fact. There is more than 1 way to skin a cat.