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Amarc

American Marc 10 - America's first Diesel Outboard Motor

I have a new favorite outboard: the Amarc 10! It was the first (and only) small horsepower diesel outboard built in the USA. It was manufactured by the American Marc Company in Inglewood California, based on the articles in boating magazines and data in my old Abos Guides, it was only available in 1960 and '61.

It is a 2-cycle diesel utilizing the Junkers/Fairbanks Morse opposed piston design where the pistons are aimed at each other and have two crankshafts. (See drawing below) It is water cooled, 21.5 cubic inch displacement, 9.25hp at 3500 RPM and was reported to burn 3/4 a gallon of #1 diesel oil per hour at full throttle. It also incorporates a "total loss" oiling system for many parts such as the top of the crankshafts and has a separate gearcase filled with hypoid oil under the powerhead to lubricate the various gears connecting the two crankshafts. There is a glow plug for frosty mornings and starting is by electric start only with no manual backup. (This also necessitates having a 12v car battery for the starter system) Various ads claim that the superior torque of the diesel makes this motor the equivalent of a 14hp outboard. All this goodness in a package that weighs in at a hefty 135lbs (estimated) - about the same as a Johnson 40hp from that era - and that doesn't include the battery!

Small diesel generators and other diesel equipment for the US military were American Marc's bread & butter, no doubt this outboard was an outgrowth of their military products. They also got into the boat manufacturing business for a brief period in the early 1960s - there is a great recap over on the Fiberglassics website about them.

That American Marc would dare to build a 9.25hp diesel outboard motor for consumers utilizing the Junkers/Fairbanks Morse opposed piston design can only be described as (in the words of the The Mamas and the Papas) California Dreaming! A 1960 article in Boating magazine indicated the factory was ramping up to produce 4,000 Amarc 10s per month, unless there is an Indiana Jones type government warehouse full of them, it does not appear that they got even 1/10 that number during the entire production.

Back in 1960-61 when the Amarc was made, engineers and product planers here in America took risks with unusual engineering and their products to try and build a better mousetrap. In today's world with Casper Milquetoast MBA's running things, no company would ever take a risk building such a product - and I feel our country is all the worse for that.... I often think that all of our great engineering achievements were made with slide rules: winning WWII, development of the atom bomb and atomic power, supersonic jets and even putting man on the moon! Today with all our computer power and connectivity, what really great thing have we humans done? The Amarc 10 is a small monument to America's greatness in the past....

If you have one of these motors or parts for them (or know of a parts source for them) I'd be interested in hearing from you!

1960-61 American Marc - Amarc 10, 9.25hp

1960-61 Amarc 10 - 9.25hp

Year & Model: 1960-61 Amarc 10
Horsepower: 9.25 @ 3,500 rpm
Cylinders:
1 - Pistons: 2
Bore: 2 5/8"
Stroke: 2" x 2
Starter: Electric
Glow Plug : Bosch
Injection Pump : Bosch
Cooling: Water by impeller
Condition: Unrestored
Retail price when new: $495.00
Weight: 135lbs (estimated)
Oil: #1 diesel fuel + separate oil tank SAE 30 non-detergent. Upper gear case 1 pint hypoid 90wt - lower gearcase 1/2 pint hypoid 90wt.

Comments:
It's not running yet but it's sure cool!

 

 

The Amarc diesel - the first diesel outboard

This is an early brochure (I think this was produced before the production details were finalized. Image of the motor is a rendering, not a photo - looks like a Mark 25 leg with a soda fountain top! Specifications mention it could be air or water cooled - production models are all water cooled. 7 1/5, 15 and 22hp models offered, only the 9 1/4hp was produced. And since the 9 1/4 is a beefy 135lbs, I think the 22hp would be a real back-breaker!)

Later Brochure

How The Amarc Works:

Here are a few additional photos:

Amarc Decal
Does anyone else think Star Fleet stole the Amarc logo?
Amarc front showing gearshift and key for starter and glow plug. Got the fuel tank with it. Looks to be the same as Clinton, Eska and even the small Mercury tanks.
Starboard view - oil tank (on right) holds about 1 pint of SAE 30 oil for the "total loss" oiling system.
Port view - injector in the middle of the block, note large starter motor on the right.
Pencil points to the upper gearcase (crank case) fill - use a pint of Hypoid 90 gear oil Drain is located on the bottom front of the powerhead- tilt the motor to drain it.
Another Amarc owner I've spoken with indicated his motor didn't have the typical lower unit drain & fill on the gearcase that this motor has.
No beauty from this angle either....

 

12/15 Update - bad news, 3 broken teeth on the forward gear! (Click on it for larger photo)
Closeup of forward gear - I'm hoping it's not Amarc unique. I'm pretty sure it isn't Scott, maybe West Bend?
Forward gear dimensions
Side dimensions

 

 

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