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I inherited a 12 year old Montauk 17 with a 70 HP Evinrude 3 cylinder two-stroke. The prop is the original aluminum 14 x 17 it was set up with, but is starting to pit and show flaky looking cracks.
I have not been overjoyed with the performance, although its adequate and I don't want to look a gift horse in the mouth. The 70 Hp Evinrude is sitting as low as it can go on the transom. I have been thinking of raising it a bit to see what happens, but since I also need to buy a new prop I thought I would wait and just change one thing at a time. I think thats good sound scientific method.
Does anyone have any advice on what prop to run? I want to stay with aluminum, mostly due to the advice of long time local boat operators (I am in the Caribbean with lots of coral, limestone etc.) they tell me that when (not "if" I hit a rock or coral, the aluminum is soft and might break with a total engine stoppage, but the stainless steel props DON'T break and thus the drive train takes the strain of a sudden stop. Besides, down here I can buy three alum. props for the price of one stainless. This one lasted 12 years, so thats good enough.
My question is mainly, is there a better prop choice than the 14 x 17? The engine seems to get up to about 4900 RPM at WOT. I say "seems" to because I don't believe the tachometer. It says 1000 RPM when the engine is turned off.
I had the same engine on my 1978 Montauk for 15 years. Great engine.
My Evinrude 70 was a 1985 model and the WOT was 4500 to 5500 RPM.
What year is yours? The newer ones have a WOT of 6000 RPM...
Props for my engine....
OMC Aluminum # 391198 - 13 3/4 x 15 pitch
OMC Aluminum # 391199 - 13 1/4 x 17 pitch
I had both props above. The 17 pitch would have a couple miles per hour more top end speed and the 15 pitch had a better hole shot. I preferred the 15 pitch as it seemed to give me everything I needed.
My engine was also mounted all the way down. I would have liked to raise it a hole but the Montauk used the blind bottom holes to mount the engine. The only way to raise the engine was to drill new lower holes and plug the old holes or buy a jack plate. I did not want to do either and left the engine where it was.
Your tach is normal. When you turn the key off they do go to 1000 RPM. Just the way it is...
I answered your question elsewhere but let me add that the 13-14" x 15" might be what you want. BRP does not offer this prop anymore, just the 13-3/4" x 17" #391198 and the 14" x 17" #176214.
If you want the former, keep an eye on Ebay or try to talk Joe out of one of his ;-)
Michigan makes some pretty good imitations of the OMC/BRP props. They have an equivalent of the old OMC 13-3/4" x 17" aluminum propeller and it is not much more than $100 USD.
I hit a rock or coral, the aluminum is soft and might break with a total engine stoppage, but the stainless steel props DON'T break and thus the drive train takes the strain of a sudden stop. Besides, down here I can buy three alum. props for the price of one stainless. This one lasted 12 years, so thats good enough.
