1963 merc

i have a 63 merc 50hp, i put it on my boat and went out today and its slow as hell about 10mph or so, but my boat is very heavy and says on the tag 150hp. when i got it it had a 40hp on it. the engine seems like it runs great think my boat is too heavy? its a 16ft starflite
1964 i think im thinking about swaping everything onto this plywood boat i have same size but lighter but is it worth it how fast can a 50 push a lighter boat or is 10-15 good? :'(

Re: 1963 merc

DARKCLOWN said:

i have a 63 merc 50hp, i put it on my boat and went out today and its slow as hell about 10mph or so, but my boat is very heavy and says on the tag 150hp. when i got it it had a 40hp on it. the engine seems like it runs great think my boat is too heavy? its a 16ft starflite
1964 i think im thinking about swaping everything onto this plywood boat i have same size but lighter but is it worth it how fast can a 50 push a lighter boat or is 10-15 good? :'(

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any help on this?????

Re: 1963 merc

Sounds slow to me. I have a '65 100 HP on my 16' 1970 Stevens runabout (with the thick fiberglass common to that era) and with my 17 pitch prop it runs right to 40MPH. I'm sure that doubling horsepower shouldnt double speed, but that would only make it 20mph.

I also had a 16' wooden cabin cruiser (glass windows, upholstry, etc) with a Merc 30hp and it would get right up on plane and run all day with two people.

Guess its not a real answer, but I dont see why it wouldnt do much better than 10 MPH.

Re: 1963 merc

it says on my prop that its a 10 1/4 x 18 i think the 18 could be 10 or 13 its a little worn but im almost sure its 18 is this a good prop

Re: 1963 merc

if its an 18, its a pretty old prop as they havent made even numbered pitches for awhile. What that means is that the over all diameter from prop tip to tip is 10 1/4 inches and for every revolution it would travel 18" forward (with no slippage, which isnt possible in real life). A higher pitch prop (19, 21, etc) will create lower RPM's and a lower pitch prop (17, 15, etc) will create higher RPM's.

You want to find a prop that gets your RPM's at wide open throttle to be right at redline for your motor, then run it at 1000-1500 RPM's below redline for best longevity and economy. That will get you your best speed. If you dont have a tach its a bit tougher. If you are able, you will want to try a lower pitch prop and see if your speed increases a bit. You may be lugging the motor too much.

On my 100 hp, the 17 pitch will get it within 500 RPM's of redline and I can go 40 MPH. If I ran an 19, it would lower both. If I ran a 15 (which I have) it raises RPM's but lowers top speed considerably. Its not an exact science, just trying to find a compromise.

Re: 1963 merc

I tried to run your setup on mecurymarine.com prop selector tool and it wouldn't give me a recommended prop. It just said the engine was to small or the boat to big. This is odd since I used to have a 15' or 16' ebbtide fiberglass open bow runabout with a 50hp merc on it and I seem to remember getting something like 18 or 20mph out of it.

Re: 1963 merc

well i like this motor and i am on tight funds would there be a boat i could put it on that could pull a tube maybe i should look for like a 14' or somthing and if i keep the boat will the prop really give me that much more speed?

Re: 1963 merc

another Q i have that has nothin to do with my boat is how do you move up in rank on this site?o

Re: 1963 merc

Is it possible that your fiberglass boat is waterlogged?

Re: 1963 merc

Motor said:

Is it possible that your fiberglass boat is waterlogged?

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how would i find that out? its the first time i had her in the water since i had it its been in the yard for 4 months or so, the boat is so heavy that 3 guys couldnt pick the ass end up

Re: 1963 merc

DARKCLOWN said:

well i like this motor and i am on tight funds would there be a boat i could put it on that could pull a tube maybe i should look for like a 14' or somthing and if i keep the boat will the prop really give me that much more speed?

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:'(

Re: 1963 merc

I ran a 1952 Tolleycraft utility for years with a 1963 Merc 450 (45 horse). The boat was a marine plywood runabout with a closed bow, about 14.5 feet long. With some patience, my wife and two small boys on board, I could get up salom behind it, and once I figured that out, I stopped dropping a ski. I figure it went about 30 mph full throttle with its cool bronze prop.

man, what memories.

fp