Mecury Classic Fifty Prop???

[MyBoatIsOlderThanMe]

Hello,<br /><br />I just bought an alumacraft lunker, 16' long, aluminum hull, with a merc classic fifty with 45hp; Serial Num: OB171313 and model number 1045727. The prop is all torn up and I need a new one.<br />The boat will be primarily used for fising and problably to go waterskiing.<br />Anybody have any good suggestions as to which prob I should get?<br /><br />Also I am currently using a 50:1 fuel oil mixture and the engine seems to run a little rich with it. Just removed the spark plugs and they are very oily; getting new ones today. Any suggestions on fuel/oil mixture would also be greatly appreciated.<br /><br />Thanks for your help in advance.

 

[Silvertip]

Re: Mecury Classic Fifty Prop???

Did you read the post right above yours? Without any current wide open throttle rpm and speed information we have no idea whats best for your boat. The part number should be stamped on your current prop. Start with that diameter and pitch. Then take accurate speed and rpm readings at WOT with normal load. Go up in pitch or down in pitch as required.

 

[MyBoatIsOlderThanMe]

Re: Mecury Classic Fifty Prop???

I did not read the post above sorry; will do so right now.<br />I cannot get a accurate rpm or speed reading since I don't have any gauges.<br />I'll take a look at the prop.<br /><br />Thanks

 

[rickdb1boat]

Re: Mecury Classic Fifty Prop???

You may consider investing in a Tach. Here's an easy one to install and relatively cheap.<br /><br /> www.tinytach.com

 

[Silvertip]

Re: Mecury Classic Fifty Prop???

For speed tests you can use a hand held GPS. The tiny tach referenced above works well. With the proper prop, at wide open throttle and normal load the rpm should be at the upper end of the recommended RPM band for you engine. (Probably 5500 RPM). If its higher than that, you need a prop with more pitch. If its lower than that the engine is lugging and you need a prop with less pitch.

 

[River - Runner]

Re: Mecury Classic Fifty Prop???

Congratulations on your purchase. You should really like your rig. I owned a 1988 boat and motor like you describe. The boat was a Lunker SS.<br /><br />This is what worked for me. So you may use it as a reference. My motor was a tiller steer and I used a Mercury 13" pitch SS (stainless steel) prop and it tacked out at 5,200 RPM at WOT. A Mercury 13" pitch aluminum prop will run about 5,350 and it didn't make much difference with passengers or me alone. The motor WOT operating range is 5,000 to 5,500 RPM.<br /><br />I always used the boat for fishing. If you are going to do waterskiing you might want to use a 12" pitch prop instead.<br /><br />Keep using the 50:1 fuel oil mixture... It's what's recommended for the motor.<br /><br />That is a great boat... 550 lbs. and a super nice motor... 4 cyl. 2 stroke. Enjoy it!

 

[MyBoatIsOlderThanMe]

Re: Mecury Classic Fifty Prop???

Thanks for all your help. This is my first boat so I am learning a lot of new things.<br /><br />Any suggestions on weather to get a composite prop or an aluminum one.

 

[fishingdan]

Re: Mecury Classic Fifty Prop???

I also used the 13" factory aluminum prop on my 16' center console with the same engine. My boat has a similar hull shape and weight.

 

[River - Runner]

Re: Mecury Classic Fifty Prop???

Always try to be careful with a prop, as to not hit things and even sand. You say the old prop is all torn up. It usually takes rocks or stones to do that and since this is your first boat I would recommend a aluminum prop and trim the motor up and go slow in uncertain waters. I wouldn't use a composite prop other than for a backup or spare and I think a SS (stainless steel) prop is better suited for one that knows the waters, because of the expense of repair or replacement.<br /><br />With care a aluminum prop should last a long time with great performance on your rig.