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What prop do i have

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daviddunivan

Contributing Member
"Hi i have a 3.7 170hp mercrui

"Hi i have a 3.7 170hp mercruiser engine with an alpha one in a runabout/ski boat 18.5 feet long and swim deck on back... i am looking on replacing my 3 blade aluminum with a four blade aluminum...any thought on this... are they better or not, kind of want to keep cost down so i would like to stay with aluminum. the part number on my prop is 48-832830-C1 so my next question is what prop is this in size and pitch... gotta know that if i go to four blade cause i belive you go down in size when switching.. i am also going to install a hydrofoil with this new setup to help me plane quicker and stay on plane at low speeds...we use this boat for tubing some and fishing some in fresh water only... boat weights about 3300 accorging to the title papers...hope this helps and thanks for anyone who can help me"
 
"David;
3300 lbs sounds like

"David;
3300 lbs sounds like a heavy boat for 170 hp.
That prop PN looks like a Merc number, and the pitch should be stamped into the prop body along side one of the blades. It will say something like 17P or 19P. It is likely one of these.
Once you know what you have, you can decide if you want to go down a couple of inches to get better low end jump. Bear in mind that at WOT, the engine should be in the recomended RPM range. I don't know exactly what that range is for your 3.7, but it's likely 4400-4600 RPM. If you are already in that range at WOT, you likely don't want to go to less pitch. I don't think a 4 blade will get you any improvement. Too much blade.
You could go to a high performance stainless prop like a high five, or Mirage and gain some.
The hydrofoil is a good low buck adder. It will definitely help get you on plane faster.
Good luck
Rod"
 
"yeah i thought it were rated

"yeah i thought it were rated a little high for weight... i am guessing it is more like 2400 pounds cause i think the rating onthe title is with trailer and it's a steel trailer... anyway i think this prop is a 14 1/2 x 19 it is the original i think... i am looking for a new prop and wondering what would be a good one for about 200 or less.. i would like to stay aluminum to keep cost down. i was looking at getting a four blade but you seem to disagree with that so how about other's opinions on the four blades on similar boat's any luck??? need to get one soon as i hope to get in the water in the next few weeks, thanks"
 
"Thanks Rod but the site you l

"Thanks Rod but the site you listed doesn't go back to 86 nor does it have my engine listed, thanks for the site though other's may find it useful to them if they have a 2000 or newer boat."
 
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