What prop do I have?

[mikebc]

OK,<br /> I have a spare prop that came with the boat, and the guy I got it from said it was the same as what's on the boat. The numbers on it are as follows:<br />-a number 20 stamped on the end of the brass<br />-48-78120-19 molded above where the shaft comes out, but it's in the paainted alum above the brass<br />-US Prop U6914 on one of the outsides<br />-48-78120 A40l 19P on the other outside<br />- and a number 4 in a square box molded on the outside.<br /><br /> I would like to know the specs on this prop so I know what to order, I need more out of the hole shot, getting skiiers up. It's a alpha 1 1987 3.0.<br /> Also, the one on the boat is dinged up on the leading edges, how bad can it be before it makes a noticable difference?

 

[QC]

Re: What prop do I have?

First, what is your WOT RPM with the boat trimmed out and going as clean (fast) as it can? Need this to determine prop sizing changes. Have you looked for similar numbers/info on the installed prop?<br /><br />The one you're askinbg about was/is a 19 inch pitch prop. It may have been reworked, and it is possible that it is no longer a 19.<br /><br />Small dings can make a negative difference. The real issue is vibration; propellers that are out of whack can cause drive damage. Ususally you can feel that in the steering wheel. You can also fix small dings prety easily with a hammer and something to use as an anvil. A file can help too, just depends on how bad. Many will say that they need to be perfect, and that is always best . . .

 

[Bondo]

Re: What prop do I have?

Well,..... Just Guessing here......<br /><br />You've got a Merc. Prop that is a 19" pitch,..... Or it's been bent out to a 20",...... Maybe.......<br /><br />The Next Step would be a 17" pitch.....

 

[mikebc]

Re: What prop do I have?

Well........<br /> <br /> The darn tach quit working a few weeks ago and I just ordered one thru overtons. The wot rpms were about 4000~4200, but that was before I got it running right, now who knows? I will not order a new one before I get the tack installed. My manual says wot at 4200-4600, once I get the tach in I will see if I can drop down to a 17, maybe a 4 blade. Another question, anyone change a prop while in the water? We just leave it in the water now, my car is too small to pull it out and we don't have a hoist/lift. It just floats off shore tied to our pier. The prop on the boat looks so-so, I will not change it 'till the water hits 75, just in case I have to get in!! Thanks guys!

 

[QC]

Re: What prop do I have?

I've done it in the water many times. The biggest worry for me is dropping something. The item that can really screw you is the thrust washer just in front of the propeller. Sometimes due to grease (good) it can stick to the front of the prop when you pull it off and if it falls and you don't have a spare you're screwed. Also, I think they cost around $30. I wouldn't pull the prop all the way off of the shaft until I had confirmed that the washer had stayed behind on the shaft.<br /><br />The other big problem you can have, is if the previous owner didn't use grease on the propshaft, they can be a real bear to get off. Slop some on the shaft before you go back together.<br /><br />P.S. This is a fairly large "washer". It has a little heft to it. I only mention this because if it stays on the shaft like it should, you may be looking forever for this little washer that isn't there . . .

 

[achris]

Re: What prop do I have?

Originally posted by Mikebc:<br /> ..... once I get the tach in I will see if I can drop down to a 17, maybe a 4 blade. Another question, anyone change a prop while in the water? .....

4 blade props are a real nice thing, been running one for about 8 years now. Just be aware that they come in even numbers, not odd, and only 3 pitches 16", 18" and 20".<br /><br />Changing prop in water is not too hard, just be careful and don't drop anything <br /><br />Chris............

 

[mikebc]

Re: What prop do I have?

Chris,<br /> <br /> What brand and type, (stainless/composite/alum,) of 4 blade do you run? I am mostly concerned about pulling skiiers with 3~4 people in the boat, that is without asking them to all grab a paddle and row!!!! If I am still running 4,200 ish with a 3 blade alum, would a 4 blade composite get me up to 4,400ish? Thanks for the heads up on the washer, my luck I woulda lost it in the Carolina mud!

 

[bluewater19]

Re: What prop do I have?

For pulling skiers go with a highfive. Best prop for holeshot out there. I would run a 17 pitch.<br />You will lose a little on top but your holeshot will be improved bigtime!

 

[achris]

Re: What prop do I have?

Originally posted by Mikebc:<br /> Chris,<br /> <br /> What brand and type, (stainless/composite/alum,) of 4 blade do you run? I am mostly concerned about pulling skiiers with 3~4 people in the boat, that is without asking them to all grab a paddle and row!!!! If I am still running 4,200 ish with a 3 blade alum, would a 4 blade composite get me up to 4,400ish? Thanks for the heads up on the washer, my luck I woulda lost it in the Carolina mud!

Hi again,<br /><br />Forget composite, waste of time. 4,200 is too low even without pulling skiers. From memory that engine is specced to run 4200-4600. You should be aiming at the higher number, 4600. Currently running a 19" , no skier, getting 4200. A 17" should get you around 4600, no skier, which would be ok, just, for a skier. Personally, I'd go for a 16" 4-blade Aluminium Merc prop. Good low down, hold on REALLY well, but you lose a bit of top end speed. <br /><br />My boat is as follows:<br />4.3LX Merc, weighs about 4,500lb. Running a 4-blade 20" Ali Merc prop, pulls about 4700rpm at 38 knots. I also have a 3 blade 21" SS that pulls just on 4800revs at 41 knots, but prefer the 4-blade, it's so much smoother and doesn't suffer from 'weeding up',<br /><br />Chris..........

 

[bluewater19]

Re: What prop do I have?

The 4 bladed alpha4 prop is no comparison to the highfive. I have tried both on my glastron along with the merc offshore 4blade, trophy 4blade and quite a few 3 blades. On a runabout used for watersports the highfive is the best prop merc makes. <br />I use a 23pitch highfive, and the boat will pull 2 people up with no problems. With the stock 23 pitch aluminum prop we had to struggle.<br />I say with out putting tabs on the boat The highfive is best.

 

[Bondo]

Re: What prop do I have?

Get a Torque-Shift,+ It's the Only 1 You Need........................ <br /><br />Starting at 11"s pitch,.... I can bring Tears to the eyes of Skiers..............<br /><br />At about 20"s,.. Topend is about 48/4900rpms,.. 43/44gpsmph........ Freshwater............... <br />4.3LX,..Alpha 1.......

 

[novicetech]

Re: What prop do I have?

Mike how high is the pier? Can you tilt it enough to get close to the surface of water and change from the pier? You woudlnt have to get cold that way.

 

[Dunaruna]

Re: What prop do I have?

I recently changed a prop in deep water, I used the kids tube (the blow up thing that tows behind the boat). Worked a treat.<br /><br />Aldo

 

[mikebc]

Re: What prop do I have?

Thanks guys,<br /> <br /> My pier will work to change the prop, but my outdrive trim never gets the prop out of the water, maybe the top blade is 3 inches or so from the surface. It has a built in extended swim platform, I think that's why it doesn't go very high. I one though of putting a towable tube under the stern of the boat and blowing it up under water with a compressor, but na, too much work. If I get a little wet I most likly will not melt, our water is sticking in the mid-upper 60ish range, I woulda skied in that back in Michigan! Two more questions: 1. Who sells the hi-five? 2.Who sells the Torque-Shift? I'm not looking for a magic bullet, I realize it's only 130HP, I don't need to go over 40, just wanna pull some shoulder sockets! Really, just wanna get my butt up and out of the water with 3-4 people in the boat. Thanks guys!

 

[achris]

Re: What prop do I have?

1. Merc dealer<br />2. Merc dealer<br /><br />If you're looking for straight out hole-shot, then the high-five is the duck's nuts.<br /><br />Chris...........

 

[QC]

Re: What prop do I have?

High-five is Mercruiser/Quicksilver<br /><br />Check Ebay for Torque-Shift as they are no longer made. Here is a link to one that has a buy-it-now for $500.<br /><br /> http://cgi.ebay.com/ebaymotors/ws/e...ry=26456&item=4547349813&rd=1&ssPageName=WDVW

 

[mikebc]

Re: What prop do I have?

Anyone interested in buying the prop I mentioned in the first string of this post? It's in really good shape, don't think it was ever used. I'll send hi-res pics to anyone interested. Thanks!