13x16 or 13x17 RH 1" Bore
Printed From: CorrectCraftFan.com
Category: Buy and Sell
Forum Name: Boat Parts Wanted
Forum Discription: Parts wanted only
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=8443
Printed Date: November-24-2024 at 7:05pm
Topic: 13x16 or 13x17 RH 1" Bore
Posted By: Bhedbloom
Subject: 13x16 or 13x17 RH 1" Bore
Date Posted: September-18-2007 at 4:38pm
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I'm looking for a 13x16 or 13x17 RH-1" bore for my Southwind. If anyone has one to sell or has a source for one please let me know. Thanks all!
------------- Barry, South Carolina |
Replies:
Posted By: TRBenj
Date Posted: September-18-2007 at 5:02pm
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Thats an awfully big prop. What motor/tranny are you running? ------------- |
Posted By: reidp
Date Posted: September-18-2007 at 6:01pm
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Maybe it's that 460 Twin Turbo. ------------- ReidP /diaries/details.asp?ID=231&yrstart=1971&yrend=1975 - 1973 Mustang |
Posted By: Bhedbloom
Date Posted: September-19-2007 at 9:52pm
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TRBenj,
It's running a 351 Holman Moody Ford. I am looking to prop it out for the winter so that we go further at lower rpm's while running down the lake. I figure since hole shot won't matter during the winter why not increase fuel efficiency while running. During the summer I run a 13x13 and it does fine for skiing and wakeboarding, but the rpms are too high for me while running down the lake. Any other thoughts on proping one out? Thanks! ------------- Barry, South Carolina |
Posted By: 8122pbrainard
Date Posted: September-20-2007 at 10:01am
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Barry, I'm sorry to say that it doesn't quite work the way you're thinking. The engine will be under a greater load and will burn damn close to the same amount of gas. Plus, beyond a 15 pitch on a inboard type prop, the efficency drops way off due to the prop blade angle. The prop will start throwing more water out the sides (radially) than out the back. With this in mind, you may even get less MPG! You may want to consider just going to a 13x14. What WOT RPM's are you getting? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Bhedbloom
Date Posted: September-20-2007 at 12:55pm
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8122, I'm getting about 5500 rpm wot. What you stated makes good sense. Do you think a 13x15 will help me reach my goal? I don't want to waste money on the wrong prop or sacrafice cruising performace during the winter. Thanks! ------------- Barry, South Carolina |
Posted By: TRBenj
Date Posted: September-20-2007 at 1:08pm
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5500 seems way high. I didnt think a 351 could push that big a boat that fast, even if it is a H-M. What kind of 13x13 do you have? Are you sure the tach is reading correctly? Whats the top speed (preferably GPS)? ------------- |
Posted By: Hollywood
Date Posted: September-20-2007 at 1:38pm
Already answered.
------------- |
Bhedbloom wrote:Posted By: boat dr
Date Posted: September-20-2007 at 1:38pm
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Tim, you need this motor in your project boat....
13x13 with a 1:1 tranny @ 5500 rpms with 15% slippage will give him 57.6 MPH. That H/M must be putting out 450HP to push a 2000 lb. boat that fast. Or his numbers are all wrong, you do the math.Pitch ,rpm's, ratio,slippage,will give you speed, and I factored in 15% slippage. That is way high even on an old Federal prop. Something ain't rite here, BS maybe???? ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: 8122pbrainard
Date Posted: September-20-2007 at 2:02pm
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Barry, I'm glad the Doc went a step farther than I did with the math. The guys are correct that something isn't correct! Get a shop tach on it to check the RPM's. The H/M's always had the loudest tone to them so it may sound like it's really cranking! They are so loud that it would really get Barney in Green Lake going wild with his DB meter. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Munday
Date Posted: September-20-2007 at 10:02pm
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I would think the prop has been de pitched,try another or have it checked.
The otherside is you got a really hotrod motor maybe a little cup to controll rpms would get ya the extra cruise ya want ------------- If the only tool you have is a hammer,everything starts to look like a nail. |
Posted By: Bhedbloom
Date Posted: September-21-2007 at 12:26pm
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TRBenj,
The Tach on my southwind is not stock, and after reading the other posts I don't think it is reading correctly. The prop is a federal 13x13 cuped and has a few small dings on it. boat dr, I know for a fact that my H-M motor isn't producing 450HP, and my top speed is around 42-43 mph GPS with the 13x13 federal. Could you post the formula that you use to calculate the information in your previous post? It would be helpful to many here. Thanks! ------------- Barry, South Carolina |
Posted By: TRBenj
Date Posted: September-21-2007 at 12:55pm
That would make sense if it werent reading correctly. 42-43 MPH is about right, and I would say youre likely turning ~4400 RPM with that cupped 13x13. Like was previously mentioned, you might pick up a little economy with a 13x14. It would take you a long time to recoup the money in gas savings to justify the expenditure on a new prop, though. I think the Doc is using a fairly simple formula, and Im not sure its very useful. The pitch of the prop is how far it would turn in one revolution (in inches), so subtract a % for slip, multiply by RPM and convert to MPH. There are several problems with that formula- namely slip % is nearly impossible to calculate accurately if you dont know the boat speed and prop RPM. Prop diameter, cup, rake, and efficiency all factor in, as does hull efficiency. ------------- |
Posted By: 81nautique
Date Posted: September-21-2007 at 1:04pm
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Barry,
I run several props on my 351w, typically an Acme 540 or oj 13x13 for skiing depending on boat loading. When I am going to run around and cruise the river which can be a 26 miles run each direction I will put on my OJ 13x14. This drops my rpm about 400 and lets me cruise in the upper 30's at relatively lower rpms. Saves Gas and I'm not working the engine as hard. A used 13x14 shouldn't be hard to find or cost you that much so I would go that route. ------------- You can’t change the wind but you can adjust your sails |
Posted By: boat dr
Date Posted: September-21-2007 at 1:09pm
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It did not copy as well as i wanted but hope this will do..........boat dr
http://continousWave.com:Whaler:Reference:Propeller Calculator -------------------------------------------------------------------------------- Propeller Calculator The propeller calculator computes any one of the five parameters shown below based its relationship to the other four as described below. The calculator is not a Greek Oracle; it simply computes an answer based on your inputs. Prior to clicking the Calculate button, you must have one field blank. You can select the units for the BOAT SPEED parameter. (If units are changed you must force a recalculate.) The calculator returns advisory messages based on your input. Propeller Calculator v1.1. Written in PERL by James F. Hebert. ENGINE PROPELLER BOAT Speed Ratio Pitch Slip Speed RPM :1 in. % MPH KN KPH Number of decimal places to show: NOTE: Some features require a browser with Style Sheet capability. Ideas for Use The most commonly calculated value is BOAT SPEED, based on the other four parameters. Set the SLIP value to zero to see what the maximum speed could be. A typical actual value for SLIP would be in the range of 6-10 percent if the propellor is in good condition and running near the maximum speed at which it was designed to operate. If accurate observations of boat speed versus engine speed have been made, the propeller SLIP can be deduced. This will allow analysis of the propeller performance. Typically values of SLIP will be at least 6% at wide-open-throttle speeds. At lower speeds slip can be much higher, often 50% or more. Generally SLIP decreases as SPEED increases, typically tapering to less than 10 %. If a negative value for SLIP is calculated, the propeller PITCH was understated. Add one-inch to the PITCH for any propeller with cupped blades. If the PITCH of the prop is not known, it may be deduced by observing the other parameters and using various values for SLIP in the anticipated range. Probably the best assumptions about SLIP can be made at wide-open-throttle speeds, where it will probably be as low as 10% or lower. Your engine manual will contain information on the GEAR ratio. Usually it is around 2:1, but it varies with horsepower. For 200-HP engines a ratio of 1.86:1 is common. For smaller horsepower engines, higher ratios are used, more like 2.33:1. For more information on the relationship between these parameters, read my articles on propellers in the Reference section. Foundation The calculator is based on the following relationship: RPM PITCH SPEED = ----- X ----- X [ 1- (SLIP/100) ] RATIO C Where: RPM a positive number; the crankcase speed in revolutions-per-minute. RATIO a positive number; lower unit gear reduction ratio; the number of revolutions of the crankshaft to produce one revolution of the prop shaft. PITCH a positive number; blade pitch of prop in inches. SLIP a percentage, 0-100; index of propeller performance. SPEED a positive number; the boat speed. C a constant to convert inches-per-minute of revolution to boat speed; for miles-per-hour, 1056; for nautical-miles-per-hour, 1215.2; for kilometers-per-hour, 656. (See below for derivation.) By manipulating the elements using algebra, any of them can be computed if the others are known. Hence: SPEED X RATIO X C SLIP = 100 X [ 1 - (-------------------) ] RPM X PITCH SPEED X RATIO X C PITCH = ( -------------------------- ) RPM X [ 1 - (SLIP/100) ] RPM X PITCH X [ 1 - (SLIP/100) ] RATIO = ( ---------------------------------- ) SPEED x C SPEED X RATIO X C RPM = ( ---------------------------- ) PITCH X [ 1 - (SLIP/100) ] The constant C is derived from the analysis of the dimensions involved in the calculations. The propeller advance is generally given in INCHES/REVOLUTION and the speed of the propeller rotation is generally given in REVOLUTIONS/MINUTE. The speed of the boat would then be calculated in units of INCHES/MINUTE, an unusual dimension which needs to be converted into something more commonly used for boat speed. The most common conversion is to MILES/HOUR (MPH), which is derived below: 1 HOUR 12 INCH 5280 FOOT 1056 HOUR INCH ------- X ------- X --------- = -------------- 60 MIN 1 FOOT 1 MILE 1 MIN MILE Similarly, if the results are desired in NAUTICAL MILES/HOUR (KN): 1 HOUR 12 INCH 6076 FOOT 1215.2 HOUR INCH ------- X ------- X ----------- = ----------------- 60 MIN 1 FOOT 1 NAUT-MILE 1 MIN NAUT-MILE And if results are desired in KILOMETERS/HOUR (KPH): 1 HOUR 12 INCH 3.28 FOOT 1000 M 656 HOUR INCH ------- X ------- X --------- X ------ = -------------- 60 MIN 1 FOOT 1 METER 1 KM 1 MIN KM Comments or questions about the prop calculator can be posted in a message thread in the forum reserved for that purpose. Acknowledgements The propeller calculator was inspired by a JavaScript version that was created by Gary Polson. ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: Bhedbloom
Date Posted: September-21-2007 at 2:25pm
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Thanks everyone for all the great info. and steering me in the right direction!
I'm going with a 13x14 and not wasting money on the 13x16 or 17 as I now realize it won't work for my application. ------------- Barry, South Carolina |
Posted By: 8122pbrainard
Date Posted: September-21-2007 at 3:23pm
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Barry, I would still borrow a shop tach so you can check the RPM's. Tim (TRbenj) is correct that slip is a difficult factor. The only way to get a semi accurate % is at a steady RPM getting a GPS speed and then calculating backwards. Do get the shop tach hooked up because we would like to know what it's running at.
Go to Delta (one of our sponsers) and look in their used/reconditioned section for a 13x14 ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: boat dr
Date Posted: September-21-2007 at 3:36pm
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Here are the numbers that I used on mine, slip will vary on boat to boat.....
RPM'S 5100 Ratio 1:1 Prop 14" Speed 54.5 Slip% 17.8 Auto Meter tach could be off 1to2 percent GPS speed don't lie ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: 81nautique
Date Posted: September-21-2007 at 4:13pm
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Good info but way too technical, Put the 13x14 oj on it. The stock 351 will turn around 3800-4200 max and go cruising. My bet is he's turning 4300-4600 with the 13x13 as long as it's not trashed. ------------- You can’t change the wind but you can adjust your sails |
Posted By: 81nautique
Date Posted: September-21-2007 at 6:21pm
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I spent a few minutes and put together an excel spreadsheet using the formulas from Billy above. It helps you figure out your baseline and then allows you to enter some hypothetical numbers and see what the results would be. Be interesting to hear some opinions and if it is actually helpful.
You will have to download it from my FTP site, if you have password problems let me know and I'll email it to you. http://actionscreen.com/pic/prop guide.xls - Prop Guide ------------- You can’t change the wind but you can adjust your sails |
Posted By: tullfooter
Date Posted: September-21-2007 at 6:25pm
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This thread hurt my brain.
Lefty ------------- Play hard, life's not a trial run. '85 BFN '90 BFN White Lake, Michigan |
Posted By: 8122pbrainard
Date Posted: September-21-2007 at 6:58pm
Alan, Send it to Tim so he can put all his test results into it. I mentioned a long time ago when he said he was going to do the testing that a % of slip would be a very good indicator of a efficient design prop. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 81nautique
Date Posted: September-21-2007 at 7:21pm
Pete, were you able to download it and play around with it? ------------- You can’t change the wind but you can adjust your sails |
Posted By: 8122pbrainard
Date Posted: September-21-2007 at 7:41pm
No, What program do I use to open it? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 81nautique
Date Posted: September-21-2007 at 7:48pm
It's an excel spreadsheet, it may not be downloadable because of permissions on my server. I think I have your email, I'll send it to you. ------------- You can’t change the wind but you can adjust your sails |
Posted By: Hollywood
Date Posted: September-21-2007 at 7:52pm
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Alan, I was just using it fine. ------------- |
Posted By: 8122pbrainard
Date Posted: September-21-2007 at 8:14pm
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Ok, I don't have Excel on this computer but I do at work so I'll try it there. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: boat dr
Date Posted: September-21-2007 at 8:19pm
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Pete just tried to call you , must be still at work. There is a site with the info already there even easier to use.......billy ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: 81nautique
Date Posted: September-21-2007 at 8:23pm
So is this one of those A & B discusions or would you care to share the web address? ------------- You can’t change the wind but you can adjust your sails |
Posted By: boat dr
Date Posted: September-21-2007 at 8:36pm
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81, scroll up 15 posts to the one where i give the formulas, there is an adress,
continousWave bla bla bla don't know how to do the link thing so that is the best i could do. hope this helps,I hope you can do a link so anyone else can use it. And no it was not an a & b conversation, you are included too...........billy ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: 81nautique
Date Posted: September-21-2007 at 8:54pm
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Here it is, but you still have to determine the slip before you can use that fancy one otherwise you're just guessing and they always go faster when your're guessing.
http://continuouswave.com/cgi-bin/propcalc.pl - fancy Propeller guide Now don't go Cajun on me Billy, I'm just having a little fun with you. 
Edit, I take that back, it works pretty good. ------------- You can’t change the wind but you can adjust your sails |
Posted By: boat dr
Date Posted: September-21-2007 at 9:06pm
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Talked in depth to my propeller gut today as to slippage.The question was why is the slippage so high with a inboard,15 to 25% whereas an outboard or sterndrive is only about 10%.
The answer was "cause" Factor in 15 to 20% and it will give you a good idea,my data shows about 18% ...... ------------- boat dr /diaries/details.asp?ID=4631 - 1949 Dart /diaries/details.asp?ID=1533 - 1964 American Skier |
Posted By: 8122pbrainard
Date Posted: September-22-2007 at 11:13am
I like it!! Alan, now if you can come up with a term for Chris's style it would be great! ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: 81nautique
Date Posted: September-22-2007 at 12:40pm
I think that's a style all it's own so "Don't go 79 on me" would suffice. I tend to bust balls of only those I've met and they can see through it and give it back. The poor newbies have to learn the hard way though. ------------- You can’t change the wind but you can adjust your sails |