New Prop for an Old Boat - Need help navigating the numbers

Blacktalon82

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Apr 12, 2016
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I am doing some work on my boat and need to change out the prop while I have it out on the water due to some damage to the blades. I have been researching both Hulltruth and iboats and the amount of selections, pitch, cupping, venting, rotation...oh the list goes on. After searching and reading all the stickies, I think I have all the info needed for a thorough post and have done so in both forums. Could someone please point me toward a few good options that meet the following boat/usage?


Boat:
1993 Proline 210 Bay Boat Center Console
200 Hp Yamaha two stroke, Carb'd
Deep V hull
Relatively heavy displacement for its size (previous owner said ~3500 lbs loaded but unconfimred)
90 Gal tank
Usually two persons onboard


Current Prop:
Mercury Marine Vengence
48 18314 17P (can't find this part number listed anymore, so I assume an old model?)


Current performance:
Good hole shot, WOT at around 44 mph - not sure about the rpm's. The boat gets up and goes quickly, but a bit hard to control in the "corners". I have to negotiate a few tighter turns in the creek on my way out and find the boat lacks much grip in the turns. The boat runs well at high speeds, but I find it needs constant input from the helm at lower rpm's or as the motor is trimmed way up to avoid shallow areas.


Usage:
- Mainly short trips in and around the James River, fishing the bridge tunnels in the Chesapeake Bay area of VA. No more than 30 min travel from launch to destination, then slow trolling or pleasure cruising with friends. I keep it at my dock, with daily short trips out through a systems of creeks to drop an anchor and relax.

-Shallow...can't stress this enough. I have to play the tides where I am and have to be so cautious as there are plenty of rock filled areas that are less than 3 ft deep. Constantly trimming the motor up so durability is going to be very important. This prop will be hitting the bottom, no matter how careful I am.



Any suggestions are very welcome, hopefully with personal experience using a certain prop attached with them. I would like to keep the price less than $500.

Thanks in advance!
 

SkiDad

Lieutenant Commander
Joined
Jul 18, 2010
Messages
1,518
the prop you have seems about right as far as pitch goes. I'm estimating 5700 rpm. You could just have the prop repaired and have them add some cupping - i had cupping added to my prop and it made a world of difference - you will only be talking 150-200 bucks. This is the the cheapest route if you are going to hit the prop anyhow.
 

Blacktalon82

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Apr 12, 2016
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I had thought about that, but it is pretty dinged up from years of use and now bent a little. It is time to be replaced, I just want to make sure I make a smart purchase as these things are not cheap!
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
Messages
12,345
Current prop WOT rpm is a must know as currently tested if wanting maximizing a new prop from there for top combo performance. Probably current prop performs good, but without a tach won't be 100% sure. Don't have a installed tach ? Strange a Yam OB uses Mercury props, Yam has a wide selection of original props to choose from.

Happy Boating
 
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Blacktalon82

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Apr 12, 2016
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I do have one, but it is an original 1993 LCD display and pretty faded. MPH I am getting off my gps and I'll try and run at WOT to get some better data if I can make out the display. The issues will be that the prop is damaged now from a friendly rock run in and won't be at optimal running attitude.

I'm glad I wasn't the only one that thought it a bit weird to see a Mercury prop, but that is what was on it when I bought it and I have yet to have a need to change it.
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
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Speed is irrelevant, will not know max wot rpm to check current prop no matter if in bad shape as long prop does not have a spun hub nor blades are severely damaged, bent. That should be your starter prop. For that will need to install a standard new tach or go for a Hardline Hour/Tach model : https://www.hardlineproducts.com/product/hourtach-meter-up-to-8-cylinders/

From that wot run can maximize a Yam prop to suitl your boating needs, loads, passengers for OB to run safely indisde Yam's wot range for that OB.

Happy Boating
 

Blacktalon82

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Joined
Apr 12, 2016
Messages
10
Current prop WOT rpm is a must know as currently tested if wanting maximizing a new prop from there for top combo performance. Probably current prop performs good, but without a tach won't be 100% sure. Don't have a installed tach ? Strange a Yam OB uses Mercury props, Yam has a wide selection of original props to choose from.

Happy Boating



Ok Sir, went out today and did a few runs. Here is what I came up with.

Against tide, 5100 rpm @ 41 mph with motor fully trimmed in
Against tide, 5300 rpm @ 41.3 mph with motor trimmed out as far as possible

With tide, 5400 rpm @ 44.3 mph with motor at standard running attitude.
Trim made little to no difference either way or my tach was not sensitive enough

Boat ran very squirrelly with the motor trimmed up and steerage was tough to maintain


Hopefully that was the data you guys needed. What recommendations would you make?


Thanks in advance!
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
Messages
12,345
You should be trimmed for combo to run near parallel to water level when on plane, provided that boat has a evenly distributed deck weight.. What's the max-min rpm wot range of that OB ? If standard attitude happens to be while planing parallel to water level, maintain that trim, 5400 rpm and 43.3 mph are the best numbers of the previous 2 runs. Was the test done with you alone or with 2 up ? How's hole shot.

Happy Boating
 
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Blacktalon82

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Apr 12, 2016
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Yes, that's what i meant by standard running attitude. WOT, motor trimmed how I normally would. The test was done alone, half a tank of fuel, regular gear onboard. I've been trying to find spec on my motor, but being a 23 year old motor made pre internet its not as available. Max rpm's from what I could find was 5500

Hole shot is good, no complaints there
 

Sea Rider

Supreme Mariner
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Sep 20, 2008
Messages
12,345
If 5500 revs is the max and you're runningl already at 5400 rpm, you're already at the sweet max wot rpm range. If boating with more boaters or heavily loaded one less pitch size will make the day, If that won't happen stay with current prop. Good to read that like boating riding parallel to water level, same as me,

Happy Boating
 
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