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motor hight advice single 4.3l 300 2520 xld

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chas650r

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Hey guys looking for input . I have searched and learned a bunch here, thanks for all the info already gained. I have a new to me 2012 2520 xld w/ a single 4.3 yamaha 300. As recieved the motor is mounted all the way down and when running I get a lots of spray up on both sides almost up to the intake openings. I cant even see the cavitation plate , not unusual from what i have read here. As is the boat is over propped imo w/ a 15?x 17p painted yamaha stainless, 5500 wfo trimed w/ 1/2 tank and no gear . New prop on the way is a power tech ofs4 15.25 x 13 . Boat has the stock (I believe) lenco tabs 10"wide x 20" long which seem ok for now at least.

So, my question is to those w/ the same set up how far should I raise the motor on my first try ? The boat is on the trailer and the cherry picker is here . i am thinking go up 2 holes (1 from all the way up) but wanting to do this once only thought I would seek info from owners of the same exact boat and motor .

thanks!
 

Andy

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Hey guys looking for input . I have searched and learned a bunch here, thanks for all the info already gained. I have a new to me 2012 2520 xld w/ a single 4.3 yamaha 300. As recieved the motor is mounted all the way down and when running I get a lots of spray up on both sides almost up to the intake openings. I cant even see the cavitation plate , not unusual from what i have read here. As is the boat is over propped imo w/ a 15?x 17p painted yamaha stainless, 5500 wfo trimed w/ 1/2 tank and no gear . New prop on the way is a power tech ofs4 15.25 x 13 . Boat has the stock (I believe) lenco tabs 10"wide x 20" long which seem ok for now at least.

So, my question is to those w/ the same set up how far should I raise the motor on my first try ? The boat is on the trailer and the cherry picker is here . i am thinking go up 2 holes (1 from all the way up) but wanting to do this once only thought I would seek info from owners of the same exact boat and motor .

thanks!
I have almost the same boat (late-in-the-year 2013 Parker 2520 XLD; and a 2014, Yamaha 300 UCA which I believe is the shorter engine than the XCA? (Which is yours?) The prop is the S/S Yamaha Salt Water Series II 15 X 17 and 17-T what ever that means..... I have similar trim-tabs; only use them occasionally to balance port to starboard. l The engine is mounted on an Armstrong bracket. and is mounted in the TOP of the 4 holes, meaning the engine is mounted as low as it can be.... As far as I understand, my wake is perfect, and when at cruise speed (around 30 mph) I never get any spray/water on the engine cover. When i slow down in the low 20's I get some spray up there, but nowhere near as high as the air-scoop-intakes.... here is a short video that shows my wake; And by the way, I can't see the anti-cavitation plate when running on plane...
 
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Andy

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thanks andy .........F300 uca........ have u considered raising to lower drag ect.?
Hi Chas, Yes I have thought about raising it a number of times, if for no other reason, out of curiosity. Also when planing I'd like to be able to see the anti-cavitation plate (cavitation plate?) as many recommend on ClassicParker. The best I can tell my speed, rpms, mpg, etc are as good or better than most that I see here, but maybe there is room for improvement. My issue is I live in a fairly remote area. We have only one good local boat company (Radcliff Marine, and they are very good folks!) but they are always booked up. I understand it is not an overly complicated job if you have access to a building, gantry crane and/or fork lift, but I have none of that. I'm looking forward to hearing how yours works out.....
 

Andy

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thanks andy .........F300 uca........ have u considered raising to lower drag ect.?
I meant to ask. Does your boat have the actual 200 gallon gas tank? Do you keep it full? And I ask this wondering if you might be carrying extra weight in the stern? I have the 200 gallon tank but mostly try to maintain the gas about half to 3/4 full. I only fill up for long trips. (As far as I know my boat does not have 'that EPA device' that prevents filling the tank all the way..... Also, what are the expectations when you change to the 15.25 X 13 prop?
 

Antidote

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The sets for what you are trying to do:

1. Raise the engine until the anticavitation plate is on top with your typical load onboard (Pic below). The extra drag caused by a low engine is a lot of drag.
2. Select a prop that gives you within 500 RPM of max RPM. If you get performance numbers you'll be amazed at the expertise of the Prop Gods in picking it right the firs time.

IMG_0637.jpg
 

warthog5

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Chas650r.......You raise the motor before a prop change....Yea 3rd hole on motor at Top is where I'd start. Freeing up the drag will change the RPM band.....Thus inturn may.....or may Not need a prop change
 

chas650r

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Thanks for the replies,

yes, 200 gal tank about 1/2 to 2/3 full on the maiden . And if i ever get the Command Link Plus fuel management / tank level understood completely I will run on partial tanks when possible to lighten the stern. I see the fuel tank sender wires leave the tank but not sure if they actually go anywhere in my set up ( no stand alone fuel gauge).

I have been lurking here for quite some time while my search for a new boat continued and as stated above absorbed lots of great info on set up from the posts from threads on height motors , propping ect. specific to my boat. I am an old outboard guy from way back , using them for commercial and sport for years , so I understand the value in model specific info.

The pic in Antidote's post is what I have always tried to achieve in general . So if I understood Warthog correctly 1 hole from the highest setting to start? just want to be sure.

As far as the prop goes I get the value in 1 change at a time but my experience tells me I will never be happy as propped and its a bit of a project back and forth to the water. For the short duration combined seas we deal w/ just about every afternoon here 18-22 mph is about it if you want to enjoy the soft ride that I have come to love in older 2520dv's that I fished on quite a bit . In the past most if not all of my outboards would over rev if left on the pin but we just can't use them that way speed wise so torque , lower speed planning, and swell climbing ability is king. Has anybody out there tried a 13 or 14" pitch 4 blade w/ a single 300?

Having fished on a i/o volvo diesel 2520dv was truly an eye opener for what these hulls will do IF they stay in the water at lower planning speeds. When I first decided the look for a 2520xld my biggest concern was over all balance w/ the bracket and outboards hanging out there and being able to achieve low speed performance similar to the i/o boats. So I went w/ the single 300 to keep the stern weight down. Interestingly , so far the balance seems better than I expected but the bottom end on the 300 worse than expected at least as propped. As of yet I can not find a torque curve for the 300 4.3l but it feels like under 3800-4k it's pretty much done.

So I guess I raise the motor, prop way down w/ a stern raising 4 blade (most likely give up some mpg ), put weight forward if possible and see what happens. All comment and thoughts appreciated.
 

Antidote

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"The pic in Antidote's post is what I have always tried to achieve in general . So if I understood Warthog correctly 1 hole from the highest setting to start? just want to be sure."

One hole from the highest is where my engines are mounted. Since that picture I have added more weight to the boat (center rigger, outriggers, solar panels and house battery, more rod holders, ect...). I have also added 4 blade props which decreased my top end by 2 MPH; but, increased my cruise numbers. As we have suggested lift the engine first then change the prop. You will do a lot less work and spend less money that way.

Edit: When I went to the four blade props my cruise numbers (speed vs. fuel at a set RPM) actually got better.
 
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tjd24

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Chas
I wonder too what you expect from the OFS 4 - 15.5" X 13" Powertech prop?
Was this size a recommendation or did you change it from past experience?
I'm researching a new prop for my 2320 w F250 and someone suggested a 15.5" X 14" prop.
Any info appreciated.
 

chas650r

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One hole from the highest is where my engines are mounted. Since that picture I have added more weight to the boat (center rigger, outriggers, solar panels and house battery, more rod holders, ect...). I have also added 4 blade props which decreased my top end by 2 MPH; but, increased my cruise numbers. As we have suggested lift the engine first then change the prop. You will do a lot less work and spend less money that way.

Edit: When I went to the four blade props my cruise numbers (speed vs. fuel at a set RPM) actually got better.
OK and thanks. If I get close to the 2mpg area great but I expect w/ a load and a bunch less pitch I will loose some. That being said, at the speeds I will run most of the time the engine vacuum will be up from now, no doubt, so at slow to midrange planning speeds it may be similar . It's a rare trip when we have seas that allow 30 mph.

As far as the prop choice goes I ran a maiden and took the numbers and did the math . The pitch speed to actual speed slip was more than 20% even at wide open . Even with all the variables thrown in the 20 -30 % I saw is to much, imo. IF the throttle by wire is linear , roughly the last 1/4 of the throttle had little affect and I only saw 5500 revs. All this tells me I am pushing a heavy boat w/ to much pitch by a fair bit. Also I simply need to see more revs at a slower speed to get in the torque curve and hold the boat on the plane at the speeds we can run with out beating the boat and ourselves . The 13 pitch should turn 6000 easy and w/ less slip I should be able to cruise close to 30 mph at reasonable revs on the few days we can. It will be fun to see what happens.

I did then call our west prop guru , Brian at Valley Prop in Ventura where I will buy the prop and discussed my needs and said I thought I might go as low as 13" and he thought 13-14 would be the range for our area ( w/ a 4blade) He likes the Powertech prop and hub design . He also has a no hassle exchange policy so I may go to 14"

It really depends on what you need and can use speed wise, if you have flat water a couple more inches of pitch is very realistic.

thanks for the replies
 

John_Madison CT

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Maybe I don't understand your issue, but two things I'd like to comment on:

1. I wouldn't change my prop until you get the engine mounted to the proper height.

2. A 13" pitch prop seems way too low for a 25' Parker and a 300hp engine.
 

chas650r

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Maybe I don't understand your issue, but two things I'd like to comment on:

1. I wouldn't change my prop until you get the engine mounted to the proper height.

2. A 13" pitch prop seems way too low for a 25' Parker and a 300hp engine.
both are good comments.......
1. If changing motor height was as easy as changing a prop I would agree 100% . And no doubt the performance will change w/ proper motor height adjustment , I just don't believe it will be enough to get where I need to be . My understanding , and it could be wrong ( although our prop man also says so )is that a 4blade prop will raise the the stern effectively raising the motor. I have no idea how much a specific prop will change this and is why I asked for mounting locations from like kind boat, motor, prop, ect.
2. 13" pitch is low if sea conditions allow 30+mph regularly, agreed. But some on here C/P have reported good results w/ 15.25 x 15 4b props and still run long relatively high speed trips ( must be smoother water than we have ). So my thinking is I am really only going down 2" of pitch from there and in the end 1"down or a 14" may be best for me. Bottom line is I don't need to go 40 or cruise at 35 near as much as I need good performance at 20-25 mph. Both would be great but................

I always start with the math and add in the real world facts as I can get them. There have been many and varied discussions re. prop slippage but most agree less is better. Maybe 10-15% at top speed (40mph)sliding scale to ~18% at 20 mph

For those who care here is some of the math;

As is ; wfo trimmed out 5500 @ 40 mph
pitch speed from rpm , gear ratio, and pitch (17") = 50.4mph = more than 20% slip
pitch speed as above @ 4000= 36.8 mph , I get ~ 27mph= ~30% slip
pitch speed at 3500rpm = 32.2 and I cant even stay on plane

Some projections and guesses for a 4b w/ 13" pitch with more bite and less slip;
Should be able to get 6000 rpm, so ......
pitch speed@6000 = 42mph = 35.7 with 15% slip , ~37mph with 12% slip.
pitch speed@4000 = 28mph= 22.4 mph with 20% slip . this speed is realistic for our swell and chop and should get enough rpm to make the torque to stay on the plane. it's just a guess because yamaha wont give us a torque curve to the best of my knowledge but it seems somwhere around 4k+ is where the power is.
 

SBH2OMan

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I went through this whole exercise back in 2016, using Valley Prop and trying the OFS4 prop (which was a dud for me for reasons I can explain later). One thing that was very helpful to me was plotting the numbers on a spreadsheet (I'm an Excel jockey).




I found that the OFS4 prevented me from getting past 5,000 RPM, even though it was a 13P

Some other interesting data points - I tested with and without a Permatrim installed. (shown as "PT" on the graphs). You can see the minor differences. Also I noticed that the "time to plane" was 8.7 seconds without the Permatrim versus 7.2 seconds with the Permatrim. (Deep Vee hull)

Since we are neighbors, and I'm going to be going through this exact exercise again myself, I'm happy to help you with yours, including if you need a hand to move the engine up or down (I usually rent a cherry picker from Milpas Rentals and do it at the launch ramp then run out and do some testing, then come back and continue testing, etc).

I've attached a PDF of my research findings using actual empirical data, not just my opinion. :) Yea, I'm a bit OCD...

I planned to do additional testing with various loads (full fuel, etc.) and adding weight to the bow as well as different engine trim settings, but the initial baseline performance was so discouraging that I just left it at this and tried an Enertia prop (and I'm trying to find my research results from that one, but suffice to say that the original Solas prop went back on and stayed there until we just repowered)
 

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SBH2OMan

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And speaking of prop slip, here are my calculated prop slip data for comparison with a 13P prop on a 23' DV hull and Honda 225 (the previous motor):

 

chas650r

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Lots of good info ..........it's going to take me a bit to digest it , but it looks like we come from the same place info wise :) . Was the solas a 4b ? I have used solas props in the past and thought I got a lot for my money. Do you still have the power tech? Brian is having a hard time getting me one at this time . What was the issue w/ the Powertech if you dont mind?

thanks.
 

SBH2OMan

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Honestly I don't know which model of Solas prop (other than being a "Titan") - whatever came stock with the Honda BF225 back in 2011. The OFS4 is long gone - I returned it and took a hit on Brian's shipping cost and a 15% restock fee. It didn't work because the BF225 just didn't have enough torque to push it up to redline. It provided worse performance nearly all around - worse performance, worse mpg, and lower top speed. It basically felt a lot like putting 37" tires on a Jeep with 3.21 gears that can't push past 50 mph on the freeway because of wind resistance... (if that reference means anything to you).

However, with a lower final drive ratio/more torque, it probably would have been great. I will probably try again with the new motor, which I can feel has a LOT more torque (its having NO problem spinning a 15p Solas Titan prop)
 

chas650r

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Yep I get it . Nothing worse than to much prop in the slop. What you describe is how my boat feels now , in 4th gear trying to climb a mountain when it should be in 3rd. I think adding a blade and going down 4 inches in pitch should change things up.
 
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