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Speed Problem

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fishing guy

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I have a 2016 (bought new) 2350 RSR boat with a WOT speed of 32 MPH (measured with a GPS) and an RPM of 5550.  Everything I read says my prop is close to ideal and I should be getting between 38 and 41 MPH.  Any idea what is wrong?  The dealer has not been very helpful.  For the tech info:


One 200 pound rider with 50 pounds equipment.


Correctly trimmed and nothing dragging.


Yamaha VF150LA SHO 25" Engine


Twin elliptical pontoons performance package with a length 23' 6" acid washed half way through ownership with no effect.


OEM Reliance 14 1/2" diameter 15" pitch stainless steel prop.


Fuel tank only holds 23.2 gallons.


Pretty standard floor plan, no galley or head. 


Bimini top down.


On flat fresh water lake in NY.


I have no cavitation but if I have too many guest in the bow I do, so I believe the height is set correctly.


Other then the color (black) I think I have provided everything.  I know the RPM is a little low and are considering a 14 1/2" diameter 13" pitch but I am not convinced that will make more then 1 or 2 MPH  difference.   Any help will be greatly appreciated.
 
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Do you have the ESP (tritoon) or dual ellipticals?   
 
Your max speed should be at least 40 mph.  My previous 23 ft tritoon with Yamaha F150LA maxxed out at 40 mph (gps) at 5700 rpms with Yamaha Reliance 14-1/4x17 SS prop.  That was with 2 adults, full tank fuel (52 gal) and around 200 lbs gear.    


You may have algae/growth on pontoons especially if you keep the boat in water or may have water in a pontoon.  


I assume you are using gps to measure speed.  Older type speedometers are not so accurate.
 
My previous Bennington was a 2375 gcw arch model with a 200 and when the toons were clean it would go 39mph but when they were dirty would only do 33mph...
 
Thanks for everyone input.  I have update the original post to make it clearer.  Yes, the boat has two pontoons and it is pretty clean. I have been having this problem since brand new.


@sunnyside360 your previous prop has much more pitch.  If I put that on this boat my RPM would below 5,000.


I still have a mystery here.
 
Have you had the engine checked for any internal codes?  A long shot...
 
Does that engine have the recall that was discussed on this forum? If I remember correctly it created a speed and rpm issue?
 
fishing guy said:
@sunnyside360 your previous prop has much more pitch.  If I put that on this boat my RPM would below 5,000.
Click to expand...

Yes, but mine was a tritoon (3 tube package).  I thought your original post indicated you had the ESP option which includes 3 tubes.   A number of owners on this forum who have tritoons with F150 outboards have posted high 30's to low 40's max speed.  Not sure what 2 tubes with F150 will do.
 
@adkboater I do not see any recall on this forum for a Yamaha 150.


@sunnyside360 You are correct that I miss stated the ESP option in the original post.  I have elliptical toons, but just two of them.  I would think they would provide less lift then three but, with less weight I would still have less surface area in the water and therefore be faster.  I think 3 toons only allow more speed when you couple it with a bigger engine.


My mystery continues.  Next time I go out I will give the bottom side a real good inspection and scrubbing to see if that helps.  Maybe the factory guys at Bennington forgot to attach something properly.
 
fishing guy said:
My mystery continues.  Next time I go out I will give the bottom side a real good inspection and scrubbing to see if that helps.  Maybe the factory guys at Bennington forgot to attach something properly.
Click to expand...

You have a:


- Prop problem


- Motor height problem


- Dirty 'toon problem.


The "factory guys at Bennington" didn't "forget to attach something."


Good luck, but accusing the good folks at BM is a zero sum game.
 
@goldnrod24  Hey I run a factory and no matter how hard we try things happen.  I certainly would not accuse anyone of messing up without proof.  This is my second Bennington and I have always been pleased. For all I know my local dealer dropped it and bent something getting it off the trailer.  I just mean I want to explore all options.


As for your suggestions:


The prop is undamaged and is usually what is used for this boat/ motor combination.


The motor will cavitate if I front load the boat so it is not too deep and it is not cavitating when I am on it by myself so it is not to shallow.


I had the same problem when brand new so it can not be a dirty toon problem.


The easiest thing for me to do would be to do a proper inspection,  What if I found an old rope wrapped around the works or some of my sonar wires hanging down.  It would be silly not to do this first.  Second maybe my throttle cable was not set up correctly.  An extra 400 RPM could really make a difference.  Thanks for the luck I could certainly use some on this one.
 
Do you have strakes on the elliptical tubes? Usually those boats are faster than the triple toons.
 
Water in a pontoon would slow it down...  does it list at all?
 
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Your ellipticals are the fastest of all Bennington hulls.  They're usually about 2 to 3 mph faster than the tritoons with strakes because of less weight and less drag.  They're great for owners that are cruisers (in straight lines)  or those that do some long distance cruising.


The propeller you have is the most popular model for Yamaha 150 hp motors.  My boat with a Reliance 15 pitch is getting 40 mph @ 6000 rpm's with the F150's 2.0:1 gear ratio.  With a 1.86:1 gear ratio on your 150 SHO, your boat should be running 42-43 mph if you could get the 6000 rpm redline out of it--and if the hull was clean.


My hull is the Express Tube, and I assume my engine pod is the same you have.  My engine is set up 3/4 inches off the lowest point on the transom--or one notch up.  When I trim my engine high, I get a little prop ventilation starting out--just like I like.  When I trim the lower unit down and go into a corner, no ventilation is experienced--like it should be.


Have you checked your model number to see if you're running the correct XL 25" lower unit?  A tape measure would also work.  If you've got a 20" motor, you'd also need an engine pod designed for a 20" motor.


I'm old fashioned in that I think any boat dealer should setup a boat properly--and stay with it until the boat is operating at peak efficiency.   Take it back to them and tell'em you want to see the redline and the speed the boat's capable of producing.  At a minimum, you should see 40 mph and 6000 rpm's--hopefully 42 mph.  There are too many owners seeing those numbers.
 
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Okay, you guys have given me a lot to check out.  I will be at the boat on Sunday and will report back.
 
Sorry the trip to the boat was delayed by the remnants of Harvey.  I have attached two pictures.  The boat shows no list. The bottom is getting pretty fowled this late in the season but that is to be expected and boat was slow at the beginning of the season.  The motor is not trimmed now no worries there.  It looks placed well to me but I am willing to here feedback.

20170904_133907.jpg

20170904_133631.jpg
 
As was mentioned previously, I'd invite your dealer to come along for a ride. I would also head to the nearest sandbar and wipe those toons down top to bottom, based upon the water line I see in your photo. My boat sits in the water all season and don't look like that because I wipe them down every week or so. As you stated, you had the problem from the beginning but dirty toons will also magnify the problem.
 
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