Too little power to go faster?

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Marc K
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Too little power to go faster?

#1 Post by Marc K » Sat Jun 02, 2018 7:24 pm

OK, major newbie questions......... I signed up here after perusing the board for a long time, because I see a style that suits me! I now own my first pontoon. AND my first outboard.

It is an older 25' 2000 Crest II DL, powered by a Yamaha F115 4 stroke. Upholstery, carpet and Bimini top are in great shape because the boat saw very little use (189 hours) and had been sitting covered on a sling sitting in the boat house for 3.5 years. It lived at a weekender lake house that I bought. Mildew was NASTY but Marine 31 always works.

I replaced the water pump impeller, changed the lower unit oil, the crankcase oil and filter, new spark plugs, both fuel system water separator-filters and air intake. While flushing out the fuel system, I was forced to redefine my personal definition of "bad gas." Oh Wow.......I had no idea!!

I was expecting to change the injectors (the first year using EFI for this motor) but they started firing great after 1/2 to 3/4 gallon of fuel heavily laced with injector cleaner. My test for this is to slap to full throttle from idle, in gear. If there is NO (I mean zero) bog down or hesitation, I'm good to go.

So, realizing that my frame of reference is 40+ years of offshore boating in the Pacific - and I understand that I don't have a planing deep V hull, but...... I feel like I am plowing, no matter what I do. The front of the pontoons never get up in step.

WOT with with four adults and four kids, speed measured by GPS: 24-25 MPH at 5800 to 5900 RPM 6000 is maximum rating.
If I trim up, it quickly ventilates and the bow never rises. If I trim down, I can clearly feel the plow and I lose speed first, then RPM, then steering.

Other data points
4500 RPM is 16 MPH @ 5.8 GPH
3000 RPM is 12 MPH @ 2.6 GPH

The layout is full couches all the way around, so it is front heavy. The bow sits high when sitting in the water - about the balance that I would want to see based on experience. I do not know what the prop is yet - I was focusing on getting her running healthy for the Grandkid visit!

My instincts tell me "all is well" I am simply under powered for for the weight,size and pontoon tube design. Is it possible that the prop needs to be lower in the water? Or should this boat have a 150+? Picture of the pontoon profile is below.

Thoughts are welcomed!

Marc

Image

Image
Last edited by Marc K on Sun Jun 10, 2018 5:46 pm, edited 1 time in total.
Big and ugly but we love our 1999/2000 Crest II DL with a Yamaha F115

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Marc K
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Re: Too little power to go faster?

#2 Post by Marc K » Sat Jun 02, 2018 7:48 pm

Actually, I should have titled my post "Too little power to get on step?"

I don't need to go faster. Party in slow motion is where it's at for me.
Can't help but think of efficiency so I will likely just have to learn to "embrace the plow."
Big and ugly but we love our 1999/2000 Crest II DL with a Yamaha F115

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Rick McC.
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Re: Too little power to go faster?

#3 Post by Rick McC. » Sat Jun 02, 2018 8:17 pm

It actually sounds like it’s doing pretty good to me.
Rick

Sights are for the unenlightened.

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steve1313
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Re: Too little power to go faster?

#4 Post by steve1313 » Sun Jun 03, 2018 3:37 am

A pontoon is basically a displacement hull and really doesn't get up on plane like you are used to. As a result, trim has less effect than on a V-hull, especially when it comes to trying to get more of the hull out of the water. Tritoons plane a bit more and the center tube also allows for increased weight capacity and larger motors. There's a good chance that your boat is only rated for a max of 115 HP. If the capacity sticker is still on the boat it should tell you the max HP.

But as Rick says, your speed is pretty good for your setup!
Steve
"Serendipity" - 2017 Sweetwater 2286 WB Tritoon w/ 150HP Yamaha
Slipped at Lake Anna, Virginia
Primary Residence: Richmond, Virgina
Lake House: Lake Anna, Virginia

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bansil
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Re: Too little power to go faster?

#5 Post by bansil » Sun Jun 03, 2018 5:07 am

You would beat me back to the dock, 90 suzuki and i cruise at 12 mph, i have plenty of throttle left but any more and i get cavitation and serious rear slap from rear sinking in (trim doesnt make a difference)

Godspeed...

I JUST EDITED to reflect actual NON-SPEED we can do :happy
Last edited by bansil on Tue Jun 05, 2018 1:51 pm, edited 1 time in total.
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Marc K
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Re: Too little power to go faster?

#6 Post by Marc K » Sun Jun 03, 2018 2:48 pm

I sincerely appreciate the input - I am learning with help from you folks!

Sounds like all is well. I honestly don't need to go any faster, and I surely don't want to pay to go faster - it's just a guy thing....... :lol3

I took 'er out today to find some "sweet spots" with various loads on board. Started with just me and my dog, then added neighbors, a few at a time.
4000-4500 RPM looks to be a good balance point of forward motion and fuel consumption when I want to get somewhere. 3000 to 3500 looks be a good "miles per gallon" target for long runs.

But then this is all theory! MUCH more experimentation is required :biggrin2, so I obviously need to do some more runs after work tomorrow and the day after and..........It's a 45 mile round trip to the top of the lake and back, but only a 25 mile R/T to the Tiki Hut Bar and Grille. This whole week will be in the 90's and they have very, very cold beer there. Hmmmm..........

Marc
Big and ugly but we love our 1999/2000 Crest II DL with a Yamaha F115

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bansil
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Re: Too little power to go faster?

#7 Post by bansil » Mon Jun 04, 2018 3:52 am

wish we had a tiki bar on our lake :cry:

I need to quit work and open one I guess :drink2 :drink
Check out "Dudes" site www.whereisdude.com

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steve1313
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Re: Too little power to go faster?

#8 Post by steve1313 » Mon Jun 04, 2018 3:58 am

Marc K wrote:
Sun Jun 03, 2018 2:48 pm
I sincerely appreciate the input - I am learning with help from you folks!

Sounds like all is well. I honestly don't need to go any faster, and I surely don't want to pay to go faster - it's just a guy thing....... :lol3

I took 'er out today to find some "sweet spots" with various loads on board. Started with just me and my dog, then added neighbors, a few at a time.
4000-4500 RPM looks to be a good balance point of forward motion and fuel consumption when I want to get somewhere. 3000 to 3500 looks be a good "miles per gallon" target for long runs.

But then this is all theory! MUCH more experimentation is required :biggrin2, so I obviously need to do some more runs after work tomorrow and the day after and..........It's a 45 mile round trip to the top of the lake and back, but only a 25 mile R/T to the Tiki Hut Bar and Grille. This whole week will be in the 90's and they have very, very cold beer there. Hmmmm..........

Marc
You'll need to do a very thorough cost/benefit analysis. The shorter distance to the Tiki Bar may result in fuel savings, but it could also allow for more time at the bar, which may in turn increase your overall Tiki Bar bill. Remember, any analysis is more accurate if you have more data. This project probably will need extensive and repetitive analysis throughout the boating season so you'll be sure to capture the most possible data! :drink4 :mrgreen:
Steve
"Serendipity" - 2017 Sweetwater 2286 WB Tritoon w/ 150HP Yamaha
Slipped at Lake Anna, Virginia
Primary Residence: Richmond, Virgina
Lake House: Lake Anna, Virginia

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TWB
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Re: Too little power to go faster?

#9 Post by TWB » Mon Jun 04, 2018 5:16 am

steve1313 wrote:
Mon Jun 04, 2018 3:58 am

Remember, any analysis is more accurate if you have more data. This project probably will need extensive and repetitive analysis throughout the boating season so you'll be sure to capture the most possible data! :drink4 :mrgreen:
Gotta agree with Steve... it's amazing how much smarter I get the more I consume data. Especially very, very cold data. :drink
Paul & Michele
2003 Landau DX 24' Cruise "Loretta Jane"
2003 Mercury 75hp
My Rebuild: http://pontoonforums.com/viewtopic.php?f=16&t=26135

"Don't waste brain cells over something you can do nothing about." --My Wife

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Marc K
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Re: Too little power to go faster?

#10 Post by Marc K » Mon Jun 04, 2018 9:40 am

Man, I like the way you guys think! LOL :lol3
More data must be collected!
Big and ugly but we love our 1999/2000 Crest II DL with a Yamaha F115

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trucky
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Re: Too little power to go faster?

#11 Post by trucky » Mon Jun 04, 2018 10:45 am

It's just about 12 miles to the Tiki Bar on Lake Greenwood. The last time I was there they had about 4 full pages of different kinds of shooters. This cost/benefit analysis could take all summer I'm afraid. Then I'm told there's the sandbar just under the bridge where the ladies who partake of possibly too many shooters like to go...
07 Bentley 240 Cruise - 115 Mercury EFI Four Stroke

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bansil
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Re: Too little power to go faster?

#12 Post by bansil » Mon Jun 04, 2018 3:55 pm

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curtiscapk
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Re: Too little power to go faster?

#13 Post by curtiscapk » Tue Jun 05, 2018 6:12 am

I wish mine did 25! I got 23 out of her once! Sounds like your good to go...
Craig and Paula
"THE FLOATER" rebuild Spring 2013
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