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2nd Week In June Cannot Come Soon Enough!!!

McZiggy

McZiggy

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Hey everybody!  My wife and I just purchased a brand new 2014 21SLX with the new Yamaha 115 4 stroke.  Unfortunately the engine won't be in for a couple of weeks.  I feel bad for the salesman having to field multiple questions a day from me  :) .

I've been doing a ton of reading about what kind of speed is possible with such a setup, and really haven't found a ton of info as the 21SLX is a new model this year.  The boat has two 25" toons with no performance package, pretty much a basic SLX with a couple extras up top.

My wish is to be able to crack into the 32-33 mph range by myself on a top speed run under optimum conditions, and to run in the upper 20's with a boat full of people.  I don't plan to run around at WOT at all times, but would like to be able to cruise comfortably in the low 20's with a boat load of people and not suck a ton of fuel.

Thanks for the help.

Chris
 
Congratulations .It will be here shortly .
 
McZiggy said:
Hey everybody!  My wife and I just purchased a brand new 2014 21SLX with the new Yamaha 115 4 stroke.  Unfortunately the engine won't be in for a couple of weeks.  I feel bad for the salesman having to field multiple questions a day from me  :) .

I've been doing a ton of reading about what kind of speed is possible with such a setup, and really haven't found a ton of info as the 21SLX is a new model this year.  The boat has two 25" toons with no performance package, pretty much a basic SLX with a couple extras up top.

My wish is to be able to crack into the 32-33 mph range by myself on a top speed run under optimum conditions, and to run in the upper 20's with a boat full of people.  I don't plan to run around at WOT at all times, but would like to be able to cruise comfortably in the low 20's with a boat load of people and not suck a ton of fuel.

Thanks for the help.

Chris
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Don't feel bad, it's what they get paid to do. :) Congrats on the new boat.
 
I have a 2011 2275 RL with tri toons and lifting stakes, With the 115 Yami it would only go 27 mph with 2 people on the boat and struggled with four people to stay around 21 mph. I upgraded this year to a 150 Yami and it will go around 34 mph with 2 people and lots of power I didnt have with the 115. I was unhappy with the power for 2 seasons, So if you have the coins spend it on what you want on the front end for sure.
 
KC24 said:
I have a 2011 2275 RL with tri toons and lifting stakes, With the 115 Yami it would only go 27 mph with 2 people on the boat and struggled with four people to stay around 21 mph. I upgraded this year to a 150 Yami and it will go around 34 mph with 2 people and lots of power I didnt have with the 115. I was unhappy with the power for 2 seasons, So if you have the coins spend it on what you want on the front end for sure.
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That surprises me.  There is a review on youtube of the exact boat I have, but with an F90.  27.5 MPH top speed with one person.  I would think that extra 25hp would gain me a couple mph.
 
Last year I had a 22SLX ,2 tubes and a 90 Merc.With my wife and myself I got 28.3 gps .

I dont know if it is true, but I have been told for every 10 hp increase  = 1 mph .Once again,

I do not know that to be true ,just what I had been told in the past .
 
KC24 said:
I have a 2011 2275 RL with tri toons and lifting stakes, With the 115 Yami it would only go 27 mph with 2 people on the boat and struggled with four people to stay around 21 mph. I upgraded this year to a 150 Yami and it will go around 34 mph with 2 people and lots of power I didnt have with the 115. I was unhappy with the power for 2 seasons, So if you have the coins spend it on what you want on the front end for sure.
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If you're only getting 34 mph there's something wrong. What prop do you have?

McZiggy said:
That surprises me.  There is a review on youtube of the exact boat I have, but with an F90.  27.5 MPH top speed with one person.  I would think that extra 25hp would gain me a couple mph.
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25hp won't get you much with no strakes. You'll just be plowing more. IMO
 
McZiggy, KC24 is an R model boat which is quite a bit heavier.  I have an Rl and when it was new it did 27 WOT but I am down to 24 after a few years.  Here is the link to Yamaha performance bulletins: http://www.yamahaoutboards.com/owner-resources/performance-bulletins it shows for a 20' SLX which is close to you; you should have WOT of 31.  With a few people to run in the low 20's you will use 4 - 5.5 gallons of gas per hour, my guess is with a crowd of people to run in the low 20's you will be close to WOT. 

I am in the same boat as you as I like to travel with a full boat, the 115 is sufficient for just me and the wife but I made a mistake, I should have bought the F150 for when I have a full boat
 
Unfortunately, the 115 is already maxed for the boat.  My father has a Bennington RL210 with a Honda 200 on the back for when I wanna go fast, plus jet skii's and such.  With 2 weeks to go, I have nothing to do but hope, wish, dream, about what the boat can do.

I am super impressed by this forum btw.  Most places you post it takes days for anybody to respond, and most of the time is silly gibberish that doesn't pertain to the ops question.
 
Get strakes to have any chance of speed.  Carl is right, the extra hp only gives you a bigger wake.  Bennington might let you put a 150 on it and change the capacity placard. 
 
Hi,  just did the breakin and test runs on our new 22SL  over last wkend   It is a twin log  with  the 115 yamaha , strakes and a 13.5 x 15  yamaha  prop.   With one person on board and full tank of fuel,  34/35mph by gps.   4 adults etc. , 23/24 mph by gps.   It was a good wkend.  I am happy with those numbers.
 
Thanks for posting Dano.  Have to admit I am a little surprised that adding 3 adults knocked WOT down 11mph.  I have a 115 on an R and due to the R being heavier my WOT with only one person on board is 24-25 gps.  Never tried WOT with a full boat but perhaps I will next time just to see results
 
Well the 4 adult test is going to have to be redone I think.  I had the strakes added after boat delivery and the the shop that added them to the pontoon didn't put the the nose caps on the strakes, so I am currently running open noses on  all the strakes makes for an interesting ride.  That being said, with one person on board you can get the bow high enough to get the strakes to do their job. the numbers show that.  Situation wil lbe corrected shortly though.
 
dano said:
Hi,  just did the breakin and test runs on our new 22SL  over last wkend   It is a twin log  with  the 115 yamaha , strakes and a 13.5 x 15  yamaha  prop.   With one person on board and full tank of fuel,  34/35mph by gps.   4 adults etc. , 23/24 mph by gps.   It was a good wkend.  I am happy with those numbers.
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An important part that you left out is what were your rpms @ WOT?
 
sorry, rpms at WOT were right at 6000
 
dano said:
Hi,  just did the breakin and test runs on our new 22SL  over last wkend   It is a twin log  with  the 115 yamaha , strakes and a 13.5 x 15  yamaha  prop.   With one person on board and full tank of fuel,  34/35mph by gps.   4 adults etc. , 23/24 mph by gps.   It was a good wkend.  I am happy with those numbers.
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Wow.  That could be a record.  My 24SSL hit 35 when I had the 115, but I have the express package with 6 strakes.  Can you post a pic of your new strakes???  Sounds like whoever did it either really knows what he's doing or go lucky.  Good for you!
 
You're right on the edge between the "old" and "new" models of the Yamaha F115 engine.

Since you're waiting, maybe you'll get the new model engine with the counter rotating vibration system--like the F150.

If so, no one here's had any experience with that completely new motor.
 
I read that for a displacement vessel (big ship, small ship, pontoon, submarine, etc) max speed is capped by the length of the boat.  That's right, length of the boat.  There was a big hairy math formula that proved it to me, and I'd have to go dig it up again, but no one wants to see that.  Bottom line is you basically cap out at a certain speed, and no matter how much more HP you throw at it, your increases in speed are negligible.  UNTIL you start to plane up on top of the water...

You HAVE to get up on plane to get any serious increase in speed.  So whatever tube package you get, the strakes are a big bang for the buck.  In my opinion, once you're up to the 90HP range or so, you should spend your next pile of cash on strakes before spending any more money on a bigger motor.  I'm talking about the Express, Ellipticals, and twin toon setups.  The SPS and ESP hulls have fins/strakes built in and are specially designed and placed for handling reasons, and you can't "add" strakes to either of these hulls (far as I know),  But they both plane very well, so no need to add strakes to them.  But for the lower-end hulls, strakes can be the only thing that gets you up on plane so you can actually achieve the speed increase that a bigger motor should get you. 

Once again, what Carl said.  Just my extra 2 cents.
 
dano said:
Well the 4 adult test is going to have to be redone I think.  I had the strakes added after boat delivery and the the shop that added them to the pontoon didn't put the the nose caps on the strakes, so I am currently running open noses on  all the strakes makes for an interesting ride.  That being said, with one person on board you can get the bow high enough to get the strakes to do their job. the numbers show that.  Situation wil lbe corrected shortly though.
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Again, post some pics if you can of those strakes.  I'm sure a lot of guys here would like to see what you had done.

I can't imagine coming down off plane on strakes with no nose cones...  I assume there are no "tail" cones either, or you would stop pretty quickly!

How big are the strakes?  I think my factory strakes extend out 6 inches from the bottom of the tube.
 
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