Jet Boat Yes/no?

kengladd

Seaman
Joined
Jul 16, 2006
Messages
62
Thinking about a yamaha 23, never had a jet, would
you be so kind as to give me some opions on the new 23? Thanks
 

bjcsc

Lieutenant Commander
Joined
Jun 1, 2006
Messages
1,805
Re: Jet Boat Yes/no?

Can't help with a Yamaha opinion, but jets in general: I love mine...
 

deejaycee_2000

Captain
Joined
Mar 28, 2006
Messages
3,447
Re: Jet Boat Yes/no?

yamaha, is a great choice .... but the jet part I know nothing about .....
 

ziggy

Admiral
Joined
Jun 30, 2004
Messages
7,473
Re: Jet Boat Yes/no?

the mr-1 engine in these boats is pretty darn good. high revin, but seems irrelevent... i had that engine in a pwc and got 239 hrs out of mine w/o any engine issues at all. had valve inspected at the 200 hr mark per the maint. schedual. valve specs. were right in the middle of tolerance. i know nothin of the boats. but the engine served me well in a pwc.....
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Jet Boat Yes/no?

just remember even though Yamaha is one of the best, in jet boats, you still have the loss of hp, compared to a propped boat. most jets are 30-40 percent loss thru the jet drive, compared to a propped boat. like i said, Yamaha has the jet done right. i have 2 pwc's, but i have propped boats.
 

tommays

Admiral
Joined
Jul 4, 2004
Messages
6,768
Re: Jet Boat Yes/no?

Well the yamaha has a 10250 WOT at 50 MPH and you will be spinning 7000 RPM to run at 28 MPH

Twin 160 HP motors


The same boat from Sea Doo has 8000 RPM WOT at 57 MPH is able to run 28 MPH at only 5500 RPM

Twin 215 Hp motors


Tommays
 

rndn

Commander
Joined
May 20, 2007
Messages
2,323
Re: Jet Boat Yes/no?

Yamaha didn't get to where they are by selling junk. Interesting comment about the efficiency of jet boat verses propped.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Jet Boat Yes/no?

yes it is. you burn 30-40% more fuel to achieve the same thing.
 

180shabah

Rear Admiral
Joined
Mar 26, 2005
Messages
4,995
Re: Jet Boat Yes/no?

yes it is. you burn 30-40% more fuel to achieve the same thing.

Test Power: 2 x 160-hp Yamaha MR-1 H.O
RPM MPH Knots Total GPH MPG NMPG Range NM Range dBa
3000 6.4 5.6 2.0 3.20 2.78 144 125 75
4000 7.3 6.3 2.3 3.17 2.76 143 124 77
5000 8.4 7.3 3.5 2.40 2.09 108 94 79
6000 13.7 11.9 5.2 2.63 2.29 119 103 80
6500 20.2 17.6 6.5 3.11 2.70 140 122 80
7000 28.4 24.7 7.6 3.74 3.25 168 146 83
7500 31.7 27.6 8.6 3.69 3.21 166 144 85
8000 33.4 29.0 9.5 3.52 3.06 158 138 87
8500 38.6 33.6 11.4 3.39 2.94 152 132 88
9000 42.4 36.9 13.8 3.07 2.67 138 120 92
9500 44.9 39.0 15.8 2.84 2.47 128 111 92
10250 50.4 43.8 21.0 2.40 2.09 108 94 93


This thing isn't exactly a gas hog. 23', twin engines with 320 total hp and nearly 4mpg.

Mercury also hs some great jet drives out there now. 200+ hp AND still capable of 5mpg at cruise and 50+ mph.

Check out Sugar Sand Boats
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: Jet Boat Yes/no?

The 30 to 40% more fuel usage is in outboard jets, not inboards jets. The design of an OB jet is very inefficient, I/B jets are much better.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: Jet Boat Yes/no?

you can test all you want to. put them side by side, and see what happens.
 

Skinnywater

Commander
Joined
Mar 7, 2002
Messages
2,065
Re: Jet Boat Yes/no?

The 30 to 40% more fuel usage is in outboard jets, not inboards jets. The design of an OB jet is very inefficient, I/B jets are much better.

Agreed, but the fuel usage and power drop is closer to 30% then 40%. And closer to 25% with aftermarket impeller and intake shoe mods.
 

bigmacfan

Seaman Apprentice
Joined
Jul 2, 2007
Messages
38
Re: Jet Boat Yes/no?

Yes, for sure!

I had a Sea Doo Speedster that I totally loved! The only reason I got rid of it is that I moved to live on a lake that outlaws jet drive engines. It was traumatic to get rid of it and get my Sea Ray bowrider.

I love the way the Yamahas are set up. I would really look at those if I could have a jet boat. They look so comfortable. They have much less hosepower than the Sea Doo's though, so that is a consideration.

Like someone said, Sugar Sands has some nice boats as well.

I much prefer a jet boat over a prop, personally.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Re: Jet Boat Yes/no?

We live jet boats here in the NW. I have outboard jets (and so do many of my friends) and some of my buddies have inboard jets, there's a huge difference in how efficient each design is. Out boards jets suck when it comes power loss and fuel consumption, inboards are far better, not as good as a prop, but much better than an O/B. My freinds and I also have O/B's with props and I/O's, so we're able to do direct comparisons. If an inboard jet is what I wanted or thought I needed, fuel consumption wouldn't be the an issue. I have several jet boats at my place right now, one tied to the dock that gets used every day.
 

QC

Supreme Mariner
Joined
Mar 22, 2005
Messages
22,783
Re: Jet Boat Yes/no?

When you get down to it, it really doesn't matter whether the jet is more or less efficient, or the hull is more or less efficient. What matters is the efficiency of the package. There are very few 50+ MPH 23 footers that get over 3.5 MPG . . .

Also, one of the most memorable thoughts I was ever given concerning boats was "you're only talking $5 to $10 a weekend". That was almost 25 years ago and I bet it's still close to true. Fuel is a small part of the cost with a pleasure boat. So go with the application like ondarvr hints.
 
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