Jet boat loses 30% efficiency or worse, true??: talk me into still getting a jetboat!

[JoshCanSwim]

EDIT as I had bad info:

I was TOLD that a jet boat is 30% less efficient in HP usage or rather applying the HP of the engine into moving the boat.

The claim was with the same HP engine the jet boat gets 30% less 'power' than the same HP rated engine in a prop boat. So for a jet boat to match a 175 HP prop boat the jet boat would need a 250HP engine.

IF it is true that the jet boat engine design is less efficient for horsepower, why still get a jet boat?

How can I talk myself into the jet boat, I love the safety and everything else about them, but that MPG and HP loss.... that hurts if it is true

 

[Scottintexas]

With a jet boat engine design being less efficient for horsepower, why still get a jet boat?

How can I talk myself into the jet boat, I love the safety and everything else about them, but that MPG and HP loss.... that hurts

Do you have an documentation, links or such to help us understand what you are comparing ?

I don't feel my boat uses to much gas or doesn't go fast enough and my boat usually gets on plane faster and without any bow rise compared to my friends,

I suggest you get with a dealer for a water trial, only you can decide what is acceptable.

 

[Epsmith19]

With a jet boat engine design being less efficient for horsepower, why still get a jet boat?

How can I talk myself into the jet boat, I love the safety and everything else about them, but that MPG and HP loss.... that hurts

I dont know that this is true... all engines experience drive train loss. I've never hear that jets are less efficient than I/O or outboards in that dept

 

[Julian]

Can you show us the 30% efficiency data?

I just went out and grabbed the first recent review of a 24' boat to compare to a 24' Yamaha.

Searay 250 Sea Ray SDX 250 OB (2019-) | BoatTEST

At 26mph, 2.7 MPG

Yamaha 242LS Yamaha 242 Limited S (2019-) | BoatTEST

At 28mph, 3 MPG.

FourWinns TS242 Four Winns TS 242 (2017-) | BoatTEST

At 26MPH, 3.1 MPG.

I'm curious what you are seeing differently.... (I just chose 26mph as a frequent cruise speed....but looks to work for other speeds.....)

 

[Jameson Clark]

Someone show me how to get 3mpg out of my 212x!!!

 

[TheArk]

With a jet boat engine design being less efficient for horsepower, why still get a jet boat?

How can I talk myself into the jet boat, I love the safety and everything else about them, but that MPG and HP loss.... that hurts

I had/have the same concerns, so I started taking a look at some of the data out there. See this thread:

https://jetboaters.net/threads/thinking-of-switching-prop-vs-jet-in-charts.25316/

Specifically this image:

When you look at similar boats, the fuel economy isn't that far off. I think the fuel economy compromise is well worth the performance, better interior layout, and enhanced safety.

Plus, when you're not dragging a stern drive through the water, the avoided underwater strikes (like the one I had early this season) will easily make up for the slightly increased fuel costs:





That lower unit was virtually brand new, the prop was untouched in that incident ... The cost of the new lower unit could buy multiple seasons worth of fuel.

 

[Julian]

Someone show me how to get 3mpg out of my 212x!!!

Not going to hit 3mpg on the 212X

 

[Ronnie]

I can’t speak to the MPG differences if any but a jet boat will out accelerate a comparable prop boat off the line. A comparable prop driven boat will have a higher top speed.

Safety wise there is no comparison, any boat can kill you but at least a jet boat won’t leave you or anyone one hit by it in pieces. Finally, not to be penis but if you are worried about the cost of gas when it comes to which $40k+ boat to buy are you really in the market for such a boat?

When is comes to boating costs, recurring and non recurring, gas is on my list but is not very high on it. For example insurance costs me $750 per year, the luxury tax is currently about $250 per year, my upgrade and repair costs im too afraid to calculate. 87 octane fuel is around $3 per gallon or $150 per 50 gallon tank. Two weeks ago it took me nearly three days of boating and tubing to burn through one tank of fuel which was a good thing since fuel on the water that weekend was priced at $5.25 per gallon. My camping and RV fees were 5 times my fuel cost. Still worth every penny from my perspective. When I’m on my death bed I will not regret spending money on boat fuel but I think I would regret not spending it and not having the experiences that come with boating with friends and family.

 

[bronze_10]

What's the efficiency of the 230!? I always tell my friends that I am boating on 2.2 lotter of displacement against their 4.3 5.0 or 5.7

 

[Julian]

What's the efficiency of the 230!? I always tell my friends that I am boating on 2.2 lotter of displacement against their 4.3 5.0 or 5.7

Yamaha AR230 | BoatTEST

Yamaha boat tests with speed, fuel burn, video, pix, specs, reviews, comparisons, prices, engine test reviews, and maintenance videos. BoatTEST.com

boattest.com

 

[JoshCanSwim]

I was told by several boating friends that the reason they all went with props over jets is that the prop boats are always much faster than the jet boats for the same engine size/rating.

I know the jet boat can get a bit less fuel efficiency,5% to 15% it seems depending on what source you look at, etc...

What surprised me was the claim that the prop boats will always go faster overall than the jet boat.

I appreciate all the replies in this thread as well to help disabuse me of this notion.

 

[the MfM]

I was told by several boating friends that the reason they all went with props over jets is that the prop boats are always much faster than the jet boats for the same engine size/rating.

I know the jet boat can get a bit less fuel efficiency,5% to 15% it seems depending on what source you look at, etc...

What surprised me was the claim that the prop boats will always go faster overall than the jet boat.

I appreciate all the replies in this thread as well to help disabuse me of this notion.

Yamaha doesn’t advertise HP for jet boats anymore, so you can tell them whatever number you want. If you really want to blow their mind just get some 90hp decals and slap them on the sides of the boat.

 

[bronze_10]

I think Most of these articles are referring to the first gen jet's with massive v8 engines....

 

[bronze_10]

The time we did the newbern to beaufort run I calculated 3.3 I think... and that was a grounded down estimate.

 

[Troch1]

Someone show me how to get 3mpg out of my 212x!!!

Agreed! My 242X has never done better than 2mpg, even on 3+ hour 90 mile cruises. Maybe I’m doing something wrong? I know I’m enjoying every single gallon !

 

[Inthrustwetrust]

My 240 with twin 1.8s will hit low 50s fairly empty, mid high 40s fully loaded. Your gas mileage will very with conditions, weight, and how you are using your boat. We typically cruise 30-45 minutes to the sandbar, and then do that back home, with some occasional tubing. I fill the boat up after every use, I don’t think I’ve ever put more than $35 in at $2 a gallon, even after extra cruising and a hour or two of water sports.

If I wanted a fast boat I would have a bought a boat built for that. If I was worried about gas mileage I wouldn’t have bought a boat. What sold me were no other 24ft boat really came close in price, offered the safety of no prop, and two motors just in case, plus some of the other Yamaha features, tower, swim deck, etc.

 

[Bluewater272]

Can you show us the 30% efficiency data?

I just went out and grabbed the first recent review of a 24' boat to compare to a 24' Yamaha.

Searay 250 Sea Ray SDX 250 OB (2019-) | BoatTEST

At 26mph, 2.7 MPG

Yamaha 242LS Yamaha 242 Limited S (2019-) | BoatTEST

At 28mph, 3 MPG.

FourWinns TS242 Four Winns TS 242 (2017-) | BoatTEST

At 26MPH, 3.1 MPG.

I'm curious what you are seeing differently.... (I just chose 26mph as a frequent cruise speed....but looks to work for other speeds.....)

I think the point he's getting at, comparing the Searay to the Yamaha, is that the Searay is doing what the Yamaha can do with 60 fewer ponies. an extra foot of hull, and close to a ton of extra weight. I think if you put twin 150 OBs on the back of a 242, it'd haul ass, and cruise much more efficiently.

Also, I don't buy that 3MPG figure at all, but that's just me

 

[Dixie Highway]

I’ve heard the 30% rule applied to jet outboards like these:

In typical human fashion they take that and apply it to ALL jet boats (which would include PWC’s, they don’t run outboards you notice).

 

[OrangeTJ]

I would agree that generally propellors are more efficient at transfering engine power to the water and so a similarly designed hull with similar weight driven by a similarly powerful engine connected to a prop will probably have a higher top speed than one driven by jets. Does it matter? How often do you really plan to cruise at more than 30 mph? If you want a "fast" boat, and you don't mean holeshot, then there are probably better options. The jet drive setup has its own advantages over props, too. Jets require considerably less maintenance and have considerably less that can go wrong than most inboard or I/O boats. Outboards eat up the transom real estate. Everything is a compromise. Personally, I find the lower rpm operation associated with prop boats driven by larger engines to be more enjoyable than the relatively high rpm the jets use but that is just me.

 

[bronze_10]

These engins do spin!!!