Bass Boat Speed

[RightOnTarget1]

Guys, I'm a newbie here and this is probably a dumb question, but I see these guys claiming 70mph+ for their 22 ft bass boats with a 225 hp outboard.

According to posts I have seen here, a Speedster 15 with 215 Hp will do 55-60 mph (Mine is still in break-in. I haven't pushed it yet.).

The Speedster probably weighs half or 2/3 as much and has less drag (no lower unit, very little touching the water) and a ducted jet should be ~30% more efficient at converting shaft horsepower to forward motion than a prop due to edge effects.

What am I missing?
Thanks,
Jim

 

[seadoosnipe]

What your missing?.........

What your missing................understanding the difference in rated horsepower. That's all I can figure.

An outboard motor, now days, is rated horsepower at the prop. In the older days, they were rated horsepower at the powerhead.

A jet drive boat is in no way, comparable to a prop driven boat. The horsepower of a jet drive is rated at the power head.

For a 110 hp 787cc engine for instance,..........and don't quote me, but I think it was said to be rated at 65 hp at the pump.

So, when you see the words horsepower, it's not necessarily an equal equation to be used on all boats...........

You can't compare the horsepower of a jet boat to a prop and vice versa. You can't compare the horsepower to any boat, unless you know the rated power is specific to either the power head or the pump/prop.

Lastly, horsepower in a jet is built in two ways, engine power and forward momentum. The jet is a compressor. The low pressure area feeds the compressor. The faster you go, the more power you'll create.........:cheers:

 

[sporsterjoel]

Jet boats use high pressure water to propel the boat, prop boats bite and dig into the water. I have 24.5FT Doral with 5.7L V8 300hp and out of the hole and top speed it kick my sportsters *** and it weights 5000lb.

 

[BRJ]

Less efficient

I own both a bass boat and Seadoo jet boat. My 18.5 bass boat with 150 outboard will run 62 mph GPS and my Speedster 16 w/twin 110hp will GPS at 52. My first guess is you have the efficiency backwards, if you look at the major outboard manufactures websites you will see the exact same spec'ed motor will be rate at 1/3 the HP with a jet drive bolted on. Example on mercury motor's website The 110 hp jet outboard has the exact same spec's for as the prop driven 150/175 hp motor. Secondly I believe a bass boat has a lot less drag, both as it cuts the air with its lower profile and in the water with the pad V type hull. At top speed I would guess only the last 12" or so of my hull touch the water on my bass boat. With a deep V hull design of speedster I know a lot more of my hull drags in the water.

 

[RightOnTarget1]

Very interesting

Well, live and learn. To be perfectly honest, I think 55-60mph is plenty for me. I really appreciate the replies. Thanks!:cheers:
Jim

 

[xrider]

there is some bass boats out there that are wicked fast. one dude had a small bas boat with dfferent engine that factor (he didnt said what it is and it had no markings on it) said it will run clos to 80pmh on nice water.

I saw some damn fast boats out on potomac past weekend, donzi, formula and some others, most with thruhull exhaust so you can hear them from mile away.

 

[scary]

better not hit any waves in a bass boat at 50+ you will most likely be taking a ride 60+ for sure air lift kills

 

[xrider]

ohh this boat was on local river thats only about 20-30 feet wide and flat as glass. love flying around, its awsome. it does widen to some 50-70 feet few miles down but at some areas its tigh to get around stuck trees.

 

[Nate Surveyor]

A direct prop is more efficient. When you run that power through a gear box, you loose a little power. When you run that power through the JET boat stuff, you loose alot of the power.

So, to make a jet boat keep up with a prop boat, you would need more hp due to loss in the jet. So, put an open prop on a jet ski, and you would ... pass alot of boats on the lake, if you got the modification just right!

Also, some of the Jet boat manufacturers are deliberately doing stuff to keep the top speed down. Because they don't feel that their craft is safe at 70 MPH. You may have a ski that says 265 hp, that will not go as fast as one that says 135 hp. This is probably due to the tuning of the motor. And, the 265 one is alot heavier.

A long time ago they outlawed 3 wheeled ATV's due to folks turning them over, and getting killed. The PWC manufacturers are concerned about what can happen at 70 mph, and deliberately tune the motor to stay below 65. It sure gets to 65 fast though!

Just some thoughts on the matter.

Nate

 

[unclejay]

Difference Between

Jet boats handle differently, especially in hard turns or on a top of wakes ( who me ?) Difference between a 400 hp pickup truck and a 400 hp Corvette.

 

[vilord]

I'd say its more the difference between a 900hp corvette and a 400 horsepower nissan silvia/honda prelude.

The corvette has much more raw power and can outrun the prelude, but the prelude is more fun any day.