? on fuel effeciency

[aerobat]

Re: ? on fuel effeciency

hm... on the other hand i wonder that at the fuel prices in USA you even talk about fuel efficiency...

what does gas cost ? 3.8 $ per gallon ? in germany we pay currently about 1.6 euro per litre , not gallon . thats about 2.2 dollar / litre. one gallon equals 3.78 litres, so per gallon we have here 8.3 dollars :facepalm:

 

[steelespike]

Re: ? on fuel effeciency

Crazy thread.
You get the the boat on plane at full throttle, than back off the throttle so it stays on plane.

Absolutely right to a point. Typical outboard best practical cruising speed is somewhere between just on plane and about 1000 rpm higher depending on the setup.

 

[emilsr]

Re: ? on fuel effeciency

[is it unsafe to go 60Knots in an aluimin? water conditions will be flat water for this every now and then speed, just to know I have the capability when I fell like surprising a real power boat.

[/QUOTE]

Not unsafe if you've got plenty of seat time at speed and perfect conditions, but a potential widow maker for the inexperienced pilot. I like speed, but you wouldn't get me in it going that fast.

Like others have said, it's probably a 40mph boat with that power.

To surprise a "real" powerboat you're going to have to run fast in rough water. That's what they're made for. (see my avatar; about 50mph in rough conditions. Wifey was NOT happy that day!)

 

[steelespike]

Re: ? on fuel effeciency

Its not unsafe to go 60 in an aluminum boat that is intended to make that speed with its max rated hp. However at that speed any boat could turn into a killer very easily and quickly.
He says his 25 on a 15ft aluminum goes 45knots. That about 52 mph.
That setup would make about 27 on a good day according to the calculator I use.
The 21 footer with a 115 would probably run about 35-40.
Only thing I can figure is he thinks km is knots when its actually kolometers. 45km converts to about 27 mph.

 

[86 century]

Re: ? on fuel effeciency

A worked over 200merc on an '80 starcraft ss would only make 55mph on a good day. That 115 would make a nice setup but no speed demon.

 

[thebrain]

Re: ? on fuel effeciency

A worked over 200merc on an '80 starcraft ss would only make 55mph on a good day. That 115 would make a nice setup but no speed demon.

sounds about right 55mph w/ a 200hp I believe the SC SS is a much heavier hull compared to the older MR210s.
STB

[is it unsafe to go 60Knots in an aluimin? water conditions will be flat water for this every now and then speed, just to know I have the capability when I fell like surprising a real power boat.

Not unsafe if you've got plenty of seat time at speed and perfect conditions, but a potential widow maker for the inexperienced pilot. I like speed, but you wouldn't get me in it going that fast.

Like others have said, it's probably a 40mph boat with that power.

To surprise a "real" powerboat you're going to have to run fast in rough water. That's what they're made for. (see my avatar; about 50mph in rough conditions. Wifey was NOT happy that day!)[/QUOTE]I do have plently of seat time I'm just tried of sitting on the edge of the seat all hunched over and ducking down just to stay in the small boat at WOT.

I would'nt try a real power boat unless the water was flat. why do you say trying a real power boat must be done in rought water?

For me when leaving FT.Walton,FL toward the East pass it's all one big race everyone is racing up to the no wake zone.
STB

Crazy thread.
You get the the boat on plane at full throttle, than back off the throttle so it stays on plane.

yes that's for fuel effiency I should have edited the subject to researching fuel effiency, top speed & GPH. for a desired hull.
here's a thread for my desired hull.
http://www.sportfishermen.com/board...ter-console-aluminum-v-hull-2200-a-27208.html
seller states 30-35mph w/ a older 1985 120HP.
so w/ limited infor. I'm using this add as a benchmark.

what do you guy's think about the speed increase if any w/ an additional 20HP (140)
STB

 

[aerobat]

Re: ? on fuel effeciency

when it comes to speed i,m pretty sure 60 knots are nor with a 115 neither in a 140 in the cards when we talk about a real gps speed value.

it much depends on the hull design ( deep vee or flat bottom) , the mass of the boat and the prop .

my 21 ft fisher cabin with roughly 3200 lbs runs with a V6 150 ficht ram about 41-42 mph measured with gps.

 

[thebrain]

Re: ? on fuel effeciency

41-42 that's moving along for a 3200LB boat.

the older MR21 hull is 900LBs engine around 300-350 plus battery, cooler, live well, anchors, fuel ect.add 250 estimated total 1500LBs

hull is a deep V hull.
image of rear

attached image of front & bottom.
STB

 

[aerobat]

Re: ? on fuel effeciency

well, try out and report how fast it will go . the 140 of course will have a advantage of some mph above a 115 .

but when you really talk about 60 KT , so 70 mph or 111 kmh look at the bass boat freaks which have to put a 250hp etec on the back to go 70mph with a boat roughly 1500lbs mass. and they have flat bottoms not deep vees- with all the negative aspects when the water is something other than perfectly calm.

beyond that a 115 on your boat may be a sweat combination with many fun- even when not at 60 knots.

 

[emilsr]

Re: ? on fuel effeciency

I do have plently of seat time I'm just tried of sitting on the edge of the seat all hunched over and ducking down just to stay in the small boat at WOT.

I would'nt try a real power boat unless the water was flat. why do you say trying a real power boat must be done in rought water?

For me when leaving FT.Walton,FL toward the East pass it's all one big race everyone is racing up to the no wake zone.
seller states 30-35mph w/ a older 1985 120HP.
so w/ limited infor. I'm using this add as a benchmark.

what do you guy's think about the speed increase if any w/ an additional 20HP (140)
STB

When I say seat time, I mean seat time in that boat at that speed. Things can go downhill quickly going that fast. If you're aware how to compensate for things like chine walk, great. If not it can get out of hand.

As for flat vs rough water, I'm not surprised at all when one of the bass boat guys pass me on smooth water. Let it get choppy though and that's where the beauty of the deep v comes out (bless you C. Raymond Hunt!). I've seen the south end of Choctawhatchee bay turn snotty with just a little bit of wind in the afternoon.

An extra 20hp will give you a few extra mph but not a lot. If you want to go fast, get a fast boat....but remember that someone will ALWAYS have a faster boat.

 

[thebrain]

Re: ? on fuel effeciency

When I say seat time, I mean seat time in that boat at that speed. Things can go downhill quickly going that fast. If you're aware how to compensate for things like chine walk, great. If not it can get out of hand.

As for flat vs rough water, I'm not surprised at all when one of the bass boat guys pass me on smooth water. Let it get choppy though and that's where the beauty of the deep v comes out (bless you C. Raymond Hunt!). I've seen the south end of Choctawhatchee bay turn snotty with just a little bit of wind in the afternoon.

An extra 20hp will give you a few extra mph but not a lot. If you want to go fast, get a fast boat....but remember that someone will ALWAYS have a faster boat.

edit I don't have seat time in a over powered boat I can relate to the chine walking when my way overpowered Trans am decides to fish tail it can get to the point of no return of control real easiely got to know your equipment. there will be a serious learning curve.

I'm now on the look out for a 115-140HP OB seams like the 115 is the most senseable choice for my desired mr21 hull. I plan a diet for this project boat maybe w/ weight reduction I can squeese I few more MPH and still have an ecomincal boat on fuel.

So you boating in my area Choctawhatchee bay, I allways chech the forcast mainly wind and direction before I head out if I see white caps in bay it's a no go w/ my 15' this is another reason to get a larger boat. it's funny when the North wind affects the bay the ocean it nice, w/ a larger boat I won't get beat to death so much getting to the pass.

BTW off topic. why do these insurance auctions allmost allways remove the prop. off these engines? are the folks that work at the auctions or the observers running off w/ the props.?

STB

 

[ezmobee]

Re: ? on fuel effeciency

115 will get the job done. 140 would be ideal.

 

[wagnerz]

Re: ? on fuel effeciency

Throw a 200 on there and see what she can do.

 

[thebrain]

Re: ? on fuel effeciency

EZ I'm using post #15 as a bench mark (did you read the for sale add) about how much more speed will an additional 25HP provide? comparing the 115 to the 140?

STB

 

[dingbat]

Re: ? on fuel effeciency

41-42 that's moving along for a 3200LB boat.

Why do you say that? Most "ideally" powered boats run right about that speed @ WOT. I run the same speed with a boat that weighs almost twice that.

 

[zopperman]

Re: ? on fuel effeciency

Throw a 200 on there and see what she can do.

no.
that's drastically overpowered. I'll tell you what it will do, it will chine walk or sit really low in the water.

 

[aerobat]

Re: ? on fuel effeciency

EZ I'm using post #15 as a bench mark (did you read the for sale add) about how much more speed will an additional 25HP provide? comparing the 115 to the 140?
STB

nobody can say for sure since it depends on the additional weight of the other engine and the overall boat layout. but with 5 extra mph and a noticeable better holeshot you are pretty close to reality.