14 foot boat 79' 70hp

[Lakers Fan]

Does anyone have an idea how fast my 300lb boat can approximately go with a 70hp engine? It is my first boat first time ever getting a boat(used) working on it. Don't know too much about them.

 

[Lakers Fan]

Re: 14 foot boat 79' 70hp

this is my first time on any forum as such lol. Restoring an old boat. It is fun but alot of questions.

 

[tashasdaddy]

Re: 14 foot boat 79' 70hp

1st there are not many 300Lb boats rated for a 70hp. what kind of boat is it? pictures?

you can up load to a free service like photobucket.com then you choose the pictures you want( clik the little box at the bottom left of the picture) scrool to the bottom of the page, clik generate html, it will take you to the next page, scroll down to thumb nails clik on that and copy, then insert it into your post.

also if you are planing on posting pictures, you can use the Blue post reply or the go advanced, there you can upload directly from your computer. besure you pictures have been resized to fit the format. 640x480 max

 

[Frank Acampora]

Re: 14 foot boat 79' 70hp

My 14 foot flat bottom with a 60 did 45 MPH. With a 90 it goes 56 MPH. Notice that 33 % horsepower increase only gave about 24 % speed increase. This number is artificially high because the larger engine lifted more of the hull out of the water, thereby causing drag to increase less. Drag increases faster than speed so exponentially more horsepower is required to continue to increase speed. At this point, a 120 might yeild only 4 MPH more.

If yours is a flat bottom, then expected speed (not actual) should be somewhere in between; a deep vee or modified vee bottom will be somewhat slower. Of course, nothing is etched in stone: speed depends upon a number of factors besides boat length and weight. Design, and engine performance are two others. Propping correctly also counts for a lot.

 

[JB]

Re: 14 foot boat 79' 70hp

Well, lemme see. . .
Boat= 300
Engine= 250
Operator= 175
Fuel, battery and misc = 100

Total weight = 825

Square root of 70/825 = .29
times bottom factor (flat) 200 = 58.26mph theoretical WOT if ideally propped and rigged.

That is too fast for a 14' flat bottom boat.

 

[Texasmark]

Re: 14 foot boat 79' 70hp

Agree JB and to add to the potential for disaster, this is his first boat; that translates to no or limited experience.

Laker's Fan, you had better back up and reassess your situation before you kill yourself or some innocent bystander.

Mark

 

[jtexas]

Re: 14 foot boat 79' 70hp

70 would be about right for a 14' boat with remote steering if the transom is at least 20 inches high and over 5? feet wide.

nothing about "flatbottom" in the original post.
what kind of boat? how did you arrive at 300lbs?

 

[tashasdaddy]

Re: 14 foot boat 79' 70hp

maybe he will post some pics, like i ask. there is no way to assess what he has until then.

 

[Chinewalker]

Re: 14 foot boat 79' 70hp

There are definitely SOME 14-foot hulls capable of handling a 70hp, in capable hands. A high performance hull that is designed for it would LOVE that sort of power. But, you can't polish a turd. If you're putting a 70 on a 14-foot john boat, bad things are likely to happen...
- Scott

 

[JB]

Re: 14 foot boat 79' 70hp

Well, yes. He didn't say it is flat bottom.

If is a semi-vee the WOT comes out 50.75mph,

deep vee comes out 43.5mph, and

sponsoned hydroplane come out at 72.5mph.

Sure would like to see pix, like daddy said.

 

[Dhadley]

Re: 14 foot boat 79' 70hp

Just for kicks -- an SST 60 runs a stock 3 cylinder OMC / BRP powerhead and typically runs in the low to mid 80's.