How fast does your small ob push?

[a_bullfrog_a]

Hi All, I want to read some brags to find out<br />what kind of Speed I could expect out of a small<br />ob on my 14 ft tri-hull. anyone with 20 hp or less:<br />what size boat and how fast(mph)? I've been eying<br />up the briggs stratton 5hp so any speed examples<br />with this ob would be great.<br /><br />3 motors are planned for my boat: Main, Trolling, and briggs stratton.<br /><br />main goal: putt around(not to slow though) and catch some fish.

 

[Snowdrggn]

Re: How fast does your small ob push?

10ft Zodiac, 1989 15hp Evinrude (modified), Pirhana prop (drilled), Smart Tabs, rigged boat weighs 170-175 lbs with fuel. 32mph (GPS verified)on fresh water, turning 6936 rpm. To date I haven't had a boat with a 5hp Briggs and Stratton go past me <br /><br /> On the other side of the coin, I also have a 1986 Evinrude 8hp, which push the boat around 18 mph, but it is also slightly under propped. Also in my collection I have a 1976 4hp Evinrude with a weedless drive, although it will run all day on pretty much no gas, I have had the odd energetic duck paddle past me! Top speed with the 4hp has never been measured, but I wouldn't be suprised if an electric trolling motor would outrun the 4hp weedless The beauty of the 4hp is that is will idle from dawn until dusk without a stumble, and it makes small lakes seem so much bigger.<br /><br /> Cheers,<br /> Snow. <br /><br />

 

[Winger Ed.]

Re: How fast does your small ob push?

I used to have a 12' Alum. flatbottom jon boat that was light enough I could pick up and carry, with a old early 60's era Johnson 'fastwin' on it. It was either a 18-20hp, something around in there. <br /><br />I got it up on flat water so fast it scared me. And I thought I was fearless. <br /><br />I don't know exactly how fast it was going, but I thought I was about to break the sound barrier.<br /><br />After that episode, I quit putting a gallon or so of racing model airplane fuel in it too.

 

[lark2004]

Re: How fast does your small ob push?

didn't like the nitro huh? what % was it you were running? just out of curiosity.

 

[rodbolt]

Re: How fast does your small ob push?

hello<br /> I occasionally run a 33 jonnyrude on my 14ft wide body jon, dont know how fast it is but sometimes I end up in the marsh when racing buddies down the ditch. the biggest proplem I have is cavitation burn eating up the props.I ran a 5 hp eska on a 10 jon years and years ago that powered me my dog 2 trolling motor batteries and fishing gear all over pascagoula MS harbour<br /> went 15 MPH or so.<br />plenty fast when your 12

 

[JasonJ]

Re: How fast does your small ob push?

I can get about 5-6 mph out of my 5.5 kicker when it is wide open in my 16.5 foot trihull.

 

[cobra 3.0]

Re: How fast does your small ob push?

15 hp Evinrude on a 13 1/2' Aluminum Princecraft cartopper. Speed 30 mph (GPS) alone.

 

[Winger Ed.]

Re: How fast does your small ob push?

Originally posted by lark2004:<br /> didn't like the nitro huh? what % was it you were running? just out of curiosity.

I don't know the percent, I just dumped almost a gallon of it in a halfway or so full 6 gallon O/B tank.<br /><br />I liked it fine, its just REAL hard on the engine.

 

[55Crestliner]

Re: How fast does your small ob push?

My 12'er is doing 24.9 with an 18 horse Johnson. I'm way under propped, it's turning 5650rpm - supposed to be 4500. <br />My boat is about 500-550 pounds with me and my boys when we did that speed.

 

[phatmanmike]

Re: How fast does your small ob push?

14foot jonboat with 14hp 1988 evinrude. me, motor, gas and boat weigh about 500 and go 32mph

 

[a_bullfrog_a]

Re: How fast does your small ob push?

thank You for the input folks. Now all I need is <br />to Find out is how that briggs stratton motor<br />performs. It's cheap and air cooled which is perfect<br />for some of my favorite fishing spots that are loaded with plant life.

 

[lakelover]

Re: How fast does your small ob push?

Starcraft SF 14' + 20 hp Mercury=29.1 gps

 

[walleyehed]

Re: How fast does your small ob push?

18ft deep-V dual console Starcraft, 7.5hp Johnson kicker Wide open.........8.2MPH.....

 

[jsfinn]

Re: How fast does your small ob push?

12 foot aluminum modified V Starcraft. With my old 5 HP Gamefisher I'd do about 18 MPH. I do about 22 with my 15 HP evinrude and smart tabs. I'm sure I'm underpropped too.<br /><br />This is by GPS.

 

[Winger Ed.]

Re: How fast does your small ob push?

Originally posted by a_Bullfrog_a:<br /> Now all I need is to Find out is how that briggs stratton motorperforms.

I'd recomend you find someone that rents them.<br /><br />Then for a few bucks you can take their's, run it as hard & fast as it'll go, hit a few stumps to see what happens, run it up on the beach, see how long it takes to starve out and die at full throttle, just basically beat the snot out of it.....<br /><br />Then if you don't have to call the neighbor to drag you back to the dock,,,, then decide it that's the motor you really want.

 

[cobra 3.0]

Re: How fast does your small ob push?

jsfin a 5 hp doing 18 mph? Is that a typo error?

 

[steelespike]

Re: How fast does your small ob push?

You may want to do a search on the 5 Briggs.<br /> No salt water at all.Not reccomended for trolling.<br /> Pretty serious vibration.Early models had trouble with with the over rev switch.Dont know if it was ever solved.<br />Ive heard Briggs service centers dont have a clue about them.<br /> We had a Gale 5 on a 12ft. flatbottom steel boat it planed very briskly with one in the middle seat with tiller extension.Ran about 15 to 18 mph.<br />The flat will generally run much faster than a similar sized soft chine bottom.

 

[Capn Mike]

Re: How fast does your small ob push?

Essentially, you're looking at whether or not you have enough HP to plane your boat. If you are planing, then sort of on a geometric scale, your speed will increase with horsepower.<br /><br />If the motor doesn't have enought HP to plane (as dictated by hull design and weight) then the rule on displacement boat speed applies: Sq. root of length X 1.3 = speed in knots X 1.2 = speed in mph (you finally get to use that sq. root key on your pocket calculator). Bullfrog, your 14' boat will have a maximum displacement speed of 6+/- mph, regardless of whether you use a 15 hp or 5 hp engine (14' sqd = 3.74 X 1.3 = 4.87 knots X 1.2 = 5.83 mph). <br /><br />In addition to their hull design, most tri-hulls are fairly heavy, and it takes a fair amount of HP to get them to plane. However, on a lightly-loaded aluminum boat or jon boat, sometimes it's sort of hard to tell when the boat goes from displacement speed to semi-displacement speed, thus the true claims of higher-than-displacement speed with minimal power. <br /><br />Both Spike and jsfinn are getting their boats to at least semi-plane with 5 hp....certainly possible with jon or really light boats' flat sterns and light loads. However, I know it takes much more than 5 HP to get my old, fat body on plane.

 

[jsfinn]

Re: How fast does your small ob push?

That was a typo - sorry! It should be the 5 HP pushed it along at a very steady and smooth 8 MPH!

 

[Paul Moir]

Re: How fast does your small ob push?

I've never measured speed much, but in a 14' tin utility with two adults, a child and a 6hp Johnson 2-stroke: 14+ knots = 16mph by GPS.<br />My experience is similiar to Snowdrggn's with a '72 4hp weedless and a 12' tinny.