Back to the main site

Turtle and The Hare

C

CcanDo

Well-Known Member
Messages
188
Reaction score
15
We raced the Bennington....Over the weekend holiday we took both the Bennington and the Motion to Texoma. Well, we raced one against the other. The race course was 1 mile long (GPS), the Bennington was given a 1/2 mile advantage and got to start first. (The Bennington runs 56.3 MPH) Well before the 1 mile marker the Motion had passed the Bennington, turning only 5,000 RPM, the agreed limit. (The engines were dynoed @ 6,100 RPM) Now, if the Bennington had "Bow Thrusters", it could have made a quick 180 degree heading change, gotten back to it's starting line and maybe won the race.

Then, the Bennington became the "Mother Ship", the Motion was tied on and together they floated about. How is that for a romantic ending ??
 
OK, I'm dumb,or too old. What's a Motion?
 
OK, gotcha. Offshore stuff. Lots of them at the Jersey shore when I lived there.
 
Geoffrey & Brenda said:
Nice ending to the story, and i hope you all had a good day on the lake!

Now you need to get busy designing this bow thruster setup :D
Click to expand...
Thanks, You know, I might do that if Bennington Engineering showed interest in collaborating !
 
(The Bennington runs 56.3 MPH)

What Bennington runs 56.3 MPH???? More details please!
 
Just get the engines on the outer toons option. Walk it sideways to the dock.
 
Last edited by a moderator:
A tritoon ran at the Shootout at Lake of the Ozarks, Missouri last week. He went through the radar @ 112 mph after entering the running mile @ 40 mph. It ran like a tunnel hull, with the nose about 15' in the air for a couple of seconds. Videos are on UTube.

I'm not mentioning the brand, but it had three 300 hp Mercury's on it--and had a full interior package.

Could that Motion handle that boat?
 
I like speed, but having the nose of my pontoon 15' in the air would not be good - my pontoon is only 22'.
 
Geewest said:
(The Bennington runs 56.3 MPH)

What Bennington runs 56.3 MPH???? More details please!
Click to expand...
Well.......That was behind the pickup, you know. LOL....

OK, "THE" subject boat is shown on Yamaha's web site, under performance spec for the Yamaha 350, there it ran 51. We bought the boat and put on a out-of-crate, new 350. Then, debate followed about approval for using a hydraulic Jack Plate. The decision was made to move forward. We designed a transom gusset system that was thought to be over-engineering. The center tube was found to have down deflection, before the gusset or Jack plate, with the engine mounted. After the gusset/jack plate, the engine was mounted and deflection was gone. The deflection was creating a hook. The last event was installing a prototype prop.
 
Bamaman said:
A tritoon ran at the Shootout at Lake of the Ozarks, Missouri last week. He went through the radar @ 112 mph after entering the running mile @ 40 mph. It ran like a tunnel hull, with the nose about 15' in the air for a couple of seconds. Videos are yoUTube.

I'm not mentioning the brand, but it had three 300 hp Mercury's on it--and had a full interior package.

Could that Motion handle that boat?
Click to expand...
Probably.....The Motion was at Lake of the Ozarks before we got it. It ran as the Moo-Boat. A big dairy farmer owned it, painted spots to look like a Holstein milk cow and called it his Moo-Boat. At the time, it had two 750 HP engines, ran 140+ and became the National Champion Lake Of The Ozarks Shoot out winner. The boat also stands as a National and World Champion Off Shore Winner.

We wanted the boat because of nostalgia and lay up schedule. The boat is said to be the only boat built using shuttle craft foam between an inside/outside Kevlar lamination. The lay up schedule shaved 800 +/- pounds off from that of competitors.
 
ericscher said:
About $150,000 i think... ;)
Click to expand...
Hi Eric,

That is a budget number for the bare hull, maybe a little low. Then comes the trailer, engines, transmissions, headers/pipes, gauges, throttles, interior, paint, sea strainers, rigging, props and etc.

Then comes "Dialing It in", which is no small task. Prop Shaft Ht. is controlled by drive spacers, AKA "X" dimension. (Same Physics as an adjustable Jack Plate) Whereas, the Props are designed to run with the Prop Shaft being 1/2 above the water line, 1/2 below the water line, Props are identified as surface piercing. The Tunnel Hull is Hydrodynamic untill speed introduces Aerodynamic. The transformation is referred to as "Breaking Loose". In other words, similar to an aircraft wing. Air flows over the top to crate lift and through the tunnel to create compression. Between the two factors, the boat gets lighter and even "Flies" from swell to swell. The CG effects Angle of Attack, forward will stuff the Bow, Aft will introduce Porpoise and scrub speed.

Like an Aircraft, the acceptable CG is within an envelope. The pilot is responsible for locating the load within the envelope. However, boat performance is perhaps even more sensitive to CG than the Aircraft.

Boat prop design is a science. The prop is first, responsible for Bow Lift. Bow Lift is relative to the amount of wetted hull surface. The prop cup and rake will suck the transom down, while the prop shaft is parallel to direction of travel. Trimming the drive out does not create the same results. Then, prop slip is a design consideration. Both Bow Lift and Prop Slip are sensitive to "clean water". The engine/drive that is mounted close to the hull risks "Dirty Water". (aerated and turbulent)

The above also applies to the Pontoon Boat. There is a CG "Sweet Spot", the wave shield (Bow Tip to Stern, creates compression) However, above deck, there is an abundance of parasitic drag. But, the ability to control Prop shaft Ht., "clean water" and Prop Design individually create performance in increments. However, add those points together and final results get greater.
 
Last edited by a moderator:
Ok, that settles it, CcanDo must be an engineer, i've never heard a lawyer talk like that!

So, Lloyd, where does all this technical knowledge come from? Are you a racing boat designer, aeronautical engineer, doctorate in physics...?

Now you have to post some pictures of the Motion in motion, i think we'd like to see it!

Eric, i hope you understood all that, it just made my bitty brain dizzy :D
 
CanDo: there is lots of talk here on this fourm about props. Most of the guys have smaller outboards and the props seem to make such a small difference. Most of the posts I see people go from 32 mph to 33.5 or 34 mph. From where I sit a 1-2 mph gain for all the switching out and the cost of a $400+ dollar prop is hardley worth it. My question is. I have a 350. Merc inboard/outboard with a Bravo 3 my top speed is around 43mph in the best situation what could you expect to see as far as top end with the best prop set up on a Bost like my'n
 
CcanDo said:
http://www.offshoreonly.com/forums/general-boating-discussion/231313-35-motion-udderly-fantastic-catcando-restoration.html

This will give you a partial idea of what the boat has been through !
Click to expand...
All I can say is WOW! I just read through that whole build topic, amazing. I was able to read the words, didn't have any idea what you were talking about most of the time, obviously because of my lack of knowledge in all things nautical. From the responses, they seem to understand it all. I must say, I sure have a lot of respect for your knowledge and thoroughness in this project. I can't imagine the cost of it all, but it sure seems like no expense was spared. Well done!

Derrick
 
Geewest said:
CanDo: there is lots of talk here on this fourm about props. Most of the guys have smaller outboards and the props seem to make such a small difference. Most of the posts I see people go from 32 mph to 33.5 or 34 mph. From where I sit a 1-2 mph gain for all the switching out and the cost of a $400+ dollar prop is hardley worth it. My question is. I have a 350. Merc inboard/outboard with a Bravo 3 my top speed is around 43mph in the best situation what could you expect to see as far as top end with the best prop set up on a Bost like my'n
Click to expand...
The prop design is but only a part of the over all set up. Regardless of which prop used, any prop will work better as "cleaner water" is introduced. That means, the closer the the prop is to the hull, agitation of water becomes greater. The agitated water is then less dense and increases prop slip. Prop slip robs horsepower and when calculating for slip, may be misinterpreted as a low percentage number. No different from the household washing machine, the washing machine agitates and requires power to make it go. The Bravo 3 Gimbal is thought to bolt directly to the Engine, therefore, no drive line flexibility for using what is called a "stand off box". (A "stand off box" is bolted to the transom and the drive is bolted to "stand off box"). However, even if one were to create a scheme for using a "stand off box", the transom integrity may not be adequate.

The only solution may be to engineer a "step" or "notch" under the engine/drive cavity, causing the drive/prop to think the prop has been moved back and up. However, before all of that, CG is the hinge point. Whereas, the engine is ahead of the transom, that weight moves the CG forward. Whetted surface is exponential to CG location.

Bennington has done a beautiful job of creating creature comfort furniture and amenities. However, those features add weight. Bow weight adds to the engine weight located ahead of the transom and moves the CG well ahead of the same horsepower outboard, CG. Thus, increased whetted surface, to the exaggerated point of plowing.

Mercury Racing has used the analogy, enough horsepower bolted to a barn door will make the barn door go. The same applies to the pontoon boat, enough power will overcome a lot of hurdles. Then, a high prop slip number is mitigated. A bigger, well designed prop with consideration for cup, rake, diameter and pitch will create performance. However, the 350 would require warranty canceling modifications. Even then, it may be difficult to reach a serious speed change. The typical effort is to re-power with a bigger engine. Then, the drive prematurely fails, the transom/hull fatigues.....It becomes a viscous cycle.

Your comment, "Hardly Worth It" is a good summation. The I/O package is a good option. Subject to desiring more speed, the I/O 350/Bravo 3 package may have practical limitations.
 
You must log in or register to reply here.
Back
Top