plaining my boat

[charliesracing]

i need to know how and when my boat is plained correctly

 

[oops!]

Re: plaining my boat

hi charlie...

welcome to i boats....

the people here are really great....there's pros from every feild here...

just about any question you want to ask has been discussed on these forums.
just hit search..youll have our answer...

just fyi...the moderators here are not paid for their time, and are VERY up on their stuff...so treat them with respect...theve earned it..

this board is divided into several different headings...and your question would be best asked on "boat topics and questions, not engines"..

you have placed this in dock side chat....(this is still a cool area, as you get to know the people here and really make new friends".

in answer to your question......
you will uasually pick up speed and engine rpm....your plained correctly when your engine speed is highest without loosing bite on the prop.

hope this helps
and welcome to i boats

 

[MikDee]

Re: plaining my boat

Easy, as soon as you see a roostertail in the wake your boat is planing, almost all boats have most of their hull out of the water, and are riding pretty level by then, as you go faster, the roostertail gets flatter.

 

[QC]

Re: plaining my boat

The correct definition of planing is when your boat speed exceeds that of your bow wave . . . Basically when your boat climbs over the wave that she is creating in front of her. This can be best confirmed by looking at your transom. When the transom is "dry", then she is technically on plane, whether there is a rooster or not . . . What I mean by "dry" is that there is no water up and on your transom, the boat is no longer in the water but on the water . . .

This is not to say that this point is efficient. Most boats find an efficient plane a couple of hundred RPM above that point. This actually has nothing to do with prop "bite" either. What oops describes is really a top speed run . . . An efficient plane is where the hull has completely come over, and MikDee's description of the "roostertail gets(ing) flatter" is pretty close. I don't recall what your boat is, but with an I/O this is typically between 3000 and 3500 RPM, although she may technically plane just above 2000 RPM for example. These figures have nothing to do with engine efficiency. It just happen to be where most boats are most efficient for hydrodynamic reasons which outweigh the engine efficiency points. Also has to do with the fact that you have only one gear and you just kinda get what you get . . . Welcome aboard!

 

[Nandy]

Re: plaining my boat

The correct definition of planing is when your boat speed exceeds that of your bow wave . . . Basically when your boat climbs over the wave that she is creating in front of her. This can be best confirmed by looking at your transom. When the transom is "dry", then she is technically on plane, whether there is a rooster or not . . . What I mean by "dry" is that there is no water up and on your transom, the boat is no longer in the water but on the water . . .

This is not to say that this point is efficient. Most boats find an efficient plane a couple of hundred RPM above that point. This actually has nothing to do with prop "bite" either. What oops describes is really a top speed run . . . An efficient plane is where the hull has completely come over, and MikDee's description of the "roostertail gets(ing) flatter" is pretty close. I don't recall what your boat is, but with an I/O this is typically between 3000 and 3500 RPM, although she may technically plane just above 2000 RPM for example. These figures have nothing to do with engine efficiency. It just happen to be where most boats are most efficient for hydrodynamic reasons which outweigh the engine efficiency points. Also has to do with the fact that you have only one gear and you just kinda get what you get . . . Welcome aboard!

Errr, what he said! LOL!

 

[Texasmark]

Re: plaining my boat

My definition is the same as QC's. When the water leaves the transom you are there. Agree on the efficiency spot too which you can easily prove by looking up performance curves on www for rigs and you can spot the planeout in a heartbeat and will notice the max eff. is just above that.

Course hull type has a lot to do with it too. On a Johnboat it's a no brainer. Soon as that sucker hits it the nose lays down and away you go. On some deep V's with I/O drives it will be more subtle a lot more subtle.

Mark

 

[Frank Acampora]

Re: plaining my boat

There is no "Correct Planing" The boat is either on plane or not. Now, if you want to know when you are running "best", let's assume you have power trim. Once the boat is on plane, you feed in up trim until the prop starts to ventilate. At this point you will hear the engine make more noise, speed up, and the boat will probably slow a bit. Feed in a little down trim until the prop "bites" again. This point will be close to where you get the fastest speed for the engine RPM. If you have a trim gauge, remember this setting.

If you have an outboard with no power trim, you move the adjusting pin from hole to hole until you find the one that gives the best top speed. Then, If you are towing someone on water skis, you move the tilt pin in one hole, in order to have the boat plane faster and pull them out of the water faster.

Simplified explanation: moving the lower unit closer to the transom drops the bow and gets the boat on plane faster--but top speed is lower. Tilting the lower unit away from the transom raises the bow of the boat and raises top speed until you go too far and the prop sucks air and loses bite.

In the avatar (picture in upper left), that boat is planing with the bow out of the water and it is at top speed. If you look closely, you can see the engine tilted or trimmed up to keep as much of the hull out of the water as possible.

 

[bekosh]

Re: plaining my boat

A couple of examples...

On plane. Most of the hull is up out of the water.

Not on plane. Most of the hull is in....err under the water.

 

[Boatist]

Re: plaining my boat

Advance your throttle a little at a time with the drive trimmed in just a little.
As the boat gains speed the bow wave will build and the bow will rise.
Keep advanceing the throttle a little at a time and the bow wave will start to move further toward the stern.
For most boats at about 18 to 23 MPH the boat will over take the bow wave.
When this happends the bow will come down on the water and the speed will pick up without advance the throttle.
At this point you are on plane and you can actually reduce the throttle some and stay on plane.
This clean plane speed is your best speed for Miles per Gallon on most boats.
Your motor trim can raise the bow some for even better MPG.
Most of the time you will bring the bow up for best speed and MPG and
bring it down for better wave cutting and safer ride in rough water.

 

[Texasmark]

Re: plaining my boat

Always wondered. Does Scarab and other hotdog boats have rev limiters on the the engines for times such as this?

I wouldn't really call this guy being on plane; airborne is more like it. Grin

Mark

 

[bekosh]

Re: plaining my boat

Always wondered. Does Scarab and other hotdog boats have rev limiters on the the engines for times such as this?

I wouldn't really call this guy being on plane; airborne is more like it. Grin

Mark

Yes they have rev limiters, but you are supposed to pull back on the throttle when you come out of the water then get back on it as you re-enter.
Check out this video on Youtube. It is the Bacardi Silver race boat on the Today Show. 152mph. Listen to the engine pitch as the boat leaves and enters the water. That's how you do it.
http://www.youtube.com/watch?v=OXTgdAlL9zg

 

[njlarry]

Re: plaining my boat

He was on a "flat plane" -on his back-the next day in his Chiro's office.

I throttle up to get on a plane, reduce to about the speed I want then trim up to maximize the speed at that rpm.

 

[QC]

Re: plaining my boat

Always wondered. Does Scarab and other hotdog boats have rev limiters on the the engines for times such as this?

Another coupla things about this. There is no time for a rev limiter to fix this problem . . . When the prop exits, and the throttles are wide open, the engines can blow before the rev limiter can back 'em down. Think of all that horsepower and then instantaneously it's free . . . waaaweeeeeeeeeeeee gersplunk-a-kunk-a . . . or something like that.

Also, my understanding of offshore raceboats is that you have a pilot and a throttle man, the most experienced guy is on the throttles. He has to anticipate those moments and get off the throttles slightly before the props get air.

We built some engines once for a Great Lakes challenge run that was piloted by Chuck Norris. The boat was a one-off, 48 Scarab built near here. The builder, Eddie Morenz (RIP), was the throttle man and he told me that Norris was as dumb as a stump and all they'd let him do was point it . . .