Null


Brad @ SCJB

  • Karma: +255/-0
Flat Keel Vs Round Keel
« on: June 02, 2015, 08:48:54 pm »
What is the pros or con's of either?
  • Boat #1: 1978 Liberty
  • Boat #2: 1982 Eliminator Sprint
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

More2LifeThanMPG

  • Karma: +13/-0
Re: Flat Keel Vs Round Keel
« Reply #1 on: June 02, 2015, 08:50:55 pm »
Thank you, I have been wondering the same thing...


Sent from my iPhone using SoCalJetBoats
  • Boat #1: 1989 Howard 21' River Cruiser
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #2 on: June 02, 2015, 08:52:34 pm »
What is the pros or con's of either?

I am going to go out on a limb and assume your are speaking of a delta pad?

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

Brad @ SCJB

  • Karma: +255/-0
Re: Flat Keel Vs Round Keel
« Reply #3 on: June 02, 2015, 08:55:38 pm »
I am going to go out on a limb and assume your are speaking of a delta pad?

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

Ok so that raises another question... Is there a difference between a flat keel and a delta pad? Or are they the same thing and just the proper name for it is delta pad? Why is it called a delta pad?

I'm just looking to get learned ;)
  • Boat #1: 1978 Liberty
  • Boat #2: 1982 Eliminator Sprint
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

81sprint

  • Karma: +18/-0
Re: Flat Keel Vs Round Keel
« Reply #4 on: June 02, 2015, 08:59:34 pm »
Thank you, I have been wondering the same thing...


Sent from my iPhone using SoCalJetBoats
Same here. Hear all kinds of stuff back and forth about the two
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

mobboss

  • Karma: +15/-0
Re: Flat Keel Vs Round Keel
« Reply #5 on: June 02, 2015, 09:02:48 pm »
Come on GT schools in session and your teachin!!!


Sent from my iPhone using SoCalJetBoats
  • Boat #1: boat less
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

JordanDangerfield

  • Karma: +41/-0
Re: Flat Keel Vs Round Keel
« Reply #6 on: June 02, 2015, 09:13:08 pm »
*Legal pad in hand, ready to take notes*


  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #7 on: June 02, 2015, 09:19:17 pm »
It's really pretty simple.

To answer the second question first.  A flat keel, typically tapered from about the last third of the length of the hull to the stern, is a delta pad.

The "what it does" is basically vertical lift.  You would either have wide flats on the strakes or a delta bottom. It would be rare to have both.

The delta pad offers a couple different advantages over a rounded keel.

The first advantage is the ability to plane at a lower hull speed. As a side benefit, quicker planing times from dead stop to plane.

The second benefit is a higher riding attitude at speed. It mimics a lower "x" dimension. This creates bow lift and a higher attainable top speed with moderate hp.

It also makes the boat more stable up to certain speeds. Unfortunately, once that speed is exceeded, makes it unstable, it can "step off" and create a dangerous hook to either direction.

Another drawback is they can sometimes cause odd intake flows on a jet. Necessitating creative "spoons" and shoes to keep the pump loaded properly.

It's not until the lower 70 mph ranges that any of this comes into play in my experience.

They also don't turn nearly as well as a rounded keel,  I feel it is that "step off" that causes a strange transition entering a turn.

I like delta pad hulls for the family ride that occasionally gets flogged on the weekend.

Up to about 75mph I don't think the negatives can be realized. The positives are far more beneficial for the average schmoe.

They also very seldom experience a porpoise problem and the hooks on these hulls are typically very slight.

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app
« Last Edit: June 02, 2015, 09:30:32 pm by GT Jets »
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

81sprint

  • Karma: +18/-0
Re: Flat Keel Vs Round Keel
« Reply #8 on: June 02, 2015, 09:27:12 pm »
So would putting a rounded keel on a delta bottom that is running over 75 be beneficial?


Sent from my iPad using SoCal Jet Boats
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #9 on: June 02, 2015, 09:34:35 pm »
So would putting a rounded keel on a delta bottom that is running over 75 be beneficial?


Sent from my iPad using SoCal Jet Boats

Depends on a bunch of different aspects, but the short answer is probably yes.

The 75 mph number I threw out there is just my opinion. If straight line speed is what you are after, I would think a delta pad with a properly set up shoe, ride plate and loader would kick ass. I would definitely install a turning fin just ahead of the pad though.

This is all just my personal theory.

GT
« Last Edit: June 02, 2015, 10:20:24 pm by GT Jets »
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

mobboss

  • Karma: +15/-0
Re: Flat Keel Vs Round Keel
« Reply #10 on: June 02, 2015, 09:36:11 pm »
Ok GT so you have answered there questions !!! Here's mine , why is it better to have the bottom of the hull ruff and both smooth. And why we're on the subject why does it help load the jet to put a dome in front of the loader ???


Sent from my iPhone using SoCalJetBoats
  • Boat #1: boat less
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #11 on: June 02, 2015, 09:43:17 pm »
Ok GT so you have answered there questions !!! Here's mine , why is it better to have the bottom of the hull ruff and both smooth. And why we're on the subject why does it help load the jet to put a dome in front of the loader ???


Sent from my iPhone using SoCalJetBoats

Hahaha!

What is this? Science class?

Ok, here's what I know.

For the surface question,  micro bubbles are "slippery" and a rough surface promotes those bubbles.  A smooth surface, especially a waxed surface, has too much surface tension and "is one" with the water.

As for the dome question. As it was explained to me,  a low pressure creates a higher pressure. Basically you are effectively "turning" the path of flow.

Look up Bernoulli theory.

It is the same exact thinking.

GT
« Last Edit: June 02, 2015, 10:21:21 pm by GT Jets »
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

Brad @ SCJB

  • Karma: +255/-0
Re: Flat Keel Vs Round Keel
« Reply #12 on: June 02, 2015, 09:43:18 pm »
Ok GT so you have answered there questions !!! Here's mine , why is it better to have the bottom of the hull ruff and both smooth. And why we're on the subject why does it help load the jet to put a dome in front of the loader ???


Sent from my iPhone using SoCalJetBoats

The idea of putting a 'hump' or otherwise known as a spoon in front of the intake is to bend the water into the intake. Take a spoon and put it into running water from your faucet like this.
  • Boat #1: 1978 Liberty
  • Boat #2: 1982 Eliminator Sprint
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

mobboss

  • Karma: +15/-0
Re: Flat Keel Vs Round Keel
« Reply #13 on: June 02, 2015, 09:44:55 pm »
Very cool!!! Thank you.


Sent from my iPhone using SoCalJetBoats
  • Boat #1: boat less
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #14 on: June 02, 2015, 09:46:31 pm »
The idea of putting a 'hump' or otherwise known as a spoon in front of the intake is to bend the water into the intake. Take a spoon and put it into running water from your faucet like this.

Perfect example.

Bernoulli.
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

mobboss

  • Karma: +15/-0
Re: Flat Keel Vs Round Keel
« Reply #15 on: June 02, 2015, 09:47:18 pm »
Ok what are each one worth?? As in speed how much do they add?? I'm sure it's been tested???


Sent from my iPhone using SoCalJetBoats
  • Boat #1: boat less
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

Brad @ SCJB

  • Karma: +255/-0
Re: Flat Keel Vs Round Keel
« Reply #16 on: June 02, 2015, 09:50:27 pm »
So Glenn,

I picked up this Eliminator Sprint project from Rhino here on the boards. (yeah, I needed another boat project like I needed a hole in my head  :banghead: :screwy: ) I have been back n forth on what to do with the bottom of it. Part of me is just leave it. Other part of me is to convert it to a rounded keel. The intake is cut for a ride plate but no shoe.

The idea I have for this is to create a mild gale banks turbo 454. I dont plan on sawing anyone off, just want to do something a little different, still turn key, but has some balls when I wanna jab it.





  • Boat #1: 1978 Liberty
  • Boat #2: 1982 Eliminator Sprint
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #17 on: June 02, 2015, 10:03:28 pm »
Do you see where the strakes end? That would be a major deal killer for me to round off the keel. Reason being is I would want to extend rearward the middle (second) strakes to keep the lift potential. The center strakes would be fine imho.

If it was mine, I would keep the delta and add a shimmable shoe and maybe a 3/8" (very modest) spoon.
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

81sprint

  • Karma: +18/-0
Re: Flat Keel Vs Round Keel
« Reply #18 on: June 02, 2015, 10:11:50 pm »
Very good info. Thanks GT 👍


Sent from my iPad using SoCal Jet Boats
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #19 on: June 02, 2015, 10:43:54 pm »
Very good info. Thanks GT 👍


Sent from my iPad using SoCal Jet Boats

Truly my pleasure.

8)
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

Blue2184

  • Karma: +4/-0
Re: Flat Keel Vs Round Keel
« Reply #20 on: June 03, 2015, 05:52:14 am »
Gt witch bottom does my boat have? Good? Bad? I have only had the boat in the mid 70's? But fixing to throw about another 300hp at it? Thanks Jason




Sent from my iPhone using SoCal Jet Boats
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #21 on: June 03, 2015, 05:59:50 am »
Gt witch bottom does my boat have? Good? Bad? I have only had the boat in the mid 70's? But fixing to throw about another 300hp at it? Thanks Jason




Sent from my iPhone using SoCal Jet Boats

That's a great bottom for going fast.

Very wide stakes for lift and if you look at these as compared to the ones on Brad's, they are perfectly straight.

About the only concern on this type of bottom design is chine walk.

Looking at just the phone as far as the picture, it looks like a Southwind bottom.

GT

Sent from my SCH-I545 using SoCal Jet Boats mobile app

  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

Blue2184

  • Karma: +4/-0
Re: Flat Keel Vs Round Keel
« Reply #22 on: June 03, 2015, 06:13:32 am »
So? It would be considered a rounded keel? Thanks aging gt!!


Sent from my iPhone using SoCal Jet Boats
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

GT Jets

  • Karma: +192/-0
Re: Flat Keel Vs Round Keel
« Reply #23 on: June 03, 2015, 06:22:43 am »
So? It would be considered a rounded keel? Thanks aging gt!!


Sent from my iPhone using SoCal Jet Boats

Yep. Textbook rounded keel.

Sent from my SCH-I545 using SoCal Jet Boats mobile app

  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

mobboss

  • Karma: +15/-0
Re: Flat Keel Vs Round Keel
« Reply #24 on: June 03, 2015, 07:24:10 am »
That is what the bottom of My kona looks like! Ok what is chin walking???

Sent from my VK810 4G using SoCal Jet Boats mobile app

  • Boat #1: boat less
  • Like
    Dislike
    Love
    HaHa
    Angry
    Surprise
    Sad
    Party

 


Null

SMFPacks CMS 1.0.3 © 2022