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-   -   Conventional V-bottom hydronamics question.......... (https://www.offshoreonly.com/forums/general-boating-discussion/175826-conventional-v-bottom-hydronamics-question.html)

CNC 12-30-2007 08:44 PM

Shark skin traps air bubbles .....no stickshon (sp?) between water and bottom surface

MOBILEMERCMAN 12-30-2007 08:46 PM

A bad day boating is always better than a good day inside.

Enforcer2 12-30-2007 08:47 PM

Okay now I remeber.Thanks again for the help.:cool-smiley-011:I'll keep ya posted

Knot 4 Me 12-31-2007 12:21 PM


Originally Posted by marylandmark (Post 2388314)
What is a notched transom and why is it good/bad?

Post #125 shows a notched transom. Allows you to run you drives higher for less drag but still feed them plenty of water for bite.

MOBILEMERCMAN 12-31-2007 03:19 PM

The notch is the area plugged in the mold it. It shortens the running surface, allows drives to be mounted higher and makes the bow run lighter.

Semper Fi 12-31-2007 03:34 PM


Originally Posted by MOBILEMERCMAN (Post 2387822)
A bad day boating is always better than a good day inside.

Depends on what you break :) I'd rather stay home than break a drive or engine!

MOBILEMERCMAN 12-31-2007 04:14 PM

Its still better boating, besides if it was going to break waiting a day or two doesn't make it any easier.

monstaaa 12-31-2007 07:14 PM


Originally Posted by Audiofn (Post 2387114)
Yes but on the smooth side the tile will slide from side to side much easier. America's cup boat spend more money on speed then anyone and they no longer sand the bottoms they make them as perfectly smooth as they can.

maybe for them, but sail boats dont run over 100

open87 12-31-2007 07:26 PM

1 Attachment(s)

Originally Posted by Enforcer2 (Post 2387794)
I have heard of and tried different size pitchs on outers and centers. The problem with outeres being so high is when you turn boat they will cavitate. I went to four blades and problem was non existent.

25" centers would be a lot easier to find.

I want to keep the top of engine cowlings as close to even with each other as possible.

Here's a pict of a new Homeland Security Midnight.

http://www.offshoreonly.com/forums/s...d.php?t=176114

52 ft long.... jackplates..:cool-smiley-011:

TUFFboat 01-01-2008 07:40 PM

Enforcer2;
I'm going to ditto the info from MOBILEMERCMAN and add this... Ultimately you will check your height by doing your slip calulation. If your percentage slip is much greater than about 15%, than you know to lower that motor.
On a VEE I would try to get the props as close together as possible. I remember when people used to angle the motors on the transom to get them closer at the prop.

Enforcer2 01-01-2008 08:50 PM


Originally Posted by open72 (Post 2388751)
http://www.offshoreonly.com/forums/s...d.php?t=176114

52 ft long.... jackplates..:cool-smiley-011:



LOL:grinser010: I've actuall seen one continious jack plate or trips on a Deep Impact

Enforcer2 01-01-2008 08:55 PM

2 Attachment(s)
This picture is really what I am interested in knowing.

This is an Apace and I know there are obvious differences.

water pickups on transom (CAN get for Outboards), surface propellers( Chopper or Cleaver Props for outboards ), HD drives and tons of Torque (thIs I can't come up with :p:(.)

But the realtionship of where the prop shaft is to the notch and the v on the bottom is really what I am after.

SEE PICT and tell me what u think.

Thanks again everyone for the help....:cool::drink:...........Tony

MOBILEMERCMAN 01-01-2008 09:03 PM

Are you trying to compare apples to oranges?

Enforcer2 01-01-2008 09:35 PM

No...of course not but in relationship to the drive height and the notched transom how can I take advantage of my set up and how high should I go.

Do I run prop shafts even with bottom as before with the non notched transom or can I go as high as the above pict and actually see an increase in speed without sacrificing everything else.

It is nothing new for outboards to run much high er than your conventional stern drive boat: IE jack plates in conjuction with chopper props and low water pick ups.

MOBILEMERCMAN 01-01-2008 09:43 PM

Tony, Do you have a rear angle picture of the stern?
As you now that hull has been a round and dialed in again and again. In short you can only raise the drives as high as you can get the props to carry the boat. The faster the boat the less you have to carry. That picture is probably of a 100 mph plus, maybe 110 mph plus boat. Different things apply as speed increases. What works at 80 is not what's best for 100 and vis versa.

Enforcer2 01-01-2008 09:50 PM

gotcha, 100......would be nice:D


I will just have to do as you said ....a lot of trial and error.

Just thinking in comparison purposes. I have looked at some lighter..much lighter by about 7000lbs and noticed that they are running their lower units pretty much like the Apache. They are also 100mph boats thought, but they are outboards-hydrostreams.

And also not in rough water.

MOBILEMERCMAN 01-01-2008 10:00 PM

Tony, I posted on your thread I have the templates your asking about PM me with your address and I will send them to you. As far as your heights work from the homeland boat raise the centers 1 or 2 holes and see what you've got. If all is well raise them some more. Take lots of notes and calculate your slip, Have different props on hand. And the beat goes on.

Enforcer2 01-02-2008 09:06 AM

Thanks, really apreciate info:D. All PM u with address for templates

MOBILEMERCMAN 01-02-2008 11:16 AM

They are the same and both notched. If it was not notched the transom would be one plane and it would form a V to the lowest point.

Semper Fi 01-06-2008 09:33 PM


Originally Posted by open72 (Post 2388751)
http://www.offshoreonly.com/forums/s...d.php?t=176114

52 ft long.... jackplates..:cool-smiley-011:

That's alot of motors!!

open87 01-07-2008 02:56 AM

that's alot of boat!:eek:

kubcat 05-29-2008 05:55 PM


Originally Posted by fredefox (Post 2387631)
I have considered trying to create an "air hockey table" type bottom on the last 3 to 4 feet of a v bottom boat. Use a small engine/pump to pump air under boat at high speed to reduce drag. Maybe, I have to much time on my hands during these long cold winters.

I have often thought exactly the same thing about introducing air only "my" system just had a scoop to push air instead of a pump. I figured that at 100mph there would be enough air being forced in through the scoop to the bottom of the boat to provide the air hockey table effect.

Guess the next problem is "my" system increases air drag on the boat, whereas "your" system just uses a tiny amount of horsepower to operate the pump.


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