Top Speed---Hull Efficiency

[Nattylightmike]

Just trying to get as much out of this boat as I can. It's not a flat bottom and I think it was originally designed to be a jet. Right now it has an 11 1/2 x 15 three blade, 12 degree 14 % over top loader, top rpm's are 5900-6000. According to the calculator I should be doing 78 mph. It says to use 20% for prop slip, is this # for flat bottoms or would it be close for the design of my hull?

[Nattylightmike]

Here it is on the lake: http://www.youtube.com/watch?v=pB4egz-0Uc0

[SnoC653]

I would think you'd be in the 18 to 25% slip range depending on how straight the bottom is. George or Art will be along to tell you what you really need to know. They have a wealth of both experience and knowlege about setting these things up. But, before they get here, is that a chrome plated brass prop? Hard to tell by the picture. Also, getting the most out of the boat has a lot of other factors involved to do it safely, other than just prop and go. Motor placement, shaft angle, prop location, and hull design are just a few that I can think of. Does the boat have a whirlaway? I couldn't see but does it have skid fins? What type steering does it have? Just some food for thought until the real experts show up to answer your questions.

[Nattylightmike]

The prop is stainless, calgo steering, no whirlaway, it has one fin.

[AzDon]

What kind of boat is that? It has a sharp v and the plates are in recessed pockets, right? That would indicate that it was originally intended to be v-drive, although it could still be a jet hull.
Measurements you'll need for full evaluation are:
Distance from the strut barrel to the transom, strut barrel to prop (distance) actual prop blade length and clearance to boat bottom (indicates strut height) engine plate to transom (distance), middle of the split collar to the transom (distance) where gas is centered (front to rear) location of battery(s) where weight of interior is centered (f to r)
Also, you should use a dial protractor and check the actual shaft angle relative to the keel line. On the v-bottoms, I have also noticed that George concentrates on the strakes nearest the center of the boat... 1) how far out from the keel 2) how wide 3) how far from the transom do they end and 4) are they level or turned down 4a) at what angle?
By discussing the slip ratio in the calculator, we are not suggesting that full efficiency is possible. It is merely the intangible factor that explains why your boat's actual speed may not be living up to the numbers!

[pwderman]

Just trying to get as much out of this boat as I can. It's not a flat bottom and I think it was originally designed to be a jet. Right now it has an 11 1/2 x 15 three blade, 12 degree 14 % over top loader, top rpm's are 5900-6000. According to the calculator I should be doing 78 mph. It says to use 20% for prop slip, is this # for flat bottoms or would it be close for the design of my hull?

Your boat was probably designed as a jet as you suspect. Bayon's were built in the Redding Ca area, between Redding and Central Valley, they primarly built jets and I/O's and very few v-drives. I talked to him at one time about a v-drive,but he kept trying to talk me into a jet....:mad:

[Terrible toy]

Your boat was probably designed as a jet as you suspect. Bayon's were built in the Redding Ca area, between Redding and Central Valley, they primarly built jets and I/O's and very few v-drives. I talked to him at one time about a v-drive,but he kept trying to talk me into a jet....:mad:

Profit margin is much better building jets.;)

[Nattylightmike]

Pwderman you are the first person that I have heard that even know's about Bayon's, I have not seen another v-drive just jets and I/O's. As for the measurements:
Strut Barrel to transom: 12"
Strut Barrel to Prop: 1/2"
Prop blade length: 4 3/4" from hub to longest part of the ear
Boat bottom to Prop clearence: 1"
Engine Plate to transom: 22" and 47"
Transom to middle of split collar: 81"
Battery is about 12" from the transom starboard side
Not much interior, just two buckets up front
Fuel tanks are the round 13 gallon type all the way back to the transom
I don't have an angle gauge yet
Strakes nearest center are 12" from keel
Strakes are 3" wide and end 48" from transom
Plates are recessed

[boatpoor]

Yep, but the jets sure suck the gas.

[pwderman]

Pwderman you are the first person that I have heard that even know's about Bayon's, I have not seen another v-drive just jets and I/O's. As for the measurements:
Strut Barrel to transom: 12"
Strut Barrel to Prop: 1/2"
Prop blade length: 4 3/4" from hub to longest part of the ear
Boat bottom to Prop clearence: 1"
Engine Plate to transom: 22" and 47"
Transom to middle of split collar: 81"
Battery is about 12" from the transom starboard side
Not much interior, just two buckets up front
Fuel tanks are the round 13 gallon type all the way back to the transom
I don't have an angle gauge yet
Strakes nearest center are 12" from keel
Strakes are 3" wide and end 48" from transom
Plates are recessed

Your right about the v-drive Bayon's, I've only seen one, although he said he'd built a few, very few. Art and George can weigh in on the design issues v-drive vs jet, engine placement,(seems a little far back) etc. A friend of mine in Redding had one,it rode good but performance was lacking, Olds and jet, but it was a nice ski boat and that's what he used it for...:D

[Nattylightmike]

I know it's no drag boat and never will be. I just want to get it set up to take full advantage of what it could be.

[AzDon]

The blade length to the center of the shaft should be 5 3/4" if the prop is 11 1/2"... Another basic thing to check with that new protractor is the v angle of the bottom. With the bottom strakes ending that far forward, I'm thinking "jet hull".
I once went to look to buy a 21 or 22 foot Bayon cuddy cruiser that was actually quite nice and a real buy at $3500 with bbc power. The Lebel was a better buy at $1300 though, so I bought it instead. Here's some pics of a Bayon cruiser... Tall cuddy two-step cabin like early Campbell. Huge swim step. Cav plate fastened to transom.

[pwderman]

Profit margin is much better building jets.;)

LOL...the old bottom line eh Bill...all you boat builders are the same...:rolleyes: you want to keep eating...:eek:

[RiverRacer]

Well, maybe I missed it but I didn't see any mention of what the MPH at 5900-6000 rpm?????, but the first thing to do is free the boat up, probably run 10mph faster!..:rolleyes:

[Nattylightmike]

I don't know the top speed, don't have a gps. What exactly do you meen by "freeing the boat up"?

[ABBOTTCRAFT]

getting it up & out of the Water.......:D

[fdlock890]

Well, maybe I missed it but I didn't see any mention of what the MPH at 5900-6000 rpm?????, but the first thing to do is free the boat up, probably run 10mph faster!..:rolleyes:


Ok I will ask, how would you go about freeing this boat up? Or any v-drive for that fact?

[gfinishline]

Ok I will ask, how would you go about freeing this boat up? Or any v-drive for that fact?

I have never found any two boats to be the same when it comes to "exact set ups". So for me, without knowing anything about the boat in question, who knows what it needs. Many boat hull styles, may use a "starting point" set up, but each boat will require 'fine tuning', to get positive results. Then we go to the area of "personal requirments". "Art wants THIS" "Steve wants THAT" and "I need something else", personal taste in the set up accounts for the direction taken to acheve the goal.