Sport 20 Shovel Nose design

[missbudpilot55]

OK WADE,

Hear are some measurements off of 3 of the Newton Plans and what I have come up with in "Sport 20 Dimensions" using an approximate length of 30"

Plan 101: Karelson 30' Low Profile Round Nose (used .67 as multiplier)

1/8th scale LOA: 45"/=/ SP20 = 30.150"

Beam: 20.5"/=/ 13.735"

Tunnel Width: 10.75/=/ 7.203"

Tunnel Height: 1.0"/=/ .670"

Transom Width: 10.0"/=/ 6.900"

Nose to rear of Sponson: 22.0"/=/ 14.740"

Plan 103: Jones?Straudacher 30' Conventional Pointerd Nose (same multilpier as above)

1/8th Scale LOA: 45"/=/ SP20 = 30.150"

Beam: 19"/=/ 13.735"

Tunnel Width: 9.5"/=/ 6.365"

Tunnel Height: 1.0"/=/ .670"

Transom Width: 8.0"/=/ 5.360"

Nose to rear of sponson: 21.75/=/ 14.573"

Plan 117: Lauterbach 28' Conventional Hull (used .69 as multiplier)

1/8th Scale LOA: 43.5"/=/ SP20 = 30.015"

Beam: 19"/=/ 13.110"

Tunnel Width: 10"/=/ 6.900"

Tunnel Height: 1.0"/=/ .690"

Transon Width: 10.25"/=/ 7.073"

Nose to rear of Sponson: 21.125"/=/ 14.576"

 

[Jerry Wyss]

Well That otta keep you busy Wade :lol:

 

[not2bright]

can you step the sponsons please

 

[Slideblues]

Maybe 8 inches at the sponson ends,,then to 7 or less at the transom,Maybe .Lookin' at my sport 60 (pickledork) its about 5/8ths to 3/4s depth on the ride

pad. But another thing I notice on both type of hulls is that the center section

underneath has a low spot , right across the end of the sponsons and slants

up to the front and to the back from that point. I guess its for compressing the air under the boat at the point where the "lift" needs to be applied for the weight

of the engine ,,at the balance point I would assume.

At the "Newton Marine Plans" site, some of the old boat pics I saw where some

had made use of what is called "air dams",,Trying to stop air from "spilling"out

from under the boat,,just behind the sponson ends.

I suppose that the low spot can be estimated at a point just behind the sponson

ends and the '"air dams" can be added for trimming, in leiu of testing several

different points of CG :blink:   Gawd, I sound like I know sumthin'

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Dang Jerry Im impressed!!!!

Man no kiddin on tha Newton specs thata bunch of stuff Wade

 

[Jerry Wyss]

can you step the sponsons please

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I would agree with Joel on this ,,I think it might keep the boat from "stubbing its

Toe" (so to speak) and doin' a "tunnel dive"(no pun intended) also I've heard

some say that helps ,,with the launch?? Almost all model scale type(and sport)

have them.

Hey Slidey, I'm developing a good line of "schnitz", Huh B)

 

[Slideblues]

Yup Id say ya got the hang of it

"Tunnel Dive" Think dis guy got cameras at my test pond er sumpin :lol: :lol: :lol:

 

[Jerry Wyss]

Yeah, Its like my Texas Granma useta' say "Why Any OL' Fool Kan Put Garbage

Inna Truck!!"

 

[Slideblues]

Yes Sir.........My Lone Star uncle ( Really he lived in Dumas, A far spell north a Amarille ) Usta say, Cowboy......... If ya geeet bucked off, Just keep geeet'n back in tha saddle till ya learnt sumpin

Course I was bowl legged fer a while too

 

[not2bright]

when you step the sponsons some how it handles better and is faster

 

[wswatzell]

missbudpilot55, Thanks, those #'s are going to help a bunch!!

I put a step in the sponsons. How deep should the step be? and how far back from the tip of the sponson?

 

[Jerry Wyss]

missbudpilot55,  Thanks, those #'s are going to help a bunch!!
I put a step in the sponsons.    How deep should the step be? and how far back from the tip of the sponson?

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Its dang near "Half" the sponson length on my Phil Thomas 82U55( 19" overall

and take 10 1/4" off measuring from sponson "Ends".

Phil Thomas SS45- (16" OAL - Minus 8 3/4" from sponson ends

also, There not much depth diff ( about 3/16ths on the 82U55

about less than 1/8" on the SS45

These are all "eyeball" measurements as there is no visable "centerline"

to go from,,I'm a Plumber, so **** always runs down hill unlees you want

to "hydraulic" it

 

[missbudpilot55]

Wade

To step the sponsons, the step should only be about 3/32" to 1/8" and taper to nothing about 60% of the length of the sponson surface from the rear to front and be about 3/4" wide. Figure this in on the initial design or make it an option. Also when looking at the sponson from the side a good rule of thumb on the angle of the rise is, the distance from the rear foward 6" should only be aprrox 1/8", foward of this point to the bow can be a gentle sweeping radius to the bow.

What is the dihedral of the sponson bottom? I normally use about 3 degrees. On some of the Sport 40 designs they notch the inside of the sponson to reduce the wetted area and also trap more air. (This only complicates the building process.)

 

[wswatzell]

Ok, this is a lot of info... I'll make the changes as I get a chance. I have a bunch of work now here, so it might take a bit (on my breaks) so be patient!! Hopefull tonight before I leave, I'll be able to post my progress B)

 

[wswatzell]

https://www.intlwaters.com/gallery/thumbnails.php?album=100

I made some changes, what is the general opnion? am I on the right track?

 

[Jerry Wyss]

As far as I'm concerned, Theres No track,,I'm buildin' New Road where ever I Go!

But as far as my suggestion,,,,The transom seems that it would have to go up

to allow room for the strut-n-prop. The side view now shows me it's in level flight

add the prop under there and,,AAAAHHHOOOOGGGAAA!! Dive,Dive,Dive!! :lol:

sorry

Probably better wait for "Bud Pilot"

Somewhere around here we're gonna have to add that "Big Effn' FIN"

With a Big Red Flyin" Horsey :lol: :lol:

 

[missbudpilot55]

Ok Guy's,

Looking at your drawing in file 12/14, what is the total width of the wetted area of the sponson at the rear? Looking at 14/14 with the step, that would work to help the boat break water to get on plane quicker, but what I had in mind is if you take 12/14 and add the step from the inside edge of the sponson toward the outside edge of the sponson 3/4" by 1/8" tall and extend it forward toward the bow it will reduce the acutal wetted area of the sponson in the water while on plane. I have done this with several of the wood 1/8th scale hydros I have built that would normally have flat running surfaces and had great sucess with it. Doing it the way you have it drawn is like the David Frank Sport 40 of a few years back, and it works well also. Maybe a combination of the two would also work. I'll post some pictures of what I'm talking about.

Check this out : https://www.intlwaters.com/gallery/displayimage...tup&cat=0&pos=0

 

[Paul Pachmayer]

Hello Guys,

I like the flat afterplane, on all the good running shovels I have the best run flat from the sponson transom all the way back. I think the tunnel width is a bit small but the rest of it is looking really good.

Paul.

 

[Paul Pachmayer]

One other thing, it would be really cool if you designed it as a drop sponson shovel, I love the look of those and you really don't see them out there. Just a thought.

Paul.

 

[wswatzell]

Bill, That is a lot more clear with the step, thanks for posting the pics. That will be a lot easier to do! The measurments that are in 12/14 are at the rear of the sponson, other than dimentions I have shown, I am not sure what would be considdered the wetted area.

Paul, what is a "drop sponson shovel" I'm not that familar with them to know exactly what you are talking about.

 

[Mark Walter]

looking good, I have to agree with Paul, if it was a dropped sponson shovel, it would resemble the old laugterbachs. there is nothing quite like a laugterbach on the water at full speed!!!! just my opinion! MARK U-5 CANDYMAN