Steps, Vents and Shingles

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Grimracer

Grimracer

Well-Known Member
Joined
Dec 27, 2001
Messages
9,492
Ok.. I know these are cheap looking..LOL.. it was a quicky!

None the less.. this is my understanding of Steps, Vents and Shingles.

They can be applied to any riding or contact surface..

We have been having a cool conversion on the OB forum and this conversation made be think of sharing this.

Any other input?

Grim

Shingles.jpg

Steps.jpg

Vents.jpg
 
I know the shingles were used on the Griffon powered Bud boats

A variation of the vents was used on the Miss Madison/Oberto back in the early 2000s as well as on the Fountain style offshore boats

Steps were used on the unlimited boats back in the late 40s and into the mid 50s

Beyond that, it's all theory and above my head
 
Very good.. at the end of the day not a ton of difference between steps and shingles.. however.. typically shingles dont "change" the AOA of the tunnel by design.. and shingles typically have more per bottom making themselves have a higher AOA. (the closer they are to each other and laying on the same plane the higher the AOA of the shingle)

Grim
 
The Motley Crew/Lucas Oil boats I designed for AquaCraft had Steps.. seems the less dead rise of the sponson the better they worked.

Grim
 
Interesting stuff Mr Grim . I added shingles only to the outsides of my riggers sponsons. They DID NOT reduce the maximum speed but enabled the boat to turn at its maximum speed with almost no lean to the outside. The stock planning angle is 4* but the wedges on the outside are 4* + 3* or 7* degrees. Because the sponsons have  a dihedral angle, they do not touch except when the boat is turned. The wedge pieces were cut from Ernst engine mount thrust plates which come in 1*, 2* & 3* amounts. They are epoxied in place & coated with the graphite epoxy resin mix.

JA

001.JPG

002.JPG

004.JPG
 
Interesting concept 

We have tried shingles from front to rear and side to side.  Very loose front end.

Tried a single shingle/ wedge at the vary rear of front sponson. Launch is immediate, VARY FAST BOAT.  However the boat was on edge and tends to lift and blow off.  This happened to my 60 hydro in Brandon.  Had the same on my 40 hydro for a while with same issue.  Removed the step/ wedge and finished second at Brandon

With the current motors NEW PROPS/ABC, I don’t believe steps shingles and etc are needed, especially with heat racing speeds of 80-90mph.  Steps and etc create edgy instability 
 
Gary, would this be with riggers? 

I can see how the extra "lift" would be an issue since riggers really don't have that much weight to them.

In the case of a scale or sport hydro, the extra "lift" would be an asset in the corners, as stated by Jim previously, as well as aiding with getting up on plane when doing a trolling start, something that is very popular in the scale class in the northwest.  It would actually be the most beneficial to the heavier boats that have a harder time getting up than a light boat that can jump up and go
 
The goal of these efforts is to reduce contact with the water to reduce drag.  Stability in monos and especially tunnels is also an issue.  I believe the old Prather tunnel needed its step for stability in turns.  Our attempts on reducing water contact were air traps.  We used air trap sponsons on all our later gas hydros.  It was one of Mike's off the wall ideas that added 2 to 3 mph over conventional sponsons at 100+mph when we bolted a set on.  They seem to be at their best with heavy boats.  I've tried them on a P limited rigger with mixed results.  A non trip is needed for heat racing boats. 

P1010027.JPG
 
Back in my days of Outboard / Limited inboard racing spent lot's of time  in Ed Karelsen's  shop building mostly outboard hull's and trying countless sponson designs the. most promising modification were  3 step shingles added to the inner tunnel edge and center to the sponson's  that's not saying than other configurations would not work. The shingles were easy to apply and remove for testing.

My F class 1100cc Karelsen Hydro

Scan 1.jpeg
 
Last edited by a moderator:
Most outboard tunnels plane on their transom with the sponsons for stability in the turns.  I wouldn't expect any help from shingles in the straights.  Our SAW outboard tunnel ran more like a conventional hydro with the transom mostly out at high speeds.  The heavy outboard still holds the transom down.

Lohring Miller

IMG_4057.jpg
 
Hydro Junkie said:
Gary, would this be with riggers? 

I can see how the extra "lift" would be an issue since riggers really don't have that much weight to them.

In the case of a scale or sport hydro, the extra "lift" would be an asset in the corners, as stated by Jim previously, as well as aiding with getting up on plane when doing a trolling start, something that is very popular in the scale class in the northwest.  It would actually be the most beneficial to the heavier boats that have a harder time getting up than a light boat that can jump up and go
Click to expand...
Yes especially hydros.  Even with heavy twin 101’s we have pretty much abandoned shingles and steps.  

Launch has a lot to do with weight distribution.  With the more rear placement of the motors launch is not an issue

In the past motors were placed forward requiring wider sponsons and steps etc to launch and get up on step

Ideal weight distribution is 1/3 of the total weight on each front sponson and at the transom.

Years ago with forward placed motors radio and etc, we would use a FISH SCALE and attach it to the transom and see how much weight it took to lift the transom/rear sponsons of the table.

If too much weight the boat would not run well

NOW WE LIKE TRANSOM WEIGHT AND LESS ON THE FRONT
 
My mono Cal Craft 101 the motor is where the manufacturer recommended 

Ran 76 mph at the Internet’s 2017

Since motor work and fuel change it is running stronger
 

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