V8 Hydroplane design.

[afrhydro]

wow i just found this post
ill have to come back and read some more
thanks for all the great link guys

[Wavewacker]

When I was 15, my neighbor had a window manufacturing admin job, I think he was in marketing and his son and I built a C class hydro. it was plywood and 8' long as I recall. A guy came over a few times from here in town who had built a similar boat, different class, with a blown chevy, it was 16' I think. These were rounded bows, flat bottoms and an open tunnel to the transom. Ours had a 25hp outboard. We took it to Indian Point Boat Dock on Tablerock Lake. Put it in and neighbor's dad ran it first, then his son and then I got my chance. In those days there were styrafoam wake breakers in the cove. We did not have the steering hooked up, running it with the handle down on the motor. The throtle control came off while I was running flat out, just fell off! I tried picking it up and started hitting rougher water, the boat bounced and actually left the water. I was leaning forward trying to hold the bow down and slamming down from flight. It went over a wake breaker and turned toward the dock. People were standing there watching us on the dock. I just lost control and was headed for the dock and people ran off, wide eyes and open mouths, all saying something! I decided to jump, when I did I guess I changed the course. It then circled and I was out there diving underwater to stay away from the prop. I came up and it had passed near me and it was headed for the opposite shore line away from the dock. It ran out of gas and coasted up on the shore with a soft landing as if it had been beached.

The neighbor (the dad) got the boat back and pulled it out. He talked to the dock manager and came out of the store with a FOR SALE sign. He left it in the parking lot with the sign on it. That's the last I ever saw that little boat.

If you end up building that boat, please slow down when I'm out there as you blast by me. Thanks!

[Submarine Tom]

Ah, to be 15 and invincible 'eh!

Oh, and lucky as hell!

Who needs safety gear anyway. Sound construction, maintenance, kill switch, and common sense. A 15 year old at the helm of a V8 hydro...

Great story though.

-Tom

[afrhydro]

Originally Posted by Submarine Tom

Ah, to be 15 and invincible 'eh!

Oh, and lucky as hell!

Who needs safety gear anyway. Sound construction, maintenance, kill switch, and common sense. A 15 year old at the helm of a V8 hydro...

Great story though.

-Tom

Tom a class c hydro is what he was in not the v8 as in the topic head line

[Submarine Tom]

Oops.

Thanks for the correction, my mistake.

-Tom

[Wavewacker]

LOL, I also remember the ride home. He said get in the car! It was just over 50 miles back home, no one spoke for about 45 miles, even after I appologized several times. He finally said it was not my fault, that it was his for building that type of boat. His son was younger than I and not as athletic. It was too dangerous for his son to have and that accident made him realize that. He later built a small rowing skiff for the Jame River just outside of town. The boat was not checked out sufficiently, that was the problem....and you're right, no safety precautions taken, not even a life jacket! But we were only in a large cove! (lol)

Didn't mean to hijack the V8 Hydro, but they can be built from simple plans, they float and are fast and fun, doubt such a boat would be race worthy. If a storm window salesman and two teenagers can build an 8' er, a guy with a little salt should be able to build one at 16', for pleasure.

[rebar]

I abandoned the idea over one year ago. I wasn't about to risk my ass and a bunch of money on a unproven design. But the other day a unnamed well known racer from the past sent me a email with these details.

Conventional hydroplanes back in the day had an AOA of 5 degrees.

If the strut height is lowered, or raised it changes the AOA at the trailing edge of the sponson.

The depth of the original hydroplanes was 7"

Henry Lauterbach reduced the sponson and strut height to 6 1/2"

Miss Bardahl had a sponson depth of 7"

Propellers diameter of 12", so a clearance of around 1" from the bottom of the hull to the tip of the propeller.

Dihedral was 5 degrees on almost all the hydroplanes.

Angle up to the chine on the side of the sponson was 37 degrees. It didn't matter if it was an unlimited or a 280 hull. 16' in length to the unlimited at 30' 6".

He also offered to sell me original full size Lauterbach plans..

[afrhydro]

Originally Posted by rebar

I abandoned the idea over one year ago. I wasn't about to risk my ass and a bunch of money on a unproven design. But the other day a unnamed well known racer from the past sent me a email with these details.

Conventional hydroplanes back in the day had an AOA of 5 degrees.

If the strut height is lowered, or raised it changes the AOA at the trailing edge of the sponson.

The depth of the original hydroplanes was 7"

Henry Lauterbach reduced the sponson and strut height to 6 1/2"

Miss Bardahl had a sponson depth of 7"

Propellers diameter of 12", so a clearance of around 1" from the bottom of the hull to the tip of the propeller.

Dihedral was 5 degrees on almost all the hydroplanes.

Angle up to the chine on the side of the sponson was 37 degrees. It didn't matter if it was an unlimited or a 280 hull. 16' in length to the unlimited at 30' 6".

He also offered to sell me original full size Lauterbach plans..

awsome good to see this old post come back up
im almost ready to rock and roll again with my design

[rebar]

Yea I saw your post. Very cool.
Nothing personal.. But a outboard hydro just doest run like a inboard with the CG just behind the sponsons.

Where is the CG on yours if I may ask?

[afrhydro]

around three foot behind me rigged dry weight is at the back of the sponsons i had to compensate a lot for the outboard but shes balanced in (ready to go)
it should run respectable 1/8 and 1/4 times
this is still the original plug
thanks for asking

[rebar]

Originally Posted by afrhydro

rigged dry weight is at the back of the sponsons

Can you explain that comment?

I wonder if you placed the driver, fuel etc as far forward as possible. Could you get the CG close to where a inboard CG would be? So the transom lifts?

[afrhydro]

the transom does lift now after quite a bit of bottom work and redesigning the air traps
so where ever the cg is its working now lol