Lets see those Outboard Hydroplanes!!

[Instigator]

it is all in the design of the center section and the sponsons foot print
you can set up for either way

"air traps" on your boat??

Can totally control amount of lift (or lack of) by size and design of them.

[afr]

?? if
i got one
i was told i do ??
maybe im wrong in calling it a air trap
what else could it be
the da marco i have and mine are very close to the same

anyay ill be back later
anyone would like to comment feel free

[Instigator]

?? if
i got one
i was told i do ??
maybe im wrong in calling it a air trap
what else could it be
the da marco i have and mine are very close to the same

anyay ill be back later
anyone would like to comment feel free

"air traps" are pc's that extend from the back of the sponsons to the transom.

You use them to keep the pressurized, lifting air from escaping out from behind the sponsons.

If you had your hull upside down, run a string from the rear of the sponson bottom to the rear, outside corner of the main bottom at the transom.

You take a pc of wood and cut it to the shape of the area between the string, back of sponson, main hull sides and where the string merges to the main bottom.
Kind of a stretched out triangle.

That is known as a "full" air trap and gives/builds maximum lift by "trapping" all of the compressed air and not allowing it to escape.

You can then further "tune" it based on what the boat wants.

Too much forward lift = trim the traps (depth) just aft of the sponsons.

If the rear main bottom is popping too soon = shorten them.

If the boat still is not fully lifting "and" the rear of the main bottom is "sealing" to the surface of the water = shorten them so your not dragging them in the water sense the bottom is sealing w/o the traps being there.

Make sense???

If you look close at this picture, the boat is upside down and you can see the air trap extending rearward from the back of the sponson.

[Way2slow on H2O]

Yeah Scot, learning curve for sure...
Take any V-bottom or tunnel hull design and start asking about set up, rigging, etc. and you can rest assured you'll be running real close to their foot print 1st try. I've done it, and still doing it.

Now, start asking questions about a hydro and you'll find there's NOT many. The ones that ARE competing are comfortable with their set up and like Jim Dunn, very competitive. (very impressive actually, 9.0's without nitrous)

My neighbor has always been a car motor kinda guy, and stepped up to Pro Mod this year. Prior to, he always made jokes about "whackers" and I always pointed at the fast outboard guys back in the mid 80's thru mid 90's. He just asked "where are they now?" Good question.

The early ob hydros ran a skeg which proved to be fatal and soon incorporated a rudder and removed the skeg. The 1st rudder hydros were "ill handeling" at speed and some changes were made. Mine has the deep rudder (loss of 1/10 on ET) but safe to 200 mph (according to Kaase based on their Top Fuel Hydros) I tried to snap a pic of the GPS at 140 but the thought of my camera being blown from my hand, lol, i wanted a shot of the nose AND GPS, funny how fast your heart rate is at that speed and to multi-task... forget it. Can you say Helmet cam???? I've thought of installing a mini cam on the cowling to show the torque of a V-6 when sprayed... I have video taken from another boat but when the sponson lifts, it sprays too much water to the side and drowns the shot.

I tried a trim ram and was a bad idea. My nose was digging too much from torque and I thought maybe i could give it a lil positive trim to launch and go 2* negative once set. I had the stop lock set at 2* neg so it couldnt go any further and away I went. The boat launched hard allright, lifted both sponsons 2' off the water and dug so deep when it hit the boat made a hard left turn straight towards the tree.... hydros dont turn!!! I missed the tree, but felt SOOO stupid, lmao.... the motor died when i chopped the throttle, refired and made the most impressive time of the year, 14.89 @ 58.56. Talk about embarrassing, I wanted to go home. Later everyone that was watching asked what happened and said "it looked GOOD, did your hands fall off the wheel?" I just laughed and said "Marty Logan ran over a buoy I cant be outdone"

Live and learn!!!

Ronnie

[Mark75H]

Back in the late 1950's Hu Entrop ran his 3 point proprider in F outboard hydro. At first he dominated the class as the only proprider, but in fact the reason he dominated was because he was the only one with a motor about 100 hp. Set up for straight line running the rig was capable of about 110 mph while most of his competition could only go 80 mph flat out. After about 5 years some other guys started showing up with 100 hp motors on tail dragging 3 point F hydros. They couldn't match Entrop on top speed, but they did beat him around the course.

At the kilos it matters who's fastest, on a circle course around the buoys it matters who's "first-est"

My personal guess about the different handling characteristics is that the taildraggers can turn closer to the buoys and have better acceleration in the 40 to 60 mph range while the propriders have to take a wider line in the corners and have better acceleration in the 60+ mph range

[Instigator]

I'm old enough and lucky enough to have seen a few of those run right at the end of their era and had completly forgotten about them.

Helped carry an ancient Ron Jones into the water back in the early 70's.

Had an in-line with pipes. Was those most blood curtling sound I ever heard!

Got his ass spanked bad though by the newer, faster 4 bangers on smaller boats and they all flew the bow.

[afr]

ahaha
i got ya
yep no air trap on mine at all
i need to lift the tail up about two three inches and it will be popped
with the step pad hull addition thats on there now
so ill play
with one all the way back first
but man its fast now

thanks guys
im on it

[Freddie Webb]

Here is a side shot of my pugh hydro. I tend to agree with Barron and that is how I try to set mine up, three points prop and tickling the front sponsons. I don't know about setting one up with the big gearcase. Gary Pugh said not to do it on his hydro it would swap ends at about 80 and I took him for his word. He said when the tail popped up the large diameter prop would walk the rear of the boat around. I still haven't figured out how to post large pics, so I hope you make heads or tails of this photo.

[afr]

so what is the speed record for a stock 115 4 cyc merc on a hydro
mark75 ??

[afr]

the photo is cool
i see you got negative trim going on there

[Freddie Webb]

Thanks afr, but I can't take all the credit I had lots of help and it still isn't where I want it.

[jphii]

This better Freddie?

[afr]

cool joe u r da man

i dont see a air trap
and i see the sponsons depth is real shallow
only like 3 inches

oh well other than going for the v8 record
and that aint happen even with one of your motors joe
there aint nothing i can do with mine
but drive it and drink beer
i thought i might had a shot
its as fast as it needs to be right now

[Freddie Webb]

Thanks Joe, you came through again. Afr don't give up so easily, I love my little v4 on my hydro. Thought seriously about putting the v6 omc on the hydro and as Frank put it "let the hide go with the hair" .

[Way2slow on H2O]

Freddie, are you using a rudder? The pics so small I cant make out if that's cable or not.

Gary's right about the swapping. The bigger prop has a lot of torque. Without a deep rudder you'd be lookin at where you came from real quick.

Ronnie