Sport hydro stepped center section rule

[anthony_marquart]

Is there any rule against having the center section of a sport hydro stepped upward toward the rear of the boat?

 

[Hydro Junkie]

I don't know if you're in NAMBA or IMPBA territory but, according to the NAMBA rules, all ride surfaces must be in the front half of the boat and no surfaces below the sponson bottoms are allowed. I think IMPBA rules are similar. I found nothing about steps in the bottom of the boat though there may be something about belly pans.

 

[anthony_marquart]

Another question. In a sport hydro, who feels that the back of the tub keeps the prop from getting too deep in the water? or does the rear of the hull ride entirely on the prop and air packed under the hull?

 

[Hydro Junkie]

It should ride on the prop and air. That's why all of the unlimiteds have air traps

 

[P THOMAS]

Is there any rule against having the center section of a sport hydro stepped upward toward the rear of the boat?

You mean like a break from the flat bottom up to the transom? i guess that would work some of the riggers had bottoms like that with a flat spot in the center.

The rear of the hydro is running on the prop and the bottom air flow. If youhave air trap rails that extend to the back of the boat they can be shortened or lengthened to adjust the ride.

 

[anthony_marquart]

My idea is that most of drag from the bottom of a sprt boat comes from the contact with water on the bottom of the tub. if the tub was stepped in maybe 2 steps to the transom this would help reduce contact with the water and help free up the boat.. I was thinking of this on a sport style hull that does not have the side rails on the bottom that pack in the air.. Thinking of riding a little higher off the water, venting as much air from under the tub as possible behind the sponsons,.. and then keeping the rest of the tub out of the water so to speak.. the idea is that this could result in a sport boat running with less drag from water in general,..

 

[P THOMAS]

My idea is that most of drag from the bottom of a sprt boat comes from the contact with water on the bottom of the tub. if the tub was stepped in maybe 2 steps to the transom this would help reduce contact with the water and help free up the boat.. I was thinking of this on a sport style hull that does not have the side rails on the bottom that pack in the air.. Thinking of riding a little higher off the water, venting as much air from under the tub as possible behind the sponsons,.. and then keeping the rest of the tub out of the water so to speak.. the idea is that this could result in a sport boat running with less drag from water in general,..

Yea well if the bottom is dragging you have bigger design problems

 

[anthony_marquart]

bottom is not dragging except at launch and maybe a bit in the turns,,, not that I'm trying to solve an bad issue.. thinking of an improvement over a current design..

just thinking about new designs, what, why and how..

 

[Samuel Hagan JR]

I'm going to have to agree with Phil on that one. If your dragging the center section then something is wrong. I can see during launch or mill but not at full speed or turns.

 

[Samuel Hagan JR]

If your dragging in the turns that's gonna kill your corner speed. Is yours doing that. From the videos it looks fast.

 

[anthony_marquart]

Guys,.. I'm NOT trying to solve an issue with a current boat!

Think like the stepped v hulls that are not legal here, stepped back to the transom. Even when you are running on the prop and bottom of the hull is not actually IN the water..(sp hydro) it's getting sprayed and touched and effected by water,.. TF spray, waves,..etc.. if you could get less drag of THAT water what would happen?

AND,. I think that riggers with stepped running surfaces are easier to launch.. SO,.. what could we gain if we make those gains on the entire bottom of a sport hull? Could we launch and run bigger props?

Here is what I think MIGHT happen.. the rear of the boat opens up and there is a greater distance between the water and tub bottom. could this create a low pressure area,.. like suction,.. and actually do the opposite that I want it to and pull the transom down to the water?

I'm just thinking concepts here guys.. thinking about building my own sp40 and hopefully mikes new one too..

 

[Patrick Mulvany]

Anthony,

If I am reading your idea correctly a riding pad forward of the propeller to raise the transom?? That would be fine for a "Play Boat" and be accepted at a race until you beat the "Top Dog" at that pond!! Realistically airtraps are serving the same purpose but nobody has quite figured out where the should stop and not become part of the turning surface?? Myself I haven't been able to keep my Whiplash on the water the way it is couldn't imagine any more air?? You are thinking and that's a good thing don't be swayed by Nay Sayers because till you try you don't know!!!

Later!!

Pat

 

[anthony_marquart]

This is what I mean

 

[Bert Dygert]

Anthony,

My Blazer Gen 1 Whiplash is designed with the transom higher than the center section. You just need to run the strut deeper to compensate of the angle depth. To add breaks to the bottom of the boat it may need to be reviewed by the Technical board if your in IMPBA.

Regards,

Bert Dygert

 

[Grimracer]

I can tell you that having the back roof of the floor higher then the back can make the boat very hard to tune..

 

[Hydro Junkie]

Anthony, I have to agree with Grim on this one for a couple of reasons:
1) You're trying to reduce/eliminate water contact but are forgetting aerodynamics, they work hand in hand

2) What could end up being the case is that the rear of the boat would drop due to air pressure being reduced, resulting in the boat wanting to fly as a result of a higher AOA of the bottom forward of the break and more hydrodynamic drag from a higher sponson runner AOA

 

[Jim Caldwell]

The steps will create vacuum behind each step pulling the transom down.

 

[FloridaScaleBoater]

I will have to agree with Jim Caldwell here... we are putting small air dams/breaks at the front of the hulls to create that same situation to keep the front down

 

[anthony_marquart]

I have definitely considered the low pressure or suction areas this will create. Still thinking it through. That's why we talk about it. Still I will think of a way to reduce that drag. I know it's there and I think there is a way. Cover with carp scales maybe.

 

[anthony_marquart]

Also I think some comments are based on the older designs that intentionally trap air to keep the boat up. My sp40 boat has no air traps on the sides of the hull. In fact the are areas to vent as much air from under the hull as possible.