Will my boat flip over?

[1970kayhydro]

The local boat mechanic said something about my 1970 hydroplane fliping over and now the girlfriend is afraid to ride in it if i go fast (about 40). How likely is it that it could flip? Right now the 40hp johnson is a long shaft so its slowing it down im hoping to get 50ish mph once i short shaft it, the original speedo goes to 60.

 

[mthieme]

Re: Will my boat flip over?

Very doubtful with that setup.
Relative to hydroplanes, yours looks awful heavy and at 40, it's pretty slow.
Come back when your package is under 400# (including you) and you're pushing 70 mph. (now we're talking fun)

 

[oops!]

Re: Will my boat flip over?

your an animal.......


i wouldnt ride in it over 40 either unless conditions were perfect.

forget what the speedo says.....its just a generic gauge.....

it think you are allready over powered for what you have.....the uscg rules at the top of the resto section has the calculations for max hp ratings for any given ob hull.......

in short.........yes it can flip

but it looks like real serious fun

 

[1970kayhydro]

Re: Will my boat flip over?

I run it in a river that is like glass and i just slow down when a large boat comes by and throws up a big wake. Im guessing that it weighs 500-700 lbs. Someone stole it before and left it floating in lake huron and the coast guard picked it up and set it on the ground, it took 5 of up to pick it up and put it back on the trailer with the motor on it. The coast guard guys were all young and not very big guys so thats where i am guessing my 500-700lbs. I used a speed calculator and used a weight of 600 and fast v hull type (no flat bottom option) and it came up with 61 mph.

 

[Maclin]

Re: Will my boat flip over?

At 40 mph it is unlikely to blow over. They go over if enough air gets under the hull, whether from wind speed or your own speed catching enough air. The area between the sponsons acts like a chute or a funnel, that is part of where the hull speed comes from, some of that lift from air pressure. You will see wings on the back of drag boats your size to try to keep it from blowing over as their trap speeds are 100+.

 

[tashasdaddy]

Re: Will my boat flip over?

it is possible for any boat to flip over. all depends on conditions. hitting a rouge wave can easily get you out of kilter, and cause it to do wierd things, and flip.

 

[JoeCrow]

Re: Will my boat flip over?

What make of boat is that?
Looks like a "Big Daddy" Ed Roth creation

 

[1970kayhydro]

Re: Will my boat flip over?

What about turning while going fast? I havn't tried it yet, im thinking it just won't turn well. Iv'e been in a v-hull that went 80+ and the owner was doing sharp turns at 65-70 fine.

 

[1970kayhydro]

Re: Will my boat flip over?

I have not been able to find any info on the boat. It says KAY and belleview, mich on the metal emblems on the sides. Its a 1970 and I was told it was probably a kit. Its has a fiberglass and some wood, the back half of the floor is three layers of wood covered in glass. I have not seen one like it anywhere i have looked.

 

[MikDee]

Re: Will my boat flip over?

Any boat is likely to flip, yours is more so because it's low, small, & high powered,,, but, you shouldn't have a problem if you drive it smartly, only take it out in glass calm water, or a slight chop, for full speed,,, but at other times, you'll have to determine how big a chop it can handle safely, and at what speed it can do that. Plus do as you're doing now, slow down, and keep the bow up if you encounter big waves, or wakes. Then get used to how it handles in turns, at slower, then faster speeds, so that you know it's limits, and stay below them. This is best doene alone till you get accustomed to the boat, then take the girlfriend out for a ride, once you have mastered it.

Have Fun! But don't get hurt, I envy you I'm too old, & fat to even do this anymore

Awesome boat by the way and just one tip,,, make sure your cavitation plate is paralell with the bottom of the boat (to start with, so the boat rides level), and it's height is also flush with the bottom, or a bit higher, for best speed.

 

[1970kayhydro]

Re: Will my boat flip over?

Cavitation plate? Is that the flat plate just above the prop? If so even after i short shaft the motor this winter it will still be a inch or two below the bottom of the boat.

 

[tashasdaddy]

Re: Will my boat flip over?

then jack it up till it is even.

 

[Limited-Time]

Re: Will my boat flip over?

What your concerned with is called kiting. What happens as you begin to "pack air" under the hull it creates lift kind of like a fixed wing on an air craft. Once the boat is ''Flying" running on the rideplate and sponsons (sp) you are susceptible (sp) to blowing over by additional head or even strong cross winds on flat water. Now throw in the occasional roller or unexpeticed wake and you have an even higher chance of taking flight at speed.

 

[1970kayhydro]

Re: Will my boat flip over?

I adjusted the trim on it because the last time i had it on the water it seemed as if the front was riding too close to the water. I looked at the pictures of it in the water and I could tell the prop was pointing down too much and pushing the front of the boat down. Planning on getting it back out this weekend, i need to use up the gas in it before winter.

 

[mthieme]

Re: Will my boat flip over?

I've been running hydros for decades.
That boat ain't gonna flip at 40 mph.
It ain't gonna flip at 50 mph either.
It might flip past 60 mph if you have the testicular fortitude to take it out in a squall and head into it.

I run a 11' pickle fork at 67 mph...never ever threatened to flip and I love heading into a 20-25 knot gust so she lifts.
I have had an 8' threaten to flip at 55 mph - but this was due to a broken pivot shaft. The sponsons will walk (bounce from side to side) - this is your first sign that you have the hull near is performance capability.

Take your turns wide until you get the feel of the boat.
What will happen is that the chine on the inside of the sponson will bite and inertia will throw you in the opposite direction. Doubtful this will be an issue for you since you sit low in the boat, but you should know what to expect. If you're a little chop, this can happen suddenly.

Pretty cool little boat.

 

[mrcj001]

Re: Will my boat flip over?

I adjusted the trim on it because the last time i had it on the water it seemed as if the front was riding too close to the water. I looked at the pictures of it in the water and I could tell the prop was pointing down too much and pushing the front of the boat down.

Install some smart tabs and see if that wont stabilize the boat......

 

[mthieme]

Re: Will my boat flip over?

I ran across an old ad for one of these with a 40 on the back.
Owner claimed 45 mph.

 

[Kenny1970]

Re: Will my boat flip over?

I have a 11 foot with a 30hp johnson and it did 38mph at 5600 rpm last time I ran it 5 years ago.

By the way it is for sale.