TOPIC: mantaray finally at speed..no porpoising

dropped down to the 2 hole ...smooth riding....sorry cannot post pics.tried to resize and it says a sharing violation occured.

Ron did good!

way to go guys,great job,im darned happy for ya ron.if i find a motor for mine when its done i guess ill have frank fix it up for me,john

thanks frank.

Ron
Glad to see you got it sorted out.
Looks good.
Neil

Great job Frank. Looks Awesome Ron!

Bob

Ron - I'm glad you got the bouncing stopped. Why did you change hole to begin with? I'd still like to see you riding with the bow up more. The boat should be riding on the back of the sponson at speed, not the whole thing. You may not be able to do anything about that with the notch left in the transom though. At least you're not bouncing.

brian, i don't care what its riding on.lol... its smooth and handles great. i think i had it in the 2 hole when i first bought it because it didn't porpoise the first 2 years, then i started foolin around with it and never put it back to where it was. i will be getting the prop cupped and dropping it down a hole and see if that changes anything. ron

One thing at a time Ron. Have the prop cupped, and try that in the same pin hole. Then try different pin holes. Cupping will make a big difference by itself.

Ron, glad to hear you got it runnin smooth!

Should be some nice weather in the poconos this weekend for a fall ride, before you store it for the winter...

sue and i will be taking it out to lake hopatcong on the next 70+ degree day that falls on a tuesday, thursday,sat, or sun. burn up the remaining 7 gal. of gas i have. ron

Looks like your runnin' on rails now.

not so much out of the water as some would like to see.lol maybe the cupped prop will help.

vuyosevich wrote:

not so much out of the water as some would like to see.lol maybe the cupped prop will help.

I have read this? I have never heard anyone recomend to run a hydro or multi-hull in that attitude before. It can result in a big splash!

Mr. Canazzi outlined in detail the hulls functions in his patent #3051115 www.freepatentsonline.com/3051115.pdf The Manta Ray is a 4 point planing hull, meaning there are 4 planing surfaces the boat rides on.

With the bow in the air...handling, ride & safty are greatly comprimized. The anti tripping surfaces are not in play, meaning the boat will flip easy in corners at speed. A bump in the water can send you airborn...possable blowover or tumble. But it does look cool...until

In the picture below I used blue on the port side hull to show the wet area on minimum plane. The red area is a "fin" designed to seal the step an hold the pressure in under the hull at slower speed providing lift to get the hull on plane with less energy.

As the forward force is increased the wet area is reduced. The blue on the stbd side shows the reduced wet area on maximum plane. The green is the "fin" area that is now open the vent excess air maintaining a predetermand pressure under the hull for lift. This "fin" can be modified to adjust the amount of lift under the hull.


From your pics it looks to me that the motor needs to be trimed up, replace the splash(drag) with a roostertail. I'm very interested to hear how the cupped prop works for ya. I've been lookin' at Cleaver style props to trim higher into the dirty water coming out the tunnel.

Sorry for the long read Ron...but there is a pic

I have never heard anyone recomend to run a hydro or multi-hull in that attitude before.

Formula 1 tunnels run higher attitudes....when running like on rails its a dog and your not there yet,if your not flying the hull, about to blow over..... your losing the race...its a fine line between respect the trim button and losing.

well my mantaray isn't a formula 1 tunnel is it?
cat, that is the best described explanation of the manta tunnel hull that i have ever read. i'm embarassed that i didn't understand that. i know its called a 4 step tunnel hull, but have always been told that it should plane on the last few feet of the stern.
"the manta is a 4 step planing hull. meaning there are 4 planing surfaces that the boat rides on. With the bow in the air...handling, ride & safty are greatly comprimized. The anti tripping surfaces are not in play, meaning the boat will flip easy in corners at speed. A bump in the water can send you airborn...possable blowover or tumble." i hope others who have told me the opposite take notice. ron

PC1000 wrote:

Ron did good!

after reading cat's explanation, the top pic is how a mantaray is suppose to ride. looks right on to me. ron

Ron, it sure looked good last Sunday. Maybe you shouldn't get the prop cupped!

See ya tomorrow.

Frank

well my mantaray isn't a formula 1 tunnel is it?

no sure isnt, my post was directed at CAT*FIN*k's statement about tunnel hull hydros & about his statement

frank , the only reason i would get the prop cupped is so i can trim it up a hole or two and reduce the waterfall over the transom. ron

Ron - I think that's important. You should not have water coming over the transom. Something is not right in your setup. I hope to get to the Hudson with Frank this weekend.....if it ever stops raining.

MadProps wrote:

I have never heard anyone recomend to run a hydro or multi-hull in that attitude before.

Formula 1 tunnels run higher attitudes....when running like on rails its a dog and your not there yet,if your not flying the hull, about to blow over..... your losing the race...its a fine line between respect the trim button and losing.

Maybe attitude is the wrong term. I was refering to the bow being higher in relation to the stern than designed (increased angle of attack). Also using half the number of planing surfaces it was designed to use. I don't know F1's but I would think running it on 1 planing surface and the bow higher than recomended would not be the best way to run faster.

I'm not trying to be smart. I want to know if I've learned something wrong...yet keep it simple. I'm still workin' on my apprentiship card. I've gotten to know many kinds of different style multi-hulls in S FL. The go-fasters all say the faster you go the more air is built up in the tunnel. The more air, the higher the pressure, creating more lift. Controlling the the lift is more an issue than plowing, when trying to go faster.

I think when Ron gets the motor trimed up, his speed will increase. The increased speed will come from both the reduced motor drag & reduced size of the 4 wet spots. Then I would say he's flyin' on rails. How high he wants to fly is up to him.

The possable negative results of flyin' may be old news to Ron but maybe not to others reading. Some are happy to save a second while others prefer to spend the day.

well i finally got my prop cupped yesterday at "the prop shop" in lake hopatcong,n.j. the first question out of his mouth was why do i want this? i said said so i can trim my motor up a few pin holes and see if the porpoising stops. he told me cupping would not stop porpoising and explained that cupping one area of the prop would give me stern lift and the other area would give me bow lift. i didn't know what to do so i said lets try bowlift. if i don't notice any difference he will cup the other area or return it to normal. this can get expensive at $40 bucks a shot. told him about the notched transom and he said like many of you have said that,that is the real culprit. but raising the motor up a couple inches, would only make cavitation worse. besides i can't find anyone to do it,and if its going to cost me a few hundred i would want a guarantee that it would work. if i could find someone to build that center pod with a guarantee then i wouldn't have to raise the motor. test date at hammondsport,n.y. july 16th. ron

Ron, I would try moving it up temporarily first to see how it works out then work on a permanent solution. I'm sure it would work, but I would want you to be sure before anything permanent is done. We could do that at Hammondsport.

I would raise the transom up permanently for you for free, but you would have to get it here and leave it for a couple of weeks. I wouldn't worry about the center pod, plenty of cats run fine without it if the motor height is correct.

Materials would be minimal, paint or gel also, plate would cover most of the new area. If you have the paint that would help, otherwise my brother in law could mix something up.

He has this new paint system where he can mix even two part epoxy into a spray can. Pretty wild stuff...lol...

And I thought the missing prop from the other post for the reason for no more porpoising........