Sanger porpoising

[Sanger76VA]

I made some radar runs in my Sanger and ran the best at 90mph but had right bad porpoising at high speed. I have listed some specs to look at. Suggestions welcome!!
1976 Sanger 19ft bubbledeck with two barrel seats
one peal, down plate only, t handle to lock plate down
460BBC rollor motor,single 850DB(Holley 4150)
dynode at 561hp
Casale 18% gears in a 10 degree box
Cav plates set at 1/8"
Props tried:
11x15 two blade stelling engine rpm 7200 mph ?? est. low 81-83
11.5x15 two blade cary engine rpm 6600 mph 87
11.1/4x16 two blade menkins engine 6200 mph 90
(This one has some cup in it, was set up for a 21' Howard daycruiser)
Transom to front plate 30"(balancer end)
Transom to vdrive plate 97"
Strut to prop 3/8"
When i ran first prop, quick set quick rpm and no noticeable porpoising
Second prop, quick set some porpoising
last prop porpoised so bad I had to push on down plate and back off throttle
I had thought about moving my engine forward another 5-6 inches
I even thought about buying a 113/8x16 made for a flat bottom
Help??
thanks Mike

[whiskey & water]

Prefect question to sumit to the v-drive section of hot boat magazine.

[Squirtin Thunder]

How are the springs to hold the plate UP !!! If the boat is set up right you should only be on the plate for a heartbeat. What I mean is you should only need the plate to help it take A Set. If you can check the prop shaft it may be moving in and out. Depending what size shaft you have you can space the prop shaft to help stop the porpucing, Move the point of thrust. Another thing is to move the engine forward 3". This always is standard in race boats. I have had to move my engine forward 9". In my old flat. Also check plate bushings, the plate should be up at least 1/4" at the trailing edge, I believe.
Good luck
Jim

[DetroitJim]

Mike, hate to say it but your boat, same as mine, will porpoise no matter what. The hull does not have any rocker in the bottom. My 75 bubble deck actually has a slight hook which is greater at the outer edges. I have run 3 different props, moved the prop back, moved it forward, moved the engine, threw more power at it, same thing. The bottom shape causes the hop regardless of power or speed. I looked at several race hulls, the bottom is distinctly convex about 3/8 inch with the highest point slightly forward of the prop. This allows the boat to rock back on its tail without suction, if it porpoises at all it is more gentle and controllable. You will no doubt hear a dozen theories but that's my 2 cents. My answer was to get a hydro.
DetroitJim
SLDBA PE486

[VD CRUISER]

Get a day cruiser. :D

[GofastRacer]

I made some radar runs in my Sanger and ran the best at 90mph but had right bad porpoising at high speed. I have listed some specs to look at. Suggestions welcome!!
1976 Sanger 19ft bubbledeck with two barrel seats
one peal, down plate only, t handle to lock plate down
460BBC rollor motor,single 850DB(Holley 4150)
dynode at 561hp
Casale 18% gears in a 10 degree box
Cav plates set at 1/8"
Props tried:
11x15 two blade stelling engine rpm 7200 mph ?? est. low 81-83
11.5x15 two blade cary engine rpm 6600 mph 87
11.1/4x16 two blade menkins engine 6200 mph 90
(This one has some cup in it, was set up for a 21' Howard daycruiser)
Transom to front plate 30"(balancer end)
Transom to vdrive plate 97"
Strut to prop 3/8"
When i ran first prop, quick set quick rpm and no noticeable porpoising
Second prop, quick set some porpoising
last prop porpoised so bad I had to push on down plate and back off throttle
I had thought about moving my engine forward another 5-6 inches
I even thought about buying a 113/8x16 made for a flat bottom
Help??
thanks Mike
Ok here we go again "When i ran first prop, quick set quick rpm and no noticeable porpoising" what's wrong with that?? I know not fast enough right!...Same ole thing, "power, gear, prop" combo. You have the combo to go 81-83 not 90. I would stick with the first prop since it worked with the combo you have and up the power and gear and leave the plates alone since it worked to begin with!..That statement you made said the boat handles so it's not the boat or the motor location that is the problem, it's the power, gear and prop combo that needs to be remedied for the speed you want to achieve!..Also the type prop makes a big difference as you noticed with the third prop, cruiser props are not for flats!...Yep it can be a nightmare sometimes but sooner or later it will fall into place!....

[JEA557]

Mike I also hate to say it but Jim is right. I have tried evrything to keep my uncles 74 Sanger bubble deck in the water and it just wants to launch when I get out of the plate. The bubble deck hulls were not designed to be a race boat. They were designed to be more of a ski boat. If your able to take a set, get out of the plate and getting 90 mph out of it thats a good thing. Ive been told the Sangers they raced in the 70's were not bubble decks. Runner bottoms are the way to go. Best of luck Jeff...

[Sangerboy]

Mike, it is possible to make it work, but it can take a lot of time and money. I have a 1975 bubbledeck runner bottom (18' 3" circle runner) that I bought 10 or 11 years ago. It had a terrible hop that was not even controllable with full downplate. Being inexperienced about what makes these boats handle I spent years experimenting with different engine positions, rudder depths, and prop positions. Many times I was going the wrong direction but not realizing it. ( it also didn't help that I kept adding more power to it) In the end, I had the bottom straightened, moved the v-drive forward ( along with a new strut with a shallower angle) and moved the prop back substantially. These changes finally got the boat to set with the plates neutral. The biggest difference was the prop position. It is now probably 6-8" further back than it was when I bought the boat. I was way ahead of the game when I bought the 1989 Canyon with the bottom done by Wayne Mettler. It sets quick and easy and handles the power much better. The Sanger requires much more care to drive at speed. Greg

[LeE ss13]

The biggest difference was the prop position. It is now probably 6-8" further back than it was when I bought the boat.
BINGO !!!!!

[Squirtin Thunder]

LeE ss13,
That is a great pic !!!! I have only seen a handfull of good running K-Boats that like to run that lose. But it makes for great pics !!!!
Jim

[superdave013]

LeE ss13,
That is a great pic !!!! I have only seen a handfull of good running K-Boats that like to run that lose. But it makes for great pics !!!!
Jim
p.s. that's not a K boat

[Squirtin Thunder]

Dave,
It is a Super Stock correct ???? Then it should be a K-Boat !!!! Unless it was specially built as a Super Stock, which is comon for those guys that run circles around the rest.
Jim
BTW - It is still sweet even if I am wrong !!!!

[LeE ss13]

p.s. that's not a K boat
Acutally it was. K94 ELDORADO driven and owned by the late Leo Bonner. Jerry even has an old video of in at Long Beach in the day. It does rough water very well. The avatar came from a Tom Timm photo of me at the April '03 Parker Race.
http://www.***boat.com/image_center/data/516/308ssra_parker0002.jpg

[JEA557]

Now thats riding the tail...

[DaveA]

Prefect question to sumit to the v-drive section of hot boat magazine.
***boat has a magazine??
:D :D :D

[Squirtin Thunder]

Yes Dave Wallmart has it !!!
They only get three or four a month so you have to be quick.
Do you use the airport by Stumpy Creak?????
Jim

[bigkatboat]

PROP! Prop diameter, placement (front to rear), rake, blade surface area, are some of the most important factors in your problem. You did not say what kind of 'porpoising' you have. Is it just the nose, or the whole boat, or the whole boat and the tail lands last??????? I think the Sangers with the curved down tail chines are called "gull wings". You can get the handling problem corrected, but we need more info.

[058]

Smaller the diameter prop = less porposing....go with the smaller prop, lower gear or make more power. Lack of engine power is not carrying the bow.

[Sanger76VA]

Thanks for all the help, I found the problem. The locking collar on the cav rod slipped, which left me with no spring pressure. I reset and boat handles nice now. I ran today and was very pleased. I also rasied the plates to 1/4 to let the hull air out more. :)