• If you log in, the ads disappear in the forum and gallery. If you need help logging in or getting registered, send request to: webmaster@southernairboat.com

Thanks!

Southern Airboat Gallery Archives

REMOVING A THORN FROM THE LIONS PAW
airboat submarine
Dudley Comes To The Glades
tt
1 of the many redfish we caught with grandpa yesterday
hunting
Matt,

I'm not sure about the prop...but for the bouncing try putting a wedge on your boat. it is super easy and really inexpensive compared to a trim tab.

Adam
 
:eek:ccasion5:!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
moodfood


my 2 cents my boat with dd 302 was doing good with a 72x36 stick prop then when to a 72x36 wide blade its just not the same. if i was to over i would have saved a few more bucks and got a ajustable prop.
more bang for the buck. thats if i could do it over
my boat is a dog on take off but it dont take as much to keep it there now
fuel useage is realy good dont use as much fuel now
just my 2 cents
 
I used to run a stock 350 chevy dd with truck heads and a 600 edlebrock. I ran a 72 x 30 wide blade at 3000 rpm. I tried a 72 x 38 and could only turn it around 2000 rpm. Same day 1000 rpm different. I would say that you will not have enough engine to turn the prop. If your boat is jumping then the faster you go the worse it will get. The jacks probably won't help your problem if they are under the engine. if it is bouncing you probably have a bow in the bottom of your boat. Check the engine angle with the top of the stringers level. I usually do this by putting a level on the prop hub. You want your engine to be level with the boat. I had the opposite problem with my boat (nose wanted to dig) I had a hook in the bottom of my boat. Used the jacks to push down till it started bouncing then backed them off till it was a smooth ride. If you could put the jacks in so you could pull the bottom up and pull the bow out it would help. You might need to mess with the engine angle to get rid of it. Small moves make a big difference. If you are happy with the prop you have you should get an estimate to get it rebuilt.

just my experiences and opinions.
 
I have no clue what a "jack" is in this case. A wedge is simply a few strips of fiberglass layered one on top of each other in decreasing widths that form a wedge going downward at the extreme rear of the hull. I have a 13'6 cottonmouth and used 3 strips of fiberglass and my boat quit hopping altogether. I guess you need to not have polymer for this to work though. Don't know how your setup is. It is really simple and cheap though and believe me it works!!
 
:eek:ccasion5:!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
if you do have poly on the bottom you can unbolt the back and put a shim between the poly and the hull to get the same effect. or a trim tab attached to the transom.
 
the rpm I was talking about was max rpm at wide open throttle. If you know someone who has a prop with more pitch (even shorter pitch than 38) to see what effect it will have I suggest that. A wood prop is most efficient at around 3000 rpm. With my 350 and the 72 x 30 prop I cruised about the same rpm that you do as well as now with my caddy and the 72 x 38. It is nice and it uses less gas. My opinion is that just because you can turn the prop at 3000 or what ever rpm you can, you need to save rpm to get out of trouble when needed. I had an advantage of knowing a lot of people who will let me borrow props to find the right setup. I tried a 68 x 42 stick prop (narrow), 72 x 36, and 72 x 38 on our dd olds boat and found that the best (wood) prop for our setup is the 72 x 38. It now runs the 74 inch sensenich Q blade and the 72 x 38 is on my Caddy boat. I have been switching back and forth between boats depending on what I want to do. Airboating is mostly experimentation to see what works best for what you want to do.
 
What is the max rpms your motor will turn the 72&32 prop? I get it to turn 3000, if its not turning that then get a 72&30, or something like that.. Most 350 d.d's run a 70&32, or a 72&30 wide blade prop
 
:eek:ccasion5:!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
moodfood":1uuxavll said:
I'd think bigger bites are better if there is the power to do so. That's the principle of a reduction drive, right?

matt.
Click to expand...

You said right there, Matt. That's what it all boils down to.
 
But if you put the 72&38 prop on, your motor will not put out the tourque, or power it needs to, it actually needs a blt or gear drivs to get up to 5000-6000, but for a d.d 350 i say buy a new 70&32 72&30 thats whats FAP recommends.. Call Tim Wagman at FAP and talk to him...
 
Mood: first of all it is inches of twist not degrees. you don't have enough motor for that prop. an increase of two inches in length is about the same as increase 2 inches of twist. a 350 doesn't make the same horsepower normaly as a 220 gpu does. I know there are exceptions. The best you can do is go to a wide blade that is the same length and twist that you are runnin now and that will slow your motor down some but you can stand that. I don't think you will like the bigger prop. now if it is a steal of a deal and you are gonna build a 455 or a caddy engine then get it and put it in the closet till then.
 
Moodfood,

Couple of observations from a bystander. Your hull looks to be of some age. It looks like an older Combee. You said you removed jacks that were there before. Old fiberglass airboat hulls flex. When they flex, sometimes they set up a resonance. That can cause older stringers to break loose and that is major problems. You might consider putting the jacks back in and snug them down to keep your hull stable. Hard to believe, but you can often upgrade your hull for the same money as upgrading your prop. SBC direct drives will never produce enough low rpm torque to run dry - maybe they'll hop on or off the shoreline - but, they sure ride the edges cheap. Good Luck - this is an evolving thing---airboating.
 
moodfood":f7tpy017 said:
30, 32 or 38, etc. is the size of the BITE that the prop makes in each rev.
Click to expand...

More accurately, the number of inches the prop would travel through the air in on rev if it were at perfect "stall" (no slippage)
 
i've got a 70 x 34 Air Prop for sale if you think it'd work. good condition paddle prop that i have on my 200 Lycoming. i turn it 2800 rpms.
 
You must log in or register to reply here.
Back
Top