drdmsmith
09-30-2010, 09:51 PM
I am changing props.
1600 VW (stock 40HP) with 2:1 Belt Drive
Previous prop was a 68 x 32" FL Airboat Wideblade Prop.
357
Boat was plenty fast, yet a bit slow to get on a plane.
Handled great, everything was great after you hit 10-15mph. But, if you get up on a grass or mud flat with less than say 2inches of water standing on it and stop = stuck. After you push and get it moving a little, it would get going, but I'm too old for the push part now. I want to be able to have the power to get going from a stop. I turn the big prop around 18-1900 when at a stop, just outa horsepower and that big prop really digs into the air.
I want to put less prop on it, but not a lot less. I am thinking of a ground adjustable, but am not sure I want composite. I like the character wood, so, my questions are;
If I drop back from a 68x32 Wideblade to a regular blade, will that be enough to get me the power I want from stopped?
Should I drop to 68x30 or 66x32? Wideblade? Regular?
I read about dropping an inch radius = 2-300RPM or a degree pitch=2-300RPM. So if I dropped to a 68x30 I could gain 600RPM when I'm stopped? (on the prop I guess, since I'm 2:1 that would redline my motor pretty close 4500rpm)
Furthermore:
I see ultralight props like the UltraProp and Ivo props pretty cheap, but compared to that big ole paddle, they sure do look whimpy... Can they really push like I want with that tiny blade width/thickness? My old prop was 8.5" wide with 6.5" tips= lots of area.
I only turn the prop about 1800-1900 at cruise and 2250 or so at my little motor's top end. Those puny props look they want to turn more RPM? How do they possibly make up for the lesser blade area? (remember my frame of reference is a massive wood prop almost 4" thick with nicely airfoiled blades).
Anyway, I appreciate you-all's input. You have way more experience than me, this is my only boat, and I want to try to at least make an educated guess. I get in a hurry, even when there's no reason. I want to build a new cage before I run her again, but I'm searchin' all night long for a decent priced prop I can buy right now! I need to be patient...
Ok, enough patience, back to the classifieds...
Don
1600 VW (stock 40HP) with 2:1 Belt Drive
Previous prop was a 68 x 32" FL Airboat Wideblade Prop.
357
Boat was plenty fast, yet a bit slow to get on a plane.
Handled great, everything was great after you hit 10-15mph. But, if you get up on a grass or mud flat with less than say 2inches of water standing on it and stop = stuck. After you push and get it moving a little, it would get going, but I'm too old for the push part now. I want to be able to have the power to get going from a stop. I turn the big prop around 18-1900 when at a stop, just outa horsepower and that big prop really digs into the air.
I want to put less prop on it, but not a lot less. I am thinking of a ground adjustable, but am not sure I want composite. I like the character wood, so, my questions are;
If I drop back from a 68x32 Wideblade to a regular blade, will that be enough to get me the power I want from stopped?
Should I drop to 68x30 or 66x32? Wideblade? Regular?
I read about dropping an inch radius = 2-300RPM or a degree pitch=2-300RPM. So if I dropped to a 68x30 I could gain 600RPM when I'm stopped? (on the prop I guess, since I'm 2:1 that would redline my motor pretty close 4500rpm)
Furthermore:
I see ultralight props like the UltraProp and Ivo props pretty cheap, but compared to that big ole paddle, they sure do look whimpy... Can they really push like I want with that tiny blade width/thickness? My old prop was 8.5" wide with 6.5" tips= lots of area.
I only turn the prop about 1800-1900 at cruise and 2250 or so at my little motor's top end. Those puny props look they want to turn more RPM? How do they possibly make up for the lesser blade area? (remember my frame of reference is a massive wood prop almost 4" thick with nicely airfoiled blades).
Anyway, I appreciate you-all's input. You have way more experience than me, this is my only boat, and I want to try to at least make an educated guess. I get in a hurry, even when there's no reason. I want to build a new cage before I run her again, but I'm searchin' all night long for a decent priced prop I can buy right now! I need to be patient...
Ok, enough patience, back to the classifieds...
Don