I know that any fouling on the blade surfaces cause the prop inefficiency to increase, but here is a little something that blew my mind.
I use a 10 inch diameter 3-blade motorized fan on my desk at work when I need some cooling. I had noticed that the fan was making more noise and pushing less and less air over time. I thought that maybe it was due to dirt on the blades, but there never seemed to be enough for concern.
Finally, I took the cage off and thoroughly cleaned what little gunk there was. After assembly, the fan is now much quieter AND moves several times the amount of air!
The lesson here is that it takes a lot less fouling than you think to make a HUGE difference. I must assume that boat propellers behave similarly, and I will be diving again this weekend.
Duane Ising - Past Commodore (2011-2012)
s/v Diva Di
1999 Catalina 36 Hull #1777
Std rig; wing keel, M35B, Delta (45#)
Punta Gorda, FL
http://www.sailblogs.com/member/diva-di/
I agree, a few years ago I had a small barnacle that grew on to the hub of he propellor. It cut my boat speed in half just a small barnacle.
Paul
Proud Mary
#2074
Portsmouth RI
I am curious if any of you that are in salt water have sprayed your prop with a zinc coating? I was reading on some other blogs that it was a good way for anti fouling.
Randy
Randy Sherwood
Mutualfun 1990 # 1057
T/R W/K M35a
Home. Charlotte, Mi.
Boat. St Augustine,Fl.
Randy,
We have touched on this subject in another post, I do not recall if there was any feedback there. I had mentioned that Latitude 38 had done some testing on the bottom of there dingy years ago and found Desitin Ointment that is used to prevent diaper rash and contains zinz was as effective as many bottom paints. I would expect you would call it an ablative coating and due to its consistancy/high ablation, I am not sure how long it would stay on a prop before needing a new coat.
As for prop efficiancy, yes fouling drasticly reduces efficiancy. On other airfoils as in aircraft wings, studies have been done related to icing and on some airfoils and they found the equivilent of five grains of salt per square inch on a leading edge of a wing was enough to disrupt laminar flow enough to prevent the wing from flying.
In addition to the prop inefficiancy schmutz on you bottom greatly increases drag, keeping our vessels in a condition of maximum efficiancy
requires a lot of work. As I age speed is becoming less and less of a concern for me, as I realize it just reduces my time on the water.
Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas
The absolute best thing you can put on your prop is called Prop Speed, two part system consisting of primer and top coat-nothing sticks to Prop Speed-nothing
Carl Wehe
1985 C36TM #443
Hillsboro Inlet,FL
How much would it take to coat a frying pan.
Cepheus dream
C36 MK I # 825
MK I Tech Editor No Mas
About 300 dollars worth
Carl Wehe
1985 C36TM #443
Hillsboro Inlet,FL
I've had good success with the Pettit Zinc coat spray on my 30 and 36 as long as the engine was used regularly. When the C30 was left sitting awaiting a new owner, there was a buildup of scum, grass and barnacles successfully attaching themselves.
John I--
s/v Pooka
#1339
John & Kathy Impagliazzo
s/v Pooka
Jamestown, RI
1994 C36 TR #1339, M35AC