RPM & Speed effected by barnacles ?

[gtfireftr]

So I have been fighting more than one issue evidently..
Got my port motor running finally, and went out this morning. Ran fine except it wouldn't rev over 3800. Stbd revved to 4200.
So I decided to check props..... Trailered up the alpha's and I found moderate growth of barnacles on both props.
Not a great deal on the blades, but lots on the hub and bottom of the blades.
Could this cause my issue? Weather turned bad so I can't try her out.
Hopefully this will help!!!!!!

 

[tpenfield]

Could be, so remedy the barnacle situation and see what results you get. I had one season where I tried a different anti-fouling paint on the outdrive/prop that was not as effective as what I normally use. Both speed and RPM were off that year. Next year, back to the usual stuff and all was good again.

 

[gtfireftr]

Also found trim tabs covered in barnacles!!! Not sure if that makes any difference.

 

[alldodge]

Anything on the hull, drive or prop other then a smooth surface will cause issues. Trim tabs will cause issues if not fully retracted at or around WOT. Suff on the prop and drive can cause the prop cavitation. It its bad enough the engine can over rev from ventilation.

Things that make me go hum is why your not achieving rpm, I'm seeing barnacles that would cause a low pressure behind the prop and the prop would slip. Sure could use some pics

 

[gtfireftr]

No pics. Already scrapped off barnacles.
Gonna have to wait to find out if it helped.
Thanks

 

[Alumarine]

Are there barnacles on the hull by any chance?

 

[gtfireftr]

No barnacles on hull.... maybe a little scum....

 

[Bondo]

maybe a little scum....

Ayuh,.... Anything at all beyond the paint effects the performance of the hull,....

Very little sealife makes big differences,....

 

[fhhuber]

barnacles add drag. added drag means higher power needed for the same speed. so obviously they can cause a loss of rpm and boat speed.

Barnacles on the prop can unbalance the prop and that can lead to bearing and seal damage. Extreme cases can bend the shaft.

Pull the props and clean them.

Some good hints on preventing barnacles on the props
http://www.sailnet.com/forums/gear-...st-way-prevent-barnacle-growth-propeller.html

 

[gtfireftr]

I am going to try to take her out on Friday.... Hopefully this will remedy the issues.....
Thanks...

 

[tpenfield]

I used the Zinc paint on my Bravo 3 props one year . . . it kept the barnacles away, but algae grew on the props and messed things up anyway. The next year, I still used the zinc paint as a base coat and then used the outdrive Anti-fouling over the zinc. Seems to work much better.