Fouled prop

[Ken Juul]

Took Luna Loca out last night.  Trip around the harbor with a stop at the pump out.  Due to other commitments, this was only the third time away from the dock this season.  Performance since the last time out was terrible.  Took forever to get the boat moving.  Also the max rpm's I could attain was about 2200, used to easily get 2800-3000.  My guess is marine growth/barnacles have fouled the prop.  Will a wire brush clean up the prop?  Or is some sort of scraper required?  Can it be done from the surface, or is a trip under required?  are there ways than other  brushing/scraping?  Planning a 4th of July trip, need the performance back.

[Stu Jackson]

Ken & Vicki

Whew, that's a tough one.  Question:  isn't it GOOD to need to go swimming in the Chesapeake in July?  I had been led to believe that the "critters" don't come in until August.

I know I didn't enjoy untangling my prop from an errant mooring line in December 1998 in San Francisco Bay, but I guess the water temperature here is so consistent all year round (57 degrees) that December wasn't too far different than July.

A hacksaw might do it.  A chisel and a hammer would help.

Seriously though, do you have a diver check your boat's bottom regularly?  Once every three months is what we do here, and it gets us by, with our boats in the water year round, for two years before regular haulouts for bottom refinishing (and other things like standing rigging, thru hull replacements and the like).

Actually, we almost let our boats sink until we just darn near have to have them hauled, needed or not.  It also avoids the dreaded "inspection of the hull" time, so we don't have to worry about whether or not we have the blisters, because since they're below the waterline, we almost never get to see them.

Part of the issue is the non-use of the boat, it simply grows stuff when not moving.  Wish I got to use mine more often, too.

Other part is it may not be only just your prop, but the entire hull (see above).

One man's thought:  Go look yourself, get wet, and enjoy the warm water.  While you're at it, check the thru hull to the raw water cooling to make sure it's clear.  The reduction in rpm's is unusual.

Stu

[mitch brown]

Ken-

   Just had another thought. Is the engine running at a constant max. 2200 rpm?. I have in the past experienced reduced max. rpm's when I have had algae buildup in the diesel fuel tank/filters. This has happened when my boat has unfortunately sat for months without being used. As a result I have had to change the fuel filters. There seems to be enough flow through the filters to allow the engine to run at low rpm's but when you crank it up it is starved for fuel. Just another possible explanation. Good luck with your trouble shooting.

[Ken Juul]

On Sunday I plan on taking the dive.  I looked at the rudder the other night, it had a good growth starting.  The boat is scheduled for a new bottom paint later in the summer.  When in gear there is plenty of water getting thrashed around, just not much thrust.  Posts about the correct prop size indicate too much pitch will cause the engine to bog down.  I am assuming that the extra drag caused by the build up is doing the same thing.  Thanks for the fuel filter tip, I'll keep it in mind if cleaning the prop doesn't help.  I'll post my results on Monday.

[bjmansfield]

I have found nothing that will kill engine performance faster than a barnacle fouled prop and it is amazing how few it takes.  I dive my prop every 6-8 weeks. When we go out and the engine won't go above 2500 rmp, I will scrape the prop before the next time we go out.  I normally cruise at 2300 with the M35.

I have found a "painters tool", somewhat like a putty knife but a much heavier blade and ground on the end until it is relatively sharp, to be the best scraper.  You don't want a blade that flexes.  A wire brush would be useless, it takes a serious scraper to remove them from a prop.

Best advice i can give you:  wear heavy leather gloves.  Barnacles are razor sharp, the cuts hurt like hell, are pron to get infected and take forever to heal.

[Ron Hill]

Ken: If you're sure that your Racor filter/fuel  is clean, there's a better way to get the "Nasties" off your prop and shaft than to use a HARD steel scraper/putty knife on a SOFT bronze prop.
ronphylhill@erols.com

Ron, Apache #788

[Ken Juul]

Things got backed up, finally got  under the boat last Tuesday, first time back at the keyboard.  The prop was covered on both sides with barnacles/sea growth.  Tried the recommended grill scrubber, it really didn't do much to start with.  Switched to a putty knife.  They slid right off.  Did the rough work with the putty knife, then polished the blades with the grill scrubber.  What a difference. RPM's are back to normal.  Spent 4 days on the eastern shore of the Chesapeake bay over the holiday weekend.  Great trip, boat handled well.