Propellor Fouling

[Ken Juul]

I have a terrible problem with barnacles and other marine growth on the prop.  Boat is moored in a creek off the Cheaspeake, so the water is brackish.  I scrapped the prop just before labor day weekend, used it the long weekend, then it was at the dock 6 weeks.  I pulled out last friday and had no thrust.  Quickly tied off to the end of the dock.  Upon inspection the propellor was fully coated on both sides with a 1/4-1/2" layer of growth.  Others in the marina don't seem to have the growth problem I do, they may go 2-3 months with out using the boat, pull away from the dock with no apparent problem.  I do live aboard at least 4 nights a week, but am careful not to put too many food stuffs down the drain.  Plugged in constantly to shore power, have a galvanic isolator and the zincs last about a year, which I hear is about average.  Any thoughts?

[Tom P, IMPULSE #233, '86]

Ken & Vicki,

Welcome to the Ches Bay; I've had boats on the bay for over 10 years and prop growth has always been an issue...Maybe the growth here is not as bad as some places, but bad enough to foul a bare, clean prop in a matter of weeks...

Some may tell you there are "fixes" to this problem, but after personally witnessing some of the results, I'm convinced most are wives-tails or short term solutions at best...

Some of these "solutions" include applying grease, baby oil, diaper rash cream, etc to the prop---just how long do you think this stuff is going to stay on the prop given the major friction as it churns through the water---so I guess they recommend putting it on everytime you return from sailing????

Others include Copper plating or zinc plating the prop; costs approx $50 to $150...A few friends did the copper plate thing several years ago...I closely monitored their props all summer and found the plating worked okay for the first 8 to 10 weeks before the barnacles started...And once they started, they quickly took over...I don't have any experience with the Zinc plating...

Here's what I found works the best...
With boat hauled, thoroughly clean prop/shaft.
Apply "Underwater Metal Prep System" by Petit (around $35/box, enough for 4 to 5 boats or 4 to 5 haulouts)--this stuff etches the metal and has a 2 part primer...
Next I apply the same bottom paint as used on the boat (an Ablative)...

Once the shaft and Prop has bottom paint applied, it should keep your shaft/prop clean for about 3  months before it starts slowly chipping off the prop (shaft will generally be fine all season)...

I think it's very important to use the Petit Metal Prep System first because it gives the paint something to stick to...My experience has been bottom paint will not stick to the bare metal---will chip off very, very quickly...

I perform the above steps at haulout and once in the water, scrub the bottom (and check the prop & zincs) every 4 to 6 weeks; more often if I'm racing...

Even if you don't race, I'd highly recommend having the bottom cleaned every 6 weeks...You'd be amazed at how much speed and maneuverability is lost from just a little slim/growth on the bottom---and you have learned what it does to a prop!!!

You should be able to find a diver that will do it for around $1.50/linear foot...I invested in a wetsuit, mask, and a "super Snorkel" breathing rig and do it myself...

I find it impossible to believe your dock-mates don't do anything after letting their boat sit for any length of time (months)---they must have a diver on the payroll, or not had the boat in the water very long...I guess they could have a bigger prop than you, which could maybe take more growth to foul than a smaller prop (3 blade vs 2 blade)...I think the most believable explanation is they don't use their boat enough to realize how bad their prop/bottom is hurting them...

Anyway, have the boat bottom cleaned every 6 weeks or so and that will solve all your problems---cleans the hull, cleans the prop, and replace zincs if necessary...

Hope this helps,
Tom

[Alohman]

We keep our boat on West River off the Chesapeake.  Bottom growth, barnicles, slime etc have a significant impact on the performance of our small 21hp Universal.  We find that we MUST clean every 4 weeks or lose between .5 to 1 knot of speed.  We invested in a wet suit and diving gear (we scuba so this is not just a luxury for the boat).  The difference in performance is very noticable.  Recommend bottom cleaning no less than every 4 - 6 weeks.

[Ken Juul]

fouling on the hull does not seem to be a problem.  Painted with Petit ACP50, slime/growth falls off with boat movement.  While under cleaning the prop I do a swipe test on the rudder and hull, one rub and down to clean paint.  The prop and the shaft are the only thing does not self clean, they were painted also.  But I didn't expect the ablative to last long due to the shaft rotation.  Would a hard paint work better on the prop shaft?

[Roc]

At the Annapolis show this year, at a booth I saw this stuff called 'Prop Goop'.  Anyone heard of this??  It's a kind of ointment that supposedly does not fling off.

Roc-