On a semi displacement barnacle fouled hull, how much slower?

[Comodave]

The problem is that they will cause corrosion where the small steel particles get embedded. Do you really want a 4 or 5 thousand prop getting damaged due to a wire brushing?

 

[Lepke]

To repeat everyone else, if the zincs are gone you're eating the surface of the shafts and props. Eventually you'll be able to break a piece of prop blade off with your fingers. I use to do that when I surveyed poorly maintained boats. If you travel at slow speeds, put more zincs on the shaft, maybe a prop nut zinc. A yearly diver is actually cheaper than new shafts and props. Buy a dry suit and a hookah rig.
Or find a marina in fresh water.

 

[Cigatoo]

We just had our Mainship trawler hauled in CT on Long Island Sound - first season in salt water. I had zincs on the prop shafts and trim tabs as well as on the transom. The prop shaft zincs are gone, and the trim tabs are 50% or more dissolved as is the transom zinc plate. The propellers, struts and rudders have a very light coating of white pimples - presumeably corrosion. Can I use a drill with a wire brush to remove the very small white pimples? I plan to take the props off to deal with them over the winter.

Next season I'll triple the zincs. In our former marina we suspect our port neighbor had leakage - the port trim tab zinc was noticeably more dissolved than the starboard trim tab.

The bottom paint held up well and the boatyard (Crockers at New London) did an outstanding job in power washing the marine salad off the hull and gear.

Thanks,
Jim

Don’t overthink this. Your zincs are doing their job. If they are completely devolved they need to be replaced. However your prop shafts and props won’t devolve overnight. I have had zincs last multiple seasons and then only 1/2 of a season due to changes in local boats, being at a different dock, or who knows what. Make sure that you have no wires hanging in your bilge water. A very common problem that will cause your zincs to disappear quickly. Having a few ot more barnacles on the running gear at end of season is also very normal. On and Off hull cleaner (available up the street at Defender) will dissolve them. Use it on the running gear, props, shafts, and the hull to clean the slime. Chip any remaining barnacles off with a putty knife. Replace all zincs and keep an eye on them next year. A diver can do this for you or you can take a quick swim to inspect halfway through the season. If in doubt talk with someone at Crocker’s. Very knowledgeable people there. They can check the bonding or find someone who will if you feel the need to. (I would start with fresh zincs and wait another season) Everything you have described is completely normal. Welcome to crowded marinas and salt water in New England.

 

[psneeld]

Thanks Steve and BoatNut, no steel wire brush? Wouldn't the steel filaments eventually rust and dissolve? Would the hurt the bronze rudder and running gear?

Jim

I would love to see literature saying wire brushes cause or could cause damage.


I have used one for 50 years, and so has every marine business I have worked for and also the marinas I have worked/stayed in.


Maybe it's possible...but I have not seen it so I would be curious as to their harm.

 

[Cigatoo]

I would love to see literature saying wire brushes cause or could cause damage.


I have used one for 50 years, and so has every marine business I have worked for and also the marinas I have worked/stayed in.


Maybe it's possible...but I have not seen it so I would be curious as to their harm.

I have wire brushed my props for years.

 

[Cigatoo]

No wire brushes or steel wool on deck as they will make a rusty mess.

 

[rslifkin]

Instead of wire brushes, I'm a big fan of a wire cup in a drill. They don't shoot pieces out like a regular wire wheel and it makes for a very quick, easy cleanup of parts even when they're kinda weirdly shaped.

I did just order some brass ones for prop cleaning to see how well they work. If they work well, it should have less risk of any corrosion issues.

 

[psneeld]

Sure there are many variations on wire wheels....


Cleaning an 18 inch wheel is different than cleaning a 48 inch wheel in terms of how aggressive you can go.


If there was one shred of evidence to use brass over steel I would switch..just haven't seen any yet.


And a good steel wheel, brush, cup, etc...is usually a bit stiffer and quicker to clean than brass. And like any tool has to be used judiciously not to damage what you are cleaning.

 

[Group9]

I was on a 42 foot sailboat that we couldn't get to go over 3.5 knots on the way to the yard. I figured it was going to look like a reef when we pulled it out. I was shocked to see that it didn't take nearly as many barnacles as I would have imagined, to slow it down that much.

They affect the prop efficiency a lot as well.

 

[rslifkin]

I was on a 42 foot sailboat that we couldn't get to go over 3.5 knots on the way to the yard. I figured it was going to look like a reef when we pulled it out. I was shocked to see that it didn't take nearly as many barnacles as I would have imagined, to slow it down that much.

They affect the prop efficiency a lot as well.

That last bit is the key. A little bit of growth in the wrong place can have as much effect as 10 times the growth somewhere else on the boat.

 

[psneeld]

Depends...as my usual mantra.


My boat never noticed it one bit (less than 0.1 knot) difference (maybe cause I am over propped a bit... ) when my prop was 100% covered with small barnacles on my summer trip to clear water where I felt like diving on it.


40 footer with a 6.3 knot cruise speed and it had very little effect.


On other boats sure....by the end of the season...the assistance towboat I ran...had a layer of barnacles on the hull and running gear and dropped from 22 knots to 18.


But every boat can be a little different.

 

[EngNate]

There is no nice way to say this, but make a vow today to stop neglecting your boat.

Mega dittos

 

[boatpoker]

The bottom paint is some old stuff a friend gave me for free.
Yes, Hampton gets a lot of fouling.

At our marina, everyone I talk to has just painted the same paint on the running gear as the bottom.
And never have I heard doing that caused them trouble.
I just do what they did.

If you coat the metal with waterproofing, it will prevent it from corroding, if it stays dry.
I got no reason to doubt that.

Last summer we dove on the boat, the props had few barnacles, the hull a few.
But I have noticed now there are more now on the hull where I can see .

I can pop them off sitting on the swim platform pretty easy.

This boat is mostly for short day trips into the bay, like a picnic boat, not cruising.

Painting or varning stainless steel shafts is unwise. Stainless steel corrodes in the absence of oxygen and largely corrodes from the inside out. Such corrosion may appear as nothing more than a miniscule pit on the outside such as the x-ray photo of a shaft below. The broken shaft photo cleary shows minimal external visual damage whhile the inside looks like sponge toffee. Preventing H2O from contact will hasten corrosion.

Painting propellers is unwise unless you have a "real" bronze propeller which is nott too common. The vast majority of our propellers are "manganese bronze" which is actually a class of brass due to it's 35-38% zinc content. Many anti-fouling paints have metals in them and can cause dezincification due to galvanic reaction between the prop and the paint.

 

[rslifkin]

For painting props, use of an appropriate primer of adequate thickness should prevent galvanic issues.

For the shafts, that's an interesting thought. So for those of us with stainless shafts, it's better to leave them bare and allow buildup that has to be cleaned off rather than painting?

 

[boatpoker]

For painting props, use of an appropriate primer of adequate thickness should prevent galvanic issues.

For the shafts, that's an interesting thought. So for those of us with stainless shafts, it's better to leave them bare and allow buildup that has to be cleaned off rather than painting?

No primer on a prop is going to last long unless it's a dock queen.

 

[jimL]

Thanks everyone.
As stated, this is my first season in salt water and I'm learning after years in fresh water. All of your advice has been very helpful. I'm headed to the boat this weekend to try different techniques in removing the crud from the underwater gear and to bring home the propellers for the winter.

Does anyone use any anti foul paint or coatings on your underwater gear for the season - not to include the propeller shafts?

Jim

 

[fstbttms]

Does anyone use any anti foul paint or coatings on your underwater gear for the season...

Propspeed is the best performing example of a foul-release coating for underwater metals that you can buy.

Propspeed | Propeller Coating | Foul-Release, Not Anti-Foul

 

[rslifkin]

Historically my struts, rudders and trim tabs have just gotten regular bottom paint. And the props and shafts have been bare.

This year, I'm thinking of stripping all of that down to clean metal, priming it and trying out the Pettit Black Widow paint on everything except the shafts. I'm thinking it may stay smoother on those surfaces than a regular ablative, leading to better performance and fuel burn later in the paint's life.

I'm not sure if my approach will hold up as well as Propspeed, but as long as it holds up reasonably well over a season, it might be better for me. It's certainly cheaper and unlike Propspeed, it's got antifouling properties, so there should be less stuff that starts to grow and then has to be released from the slippery coating.

 

[fstbttms]

This year, I'm thinking of stripping all of that down to clean metal, priming it and trying out the Pettit Black Widow paint on everything except the shafts. I'm thinking it may stay smoother on those surfaces than a regular ablative, leading to better performance and fuel burn later in the paint's life.

I have a customer who is not happy with his Black Widow. So much so that he's having it removed from the boat.

https://youtu.be/mbrRDbcw6so

 

[rslifkin]

I have a customer who is not happy with his Black Widow. So much so that he's having it removed from the boat.

https://youtu.be/mbrRDbcw6so

Interesting. But fortunately, we don't get barnacles up here in Lake Ontario. So for the most part, as long as it keeps slime growth down, that'll be good enough. I'm also figuring that keeping running gear growth down in general is easier on a faster boat (I cruise around 17 - 18 kts), and the areas I'm planning to use this stuff are the high water flow areas anyway.

Plus, we'll be on the hard every winter anyway up here, so if I try something and it doesn't work well enough to get through a 6 - 7 month season, I can try something else for the next season.

 

[BandB]

Thanks everyone.
As stated, this is my first season in salt water and I'm learning after years in fresh water. All of your advice has been very helpful. I'm headed to the boat this weekend to try different techniques in removing the crud from the underwater gear and to bring home the propellers for the winter.

Does anyone use any anti foul paint or coatings on your underwater gear for the season - not to include the propeller shafts?

Jim

We use Propspeed on all the underwater gear.

 

[fractalphreak]

You will be buying more zincs than you ever thought possible now that you put your boat in battery soup... but:

To help make sure you're not the corrosion victim - do you have an isolation transformer or galvanic isolator? Not sure if those are as common in fresh water. In salt, if you have a nasty neighbor both zincs and then other metals can go quick; the above (for different purposes but both provide parasitic neighbor galvanic protection) can help them from going too quick...

 

[rslifkin]

When first moving to a new marina in salt water, it's not a bad idea to hang a zinc fish in the water whenever the boat is in its slip. It'll give some extra just-in-case protection to keep a neighbor from chewing up your zincs super fast and more importantly, it gives you an idea of how fast your zincs are degrading (and you'll pull it up to look every time you leave the slip, so more often than you'd dive to check).

 

[psneeld]

To me, hanging a zinc fish just shows you don't know what's going on with your boat.

Better to get a survey done or get a zinc zinc chloride cell and do it yourself.

There's no guarantee that the zinc fish will do any better than what your existing zincs are doing depending on whether there is continuity throughout your bonding system or not.

 

[rslifkin]

The fish is certainly no substitute for knowing that your own boat is good and healthy and adequately protected anode-wise. IMO, it's more useful as a "how hot is the water in this new marina" monitor, where you can stick it out as an extra that's easily monitored for degradation. Of course, as mentioned, a healthy bonding system is a prerequisite for the fish to be of any use.

If it starts to get chewed up quickly, better watch your other zincs carefully and figure out what's going on around you. If it looks basically untouched after a while, might as well stop using it.

 

[psneeld]

Or just measure what is going on and be done with it.