Antifoul in mud

[boatmike]

So this is a 33ft motorboat. It has been copper coated in the past but has been kept on a mud berth and the lower keel sections have gone black. If I was going to keep it afloat I would sand back the black and re copper coat but its going back in the mud so any new copper coat would soon go black again. And its expensive. I can of course overcoat it with a hard racing antifoul but my feeling is that no antifouling works in mud really and its only the lower keel sections that are black. The rest is green as it should be. So I am inclined to just re launch as it is rather than waste money. While the lower sections are black they were not heavily fouled when they came out and the upper sections that usually get fouled most are still green and OK.
What do others think?

 

[neil_s]

I think you're correct - no copper based A/F will work when it is dunked in the mud. I have a half tide mooring and my boat experiences the same problem - except I get barnacles on the black bit! I have been told that it's down to the sulphur content of the mud. Copper in the A/F is converted to copper sulphide which is not active.

 

[Daydream believer]

The keel on my yacht sinks in the marina silt by about 18-24 inches at some low tides on years between dredging. Like you I find that the coppercoat- Which does not work anyway- performs worse in the mud. My solution is to apply a couple of coats of erodable antifoul paint. My theory is that the mud should fall away easier when sailing rather than remain stuck hard to the keel. When the boat is lifted mid season for its jetwash ( I lay up over the winter so it goes in clean) the keel is every bit as clean - probably more so-as the coppercoat. In the past it was the worse part- before I used the antifoul paint solution.

 

[oldgit]

Having spent many years on half tide mud berths,mainly with semi displacement boats, have always found a soft anti-foul to be more than adequate.
Remarkably little growth of any sort.
Things changed dramatically when changing to a proper grown up (ie more expensive) mooring which never dries out.
Just about everything that can attach itself, has , despite a constant change in brand and type of A/F.
Seems to vary from year to year ,everything from long strands of green maiden hair , mysterious coral growths, via small/monster barnycules and sometimes interesting combinations of all of them buried in the ever constant slime.
They do seem to get on quite well.
A nice brown stain setlling on the gel coat at the water at the moment.

 

[Stemar]

I had Coppercoat on my previous boat on a mud mooring. It didn't work, so I tried various antifouls over the years, but they didn't work either, so I resigned myself to scrubbing off a couple more times during the season. Not a big deal if you can dry out cheaply, but possibly an issue if you have to be lifted.

When we got the current boat, Management wanted a different colour AF, so she got a couple of coats of eroding AF before going on to the same mooring. The barnacles love it.

 

[Kwik Decision]

Our bilge keeler lives on a semi-tidal berth on the Hamble, with the keels regularly getting dipped in the mud. Like others, I haven't found any antifouling which works on the keels, and so do a mid season scrape to remove the barnacles and worms.

 

[vyv_cox]

To be fair, Copper coat do say that their product is not suitable for drying mud berths. We had the cheapest eroding a/f on the boat we kept in a mud berth and it did reasonably well.

 

[thalassa]

So this is a 33ft motorboat. It has been copper coated in the past but has been kept on a mud berth and the lower keel sections have gone black. If I was going to keep it afloat I would sand back the black and re copper coat but its going back in the mud so any new copper coat would soon go black again. And its expensive. I can of course overcoat it with a hard racing antifoul but my feeling is that no antifouling works in mud really and its only the lower keel sections that are black. The rest is green as it should be. So I am inclined to just re launch as it is rather than waste money. While the lower sections are black they were not heavily fouled when they came out and the upper sections that usually get fouled most are still green and OK.
What do others think?

Our boat had originally been Coppercoated 'from factory'. The former owner, who kept her in the north of Holland, gave it up. Scraped it off and put a barrier layer on. And erodable antifoul. However, I keep her in a brakish mud berth, and each layer took up a coating of sand and clay. After ten years, the surface was rough and flakey. Scraped it all off (...sigh) and have redone it with new primer and hard antifoul 'suitable for mudberths': Seajet 037 coastal. At the end of the season, I do a jetwash and some rubbing with a very wet coarse 3M scouring pad, and it looks fine again.