bottom paint on centerboard?

[sidewinder585]

I recently purchased a C&C corvette 31' sailboat. she has a cast iron centerboard which when it is in the up position is still completely submerged. I will be keeping her at a dock on lake Erie and was wondering if i need to coat the centerboard? I know that if I use a copper based antifouling paint that I will have to completely cover the cast iron to prevent galvanic corrosion. that being said, the board does not look like it has ever been painted. how much maring growth will accumulate on a raw cast iron board over a period of 6-8 months? will it prevent the board from sliding up into or down out of its case? thanks in advance for the replys. -John

[TQA]

Originally Posted by sidewinder585

I recently purchased a C&C corvette 31' sailboat. she has a cast iron centerboard which when it is in the up position is still completely submerged. I will be keeping her at a dock on lake Erie and was wondering if i need to coat the centerboard? I know that if I use a copper based antifouling paint that I will have to completely cover the cast iron to prevent galvanic corrosion. that being said, the board does not look like it has ever been painted. how much maring growth will accumulate on a raw cast iron board over a period of 6-8 months? will it prevent the board from sliding up into or down out of its case? thanks in advance for the replys. -John

I do not know how bad the fouling is in Lake Etrie but I have a centreboard boat and antifoul the board. Mine is not cast iron so gets stuck quite quickly. No antifouling and after a month in a high fouling area and it will not drop. I have to get out on a bouncy day to get it down.

[fallard]

The best approach is to sandblast--literally, with sand, not walnut shells--the cast iron centerboard and then immediately coat it with a 2-part epoxy, like Interlux 2000. Thickness matters, but about 3 coats with a solvent-proof roller ought to be the minimum. You could then apply an antifouling paint.

I had a steel centerboard and the only way to keep it from rusting was to get down to bare metal and apply a barrier coat. The only way to get down into the pitted areas is with sandblasting. If you do it right, the epoxy will effectively isolate the iron from the water and the paint.

[WanderingStar]

I believe the lakes have less fouling. Here on LI I have seen a centerboard frozen in place by barnacles. The advice above is good. Use a good primer or barrier then antifoul.

[P35juniper]

do they have zebra mussels there? if so I'd do something for antifouling, the slime shouldn't be much of a problem but any hard critters will be.

[bobperry]

I also have an iron keel and I think Fallard is spot on but you will need anti fouling paint.

I took my keel down to bare metal. Well to be honest my wife did it. The yard taped he up into a jump suit, tented the keel and sent her in with a grinder sure that she would be out in 5 minutes. Four hours later my wife emerged with a totally ground keel. The earned the respect of the yard guys.

I know her. There was a never a doubt in my mind that she could do it. Actually I didn't know she was doing it until it was done.

[Faster]

Originally Posted by bobperry

......I took my keel down to bare metal. Well to be honest my wife did it. .......

Wow... now that's good crew!

[grainedetoile]

On aluminium centerboarders, here on the other side of the earth (australasia) i will suggest the sandblasting, phosphoric acid cleaning, Altex primer #1, altex primer #3, and the antifouling coating. Is this strategy transferable to iron centerbords, that's the good question.

However on my 42 ft centerboarder (2 centerboards), this is not the place where the fouling grows fast. Probably it's too dark for them?

[sailingfool]

Ditto on stripping the board. I have striped steel keels with a grinder, a wire brush wheel was my preferred tool. Use whatever and get the metal to bright white and immediately cover. I prefer straight West epoxy, 4-5 coats as it is harder than Interprotect. Then bottom paint.

[FlyNavy]

I don't think that Zebra Mussels would present as much of a problem as barnacles. Mussels and Barnacles are filter feeders and are thickest where there is a constant flow of nutrients. The Great Lakes don't have tidal flows to constantly wash in new food sources, Zebra mussels congregate most densely on municipal water intakes where there is an artificial nutrient flow.
If you've had a lot of muscles on your hull then I would be concerned but otherwise I'm with the clean and seal followed by a barrier coat folks.